Zithromin

Each tablet contains Azithromycin (as dihydrate) 500 mg.

Pharmacology: Pharmacokinetics: Absorption: After oral administration, the bioavailability of azithromycin is approximately 37%. Peak plasma levels are reached after 2-3 hours (Cmax after a single dose of 500 mg orally was approximately 0.4 mg/L).
Distribution: Kinetic studies have shown markedly higher azithromycin levels in tissue than in plasma (up to 50 times the maximum observed concentration in plasma) indicating that the active substance is heavily tissue bound (steady state distribution volume of approximately 31 L/kg). Concentrations in target tissues such as lung, tonsil, and prostate exceed the MIC90 for likely pathogens after a single dose of 500 mg. In experimental in vitro and in vivo studies azithromycin accumulates in the phagocytes, freeing is stimulated by active phagocytosis. In animal studies, this process appeared to contribute to the accumulation of azithromycin in the tissue. In serum, the protein binding of azithromycin is variable and depending on the serum concentration varies from 50% in 0.05 mg/L to 12% in 0.5 mg/L.
Excretion: Plasma terminal elimination half-life closely reflects the tissue depletion half-life of 2 to 4 days. About 12% of an intravenously administered dose is excreted in the urine unchanged over a period of 3 days; the majority in the first 24 hours. Biliary excretion of azithromycin, predominantly in unchanged form, is a major route of elimination. The identified metabolites (formed by N- and O-demethylising, by hydroxylising of the desosamine and aglycone rings, and by the splitting of the cladinose conjugate) are microbiologically inactive. After a 5 day treatment, slightly higher (29%) AUC values were seen in the elderly volunteers (> 65 years of age) compared to the younger volunteers (< 45 years of age). However, these differences are not regarded as clinically relevant; therefore, a dose adjustment is not recommended.

Azithromycin is indicated in upper respiratory tract infections, including pharyngitis, tonsillitis, sinusitis, otitis media, lower respiratory tract infections including bronchitis, pneumonia; skin and soft tissue infections.
Azithromycin is also indicated in the treatment of uncomplicated genital infections due to Chlamydia trachomatis and uncomplicated gonorrhea from sexually transmitted diseases of men and women.
Azithromycin may also be used for prophylaxis in at-risk patients unable to take penicillins.

Upper respiratory tract infections, including sinusitis, pharyngitis, tonsillitis, otitis media, and lower respiratory tract infections including bronchitis, pneumonia, skin and soft tissue infections: The usual adult dose is 500 mg of Azithromycin (as dihydrate) once daily for 3 days, 1 dose/tablet before meals or 2 hours after meals.
An alternative to this dosage schedule is taking 2 capsules of Azithromycin 250 mg given as a single dose for the first day, followed by 1 capsule of Azithromycin 250 mg daily in the next 4 days.
Sexually transmitted diseases caused by Chlamydia trachomatis: The prescribed dosage is 1000 mg of Azithromycin (as dihydrate). 4 capsules of Azithromycin 250 mg or 2 tablets of Azithromycin 500 mg given as a single dose.
The single dose of 2 g maybe given for uncomplicated gonorrhea (4 tablets of Azithromycin 500 mg tablets).
OR AS DIRECTED BY THE PHYSICIAN.

Azithromycin is contraindicated in patients with known hypersensitivity to Azithromycin and with hepatic disease.

Azithromycin absorption is reduced by 50% in the presence of food in the stomach. It should therefore be taken 1 hour before or 2 hours after meals.
Macrolides have been known to increase the plasma concentration of digoxin and cyclosporin. Therefore, if co-administration is necessary, caution should be exercised and serum level of digoxin and cylcosporin should be checked. Precaution should be taken in patients with hepatic and severe renal impairment. No adverse effects on the fetus during pregnancy is reported. However, caution should be exercised as with other drugs.

Azithromycin is well tolerated with a low incidence of adverse effects which are mild to moderate in nature and of gastrointestinal in origin (e.g. nausea, abdominal discomfort, vomiting, flatulence and diarrhea). Allergic reactions, such as rash may occur in hypersensitive patients.

Azithromycin absorption is reduced in the presence of antacid. So, Azithromycin should be administered 1 hour before or 2 hours after taking an antacid.

Store at temperatures not exceeding 30°C.

Macrolides

J01FA10 - azithromycin ; Belongs to the class of macrolides. Used in the systemic treatment of infections.

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