"The U.S. Food and Drug Administration today approved the Gastric Emptying Breath Test (GEBT), a new non-invasive test to aid in the diagnosis of delayed gastric emptying, known as gastroparesis.
Current tests used to diagnose gastroparesis "...
Acute Hypersensitivity Reactions
Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients on penicillin therapy, including amoxicillin. Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral penicillins. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. There have been reports of individuals with a history of penicillin hypersensitivity who have experienced severe reactions when treated with cephalosporins. Before initiating therapy with PREVPAC careful inquiry should be made regarding previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens. In the event of severe acute hypersensitivity reactions, such as anaphylaxis, Stevens-Johnson Syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptoms (DRESS), and Henoch-Schonlein purpura PREVPAC should be discontinued immediately and appropriate treatment should be urgently initiated.
Use In Pregnancy
CLARITHROMYCIN SHOULD NOT BE USED IN PREGNANT WOMEN EXCEPT IN CLINICAL CIRCUMSTANCES WHERE NO ALTERNATIVE THERAPY IS APPROPRIATE. IF PREGNANCY OCCURS WHILE TAKING CLARITHROMYCIN, THE PATIENT SHOULD BE INFORMED OF THE POTENTIAL HAZARD TO THE FETUS. CLARITHROMYCIN HAS DEMONSTRATED ADVERSE EFFECTS OF PREGNANCY OUTCOME AND/OR EMBRYO- FETAL DEVELOPMENT IN MONKEYS, RATS, MICE, AND RABBITS AT DOSES THAT PRODUCED PLASMA LEVELS TWO TO 17 TIMES THE SERUM LEVELS ACHIEVED IN HUMANS TREATED AT THE MAXIMUM RECOMMENDED HUMAN DOSES (see PRECAUTIONS, Pregnancy).
Hepatic dysfunction, including increased liver enzymes, and hepatocellular and/or cholestatic hepatitis, with or without jaundice, has been reported with clarithromycin. This hepatic dysfunction may be severe and is usually reversible. In some instances, hepatic failure with fatal outcome has been reported and generally has been associated with serious underlying diseases and/or concomitant medications. Discontinue clarithromycin immediately if signs and symptoms of hepatitis occur.
Clarithromycin has been associated with prolongation of the QT interval and infrequent cases of arrhythmia. Cases of torsades de pointes have been spontaneously reported during postmarketing surveillance in patients receiving clarithromycin. Fatalities have been reported. Clarithromycin should be avoided in patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia (see CONTRAINDICATIONS) and in patients receiving Class IA (quinidine, procainamide) or Class III (dofetilide, amiodarone, sotalol) antiarrhythmic agents. Elderly patients may be more susceptible to drug-associated effects on the QT interval.
Symptomatic response to therapy with lansoprazole does not preclude the presence of gastric malignancy.
Serious adverse reactions have been reported in patients taking clarithromycin concomitantly with CYP3A4 substrates. These include colchicine toxicity with colchicine; rhabdomyolysis with simvastatin, lovastatin, and atorvastatin; and hypotension with calcium channel blockers metabolized by CYP3A4 (e.g., verapamil, amlodipine, diltiazem) (see CONTRAINDICATIONS and PRECAUTIONS: DRUG INTERACTIONS).
Life-threatening and fatal drug interactions have been reported in patients treated with clarithromycin and colchicine. Clarithromycin is a strong CYP3A4 inhibitor and this interaction may occur while using both drugs at their recommended doses. If co-administration of clarithromycin and colchicine is necessary in patients with normal renal and hepatic function, the dose of colchicine should be reduced. Patients should be monitored for clinical symptoms of colchicine toxicity. Concomitant administration of clarithromycin and colchicine is contraindicated in patients with renal or hepatic impairment (see CONTRAINDICATIONS and PRECAUTIONS: DRUG INTERACTIONS).
Oral Hypoglycemic Agents/Insulin
The concomitant use of clarithromycin and oral hypoglycemic agents and/or insulin can result in significant hypoglycemia. With certain hypoglycemic drugs such as nateglinide, pioglitazone, repaglinide and rosiglitazone, inhibition of CYP3A enzyme by clarithromycin may be involved and could cause hypoglycemia when used concomitantly. Careful monitoring of glucose is recommended.
There is a risk of serious hemorrhage and significant elevations in INR and prothrombin time when clarithromycin is co-administered with warfarin. INR and prothrombin times should be frequently monitored while patients are receiving clarithromycin and oral anticoagulants concurrently.
HMG-CoA Reductase Inhibitors (statins)
Concomitant use of clarithromycin with lovastatin or simvastatin is contraindicated (see CONTRAINDICATIONS) as these statins are extensively metabolized by CYP3A4, and concomitant treatment with clarithromycin increases their plasma concentration, which increases the risk of myopathy, including rhabdomyolysis. Cases of rhabdomyolysis have been reported in patients taking clarithromycin concomitantly with these statins. If treatment with clarithromycin cannot be avoided, therapy with lovastatin or simvastatin must be suspended during the course of treatment.
Caution should be exercised when prescribing clarithromycin with statins. In situations where the concomitant use of clarithromycin with atorvastatin or pravastatin cannot be avoided, atorvastatin dose should not exceed 20 mg daily and pravastatin dose should not exceed 40 mg daily. Use of a statin that is not dependent on CYP3A metabolism (e.g. fluvastatin) can be considered. It is recommended to prescribe the lowest registered dose if concomitant use cannot be avoided.
Concomitant Use Of PREVPAC With Methotrexate
Literature suggests that concomitant use of proton pump inhibitors (PPI) with methotrexate (primarily at high dose; see methotrexate prescribing information) may elevate and prolong serum levels of methotrexate and/or its metabolite, possibly leading to methotrexate toxicities. In high-dose methotrexate administration, a temporary withdrawal of PREVPAC may be considered in some patients (see PRECAUTIONS: DRUG INTERACTIONS).
Clostridium Difficile-Associated Diarrhea
Clostridium Difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including clarithromycin and/or amoxicillin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.
C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.
If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.
In addition, published observational studies suggest that PPI therapy, may be associated with an increased risk of CDAD, especially in hospitalized patients. This diagnosis should be considered for diarrhea that does not improve.
Adverse Reactions With Long-term PPI Use
Several published observational studies suggest that PPI therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist or spine. The risk of fracture was increased in patients who received high-dose, defined as multiple daily doses, and long-term PPI therapy (a year or longer).
Hypomagnesemia, symptomatic and asymptomatic, has been reported rarely in patients treated with PPIs for at least three months, in most cases after a year of therapy. Serious adverse events include tetany, arrhythmias, and seizures. In most patients, treatment of hypomagnesemia required magnesium replacement and discontinuation of the PPI.
The possibility of superinfections with mycotic or bacterial pathogens should be kept in mind during therapy. If superinfections occur, PREVPAC should be discontinued and appropriate therapy instituted.
Prescribing PREVPAC in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.
Clarithromycin is principally excreted via the liver and kidney. Clarithromycin may be administered without dosage adjustment to patients with hepatic impairment and normal renal function. However, in the presence of severe renal impairment with or without coexisting hepatic impairment, decreased dosage or prolonged dosing intervals may be appropriate.
Periodic assessment of renal, hepatic, and hematopoietic function should be made during prolonged therapy.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
In two 24-month carcinogenicity studies, Sprague-Dawley rats were treated with oral lansoprazole at doses of 5 to 150 mg/kg/day, about 0.5 to 20 times the recommended human dose of 60 mg/day, based on body surface area (BSA). Lansoprazole produced dose-related gastric enterochromaffin-like (ECL) cell hyperplasia and ECL cell carcinoids in both male and female rats. The incidences of intestinal metaplasia of the gastric epithelium were also increased in both sexes. In male rats, lansoprazole produced a dose-related increase in the incidence of testicular interstitial cell adenomas at doses two to 20 times the recommended human dose of 60 mg/day based on BSA.
In a 24-month carcinogenicity study, CD-1 mice were treated with oral lansoprazole at doses of 15 to 600 mg/kg/day (one to 40 times the recommended human dose of 60 mg/day based on BSA comparisons). Lansoprazole produced a dose-related increased incidence of gastric ECL cell hyperplasia. The incidence of liver tumors (hepatocellular adenoma plus carcinoma) was increased in male mice (at doses 20 to 40 times the recommended human dose of 60 mg/day based on BSA) and in female mice (treated at doses ten to 40 times the recommended human dose based on BSA). Lansoprazole treatment produced adenoma of rete testis in male mice receiving doses five to 40 times the recommended human dose of 60 mg/day based on BSA.
A 26 week p53 (+/-) transgenic mouse carcinogenicity study was not positive.
Lansoprazole was positive in the Ames test and the in vitro human lymphocyte chromosomal aberration assay. Lansoprazole was not genotoxic in the ex vivo rat hepatocyte unscheduled DNA synthesis (UDS) test, the in vivo mouse micronucleus test, or the rat bone marrow cell chromosomal aberration test.
Lansoprazole at oral doses up to 150 mg/kg/day (20 times the recommended human dose of 60 mg/day based on BSA) was found to have no effect on fertility and reproductive performance of male and female rats.
Long-term studies in animals have not been performed to evaluate the mutagenic or carcinogenic potential of amoxicillin alone. A 4:1 mixture of amoxicillin and potassium clavulanate was non-mutagenic in the Ames bacterial mutation assay, and the yeast gene conversion assay. The amoxicillin/potassium clavulanate mixture was also negative in the mouse micronucleus test, and in the dominant lethal assay in mice, but was weakly positive in the mouse lymphoma assay. In a multi-generation reproduction study in rats, no impairment of fertility or other adverse reproductive effects were seen at doses up to 500 mg/kg, approximately three times the human dose based on BSA comparisons.
The following in vitro mutagenicity tests have been conducted with clarithromycin:
Salmonella/Mammalian Microsomes Test
Bacterial Induced Mutation Frequency Test
In Vitro Chromosome Aberration Test
Rat Hepatocyte DNA Synthesis Assay
Mouse Lymphoma Assay
Mouse Dominant Lethal Study
Mouse Micronucleus Test
All tests had negative results except the In Vitro Chromosome Aberration Test which was weakly positive in one test and negative in another.
In addition, a Bacterial Reverse-Mutation Test (Ames Test) has been performed on clarithromycin metabolites with negative results.
Fertility and reproduction studies have shown that daily doses of up to 160 mg/kg/day (1.3 times the recommended maximum human dose based on mg/m²) to male and female rats caused no adverse effects on the estrous cycle, fertility, parturition, or number and viability of offspring. Plasma levels in rats after 150 mg/kg/day were two times the human serum levels.
In the 150 mg/kg/day monkey studies, plasma levels were three times the human serum levels. When given orally at 150 mg/kg/day (2.4 times the recommended maximum human dose based on mg/m²), clarithromycin was shown to produce embryonic loss in monkeys. This effect has been attributed to marked maternal toxicity of the drug at this high dose.
In rabbits, in utero fetal loss occurred at an intravenous dose of 33 mg/m², which is 17 times less than the maximum proposed human oral daily dose of 618 mg/m² .
Long-term studies in animals have not been performed to evaluate the carcinogenic potential of clarithromycin.
Teratogenic Effects - Pregnancy Category C
Category C is based on the pregnancy category for clarithromycin.
There are no adequate and well-controlled studies of lansoprazole, clarithromycin or amoxicillin (used separately or together) in pregnant women. PREVPAC should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus and there is no appropriate alternative therapy (see WARNINGS).
Reproduction studies have been performed in pregnant rats at oral lansoprazole doses up to 20 times the recommended human dose (60 mg/day based on BSA) and in pregnant rabbits at oral doses up to eight times the recommended human dose (60 mg/day based on BSA) and have revealed no evidence of impaired fertility or harm to the fetus due to lansoprazole.
Reproduction studies with amoxicillin have been performed in mice and rates at doses up to ten times the human dose and revealed no evidence of impaired fertility or harm to the fetus.
Four teratogenicity studies in rats with clarithromycin (three with oral doses and one with intravenous doses up to 160 mg/kg/day administered during the period of major organogenesis) and two in rabbits at oral doses up to 125 mg/kg/day (approximately two times the recommended maximum human dose based on mg/m²) or intravenous doses of 30 mg/kg/day administered during gestation days six to 18 failed to demonstrate any teratogenicity from clarithromycin. Two additional oral studies in a different rat strain at similar doses and similar conditions demonstrated a low incidence of cardiovascular anomalies at doses of 150 mg/kg/day administered during gestation days six to 15. Plasma levels after 150 mg/kg/day were two times the human serum levels. Four studies in mice revealed a variable incidence of cleft palate following oral doses of 1000 mg/kg/day (two and four times the recommended maximum human dose based on mg/m², respectively) during gestation days six to 15. Cleft palate was also seen at 500 mg/kg/day. The 1000 mg/kg/day exposure resulted in plasma levels 17 times the human serum levels. In monkeys, an oral dose of 70 mg/kg/day (an approximate equidose of the recommended maximum human dose based on mg/m²) produced fetal growth retardation at plasma levels that were two times the human serum levels.
Labor And Delivery
Oral ampicillin-class antibiotics are poorly absorbed during labor. Studies in guinea pigs showed that intravenous administration of ampicillin slightly decreased the uterine tone and frequency of contractions, but moderately increased the height and duration of contractions. However, it is not known whether use of these drugs in humans during labor or delivery has immediate or delayed adverse effects on the fetus, prolongs the duration of labor, or increases the likelihood that forceps delivery or other obstetrical intervention or resuscitation of the newborn will be necessary.
Lansoprazole and its metabolites are excreted in the milk of rats. It is not known whether lansoprazole is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from PREVPAC, and the potential for tumorigenicity shown for lansoprazole in rat carcinogenicity studies, a decision should be made whether to discontinue nursing or to discontinue PREVPAC, taking into account the importance of the therapy to the mother.
Penicillins have been shown to be excreted in human milk. Amoxicillin use by nursing mothers may lead to sensitization of infants. Caution should be exercised when amoxicillin is administered to a nursing woman.
It is not known whether clarithromycin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when clarithromycin is administered to a nursing woman. It is known that clarithromycin is excreted in the milk of lactating animals and that other drugs of this class are excreted in human milk. Preweaned rats, exposed indirectly via consumption of milk from dams treated with 150 mg/kg/day for three weeks, were not adversely affected, despite data indicating higher drug levels in milk than in plasma.
The safety and effectiveness of PREVPAC in pediatric patients infected with H. pylori have not been established (see CONTRAINDICATIONS and WARNINGS).
Elderly patients may suffer from asymptomatic renal and hepatic dysfunction. Care should be taken when administering PREVPAC to this patient population.
An analysis of clinical studies of amoxicillin was conducted to determine whether subjects aged 65 and over respond differently from younger subjects. Of the 1,811 subjects treated with capsules of amoxicillin, 85% were less than 60 years old, 15% were ≥ 61 years old and 7% were ≥ 71 years old. This analysis and other reported clinical experience have not identified differences in responses between the elderly and younger patients, but a greater sensitivity of some older individuals cannot be ruled out.
Amoxicillin is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.
In a steady-state study in which healthy elderly subjects (age 65 to 81 years old) were given 500 mg of clarithromycin every 12 hours, the maximum serum concentrations and area under the curves of clarithromycin and 14-OH clarithromycin were increased compared to those achieved in healthy young adults. These changes in pharmacokinetics parallel known age-related decreases in renal function. In clinical trials of clarithromycin, elderly patients did not have an increased incidence of adverse events when compared to younger patients. Dosage adjustment should be considered in elderly patients with severe renal impairment. Elderly patients may be more susceptible to development of torsades de pointes arrhythmias than younger patients (see WARNINGS and PRECAUTIONS).This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 1/14/2014
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