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Raxar

Last reviewed on RxList: 12/8/2004
Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

Drug Description

DESCRIPTION

RAXAR Tablets contain grepafloxacin hydrochloride RAXAR (grepafloxacin) is a broad-spectrum fluoroquinolone antimicrobial agent for oral administration.

The chemical name for grepafloxacin is (±)-1-cyclopropyl-6-fluoro-1,4-dihydro-5-methyl- 7-(3-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid monohydrochloride sesquihydrate. Its molecular formula is C19H22FN3O3HCl 3/2 H2O and it has a molecular weight of 422.88. It is soluble in water and very slightly soluble in ethanol.

RAXAR (grepafloxacin) Tablets are white to pale yellow, film-coated, biconvex, bevel-edged tablets containing either 200 mg, 400 mg, or 600 mg of grepafloxacin base, formulated as a hydrochloride salt. Each tablet contains the following inactive ingredients: low substituted hydroxypropyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose 2910, magnesium stearate, microcrystalline cellulose, talc, and titanium dioxide.

Indications & Dosage

INDICATIONS

RAXAR (grepafloxacin) Tablets are indicated for treatment of adults with mild to moderate infections caused by susceptible strains of the designated microorganisms in the infections listed below:

Acute Bacterial Exacerbations of Chronic Bronchitis caused by Haemophilus influenzae, Streptococcus pneumoniae, or Moraxella catarrhalis (see CLINICAL PHARMACOLOGY: CLINICAL STUDIES subsection).

Community-acquired Pneumonia caused by Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, or Mycoplasma pneumoniae (see CLINICAL PHARMACOLOGY: CLINICAL STUDIES subsection).

Uncomplicated Gonorrhea urethral in males and endocervical and rectal in females caused by Neisseria gonorrhoeae (see WARNINGS ).

Nongonococcal Urethritis and Cervicitis caused by Chlamydia trachomatis (see WARNINGS ).

Appropriate culture and susceptibility testing should be performed to determine susceptibility of the causative microorganism(s) to grepafloxacin. Therapy may be started while awaiting the results of this testing. Antimicrobial therapy should be appropriately adjusted according to the results of such testing.

DOSAGE AND ADMINISTRATION

RAXAR (grepafloxacin) Tablets may be taken with or without meals. Sucralfate; antacids containing magnesium, calcium, or aluminum; multivitamins containing iron or zinc; or VIDEX (didanosine) chewable/buffered tablets or the pediatric powder for oral solution should not be taken within 4 hours before or 4 hours after taking grepafloxacin. The usual dose for RAXAR (grepafloxacin) is 400 mg or 600 mg orally every 24 hours as described in Table 5.

Table 5
Recommended Daily Dosages

Infection*
Dose
Frequency
Duration (days)
Acute bacterial exacerbations of chronic bronchitis
400 or 600 mg
once daily
10
Community-acquired pneumonia
600 mg
once daily
10
Nongonococcal urethritis or cervicitis
400 mg
once daily
7
Uncomplicated gonorrhea
400 mg
single dose
1
 

As with other broad-spectrum antimicrobial agents prolonged use of grepafloxacin may result in overgrowth of nonsusceptible organisms. Repeated evaluation of the patient's condition and microbial susceptibility testing is essential. If superinfection occurs during therapy, appropriate measures should be taken.

Patients with Renal Failure

Dosage adjustment is not required in patients with impaired renal function.

Patients with Hepatic Disease

Metabolism and excretion of grepafloxacin are reduced in patients with hepatic failure. RAXAR (grepafloxacin) Tablets are contraindicated in patients with hepatic failure (see CLINICAL PHARMACOLOGY).

HOW SUPPLIED

Raxar (grepafloxacin) was removed from the US market in 1999 and is, therefore, not available. Information below for reference only

RAXAR Tablets 200 mg (grepafloxacin hydrochloride tablets) are supplied as white to pale yellow, film-coated round, biconvex, bevel-edged tablets containing 200 mg grepafloxacin base. The tablets are imprinted with "GX CK3" on one side and no printing on the other side.

    60 Tablets Bottle NDC 0173-0566-03
    Unit Dose Pack of 60 NDC 0173-0566-00

RAXAR Tablets 400 mg (grepafloxacin hydrochloride tablets) are supplied as white to pale yellow, film-coated, oval, biconvex, bevel-edged tablets containing 400 mg grepafloxacin base. The tablets are imprinted with "GX CK5" on one side and no printing on the other side.

    Unit Dose Pack of 10 (Rax Pack 400) NDC 0173-0657-03

RAXAR Tablets 600 mg (grepafloxacin hydrochloride tablets) are supplied as white to pale yellow, film-coated, oval, biconvex, bevel-edged tablets containing 600 mg grepafloxacin base. The tablets are imprinted with "GX CK7" on one side and no printing on the other side.

    Unit Dose Pack of 10 (Rax Pack 600) NDC 0173-0658-03.

Store at controlled room temperature of 25° C (77° F) (see United States Pharmacopoeia.) Replace cap securely after each opening.

REFERENCES

  1. National Committee for Clinical Laboratory Standards. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically - Fourth Edition. Approved Standard NCCLS Document M7-A4, Volume 17, No. 2, NCCLS, Wayne, PA, January, 1997.
  2. National Committee for Clinical Laboratory Standards. Performance Standards for Antimicrobial Disk Susceptibility Tests - Sixth Edition. Approved Standard NCtaCLS Document M2-A6, Volume 17, No.1, NCCLS, Wayne, PA, January, 1997.
Side Effects & Drug Interactions

SIDE EFFECTS

Adverse reactions were assessed in clinical trials involving approximately 2500 patients receiving single-dose or multiple-dose regimens of grepafloxacin.

Multiple dose Regimens

Most of the adverse reactions reported in clinical trials were transient in nature, mild to moderate in severity, and required no treatment. Twenty of 1069 patients (1.9%) receiving grepafloxacin 400 mg daily and 50 of 925 patients (5.4%) receiving grepafloxacin 600 mg daily discontinued RAXAR (grepafloxacin) Tablets due to an adverse reaction thought by the investigator to be drug-related.

Table 3 lists adverse events that occurred with frequencies of 1% or greater. These events were thought by the investigators to be drug-related in patients treated with grepafloxacin in multiple dose clinical trials.

Table 3
Drug-related Adverse Reactions in Grepafloxacin Treated Patients on Multiple dose Dosing Regimens in Clinical Trials

Adverse Reaction
400 mg daily (n=1069)
600 mg daily (n=925)
Nausea
11.1 %
15.8 %
Taste perversion
9.0 %
17.8 %
Headache
4.6 %
4.9 %
Dizziness
4.3 %
5.4 %
Diarrhea
3.5 %
4.2 %
Vaginitis
3.3 %
1.4 %
Abdominal pain
2.2 %
2.1 %
Vomiting
1.7 %
5.7 %
Pruritus
1.6 %
1.2 %
Dyspepsia
1.5 %
3.1 %
Leukorrhea
1.4 %
0.0 %
Asthenia
1.4 %
2.3 %
Infection
1.3 %
0.4 %
Insomnia
1.3 %
2.1 %
Rash
1.1 %
1.9 %
Anorexia
0.8 %
1.8 %
Somnolence
1.0 %
1.5 %
Dry mouth
0.8 %
1.1 %
Photosensitivity reaction
0.7 %
1.8 %
Constipation
0.7 %
2.2 %
Pain
0.6 %
1.0 %
Nervousness
0.6 %
1.7 %

Additional drug-related events, occurring in multiple-dose clinical trials at a rate of less than 1% were:

Body as a Whole: Back pain, body odor, chest pain, chills, facial edema, fever, malaise, neck rigidity, pelvic pain.

Cardiovascular System: Arrhythmia, hypotension, palpitations, peripheral vascular disorder, postural hypotension, syncope, tachycardia, vasodilatation.

Digestive System: Abnormal liver function tests, abnormal stools, cheilitis, dysphagia, eructation, flatulence, gastritis, gastrointestinal disorder, gingivitis, glossitis, increased appetite, melena, mouth ulceration, oral moniliasis, rectal disorder, rectal hemorrhage, stomatitis, tenesmus, thirst, tongue discoloration, tongue disorder, tongue edema.

Hemic and Lymphatic System: Anemia, eosinophilia, hypochromic, anemia, leukocytosis, leukopenia, lymphadenopathy, lymphocytosis, lymphoma like reaction, prothrombin decreased, prothrombin increased, reticuloendothelial hyperplasia, thrombocytopenia, thromboplastin increased.

Metabolic and Nutritional System: Dehydration, edema, electrolyte abnormality, gout, hyperglycemia, hyperlipidemia, hypernatremia, hyperuricemia, increased alkaline phosphatase, increased BUN, increased creatinine, increased gamma glutamyl transpeptidase, increased SGOT, increased SGPT, peripheral edema, weight loss.

Musculoskeletal System: Arthralgia, myalgia.

Nervous System: Abnormal dreams, abnormal gait, agitation, anxiety, confusion, depression, emotional lability, hallucinations, hyperkinesia, hypesthesia, hypokinesia, paresthesia, speech disorder, stupor, thinking abnormal, tremor, vertigo.

Respiratory System: Asthma, atelectasis, bronchitis, dyspnea, epistaxis, hemoptysis, increased cough, laryngismus, pharyngitis, pleural effusion, rhinitis, sputum increased.

Skin and Appendages: Acne, alopecia, dry skin, epidermal necrolysis, exfoliative dermatitis, fungal dermatitis, herpes simplex, maculopapular rash, skin disorder, sweating, urticaria, vesiculobullous rash.

Special Senses: Amblyopia, conjunctivitis, deafness, dry eyes, ear disorder, eye pain, lacrimation disorder, parosmia, photophobia, taste loss, tinnitus.

Urogenital System: Albuminuria, balanitis, dysuria, hematuria, impotence, polyuria, urethral pain, uricaciduria, urinary frequency, urinary tract disorder, urination impaired, urine abnormality, vulvovaginal disorder.

Single dose Regimens

In clinical trials, patients were treated for uncomplicated gonorrhea using a single dose of RAXAR (grepafloxacin) 400 mg. There were no deaths or permanent disabilities in these studies.

Table 4 lists the adverse events which occurred with frequencies of 1% or greater. These events were thought by the investigators to be drug related in patients treated with RAXAR (grepafloxacin) Tablets in single-dose clinical trials.

Table 4
Drug-related Adverse Reactions in Grepafloxacin Treated Patients on a Single dose Dosing Regimen in Clinical Trials

Adverse Reaction
400 mg daily (n=487)
Vaginitis
5.0%
Nausea
3.3%
Dizziness
2.1%
Vomiting
2.1%
Headache
1.8%
Leukorrhea
1.2%
Abdominal pain
1.2%
Diarrhea
1.2%
Pruritus
1.2%
Taste perversion
1.2%

Additional drug-related events occurring in single dose clinical trials at a rate of less than 1 were:

    Body as a Whole: Asthenia, chest pain, chills, flu-like syndrome, infection, malaise.
    Cardiovascular System: Syncope, vasodilatation.
    Digestive System: Anorexia, constipation, increased appetite, tenesmus.
    Hemic and Lymphatic System: Lymphadenopathy.
    Nervous System: Hyperkinesia, insomnia, nervousness, somnolence.
    Respiratory System: Rhinitis.
    Skin and Appendages: Acne, rash, sweating.
    Urogenital System: Balanitis.

Observed During Clinical Practice

In addition to adverse reactions reported from clinical trials the following events have been identified during post-approval use of grepafloxacin formulations. Because they are reported voluntarily from a population of unknown size estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to grepafloxacin.

    Eye: Disturbances in vision.
    Non Site specific: Allergic reactions, including anaphylactoid reaction/anaphylactic shock, angioedema, laryngeal edema.

DRUG INTERACTIONS

Antacids, Sucralfate, Metal Cations, Multivitamins

Quinolones form chelates with alkaline earth and transition metal cations. Administration of quinolones with antacids containing aluminum, magnesium, or calcium, with sucralfate, with metal cations such as iron, or with multivitamins containing iron or zinc, or with formulations containing divalent and trivalent cations such as VIDEX (didanosine) chewable/buffered tablets or the pediatric powder for oral solution, may substantially interfere with the absorption of quinolones, resulting in systemic concentrations considerably lower than desired. These agents should not be taken within 4 hours before or 4 hours after grepafloxacin administration.

Caffeine Theobromine

Grepafloxacin, like other quinolones, may inhibit the metabolism of caffeine and theobromine. These stimulants are commonly found in coffee and tea, respectively. In some patients, this may lead to reduced clearance, prolongation of plasma half-life, and enhanced effects of caffeine and theobromine.

Theophylline

Grepafloxacin is a competitive inhibitor of the metabolism of theophylline. Serum theophylline concentrations increase when grepafloxacin is initiated in a patient maintained on theophylline. When initiating a multi-day course of grepafloxacin in a patient maintained on theophylline, the theophylline maintenance dose should be halved for the period of concurrent use of grepafloxacin and monitoring of serum theophylline concentrations should be initiated as a guide to further dosage adjustments.

Warfarin

In subjects receiving warfarin, no significant change in clotting time was observed when grepafloxacin was coadministered. However, because some quinolones have been reported to enhance the effects of warfarin or its derivatives, prothrombin time or other suitable anticoagulation test should be monitored closely if a quinolone antimicrobial is administered with warfarin or its derivatives.

Drugs Metabolized by Cytochrome P450 Enzymes

The drug interaction study evaluating the effect of grepafloxacin on theophylline indicates that grepafloxacin inhibits theophylline metabolism, which is mediated by CYP1A2. While no clinical studies have been conducted to evaluate the effect of grepafloxacin on the metabolism of C.P.A. substrates, in vitro data suggest similar effects of grepafloxacin in CYP3A4 mediated metabolism and theophylline metabolism. In addition, other quinolones have been reported to decrease the CYP3A4-mediated metabolism of cyclosporine. Other drugs metabolized by C.P.A. include terfenadine, astemizole, cisapride, midazolam, and triazolam. The clinical relevance of the potential effect of grepafloxacin on the metabolism of C.P.A. substrates is not known. Patients receiving concurrent administration of substrates of C.P.A. were not excluded from clinical trials of grepafloxacin.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

The concomitant administration of a nonsteroidal anti inflammatory drug with a quinolone may increase the risks of CNS stimulation and convulsions (see WARNINGS ).

Antidiabetic Agents

Disturbances of blood glucose, including hyperglycemia and hypoglycemia, have been reported in patients treated concomitantly with quinolones and an antidiabetic agent. Therefore, careful monitoring of blood glucose is recommended when these agents are coadministered.

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Warnings & Precautions

WARNINGS

THE SAFETY AND EFFICACY OF GREPAFLOXACIN IN CHILDREN, ADOLESCENTS (LESS T.A. 18 YEARS OF AGE), PREGNANT WOMEN, AND LACTATING WOMEN HAVE NOT BEEN ESTABLISHED (SEE

PRECAUTIONS

- PEDIATRIC USE, PREGNANCY, AND NURSING MOTHERS SUBSECTIONS). Histopathological examination of the weight bearing joints of juvenile dogs revealed permanent lesions of the cartilage. Related quinolone-class drugs also produce erosions of cartilage of weight-bearing joints and other signs of arthropathy in immature animals of various species (see CLINICAL PHARMACOLOGY: ANIMAL PHARMACOLOGY subsection).

Convulsions, increased intracranial pressure, and toxic psychosis have been reported in patients receiving quinolones. Quinolones may also cause central nervous system stimulation which may lead to tremors, restlessness, lightheadedness, confusion, or hallucinations. If these reactions occur in patients receiving grepafloxacin, the drug should be discontinued and appropriate treatment measures instituted. As with other quinolones, RAXAR (grepafloxacin) should be used with caution in patients with known or suspected CNS disorders such as severe cerebral arteriosclerosis, epilepsy, and other factors that predispose to seizures (see ADVERSE REACTIONS).

In healthy male and female volunteers who received RAXAR (grepafloxacin) , prolongation of the QTc interval was observed Because of a potential risk of cardiac arrhythmias including torsade de pointes, patients receiving RAXAR (grepafloxacin) should avoid concomitant treatment with medications known to prolong the QTc interval, e.g., class I antiarrhythmic agents (e.g., quinidine, procainamide), class III antiarrhythmic agents (e.g., amiodarone, sotalol), and bepridil, as well as erythromycin, terfenadine, astemizole, cisapride, pentamidine, tricyclic antidepressants, and some antipsychotics, including phenothiazines, when appropriate cardiac monitoring cannot be assured, e.g., during outpatient therapy (see CONTRAINDICATIONS). RAXAR (grepafloxacin) is not recommended for use in patients with ongoing pro-arrhythmic conditions, (e.g., hypokalemia, significant bradycardia, congestive heart failure, myocardial ischemia, and atrial fibrillation).

Serious and occasionally fatal hypersensitivity (anaphylactoid or anaphylactic) reactions have been reported in patients receiving therapy with quinolones, often following the first dose. Some reactions have been accompanied by cardiovascular collapse, hypotension, shock, seizure, loss of consciousness, tingling, angioedema, (including tongue, laryngeal, throat, or facial edema/swelling, etc.), airway obstruction (including bronchospasm, shortness of breath, and acute respiratory distress), dyspnea, urticaria/hives, itching, and other serious skin reactions. Only a few of these patients had a history of prior hypersensitivity reactions. Allergic reactions of varying severity, including anaphylactic shock and anaphylactoid reactions, have occurred in patients receiving grepafloxacin. Grepafloxacin should be discontinued if an allergic reaction or any other sign of hypersensitivity appears. Serious acute hypersensitivity reactions require immediate treatment.

Serious and sometimes fatal events of uncertain etiology have been reported in patients receiving therapy with quinolones. Serious events are extremely rare and generally occur following administration of multiple doses. Clinical manifestations of serious adverse events may include one or more of the following: fever, rash, or severe dermatologic reactions (e.g., toxic epidermal necrolysis, Stevens-Johnson syndrome, etc.); vasculitis, arthralgia, myalgia, serum sickness; allergic pneumonitis; interstitial nephritis, acute renal insufficiency/failure; hepatitis, jaundice, acute hepatic necrosis/failure; tendon pain, inflammation, or rupture; anemia (including hemolytic and aplastic anemia) thrombocytopenia, including thrombotic thrombocytopenic purpura, leukopenia, agranulocytosis, pancytopenia, and/or other hematologic abnormalities. Grepafloxacin should be discontinued immediately at the first appearance of any such reaction and appropriate intervention should be instituted (see PATIENT INFORMATION and ADVERSE REACTIONS).

The efficacy of grepafloxacin for treatment of syphilis is not known. Antimicrobial agents used in high doses for short periods of time to treat gonorrhea may mask or delay the symptoms of incubating syphilis. All patients with gonorrhea should have a serologic test for syphilis at the time of diagnosis. Patients treated with grepafloxacin should have a follow-up serologic test for syphilis 3 months after treatment for gonorrhea.

Pseudomembranous colitis has been reported with nearly all antibacterial agents, including quinolones, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents.

Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. Studies indicate that a toxin produced by Clostridium difficile is one primary cause of "antibiotic-associated colitis". After the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated.

Achilles and other tendon ruptures that required surgical repair or resulted in prolonged disability have been reported in patients receiving quinolone antibiotics. Grepafloxacin should be discontinued if the patient experiences pain inflammation or rupture of a tendon (see PATIENT INFORMATION ).

PRECAUTIONS

General

Phototoxicity reactions have been observed in patients who were exposed to direct sunlight or tanning booths while receiving some quinolones including grepafloxacin. Excessive sunlight should be avoided. Therapy should be discontinued if phototoxicity occurs.

Information for Patients

Patients should be advised:

  • that grepafloxacin may be taken with or without meals.
  • that grepafloxacin increases the effects of theophylline, and to advise their physician immediately if they are taking theophylline.
  • that multivitamins (containing iron or zinc), antacids (containing magnesium, calcium, or aluminum), sucralfate, or VIDEX (didanosine) chewable/buffered tablets or the pediatric powder for oral solution should not be taken within 4 hours before or 4 hours after taking grepafloxacin (see DRUG INTERACTIONS).
  • that grepafloxacin may increase the effects of other drugs metabolized by the liver, and to advise their physician of any of the drugs they are taking.
  • to drink fluids liberally.
  • that grepafloxacin may increase the effects of caffeine.
  • that grepafloxacin may be associated with hypersensitivity reactions, even following a single dose, and to discontinue the drug at the first sign of skin rash, hives, or other skin reactions, a rapid heartbeat, difficulty in swallowing or breathing, or any other symptom of an allergic reaction (see

    WARNINGS

    ).
  • that grepafloxacin may cause dizziness and lightheadedness; therefore, patients should know how they react to this drug before they operate an automobile or machinery or engage in activities requiring mental alertness and coordination.
  • to discontinue treatment; rest and refrain from exercise; and to contact their physician immediately if they experience pain, inflammation or rupture of a tendon .
  • to avoid excessive sunlight or artificial ultraviolet light while taking grepafloxacin and to discontinue therapy if phototoxicity (e.g., sunburn-like reaction or skin eruptions) occurs.

Drug Interactions (See also DRUG INTERACTIONS.)

Antacids, Sucralfate, Metal Cations, Multivitamins: Quinolones form chelates with alkaline earth and transition metal cations. Administration of quinolones with antacids containing aluminum, magnesium, or calcium, with sucralfate, with metal cations such as iron, or with multivitamins containing iron or zinc, or with formulations containing divalent and trivalent cations such as VIDEX (didanosine) chewable/buffered tablets or the pediatric powder for oral solution, may substantially interfere with the absorption of quinolones, resulting in systemic concentrations considerably lower than desired. These agents should not be taken within 4 hours before or 4 hours after grepafloxacin administration.

Caffeine Theobromine: Grepafloxacin, like other quinolones, may inhibit the metabolism of caffeine and theobromine. These stimulants are commonly found in coffee and tea, respectively. In some patients, this may lead to reduced clearance, prolongation of plasma half-life, and enhanced effects of caffeine and theobromine.

Theophylline: Grepafloxacin is a competitive inhibitor of the metabolism of theophylline. Serum theophylline concentrations increase when grepafloxacin is initiated in a patient maintained on theophylline. When initiating a multi-day course of grepafloxacin in a patient maintained on theophylline, the theophylline maintenance dose should be halved for the period of concurrent use of grepafloxacin and monitoring of serum theophylline concentrations should be initiated as a guide to further dosage adjustments.

Warfarin: In subjects receiving warfarin, no significant change in clotting time was observed when grepafloxacin was coadministered. However, because some quinolones have been reported to enhance the effects of warfarin or its derivatives, prothrombin time or other suitable anticoagulation test should be monitored closely if a quinolone antimicrobial is administered with warfarin or its derivatives.

Drugs Metabolized by Cytochrome P450 Enzymes: The drug interaction study evaluating the effect of grepafloxacin on theophylline indicates that grepafloxacin inhibits theophylline metabolism, which is mediated by CYP1A2. While no clinical studies have been conducted to evaluate the effect of grepafloxacin on the metabolism of C.P.A. substrates, in vitro data suggest similar effects of grepafloxacin in CYP3A4, mediated metabolism and theophylline metabolism. In addition, other quinolones have been reported to decrease the C.P.A. mediated metabolism of cyclosporine. Other drugs metabolized by C.P.A. include terfenadine, astemizole, cisapride, midazolam, and triazolam. The clinical relevance of the potential effect of grepafloxacin on the metabolism of C.P.A. substrates is not known. Patients receiving concurrent administration of substrates of C.P.A. were not excluded from clinical trials of grepafloxacin.

Nonsteroidal Anti inflammatory Drugs (NSAIDs): The concomitant administration of a nonsteroidal anti inflammatory drug with a quinolone may increase the risks of CNS stimulation and convulsions (see

WARNINGS

).

Antidiabetic Agents: Disturbances of blood glucose, including hyperglycemia and hypoglycemia, have been reported in patients treated concomitantly with quinolones and an antidiabetic agent. Therefore, careful monitoring of blood glucose is recommended when these agents are coadministered.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies to determine the carcinogenic potential of grepafloxacin hydrochloride have not been performed. Grepafloxacin was not mutagenic in the Ames test, a forward gene mutation assay, mouse micronucleus assay, and an assay of unscheduled DNA repair (UDS) using rat hepatocytes. Grepafloxacin was mutagenic in a bacterial DNA repair test and in an in vitro chromosome aberration test.

In a rat intravenous fertility study, grepafloxacin produced no drug related changes in the estrous cycle of females; copulation or fertility of males or females.

Pregnancy

Teratogenic Effects: Pregnancy Category C. Grepafloxacin had neither embryolethal nor teratogenic effects in rats when administered orally or intravenously. There was no compound-related effect on maintenance of pregnancy, parturition, implantation of females, ovulation, nursing, or on viability, body weight, or morphology of fetuses. However, a decrease in placental weight and in the number of ossified saccrococcygeal vertebrae were observed in rats at 2.4 times the recommended maximum daily human dose based on mg/m2 (15 times the recommended maximum daily human dose on a mg/kg basis); this was associated with maternal toxicity (decreased body weight and food consumption). No effect was noted at 420 mg/m2 per day (equivalent to the human dose).

Grepafloxacin had no embryolethal or teratogenic effects in rabbits. However, fetal body weight was suppressed and there was a tendency for a decrease in placental weight at 60 mg/kg doses. Maternal toxicity was demonstrated by abortion in rabbits at doses of 40 mg/kg or higher, a finding which is common in reproductive studies with antibacterial agents in rabbits.

In a perinatal/postnatal study in rats, death and prolongation of delivery time were observed at 2.4 times the recommended maximum daily human dose based on a mg/m2 basis (15 times the recommended maximum daily human dose on a mg/kg basis). There was no drug-related effect on delivery index, lactation, or offspring.

Adequate and well-controlled studies have not been conducted in pregnant women. Grepafloxacin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus (see

WARNINGS

).

Nursing Mothers

Grepafloxacin is excreted in human milk. Grepafloxacin was detectable in breast milk of one patient who was studied on the ninth day of treatment at 4 to 5 hours after oral administration of 400 mg of grepafloxacin.

Blood and milk concentrations of radioactivity were determined after oral administration of radiolabeled grepafloxacin at a dose of 40 mg/kg in lactating rats at 12 to 13 days post partum. The concentration of radioactivity in milk reached a maximum of 9.03 mg Eq/mL at 1 hour after administration and decreased to 3.20 mg Eq/mL at 24 hours after administration. The AUC(0-48 h) of radioactivity concentration in milk was 16 times that observed in the blood.

It is known that other quinolones are excreted in human milk. Because of the potential for serious adverse experiences from grepafloxacin in nursing infants a decision should be made to discontinue nursing or discontinue administration of the drug, taking into account the importance of this drug to the mother (see

WARNINGS

).

Geriatric Use

Of the total number of subjects in clinical studies of RAXAR (grepafloxacin) , 409 were 65 and over, while 104 were 75 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Pediatric Use

The safety and effectiveness of grepafloxacin in children and adolescents less than 18 years of age have not been established.

Overdosage & Contraindications

OVERDOSE

In the event of acute overdosage, the stomach should be emptied by inducing vomiting or by gastric lavage. The patient should be carefully observed and given supportive treatment. As with other quinolones, adequate hydration and electrolyte balance must be maintained. Due to the possibility of prolongation of the QTc interval and complications including arrhythmias, ECG monitoring is recommended after overdosage with RAXAR. It is not known if grepafloxacin can be efficiently removed by hemodialysis or peritoneal dialysis.

At oral doses of 4500 mg/kg (14,400 mg/m2) in mice and 3000 mg/kg (21,000 mg/m2) in rats significant increases in mortality were noted. These doses were approximately equivalent to 39 (mice) and 57 rats times the human dose on a mg/m2 basis.

CONTRAINDICATIONS

RAXAR (grepafloxacin) Tablets are contraindicated in persons with a history of hypersensitivity to grepafloxacin or other members of the quinolone class of antimicrobial agents. RAXAR (grepafloxacin) Tablets are contraindicated in patients with hepatic failure. Because prolongation of the QTc interval has been observed in healthy volunteers receiving RAXAR (grepafloxacin) , RAXAR (grepafloxacin) Tablets are contraindicated in patients with known QTc prolongation. RAXAR (grepafloxacin) Tablets are also contraindicated in patients being treated concomitantly with medications known to produce an increase in the QTc interval and/or torsade de pointes (e.g., terfenadine) unless appropriate cardiac monitoring can be assured (e.g., in hospitalized patients) (see WARNINGS ).

Clinical Pharmacology

CLINICAL PHARMACOLOGY

Absorption

Grepafloxacin is rapidly and extensively absorbed following oral administration of RAXAR (grepafloxacin) Tablets Bioavailability of the tablet is equivalent to the bioavailability of an oral solution of grepafloxacin. The absolute bioavailability of RAXAR (grepafloxacin) Tablets was estimated by comparing the areas under the plasma grepafloxacin concentration versus time curve (AUC) after intravenous and oral administration of grepafloxacin in separate studies. The absolute bioavailability is approximately 70%.

Single-dose and steady-state pharmacokinetic parameters following administration of 400 mg and 600 mg doses to healthy adult males are displayed in Table 1.

Table 1
Single-dose and Steady-state Pharmacokinetic Parameters in Healthy Adult Males

Parameter
Single-dose Pharmacokinetic
Parameters
Steady-state Pharmacokinetic Parameters
 
400 mg (n=40)
600 mg (n=31)
400 mg (n=10)
600 mg (n=46)
*AUC (µgh/mL)
12.27 ± 3.81
22.66 ± 5.65
14.08 ± 2.80
27.51 ± 6.95
Cmax (µg/mL)
1.11 ± 0.34
1.58 ± 0.37
1.35 ± 0.25
2.25 ± 0.48
Trough (µg/mL)
not applicable
not applicable
0.21 ± 0.08
0.55 ± 0.22

    *AUC=AUC¥ for single-dose; AUC0-24 for steady-state.

On average, the peak plasma drug concentration (Cmax) is achieved 2 to 3 hours after dosing. Steady-state concentrations of grepafloxacin are achieved within 7 days of once a day dosing.

Grepafloxacin pharmacokinetic parameters were determined following administration of 600 mg grepafloxacin immediately following a high fat meal (1000 kcal, 67 grams fat, 38 grams protein, 63 grams carbohydrates) and administration in the fasted state (n=29). There was no difference in grepafloxacin pharmacokinetic parameters between the fasted and fed treatments. Milk had no effect on the Cmax, Tmax, or AUC of grepafloxacin after oral administration. Neutralization of gastric acidity by intravenous administration of the histamine type-2 receptor antagonist famotidine did not affect the absorption or other pharmacokinetic properties of RAXAR (grepafloxacin) Tablets

Distribution

The apparent volume of distribution after oral administration of grepafloxacin 400 mg was 5.07 ± 0.95 L/kg, suggesting that grepafloxacin distributes widely into extravascular spaces. Binding of grepafloxacin to human plasma proteins is low (approximately 50%).

Table 2 summarizes the concentrations of grepafloxacin in fluids and tissues compared with serum drug concentration.

Table 2
Distribution of Grepafloxacin into Tissues and Fluids After Oral Administration n=number of subjects

 
Concentration Mean ± SD
Tissue or Fluid
Oral Dose (mg)
Hours Post-Dose
n
Serum
(µg/mL)
Tissue or Fluid
(µg/mL or µg/g)
Ratio
Alveolar lining fluid
400
4-5
5
1.76
27.1
15.4
Alveolar macrophages
400
4-5
5
1.76
278
158
Cervix uteri
100
4-5
5
1.23 ± 0.26
3.42 ± 0.65
2.8
Portio vaginalis
100
4-5
5
1.23 ± 0.26
2.58 ± 0.69
2.1
Sputum
200
4
7
0.47 ± 0.11
1.04 ± 0.48
2.2

Metabolism and Excretion

The plasma elimination half-life of grepafloxacin at steady-state was 15.7 ± 4.2 hours Grepafloxacin is eliminated predominantly through hepatic metabolism and biliary excretion. Less than 10% of an oral dose is excreted as unchanged grepafloxacin in urine. Approximately 88% of an oral dose of radiolabeled grepafloxacin 400 mg was recovered in urine (38%) and feces (50%) over 7 days post dose. Approximately one half of the AUC in plasma for the 12 hours after dosing was due to unchanged grepafloxacin; 68% of AUC in plasma for 12 hours after dosing was due to unchanged grepafloxacin plus known metabolites. Unchanged grepafloxacin (6% of dose) and several metabolites (in amounts ranging from 0.08% to 5.57% of dose) were recovered in urine. Unchanged grepafloxacin (27% of dose) and several metabolites (in amounts ranging from 1.83% to 3.91% of dose) were recovered in feces. Grepafloxacin metabolites include glucuronide (major metabolite) and sulfate conjugates and oxidative metabolites. The oxidative metabolites are formed mainly by cytochrome P450 1A2 (CYP1A2), while the cytochrome P450 3A4 (CYP3A4) has minor involvement. The nonconjugated metabolites have little antimicrobial activity compared with the parent drug. The conjugated metabolites have no antimicrobial activity.

Special Populations

Gender: Following administration of RAXAR (grepafloxacin) 600 mg daily for 7 days, Cmax was approximately 30% to 50% higher and AUC was approximately 20% to 50% higher in females compared to males. The observed differences appear to be due mainly to differences in body weight. Total clearance (per unit body weight), renal clearance (per unit body weight), and half-life did not differ between males and females. The observed differences in pharmacokinetic properties by gender do not necessitate any difference between males and females in dosage and administration.

Geriatric: There are no significant differences in grepafloxacin pharmacokinetics between young and elderly subjects.

Pediatric: Grepafloxacin has not been evaluated in pediatric patients.

Hepatic Insufficiency: Two studies were performed to assess the effect of hepatic failure on grepafloxacin pharmacokinetics. Both studies evaluated subjects with normal hepatic function, with mild (Child-Pugh class A) hepatic failure, or moderate hepatic failure (Child-Pugh class B). In one study, oral clearance was reduced by approximately 50% in patients with mild hepatic failure (n=5)relative to subjects with normal hepatic function (n=6). In the second study oral clearance was reduced by approximately 15% in subjects with mild hepatic failure (n=5)relative to subjects with normal hepatic function (n=8). Due to the different results for the two studies, it is not possible to determine an appropriate dose adjustment for subjects with mild hepatic failure. In both studies oral clearance was decreased by >50% in subjects with moderate hepatic failure (n=9, n=3) compared to subjects with normal hepatic function (n=6, n=8). RAXAR (grepafloxacin) Tablets are contraindicated for use in patients with hepatic failure (see DOSAGE AND ADMINISTRATION .)

Renal Insufficiency: Renal clearance of grepafloxacin was 0.458 ± 0.04 mL/min per kg in adults with normal renal function. The effect of varying degrees of renal function on the pharmacokinetics of grepafloxacin was assessed in 15 patients with impaired renal function (creatinine clearances ranging from 7.5 to 64 mL/min) compared with five adults with normal renal function. Varying degrees of renal function did not substantially affect the pharmacokinetic properties of grepafloxacin

Smokers: In a population pharmacokinetics study of grepafloxacin in patients with acute bacterial exacerbations of chronic bronchitis grepafloxacin clearance was 35% to 43% faster in patients who smoked relative to patients who did not smoke. This observation is consistent with the involvement of C.P.A. in the metabolism of grepafloxacin and the known induction of this enzyme in smokers. However, in the pivotal clinical trials, smoking did not have an effect on clinical efficacy.

Drug Interactions

(See also PRECAUTIONS, DRUG INTERACTIONS).

Antacids: Following administration of 200 mg grepafloxacin with 1 gram aluminum hydroxide, grepafloxacin AUC and Cmax were both decreased by approximately 60% relative to administration of grepafloxacin alone (n=6) (see PRECAUTIONS, DRUG INTERACTIONS).

Probenecid: Administration of 200 mg grepafloxacin with 500 mg probenecid followed by 500 mg probenecid every 12 hours for three doses did not alter grepafloxacin pharmacokinetics (n=6).

Theophylline: Grepafloxacin is a competitive inhibitor of theophylline metabolism. Twelve healthy subjects received an individualized regimen of sustained-release theophylline alone for 7 days, followed by coadministration of the theophylline regimen with 600 mg grepafloxacin once daily for 10 days. Following the addition of grepafloxacin, theophylline clearance decreased by approximately 50%, from 0.78 ± 0.25 to 0.40 ± 0.08 mL/min per kg. Steady-state peak theophylline concentration increased from 8.30 ± 1.54 µg/mL to 15.12 ± 3.69 µg/mL (see PRECAUTIONS, DRUG INTERACTIONS).

Warfarin: Fourteen healthy subjects received an individualized regimen of warfarin alone for 14 days, followed by coadministration of the warfarin regimen with 600 mg grepafloxacin once daily for 10 days. Grepafloxacin did not alter the anticoagulant effect of warfarin. Other quinolones have been reported to enhance the anticoagulant effects of warfarin (see PRECAUTIONS, DRUG INTERACTIONS).

Microbiology

Grepafloxacin has in vitro activity against a wide range of gram-positive and gram-negative aerobic microorganisms, as well as some atypical microorganisms. Grepafloxacin exerts its antibacterial activity by inhibiting bacterial topoisomerase II (DNA gyrase) and topoisomerase IV, essential enzymes for duplication, transcription, and repair of bacterial DNA. Beta-lactamase production has no effect on grepafloxacin activity and penicillin-resistant Streptococcus pneumoniae strains have undiminished in vitro susceptibility to grepafloxacin. Grepafloxacin is bactericidal at concentrations equal to or slightly greater than minimum inhibitory concentrations (MICs).

Resistance to grepafloxacin through spontaneous mutation in vitro occurs at a low frequency (10-8 to 10-10). As with other fluoroquinolones, the mutation frequency was higher for Pseudomonas species and Stenotrophomonas maltophilia than for other microorganisms. When resistance develops, it does so through slow stepwise increases in MICs. In clinical trials, grepafloxacin-resistant mutants were rarely encountered during the treatment of infections caused by susceptible isolates When they did occur, they were usually Pseudomonas species isolates.

Although cross-resistance has been observed between grepafloxacin and some other fluoroquinolones, some organisms resistant to other quinolones are susceptible to grepafloxacin.

Quinolones differ in chemical structure and mode of action from other classes of antimicrobial agents, including beta-lactam antibiotics and aminoglycosides; therefore, microorganisms resistant to these other classes of drugs may be susceptible to grepafloxacin and other quinolones.

In vitro tests show that grepafloxacin has reduced activity against some gram-positive microorganisms when combined with rifampin.

Grepafloxacin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section:

    Aerobic Gram positive Microorganisms:
    Aerobic Gram negative Microorganisms:
      Haemophilus influenzae
      Moraxella catarrhalis
      Neisseria gonorrhoeae
    Other Microorganisms:

The following in vitro data are available, but their clinical significance is unknown.

Grepafloxacin exhibits in vitro MICs of 1 µg/mL or less against most (³90%) strains of the following microorganisms; however, the safety and effectiveness of grepafloxacin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials.

    Aerobic Gram positive Microorganisms:
      Staphylococcus aureus (methicillin-susceptible strains)
      Staphylococcus epidermidis (methicillin-susceptible strains)
      Streptococcus agalactiae
      Streptococcus pneumoniae (penicillin-resistant strains)
      Streptococcus pyogenes.
    Aerobic Gram negative Microorganisms:
      Citrobacter freundii
      Citrobacter (diversus) koseri
      Enterobacter aerogenes
      Enterobacter cloacae
      Escherichia coli
      Haemophilus parainfluenzae
      Klebsiella oxytoca
      Klebsiella pneumoniae
      Morganella morganii
      Proteus mirabilis
      Proteus vulgaris
    Other Microorganisms

Susceptibility Tests

Dilution Techniques: Quantitative methods are used to determine MICs. These M.C. provide estimates of the susceptibility of bacteria to antimicrobial compounds. The M.C. should be determined using a standardized procedure. Standardized procedures are based on a dilution method1 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of grepafloxacin powder. The MIC values should be interpreted according to the following criteria:

For testing aerobic organisms other than Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae:

MIC (µg/mL)
Interpretation
£ 1
Susceptible (S)
2
Intermediate (I)
³ 4
Resistant (R)

For testing Streptococcus pneumoniae:a

MIC (µg/mL)
Interpretation
£ 1
Susceptible (S)

    a These interpretive standards are applicable only to broth microdilution susceptibility tests using cation-adjusted Mueller-Hinton broth with 2% to 5% lysed horse blood.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible". Strains yielding MIC results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

For testing Haemophilus influenzae:b

MIC (µg/mL)
Interpretation
£ 0.25
Susceptible (S)

    b These interpretive standards are applicable only to broth microdilution susceptibility testing with Haemophilus influenzae using Haemophilus Test Medium HTM1.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible". Strains yielding MIC results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

    For testing Neisseria gonorrhoeae:c

MIC (µg/mL)
Interpretation
£ 0.06
Susceptible (S)

    c These interpretive standards are applicable only to agar dilution tests with GC agar base and 1% defined growth supplement.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible". Strains yielding MIC results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentration usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and if the microorganism is not fully susceptible to alternative, clinically feasible drugs the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where a high dosage of drug can be used. This category also provides a buffer zone which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentration usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard grepafloxacin powder should provide the following MIC values:

Microorganism
MIC Range (µg/mL)
Escherichia coli ATCC 25922
0.004-0.03
Haemophilus influenzae ATCC 49247a
0.002-0.016
Neisseria gonorrhoeae ATCC 49226b
0.004-0.03
Staphylococcus aureus ATCC 29213
0.03-0.12
Streptococcus pneumoniae ATCC 49619c
0.06-0.5
    a This quality control range is applicable only to H influenzae ATCC 49247 tested by a broth microdilution procedure using HTM.1
    b This quality control range is applicable only to N gonorrhoeae ATCC 49226 tested by agar dilution using GC agar base with 1% defined growth supplement.
    c This quality control range is applicable only to S pneumoniae ATCC 49619 tested by a broth microdilution procedure using cation-adjusted Mueller-Hinton broth with 2 to 5 lysed horse blood.

Diffusion Techniques: Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 5-µg grepafloxacin to test the susceptibility of microorganisms to grepafloxacin.

Reports from the laboratory providing results of the standard single disk susceptibility test with a 5-µg disk should be interpreted according to the following criteria:

For aerobic organisms other than Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae:

Zone Diameter (mm)
Interpretation
³ 18
Susceptible (S)
15-17
Intermediate (I)
£ 14
Resistant (R)

For testing Streptococcus pneumoniae:a

Zone Diameter (mm)
Interpretation
³ 19
Susceptible (S)

    a These zone diameter standards for Streptococcus pneumoniae are applicable only to tests performed using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO2.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible". Strains yielding zone diameter results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

For testing Haemophilus influenzae:b

Zone Diameter (mm)
Interpretation
³ 24
Susceptible (S)

    b These zone diameter standards are applicable only to disk diffusion testing with Haemophilus influenzae using HTM2.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible". Strains yielding zone diameter results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

For testing Neisseria gonorrhoeae:c

Zone Diameter (mm)
Interpretation
³ 37
Susceptible (S)

    c These zone diameter standards for Neisseria gonorrhoeae are applicable only to disk diffusion tests with GC agar base and 1% growth supplement.

The current absence of data on resistant strains precludes defining any categories other than "Susceptible." Strains yielding zone diameter results suggestive of a "Nonsusceptible" category should be submitted to a reference laboratory for further testing.

Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for grepafloxacin.

As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the 5-µg grepafloxacin disk should provide the following zone diameters in these laboratory test quality control strains:

Microorganism
Zone Diameter (mm)
Escherichia coli ATCC 25922
28-36
Haemophilus influenzae ATCC 49247a
32-39
Neisseria gonorrhoeae ATCC 49226b
44-52
Staphylococcus aureus ATCC 25923
26-31
Streptococcus pneumoniae ATCC 49619c
21-28
    a This quality control range is applicable only to H. influenzae ATCC 49247 tested by a disk diffusion procedure using HTM.2
    b This quality control range is applicable only to N. gonorrhoeae ATCC 49226 tested by a disk diffusion procedure using GC agar base with 1% defined growth supplement.
    c This quality control range is applicable only to S. pneumoniae ATCC 49619 tested by a disk diffusion procedure using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO2.


CLINICAL STUDIES

Acute Bacterial Exacerbations of Chronic Bronchitis

Two separate controlled randomized trials of grepafloxacin in the treatment of acute bacterial exacerbations of chronic bronchitis yielded overall efficacy rates of grepafloxacin 400 mg and grepafloxacin 600 mg which demonstrated equivalence to comparators. However, these studies suggest that grepafloxacin 400 mg once daily for 10 days may be less effective against S. pneumoniae than grepafloxacin 600 mg once daily for 10 days or comparator for 10 days. These studies excluded patients whose respiratory status required the initiation of steroid therapy or an increase in maintenance steroid doses greater than prednisone 10 mg per day (or its equivalent). Clinical success at end of treatment did not always predict clinical success at follow-up. Table 6 presents efficacy data from these two trials at end of treatment (1 to 5 days posttreatment) and at follow-up (14 to 28 days posttreatment).

Table 6
Clinical Efficacy in Studies of Acute Bacterial Exacerbations of Chronic Bronchitis 

Study 106-92-301
End of Treatment (1-3 Days Posttreatment)
Follow-up (14 Days Posttreatment)
 
Grepafloxacin 400 mg q.d.
Grepafloxacin 600 mg q.d.
Comparator
Grepafloxacin 400 mg q.d.
Grepafloxacin 600 mg q.d.
Comparator
Overall Efficacy
142/57
(90.4%)
140/150
(93.3%)
152/161
(94.4%)
123/153
(80.4%)
124/149
(83.2%)
137/161
(85.1%)
Efficacy by Individual Organism:
S. pneumoniae
36/42
(85.7%)
40/41
(97.6%)
43/44
(97.7%)
29/40
(72.5%)
35/41
(85.4%)
38/44
(86.4%)
H. influenzae
63/68
(92.6%)
61/68
(89.7%)
84/90
(93.3%)
55/67
(82.1%)
51/67
(76.1%)
76/90
(84.4%)
M. catarrhalis
41/43
(95.3%)
32/32
(100%)
29/30
(96.7%)
38/42
(90.5%)
31/32
(96.9%)
26/30
(86.7%)
Study 106-92-206
End of Treatment (3-5 Days Posttreatment)
Follow-up (14-28 Days Posttreatment)
 
Grepafloxacin 400 mg q.d.
Grepafloxacin 600 mg q.d.
Comparator
Grepafloxacin 400 mg q.d.
Grepafloxacin 600 mg q.d.
Comparator
Overall Efficacy
66/72 (91.7%)
66/71 (93.0%)
65/70 (92.9%)
58/71 (81.7%)
61/71 (85.9%)
54/66
(81.8 %)
Efficacy by Individual Organism:
S. pneumoniae
8/8
(100%)
8/9
(88.9%)
3/5
(60%)
7/8
(87.5%)
6/9
(66.7%)
3/5
(60%)
H. influenzae
18/19 (94.7%)
15/16 (93.8%)
17/18 (94.4%)
17/19 (89.5%)
14/16 (87.5%)
15/18 (83.3%)
M. catarrhalis
20/21 (95.2%)
20/21 (95.2%)
18/19 (94.7%)
19/21 (90.5%)
18/21 (85.7%)
15/16 (93.8%)

Community-acquired Pneumonia

The two pivotal clinical trials that assessed the efficacy of grepafloxacin in the treatment of community-acquired pneumonia excluded patients whose respiratory status required the initiation of steroid therapy or an increase in maintenance steroid doses greater than prednisone 10 mg per day (or its equivalent). Study 106-92-302 was a randomized controlled study that assessed the efficacy of grepafloxacin 600 mg once daily for 10 days compared with comparator for 10 days. Study 106-92-205 was an open study that assessed clinical efficacy of grepafloxacin 600 mg once daily for 10 days. Table 7 presents efficacy results from the two pivotal studies:

Table 7
Clinical Efficacy in Community-acquired Pneumonia in Two Pivotal Studies
     
    Grepafloxacin 600 mg q.d.
    Comparator
    Study 106-92-302
    Success
    89/110 (80.9%)
    94/117 (80.3%)
    Failure
    21/110 (19.1%)
    23/117 (19.7%)
    Study 106-92-205
    Success
    116/125 (92.8%)
     
    Failure
    9/125 (7.2%)
     

ANIMAL PHARMACOLOGY

Quinolones have been shown to cause arthropathies in juvenile rats and dogs. In addition, these drugs are associated with an increased incidence of osteochondrosis in rats as compared with the incidence in vehicle-treated rats. Grepafloxacin-associated joint toxicity (cavitation with loss of cartilaginous matrix and chondrocytes with cartilage fibrillation) was observed in juvenile dogs receiving 100 mg/kg by intravenous or subcutaneous injection for 1 week. Grepafloxacin associated joint toxicity (blisters of the articular cartilage) was observed in juvenile dogs given oral doses of 80 mg/kg per day (approximately 4.3 times the recommended maximum daily human dose on a mg/m2 basis for 4 weeks. No joint toxicity was observed at lower oral doses of 60 mg/kg per day approximately 3.2 times the recommended maximum daily human dose on a mg/m2 basis) for 4 weeks. The clinical relevance of these observations is unknown.

In the dog, oral doses of 30 mg/kg and above ( ³ 1.5 times the maximum human dose on a mg/m2 basis) caused prolongation of the QT interval, although the results were variable. Intravenous administration of grepafloxacin at 10 mg/kg elicited a moderate hypotension in anesthetized dogs and rabbits.

In phototoxicity tests, mice exposed to ultraviolet A radiation (similar to that used in tanning booths, sunlight contains a wider spectrum of UV radiation) after administration of grepafloxacin as a single 200 mg/kg oral dose (1.6 times the highest recommended human dose based upon body surface area) showed a mild redness on the ears. Phototoxic reactions such as this have been reported with other quinolones.

Lenticular opacities, sometimes observed after long-term, high-dose use with other quinolones, were not observed with grepafloxacin in a 52-week study in monkeys.

Drug interactions resulting in seizures have been reported between some quinolones and NSAIDs. Grepafloxacin did not induce seizures when administered with a variety of NSAIDs. in rats. The NSAIDs. studied were fenbufen, flurbiprofen, indomethacin, phenylbutazone, ibuprofen, and diflunisal.

Medication Guide

PATIENT INFORMATION

Patients should be advised:

  • that grepafloxacin may be taken with or without meals.
  • that grepafloxacin increases the effects of theophylline, and to advise their physician immediately if they are taking theophylline.
  • that multivitamins (containing iron or zinc), antacids, (containing magnesium, calcium, or aluminum), sucralfate, or VIDEX (didanosine) chewable/buffered tablets or the pediatric powder for oral solution should not be taken within 4 hours before or 4 hours after taking grepafloxacin (see DRUG INTERACTIONS ).
  • that grepafloxacin may increase the effects of other drugs metabolized by the liver, and to advise their physician of any of the drugs they are taking.
  • to drink fluids liberally.
  • that grepafloxacin may increase the effects of caffeine.
  • that grepafloxacin may be associated with hypersensitivity reactions, even following a single dose, and to discontinue the drug at the first sign of skin rash, hives, or other skin reactions, a rapid heartbeat, difficulty in swallowing or breathing, or any other symptom of an allergic reaction (see WARNINGS ).
  • that grepafloxacin may cause dizziness and lightheadedness; therefore, patients should know how they react to this drug before they operate an automobile or machinery or engage in activities requiring mental alertness and coordination.
  • to discontinue treatment; rest and refrain from exercise; and to contact their physician immediately if they experience pain, inflammation or rupture of a tendon .
  • to avoid excessive sunlight or artificial ultraviolet light while taking grepafloxacin and to discontinue therapy if phototoxicity (e.g., sunburn-like reaction or skin eruptions) occurs.

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