(doxycycline hyclate) Delayed-release Capsules
Doryx MPC (doxycycline hyclate) delayed-release tablets for oral use, contain doxycycline hyclate, a tetracycline class drug synthetically derived from oxytetracycline, in a delayed-release formulation consisting of pellets with a modified polymer enteric coat that has increased acid resistance.
The structural formula for doxycycline hyclate is:
with a molecular formula of C22H24N2O8, HCl, ½ C2H6O, ½ H2O and a molecular weight of 512.9. The chemical name for doxycycline hyclate is [4S(4aR,5S,5aR,6R,12aS)]-4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11deoxonaphthacene-2-carboxamide monohydrochloride, compound with ethyl alcohol (2:1), monohydrate. Doxycycline hyclate is a yellow crystalline powder soluble in water and in solutions of alkali hydroxides and carbonates. Doxycycline has a high degree of lipid solubility and a low affinity for calcium binding. It is highly stable in normal human serum. Doxycycline will not degrade into an epianhydro form.
Each tablet contains doxycycline 60 mg or 120 mg (equivalent to doxycycline hyclate 69.4 mg or 138.8 mg). Inactive ingredients in the tablet formulation are: lactose monohydrate; microcrystalline cellulose; sodium lauryl sulfate; sodium chloride; talc; anhydrous lactose; corn starch; crospovidone; magnesium stearate; cellulosic polymer coating.
Each DORYX MPC 60 mg Tablet contains 3.6 mg (0.157 mEq) of sodium and each DORYX MPC 120 mg Tablet contains 7.2 mg (0.313 mEq) of sodium.
Sexually Transmitted Infections
DORYX MPC is indicated for treatment of the following sexually transmitted infections:
- Uncomplicated urethral, endocervical or rectal infections in adults caused by Chlamydia trachomatis.
- Nongonococcal urethritis caused by Ureaplasma urealyticum.
- Lymphogranuloma venereum caused by Chlamydia trachomatis.
- Granuloma inguinale caused by Klebsiella granulomatis.
- Uncomplicated gonorrhea caused by Neisseria gonorrhoeae.
- Chancroid caused by Haemophilus ducreyi.
Respiratory Tract Infections
DORYX MPC is indicated for treatment of the following respiratory tract infections:
- Respiratory tract infections caused by Mycoplasma pneumoniae.
- Psittacosis (ornithosis) caused by Chlamydophila psittaci.
- Because many strains of the following groups of microorganisms have been shown to be resistant to doxycycline, culture and susceptibility testing are recommended.
- Doxycycline is indicated for treatment of infections caused by the following microorganisms, when bacteriological testing indicates appropriate susceptibility to the drug:
- Respiratory tract infections caused by Haemophilus influenzae.
- Respiratory tract infections caused by Klebsiella species.
- Upper respiratory infections caused by Streptococcus pneumoniae.
Specific Bacterial Infections
DORYX MPC is indicated for treatment of the following specific bacterial infections:
- Relapsing fever due to Borrelia recurrentis.
- Plague due to Yersinia pestis.
- Tularemia due to Francisella tularensis.
- Cholera caused by Vibrio cholerae.
- Campylobacter fetus infections caused by Campylobacter fetus.
- Brucellosis due to Brucella species (in conjunction with streptomycin).
- Bartonellosis due to Bartonella bacilliformis.
Because many strains of the following groups of microorganisms have been shown to be resistant to doxycycline, culture and susceptibility testing are recommended.
DORYX MPC is indicated for treatment of infections caused by the following gram-negative microorganisms, when bacteriological testing indicates appropriate susceptibility to the drug:
- Escherichia coli
- Enterobacter aerogenes
- Shigella species
- Acinetobacter species
- Urinary tract infections caused by Klebsiella species.
DORYX MPC is indicated for treatment of the following ophthalmic infections:
- Trachoma caused by Chlamydia trachomatis, although the infectious agent is not always eliminated as judged by immunofluorescence.
- Inclusion conjunctivitis caused by Chlamydia trachomatis.
Anthrax Including Inhalational Anthrax (Post-Exposure)
DORYX MPC is indicated for treatment of Anthrax due to Bacillus anthracis, including inhalational anthrax (post-exposure): to reduce the incidence or progression of disease following exposure to aerosolized Bacillus anthracis.
Alternative Treatment For Selected Infections When Penicillin Is Contraindicated
DORYX MPC is indicated as an alternative treatment for the following selected infections when penicillin is contraindicated:
- Syphilis caused by Treponema pallidum.
- Yaws caused by Treponema pallidum subspecies pertenue.
- Listeriosis due to Listeria monocytogenes.
- Vincent’s infection caused by Fusobacterium fusiforme.
- Actinomycosis caused by Actinomyces israelii.
- Infections caused by Clostridium species.
Adjunctive Therapy For Acute Intestinal Amebiasis And Severe Acne
In acute intestinal amebiasis, DORYX MPC may be a useful adjunct to amebicides. In severe acne, DORYX MPC may be useful adjunctive therapy.
Prophylaxis Of Malaria
DORYX MPC is indicated for the prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (less than 4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains [see DOSAGE AND ADMINISTRATION and PATIENT INFORMATION].
To reduce the development of drug-resistant bacteria and maintain the effectiveness of DORYX MPC and other antibacterial drugs, DORYX MPC should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
DOSAGE AND ADMINISTRATION
Important Dosage And Administration Instructions
- DORYX MPC is not substitutable on a mg per mg basis with other oral doxycyclines. To avoid prescribing errors, do not substitute DORYX MPC for other oral doxycyclines on a mg per mg basis because of differing bioavailability.
- Do not chew or crush tablets.
- The recommended dosage, frequency of administration and weight-based dosage recommendations of DORYX MPC differ from that of the other tetracyclines [see Switching From DORYX To DORYX MPC, Dosage In Adult Patients, Dosage In Pediatric Patients]. Exceeding the recommended dosage may result in an increased incidence of adverse reactions.
- Administer DORYX MPC with an adequate amount of fluid to wash down the drug and reduce the risk of esophageal irritation and ulceration [see ADVERSE REACTIONS].
- If gastric irritation occurs, DORYX MPC may be given with food or milk [see CLINICAL PHARMACOLOGY].
Switching From DORYX To DORYX MPC
When switching from DORYX to DORYX MPC:
- A 60 mg dose of DORYX MPC will replace a 50 mg dose of DORYX
- A 120 mg dose of DORYX MPC will replace a 100 mg dose of DORYX
Dosage In Adult Patients
- The usual dosage of DORYX MPC is 240 mg on the first day of treatment (administered 120 mg every 12 hours) followed by a maintenance dose of 120 mg daily. The maintenance dose may be administered as a single dose or as 60 mg every 12 hours.
- In the management of more severe infections (particularly chronic infections of the urinary tract), 120 mg every 12 hours is recommended.
- For certain selected specific indications, the recommended duration or dosage and duration of DORYX MPC in adult patients are as follows:
- Streptococcal infections, therapy should be continued for 10 days.
- Uncomplicated urethral, endocervical, or rectal infection caused by C. trachomatis: 120 mg, by mouth, twice-a-day for 7 days.
- Uncomplicated gonococcal infections in adults (except anorectal infections in men): 120 mg, by mouth, twice-a-day for 7 days. As an alternate single visit dose, administer 360 mg followed in one hour by a second 360 mg dose.
- Nongonococcal urethritis (NGU) caused by C. trachomatis and U. urealyticum: 120 mg, by mouth, twice-a-day for 7 days.
- Syphilis – early: Patients who are allergic to penicillin should be treated with doxycycline 120 mg, by mouth, twice-a-day for 2 weeks.
- Syphilis of more than one year’s duration: Patients who are allergic to penicillin should be treated with doxycycline 120 mg, by mouth, twice-a-day for 4 weeks.
- Acute epididymo-orchitis caused by N. gonorrhoeae: 120 mg, by mouth, twice-a-day for at least 10 days.
- Acute epididymo-orchitis caused by C. trachomatis: 120 mg, by mouth, twice-a-day for at least 10 days
Dosage In Pediatric Patients
- For all pediatric patients weighing less than 45 kg with severe or life threatening infections (e.g., anthrax, Rocky Mountain spotted fever), the recommended dosage of DORYX MPC is 2.6 mg per kg of body weight administered every 12 hours. Pediatric patients weighing 45 kg or more should receive the adult dose [see WARNINGS AND PRECAUTIONS].
- For pediatric patients with less severe disease (greater than 8 years of age and weighing less than 45 kg), the recommended dosage schedule of DORYX MPC is 5.3 mg per kg of body weight divided into two doses on the first day of treatment, followed by a maintenance dose of 2.6 mg per kg of body weight (given as a single daily dose or divided into twice daily doses). For pediatric patients weighing over 45 kg, the usual adult dose should be used.
Dosage For Prophylaxis Of Malaria
For adults, the recommended dose of DORYX MPC is 120 mg daily.
For pediatric patients 8 years of age and older, the recommended dosage of DORYX MPC is 2.4 mg per kg of body weight administered once daily. Pediatric patients weighing 45 kg or more should receive the adult dose.
Prophylaxis should begin 1 or 2 days before travel to the malarious area. Prophylaxis should be continued daily during travel in the malarious area and for 4 weeks after the traveler leaves the malarious area.
Dosage For Inhalational Anthrax (Post-Exposure)
For adults, the recommended dosage is 120 mg, of DORYX MPC, by mouth, twice-a-day for 60 days.
For pediatric patients weighing less than 45 kg, the recommended dosage of DORYX MPC is 2.6 mg per kg of body weight, by mouth, twice-a-day for 60 days. Pediatric patients weighing 45 kg or more should receive the adult dose.
Dosage Forms And Strengths
DORYX MPC (doxycycline hyclate delayed-release tablets), 60 mg and 120 mg are white, oval tablets containing yellow pellets and debossed on one face with “D6” and “DC”, respectively, and plain on the other. Each tablet contains doxycycline 60 mg or 120 mg (equivalent to doxycycline hyclate 69.4 mg or 138.8 mg).
Storage And Handling
DORYX MPC (doxycycline hyclate delayed-release tablets), 60 mg and 120 mg are white, oval tablets containing yellow pellets and debossed on one face with “D6” and “DC”, respectively, and plain on the other. Each tablet contains doxycycline 60 mg or 120 mg (equivalent to doxycycline hyclate 69.4 mg or 138.8 mg).
The 60 mg tablet is supplied in bottles of 120 tablets NDC 51862-560-12
The 120 mg tablet is supplied in bottles of 60 tablets. NDC 51862-559-60
Store at 25° C (77° F); excursions permitted to 15°C to 30° C (59°F to 86° F) [see USP Controlled Room Temperature]. Dispense in a tight, light-resistant container (USP).
Manufactured by: Mayne Pharma International Pty Ltd 1538 Main North Road Salisbury South, SA 5106 Australia. Revised: May 2017
The following adverse reactions have been identified during post-approval use of doxycycline. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Due to oral doxycycline’s virtually complete absorption, side effects to the lower bowel, particularly diarrhea, have been infrequent. The following adverse reactions have been observed in patients receiving tetracyclines:
Gastrointestinal: Anorexia, nausea, vomiting, diarrhea, glossitis, dysphagia, enterocolitis, inflammatory lesions (with monilial overgrowth) in the anogenital region, and pancreatitis. Hepatotoxicity has been reported. These reactions have been caused by both the oral and parenteral administration of tetracyclines. Esophagitis and esophageal ulcerations have been reported in patients receiving capsule and tablet forms of drugs in the tetracycline-class. Most of these patients took medications immediately before going to bed [see DOSAGE AND ADMINISTRATION].
Skin: Maculopapular and erythematous rashes, Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis, and erythema multiforme have been reported. Photosensitivity is discussed above [see WARNINGS AND PRECAUTIONS].
Thyroid Gland Changes: When given over prolonged periods, tetracyclines have been reported to produce brown-black microscopic discoloration of thyroid glands. No abnormalities of thyroid function are known to occur.
Antacids And Iron Preparations
Concurrent use of tetracyclines, including DORYX MPC may render oral contraceptives less effective.
Barbiturates And Anti-Epileptics
The concurrent use of tetracycline and Penthrane® (methoxyflurane) has been reported to result in fatal renal toxicity.
Drug/Laboratory Test Interactions
False elevations of urinary catecholamines may occur due to interference with the fluorescence test.
Included as part of the "PRECAUTIONS" Section
The use of drugs of the tetracycline-class during tooth development (last half of pregnancy, infancy and childhood to the age of 8 years) may cause permanent discoloration of the teeth (yellow-gray-brown). This adverse reaction is more common during long-term use of the drugs but it has been observed following repeated short-term courses. Enamel hypoplasia has also been reported. Use DORYX MPC in pediatric patients 8 years of age or less only when the potential benefits are expected to outweigh the risks in severe or life-threatening conditions (e.g., anthrax, Rocky Mountain spotted fever), particularly when there are no alternative therapies.
Clostridium Difficile Associated Diarrhea
Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including DORYX MPC Tablets, 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 antibacterial 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 antibacterial use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.
Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines. Patients apt to be exposed to direct sunlight or ultraviolet light should be advised that this reaction can occur with tetracycline drugs, and treatment should be discontinued at the first evidence of skin erythema.
Potential For Microbial Overgrowth
DORYX MPC may result in overgrowth of non-susceptible organisms, including fungi. If such infections occur, discontinue use and institute appropriate therapy.
Intracranial hypertension (IH, pseudotumor cerebri) has been associated with the use of tetracycline including DORYX MPC. Clinical manifestations of IH include headache, blurred vision, diplopia, and vision loss; papilledema can be found on fundoscopy. Women of childbearing age who are overweight or have a history of IH are at greater risk for developing tetracycline associated IH. Avoid concomitant use of isotretinoin and DORYX MPC because isotretinoin is also known to cause pseudotumor cerebri.
Although IH typically resolves after discontinuation of treatment, the possibility for permanent visual loss exists. If visual disturbance occurs during treatment, prompt ophthalmologic evaluation is warranted. Since intracranial pressure can remain elevated for weeks after drug cessation patients should be monitored until they stabilize.
All tetracyclines form a stable calcium complex in any bone-forming tissue. A decrease in fibula growth rate has been observed in prematures given oral tetracycline in doses of 25 mg/kg every six hours. This reaction was shown to be reversible when the drug was discontinued. [See Use In Specific Populations].
Doxycycline offers substantial but not complete suppression of the asexual blood stages of Plasmodium strains.
Development Of Drug-Resistant Bacteria
Prescribing DORYX MPC in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.
Laboratory Monitoring For Long-Term Therapy
In long-term therapy, periodic laboratory evaluation of organ systems, including hematopoietic, renal, and hepatic studies should be performed.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Long-term studies in animals to evaluate carcinogenic potential of doxycycline have not been conducted. However, there has been ev idence of oncogenic activity in rats in studies with the related antibiotics, oxytetracycline (adrenal and pituitary tumors) a nd minocycline (thyroid tumors). Likewise, although mutagenicity studies of doxycycline have not been conducted, positive results in in vitro mammalian cell assays have been reported for related antibacterials (tetracycline, oxytetracycline).
Doxycycline administered orally at dosage levels as high as 250 mg/kg/day had no apparent effect on the fertility of female rats. Effect on male fertility has not been studied.
Use In Specific Populations
There are no adequate studies on the use of doxycycline in pregnant women. The vast majority of reported experience with doxycycline during human pregnancy is short-term, first trimester exposure. There are no human data available to assess the effects of long-term therapy of doxycycline in pregnant women such as that proposed for the treatment of anthrax exposure. An expert review of published data on experiences with doxycycline use during pregnancy by TERIS -the Teratogen Information System -concluded that therapeutic doses during pregnancy are unlikely to pose a substantial teratogenic risk (the quantity and quality of data were assessed as limited to fair), but the data are insufficient to state that there is no risk.1 In the U.S. general population the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively [see Data].
Results of animal studies indicate that tetracyclines cross the placenta, are found in fetal tissues, and can have toxic effects on the developing fetus (often related to retardation of skeletal development). Evidence of embryotoxicity also has been noted in animals treated early in pregnancy. If any tetracycline is used during pregnancy or if the patient becomes pregnant while taking these drugs, the patient should be apprised of the potential hazard to the fetus. [see WARNINGS AND PRECAUTIONS].
A case-control study (18,515 mothers of infants with congenital anomalies and 32,804 mothers of infants with no congenital anomalies) shows a weak but marginally statistically significant association with total malformations and use of doxycycline anytime during pregnancy. Sixty-three (0.19%) of the controls and 56 (0.30%) of the cases were treated with doxycycline. This association was not seen when the analysis was confined to maternal treatment during the period of organogenesis (i.e., in the second and third months of gestation), with the exception of a marginal relationship with neural tube defect based on only two-exposed cases.2
A small prospective study of 81 pregnancies describes 43 pregnant women treated for 10 days with doxycycline during early first trimester. All mothers reported their exposed infants were normal at 1 year of age.3
Tetracyclines are excreted in human milk, however, the extent of absorption of tetracyclines including doxycycline, by the breastfed infant is not known. Short-term use by lactating women is not contraindicated. The effects of prolonged exposure to doxycycline on breast milk production and breast fed neonates, infants and children are unknown.4 The developmental and health benefits of breast feeding should be considered along with the mother’s clinical need for DORYX MPC and any potential adverse effects on the breast fed child from DORYX MPC or from the underlying maternal condition [see WARNINGS AND PRECAUTIONS].
Because of the effects of drugs of the tetracycline-class on tooth development and growth, use DORYX MPC in pediatric patients 8 years of age or less only when the potential benefits are expected to outweigh the risks in severe or life-threatening conditions (e.g., anthrax, Rocky Mountain spotted fever), particularly when there are no alternative therapies [see WARNINGS AND PRECAUTIONS and DOSAGE AND ADMINISTRATION].
Clinical studies of DORYX MPC did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. DORYX MPC Tablets each contain less than 10 mg of sodium.
1. Friedman JM, Polifka JE. Teratogenic Effects of Drugs. A Resource for Clinicians (TERIS). Baltimore, MD: The Johns Hopkins University Press: 2000: 149-195. The TERIS (Teratogen Information System) is available at: http://www.micromedexsolutions.com/ (cited: 2016 Jan).
2. Cziezel AE and Rockenbauer M. Teratogenic study of doxycycline. Obstet Gynecol 1997; 89: 524-528.
4. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); [Last Revision Date 2015 March 10; cited 2016 Jan]. Doxycycline; LactMed Record Number: 100; [about 3 screens]. Available from: http://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm
In case of overdosage, discontinue medication, treat symptomatically and institute supportive measures. Dialysis does not alter serum half-life and thus would not be of benefit in treating cases of overdosage.
DORYX MPC is contraindicated in persons who have shown hypersensitivity to any of the tetracyclines.
Mechanism Of Action
Following administration of a single dose of DORYX MPC under fasting conditions, the AUCinf and Cmax were 26.7 mcg-h/mL and 1.6 mcg/mL, respectively. The Tmax was 2.8 hours. In a single-dose study to evaluate the relative bioavailability in healthy adult subjects under fasted conditions, DORYX MPC 120 mg Tablets were found to be bioequivalent to Doryx 100 mg Tablets. When a single dose of DORYX MPC 120 mg Tablet was administered with a standardized high-fat high-calorie meal, (937kcal consisting of approximately 55% fat, 30% carbohydrate and 15% protein), the Cmax was approximately 30% lower, but there was no significant difference in the AUCinf compared to administration under fasting conditions [see DOSAGE AND ADMINISTRATION].
Tetracyclines are concentrated in bile by the liver and excreted in the urine and feces at high concentrations and in a biologically active form. Excretion of doxycycline by the kidney is about 40%/72 hours in individuals with a creatinine clearance of about 75 mL/min. This percentage may fall as low as 1-5%/72 hours in individuals with a creatinine clearance below 10 mL/min.
Studies have shown no significant difference in the serum half-life of doxycycline (range 18 to 22 hours) in individuals with normal and severely impaired renal function. Hemodialysis does not alter the serum half-life.
Mechanism Of Action
Cross-resistance between tetracyclines is common.
Doxycycline has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections [see INDICATIONS AND USAGE].
Norcardiae and other aerobic Actinomyces species
Treponema pallidum subspecies pertenue
*Doxycycline has been found to be active against the asexual erythrocytic forms of Plasmodium falciparum but not against the gametocytes of P. falciparum. The precise mechanism of action of the drug is not known.
Methods When available, the clinical microbiology laboratory should provide cumulative reports of in vitro susceptibility test results for antibacterial drugs used in local hospitals and practice areas as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. These reports should aid the physician in selecting an antibacterial drug for treatment.
Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized test method5,6,8,10,11 (broth and/or agar). The MIC values should be interpreted according to the criteria provided in Table 1.
Quantitative methods that require measurement of zone diameters can also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. The zone size should be determined using a standard test method.5,7,8 This procedure uses paper disks impregnated with 30 mcg doxycycline to test the susceptibility of bacteria to doxycycline. The disk diffusion interpretive criteria are provided in Table 1.
For anaerobic bacteria the susceptibility to doxycycline can be determined by a standardized test method.5,9 The MIC values obtained should be interpreted according to the criteria provided in Table 1.
Table 1: Susceptibility Test Interpretive Criteria for Doxycycline and Tetracycline
|Bacteriaa||Minimal Inhibitory Concentration
|Nocardiae and other aerobic Actinomyces speciesab|
|aOrganisms susceptible to tetracycline are also considered susceptible to doxycycline, However, some organisms that are intermediate or resistant to tetracycline may be susceptible to doxycycline.
bThe current absence of resistance isolates precludes defining any results other than “Susceptible”. If isolates yielding MIC results other than susceptible, they should be submitted to a reference laboratory for further testing.
cGonococci with 30 mcg tetracycline disk zone diameters of less than 19 mm usually indicate a plasmid-mediated tetracycline resistant N. gonorrhoeae isolate. Resistance in these strains should be confirmed by a dilution test (MIC greater than or equal to 16 mcg/mL).
A report of Susceptible (S) indicates that the antimicrobial is likely to inhibit growth of the microorganism if the antimicrobial drug reaches the concentration usually achievable at the site of infection. A report of Intermediate (I) 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 high dosage of drug can be used. This category also provides a buffer zone that prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of Resistant (R) indicates that the antimicrobial drug is not likely to inhibit growth of the microorganism if the antimicrobial drug reaches the concentrations usually achievable at the infection site; other therapy should be selected.
Standardized susceptibility test procedures require the use of laboratory controls to monitor and ensure the accuracy and precision of the supplies and reagents used in the assay, and the techniques of the individuals performing the test.5,6,7,8,9,10,11 Standard doxycycline and tetracycline powders should provide the following range of MIC values noted in Table 2. For the diffusion technique using the 30 mcg doxycycline disk the criteria noted in Table 2 should be achieved.
Table 2: Acceptable Quality Control Ranges for Susceptibility Testing for Doxycycline and Tetracycline
|QC Strain||Minimal Inhibitory Concentration
|Enterococcus faecalis ATCC * 29212|
|Escherichia coli ATCC 25922|
|Eggerthella lenta ATCC 43055|
|Haemophilus influenzae ATCC 49247|
|Neisseria gonorrhoeae ATCC 49226|
|Staphylococcus aureus ATCC 25923|
|Staphylococcus aureus ATCC 29213|
|StaphyIococcus pneumoniae ATCC 49619|
|Bacteroides fragiIis ATCC 25285|
|Bacteroides thetaiotaomicron ATCC 29741|
|Mycoplasma pneumoniae ATCC 29342|
|Ureaplasma urealyticum ATCC 33175|
|*ATCC is the American Type Culture Collection|
Animal Toxicology And/Or Pharmacology
Hyperpigmentation of the thyroid has been produced by members of the tetracycline-class in the following species: in rats by oxytetracycline, doxycycline, tetracycline PO4, and methacycline; in minipigs by doxycycline, minocycline, tetracycline PO4, and methacycline; in dogs by doxycycline and minocycline; in monkeys by minocycline.
Minocycline, tetracycline PO4, methacycline, doxycycline, tetracycline base, oxytetracycline HCl, and tetracycline HCl, were goitrogenic in rats fed a low iodine diet. This goitrogenic effect was accompanied by high radioactive iodine uptake. Administration of minocycline also produced a large goiter with high radioiodine uptake in rats fed a relatively high iodine diet.
Treatment of various animal species with this class of drugs has also resulted in the induction of thyroid hyperplasia in the following: in rats and dogs (minocycline); in chickens (chlortetracycline); and in rats and mice (oxytetracycline). Adrenal gland hyperplasia has be en observed in goats and rats treated with oxytetracycline.
Results of animal studies indicate that tetracyclines cross the placenta and are found in fetal tissues.
5. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing; Twenty-sixth Informational Supplement. CLSI document M100S-S27 [ 2017]. Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
6. Clinical and Laboratory Standards Institute (CLSI). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically; Approved Standard -Tenth Edition. CLSI document M07-A10 , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
7. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Disk Diffusion Susceptibility Tests; Approved Standard -Twelfth Edition. CLSI document M02-A12 , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
8. Clinical and Laboratory Standards Institute (CLSI). Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria; Approved Guideline – Third Edition. CLSI document M45-A3 , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
9. Clinical and Laboratory Standards Institute (CLSI). Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard – Eighth Edition. CLSI document M11-A8 , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
10. Clinical and Laboratory Standards Institute (CLSI). Methods for Mycobacteria, Nocardiae, and Other Aerobic Actinomycetes; Approved Standard – Second Edition. CLSI document M24-A2 , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
11. Clinical and Laboratory Standards Institute (CLSI). Methods for Antimicrobial Susceptibility Testing for Human Mycoplasmas; Approved Guideline. CLSI document M43-A , Clinical Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne Pennsylvania 19087, USA.
- that no present-day antimalarial agent, including doxycycline, guarantees protection against malaria.
- to avoid being bitten by mosquitoes by using personal protective measures that help avoid contact with mosquitoes, especially from dusk to dawn (for example, staying in well-screened areas, using mosquito nets, covering the body with clothing, and using an effective insect repellent).
- that doxycycline prophylaxis:
- should begin 1 to 2 days before travel to the malarious area,
- should be continued daily while in the malarious area and after leaving the malarious area,
- should be continued for 4 further weeks to avoid development of malaria after returning from an endemic area,
- should not exceed 4 months.
Advise all patients taking DORYX MPC:
- to avoid excessive sunlight or artificial ultraviolet light while receiving doxycycline and to discontinue therapy if phototo xicity (for example, skin eruptions, etc.) occurs. Sunscreen or sunblock should be considered [see WARNINGS AND PRECAUTIONS]
- to drink fluids liberally along with DORYX MPC to reduce the risk of esophageal irritation and ulceration [see ADVERSE REACTIONS]
- that the absorption of tetracyclines is reduced when taken with foods, especially those that contain calcium. [see DRUG INTERACTIONS]
- that if gastric irritation occurs, DORYX MPC may be given with food or milk [see CLINICAL PHARMACOLOGY]
- that the absorption of tetracyclines is reduced when taken with antacids containing aluminum, calcium or magnesium, bismuth subsalicylate, and iron-containing preparations [see DRUG INTERACTIONS].
- that the use of doxycycline might increase the incidence of vaginal candidiasis.
Advise patients that diarrhea is a common problem caused by antibacterial drugs which usually ends when the antibacterial is discontinued. Sometimes after starting treatment with antibacterial drugs, patients can develop watery and bloody stools (with or without s tomach cramps and fever) even as late as two or more months after having taken the last dose of antibacterial. If this occurs, patients should contact their physician as soon as possible.
Counsel patients that antibacterial drugs including DORYX MPC should only be used to treat bacterial infections. They do not treat viral infections (for example, the common cold). When DORYX MPC is prescribed to treat a bacterial infection, patients should be to ld that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by DORYX MPC or other antibacterial drugs in the future.
Infectious Disease Resources
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.