The Cathay Drug Co., Inc.
Each film-coated tablet contains:
Azithromycin (as monohydrate) …………………… 500 mg
Azithromycin is a semi-synthetic macrolide antibiotic of the azalide class. Like other macrolide antibiotics, azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of the bacterial 70S ribosome. Binding inhibits peptidyl transferase activity and interferes with amino acid translocation during the process of translation. Its effects may be bacteriostatic or bactericidal depending of the organism and the drug concentration. Its long half-life, which enables once daily dosing and shorter administration durations, is a property distinct from other macrolides.
Azithromycin concentrates in phagocytes and fibroblasts as demonstrated by in vitro incubation techniques. Using such methodology, the ratio of intracellular to extracellular concentration was > 30 after one hour incubation. In vivo studies suggest that concentration in phagocytes may contribute to drug distribution to inflamed tissues.
Azithromycin can be used to treat STDs due to chlamydia and gonorrhea, community-acquired pneumonia, pelvic inflammatory disease, pediatric otitis media and pharyngitis, and Mycobacterium avium complex (MAC) in patients with advanced HIV disease. Similar in structure to erythromycin, azithromycin reaches higher intracellular concentrations than erythromycin, increasing its efficacy and duration of action.
Bioavailability of azithromycin monohydrate (Azemax) is 37% following oral administration. Absorption is not affected by food. Azithromycin is extensively distributed in tissues with tissue concentrations reaching up to 50 times greater than plasma concentrations. Azithromycin becomes concentrated within macrophages and polymorphonucleocytes giving it good activity against Chlamydia trachomatis.
The serum protein binding of azithromycin is variable in the concentration range approximating human exposure, decreasing from 51% at 0.02 μg/mL to 7% at 2 μg/mL. Biliary excretion of azithromycin, predominantly as unchanged drug, is a major route of elimination. Over the course of a week, approximately 6% of the administered dose appears as unchanged drug in urine.
Azithromycin is used in the treatment of bronchitis, severe Campylobacter enteritis, chancroid diphtheria, legionnaire’s disease and other Legionella infections, neonatal conjunctivitis, pertussis, pneumonia (mycoplasmal and other atypical pneumonias as well as streptococcal), sinusitis and for the prophylaxis of surgical infection in patients undergoing bowel surgery when in combination with neomycin.
Azithromycin is also used as a component of regimen in the treatment of mycobacterium avium complex (MAC), it is also used in situations where microorganisms sensitive to azithromycin have caused upper respiratory tract infections (sinusitis, pharyngitis, tonsillitis), acute otitis media, lower respiratory tract infections (acute bronchitis and mild to moderately severe community acquired pneumonia), skin and soft tissue infections, and uncomplicated chlamydial urethritis and cervicitis.
DOSAGE AND ADMINISTRATION
Azithromycin monohydrate (Azemax) tablets may be taken without regard to food. However, increased tolerability has been observed when tablets are taken with food.
Usual adult dose: 500 mg as single dose once daily for 3 days or alternatively, an initial dose of 500 mg may be followed by 250 mg daily for 4 days or as prescribed by the physician.
Azithromycin monohydrate (Azemax) is contraindicated in patients with known hypersensitivity to azithromycin, erythromycin, any macrolide or ketolide antibiotic. The product is also contraindicated in patients with a history of cholestatic jaundice/hepatic dysfunction associated with prior use of azithromycin.
Serious allergic reactions, including angioedema, anaphylaxis, and dermatologic reactions including Stevens Johnson Syndrome and toxic epidermal necrolysis have been reported rarely in patients on azithromycin therapy. Although rare, fatalities have been reported.
If an allergic reaction occurs, the drug should be discontinued and appropriate therapy should be instituted. Physicians should be aware that reappearance of the allergic symptoms may occur when symptomatic therapy is discontinued.
Abnormal liver function, hepatitis, cholestatic jaundice, hepatic necrosis, and hepatic failure have been reported, some of which have resulted in death. Discontinue azithromycin immediately if signs and symptoms of hepatitis occur.
Clostridium Difficile-associated diarrhea
Clostridium Difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Azemax, 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.
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.
Prolonged cardiac repolarization and QT interval, imparting a risk of developing cardiac arrhythmia and torsades de pointes, have been seen in treatment with macrolides, including azithromycin. Cases of torsades de pointes have been spontaneously reported during post marketing surveillance in patients receiving azithromycin. Avoid the use of azithromycin in patients with known prolongation of the QT interval, patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia, and in patients receiving Class IA (quinidine, procainamide) or Class III (dofetilide, amiodarone, sotalol) antiarrhythmic agents.
- Because azithromycin is principally eliminated via the liver, caution should be exercised when azithromycin is administered to patients with impaired hepatic function. Due to the limited data in subjects with GFR < 10 mL/min, caution should be exercised when prescribing azithromycin in these patients.
- Symptom exacerbations of myasthenia gravis and new onset of myasthenic syndrome have been reported in patients receiving azithromycin therapy.
- Prescribing azithromycin in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and may increase the risk of the development of drug-resistant bacteria.
The most common adverse effects with azithromycin are gastrointestinal disturbances but are usually mild and less frequent in comparison with erythromycin. Other adverse effects include:
|Allergic||Arthralgia, edema, urticaria, angioedema, rash, photosensitivity|
|Cardiovascular||Arrhythmias including ventricular tachycardia, hypotension, rare reports of QT prolongation and torsades de pointes, palpitations, chest pain|
|Gastrointestinal||Anorexia, constipation, dyspepsia, flatulence, vomiting/diarrhea rarely resulting in dehydration,pseudomembranous colitis, pancreatitis, oral candidiasis, pyloric stenosis, and rare reports of tongue discoloration.|
|General||Asthenia, paresthesia, fatigue, malaise and anaphylaxis (rarely fatal)|
|Genitourinary||Interstitial nephritis and acute renal failure, vaginitis|
|Liver/Biliary||Adverse reactions related to hepatic dysfunction|
|Nervous System||Convulsions, dizziness/vertigo, headache, somnolence, hyperactivity, nervousness, agitation and syncope|
|Psychiatric||Aggressive reaction and anxiety|
|Skin/Appendages||Pruritus, rarely serious skin reactions including erythema multiforme, Stevens Johnson Syndrome, and toxic epidermal necrolysis|
|Special Senses||Hearing disturbances including hearing loss, deafness, and/or tinnitus, reports of taste/smell perversion and/or loss|
Aluminum- and magnesium-containing antacids reduce the peak serum levels (rate) but not the AUC (extent) of azithromycin (500 mg) absorption.
Administration of cimetidine (800 mg) two hours prior to azithromycin had no effect on azithromycin (500 mg) absorption.
Other drugs that may interact with azithromycin includes digoxin, cyclosporine, rifabulin, nelfinavir, coumarin type oral anticoagulants, cimetidine, zidovudine.
PREGNANCY AND LACTATION
Teratogenic Effects – Pregnancy Category B: Reproduction studies have been performed in rats and mice at doses up to moderately maternally toxic dose levels (i.e., 200 mg/kg/day). These doses, based on a mg/m² basis, are estimated to be 4 and 2 times, respectively, the human daily dose of 500 mg.
No evidence of impaired fertility or harm to the fetus due to azithromycin was found. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, azithromycin should be used during pregnancy only if clearly needed.
It is not known whether azithromycin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when azithromycin is administered to a nursing woman.
Alu/PVDC Blister Pack X 3’s (Box of 3’s)
Store at temperatures not exceeding 30°C.