Drug information of Azithromycin

Azithromycin

Drug group:

Azithromycin is an antibiotic that fights bacteria. Azithromycin is used to treat many different types of infections caused by bacteria, such as respiratory infections, skin infections, ear infections, and sexually transmitted diseases.

Mechanism of effect

Azithromycin binds to the 50S subunit of the 70S bacterial ribosomes, and therefore inhibits RNA-dependent protein synthesis in bacterial cells.

Pharmacodynamic

Azithromycin, a semisynthetic antibiotic belonging to the macrolide subgroup of azalides. Similar in structure to erythromycin. azithromycin reaches higher intracellular concentrations than erythromycin, increasing its efficacy and duration of action

Pharmacokinetics

Bioavailability 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. Metabolism: Hepatic. Biliary excretion of azithromycin, predominantly as unchanged drug, is a major route of elimination. Half life: 68 hours.

Drug indications

bacterial infection

Dosage

Usual Adult Dose for Pneumonia Community-acquired pneumonia:
Oral:
Immediate-release: 500 mg orally as a single dose on the first day followed by 250 mg orally once a day on days 2 through 5 for mild infections
Extended-release suspension: 2 g orally as a single dose for mild to moderate infections
IV: 500 mg IV once a day for at least 2 days followed by 500 mg (immediate-release formulation) orally once a day to complete a 7- to 10-day course of therapy
Usual Pediatric Dose for Pneumonia
Community-acquired pneumonia:
Oral:
Immediate-release:
6 months or older: 10 mg/kg (maximum: 500 mg/dose) orally as a single dose on the first day followed by 5 mg/kg (maximum: 250 mg/dose) orally once a day on days 2 thru 5
16 years or older: 500 mg orally as a single dose on the first day followed by 250 mg orally once a day on days 2 through 5 for mild infections
Extended-release suspension:
6 months or older
: Less than 34 kg: 60 mg/kg orally as a single dose for mild to moderate infections 34 kg or more: 2 g orally as a single dose for mild to moderate infections
16 years or older: 2 g orally as a single dose for mild to moderate infections
IV:
16 years or older: 500 mg IV once a day for at least 2 days followed by 500 mg (immediate-release formulation) orally once a day to complete a 7- to 10-day course of therapy

Alerts

1-Serious allergic reactions, including angioedema, anaphylaxis, and dermatologic reactions including Stevens-Johnson Syndrome and toxic epidermal necrolysis have been reported in patients on azithromycin therapy.
2- 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.
3-Prolonged cardiac repolarization and QT interval, imparting a risk of developing cardiac arrhythmia and torsades de pointes, have been seen with treatment with macrolides, including azithromycin.
4-Elderly patients may be more susceptible to drug-associated effects on the QT interval.
5-Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including azithromycin for injection, and may range in severity from mild diarrhea to fatal colitis.
6-Exacerbations of symptoms of myasthenia gravis and new onset of myasthenic syndrome have been reported in patients receiving azithromycin therapy.

Points of recommendation

1-The immediate-release tablets and oral suspension may be given without regard to meals; the extended-release suspension should be given 1 hour before or 2 hours after a meal.
2-Aluminum- and magnesium-containing antacids should not be used at the same time as immediate-release formulations of oral azithromycin.

Pregnancy level

B


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