Each film-coated caplet contains: Azithromycin Dihydrate equivalent to Azithromycin 500 mg.
Action
Pharmacology: Azithromycin is an azalide antibiotic, a subclass of the macrolides, and is a derivative of erythromycin. It acts by binding to the 50S ribosomal subunit and prevents the translocation of peptidyl-tRNA of susceptible organisms, and thus interfering with microbial protein synthesis.
Azithromycin is active against the following organisms both in vitro and in clinical infections: Gram-positive aerobes:In vitro and clinical infections: Staphylococcus aureus Streptococcus agalactiae Streptococcus pneumoniae Streptococcus pyogenes In vitro:Streptococcus sp. Streptococcus viridans
Azithromycin demonstrates cross-resistance with erythromycin-resistant Gram-positive strains.
Most strains of Enterococcus faecalis and methicillin-resistant staphylococci are resistant to Azithromycin. Gram-negative aerobes: In vitro and clinical infections: Haemophilus influenzae Moraxella catarrhalis In vitro: Bordetella pertussis
Campylobacter jejuni
Haemophilus ducreyi
Legionella pneumophila Anaerobic bacteria: In vitro and clinical infections: Bacteroides bivius Clostridium perfringens
Peptostreptococcus sp. Other organisms: In vitro and clinical infections: Chlamydia trachomatis In vitro: Borrelia burgdorferi
Mycoplasma pneumoniae
Treponema pallidum
Ureaplasma urealyticum
Beta-lactamase production should have no effect on Azithromycin activity.
Azithromycin is rapidly absorbed and widely distributed throughout the body after oral administration. Rapid distribution into tissues and high concentration within cells result in significantly higher Azithromycin concentration in tissues than in plasma or serum.
The pharmacokinetic parameters of Azithromycin in plasma after administering 500 mg on day 1 followed by 250 mg once daily on days 2 through 5 in healthy young adults (ages 18 to 40 years old) are described in the following table: (see table)
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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.
Indications/Uses
Azithromycin is indicated for the treatment of mild to moderate infections caused by susceptible microorganisms in the following conditions: Lower respiratory-tract: Acute bacterial exacerbations of chronic obstructive pulmonary disease due to Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae. Upper respiratory-tract: Streptococcal pharyngitis/tonsillitis, as an alternative to first line therapy of acute pharyngitis/tonsillitis due to Streptococcus pyogenes. Skin and skin structure: Uncomplicated skin and skin structure infections due to Staphylococcus aureus, Streptococcus pyogenes, or Streptococcus agalactiae. Sexually transmitted diseases: Non-gonococcal urethritis and cervicitis due to Chlamydia trachomatis.
Dosage/Direction for Use
MEZATRIN 500 should be administered as a single dose at least 1 hour before or 2 hours after meals. The recommended dose for individuals of ≥16 years of age is as follows: Upper and lower respiratory-tract infections, uncomplicated skin and skin structure infections: First day: 1 caplet (500 mg) as a single dose.
Day 2 through day 5: ½ caplet (250 mg) daily.
Total dose in 5 days is 1.5 grams. Cervicitis and non-gonococcal urethritis: 2 caplets (1 gram) as a single dose.
Contraindications
Patients with known hypersensitivity to Azithromycin, Erythromycin, or any macrolide antibiotic.
Concomitant administration with ergot derivatives.
Special Precautions
Azithromycin should be used during pregnancy and lactation only if clearly needed.
If an allergic reaction occurs, the drug should be discontinued and contact a physician.
As with Erythromycin and other macrolides, rare serious side effects including angioedema and anaphylaxis, have been reported.
No dose adjustment is needed in patients with mild renal impairment (creatinine clearance > 40 mL/min), but there is no data regarding Azithromycin usage in patients with more severe renal impairment, thus Azithromycin should be used with caution in these patients.
As the liver is the principal route of excretion of Azithromycin, it should not be used in patients with hepatic disease.
As with any antibiotic, observation for signs of superinfection with non-susceptible organisms, including fungi, is recommended.
Azithromycin should not be used in patients with pneumonia who are judged to be inappropriate for outpatient oral therapy because of moderate to severe illness or risk factors such as any of the following: Nosocomially acquired infections, known or suspected bacteremia, elderly or debilitated patients, conditions requiring hospitalization, significant health problems (including immunodeficiency or functional asplenia).
Adverse Reactions
MEZATRIN 500 is well tolerated with a low incidence of side effects. The majority of side effects were related to gastrointestinal-tract, e.g., nausea, abdominal pain, vomiting, flatulence and diarrhoea.
The less frequent (≤ 1%) side effects are as follows: Cardiovascular: palpitations, chest pain. GI-tract: dyspepsia, flatulence, vomiting, melena, cholestatic jaundice. Genito-urinary tract: monilia, vaginitis, nephritis. Central Nervous System: dizziness, headache, vertigo, somnolence, fatigue. Allergic: rash, photosensitivity, angioedema.
Transient mild reductions in neutrophil counts have occasionally been observed.
Transient elevations in liver enzymes have been reported.
Aluminum and magnesium containing antacids reduce the peak serum levels (rate) but not the AUC (extent) of Azithromycin absorption. However, each dose should be taken at least 1 hour before or 2 hours after antacids administration.
Azithromycin did not alter the anticoagulant effect of a single 15 mg dose of warfarin. Therefore Azithromycin and warfarin may be co-administered, but prothrombin time should be monitored.
Because of the theoretical possibility of ergotism, Azithromycin and ergot derivatives should not be co-administered.
Some of the related macrolide antibiotics interfere with the metabolisms of cyclosporine.
Concomitant administration of Azithromycin and Digoxin may elevate Digoxin levels.
Administration of Cimetidine 2 hours before Azithromycin had no effect on the absorption of Azithromycin.
Azithromycin may increase serum concentrations of Theophylline or Carbamazepine.
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