Azithromycin blocks transpeptidation by binding to 50s ribosomal subunit of susceptible organisms and disrupting RNA-dependent protein synthesis at the chain elongation step.

Absorption
Reduced by food (capsule formulation); peak plasma concentrations after 2-3 hours.

Distribution
Extensive into the tissues (concentrations higher than those in blood), WBC (high concentrations), CSF (small amounts).

Metabolism
Liver (demethylation).

Excretion
Via the bile (as unchanged drug and metabolites); via the urine (6% of the dose).

Elimination half-life
About 68 hours.

Information Not Available

Mild to moderate nausea, vomiting, abdominal pain, dyspepsia, flatulence, diarrhoea, cramping; angioedema, cholestatic jaundice; dizziness, headache, vertigo, somnolence; transient elevations of liver enzyme values.

Monitor

Sensitivity
Review results of culture and sensitivity testing as appropriate.

STD testing
Ensure patient being treated for sexually transmitted urethritis or cervicitis has serologic test for syphilis and cultures for gonorrhea performed at time of diagnosis and that appropriate antimicrobial therapy and follow-up tests are initiated if infection is confirmed.

Therapy response
Monitor patient's response to therapy.

Impaired liver and renal function; pregnancy and lactation; children.

Antacids containing aluminium and magnesium salts reduce rate of absorption. Increased risk of ergot toxicity.

Potentially Fatal
Increased serum concentrations of digoxin and ciclosporin.

Food interactions
Food may alter absorption

Oral

Skin and soft tissue infections.
Adult: 500 mg once daily for 3 days. Alternatively, 500 mg as a single dose on the 1st day followed by 250 mg once daily for 4 days.
Child: >6 mth: 10 mg/kg; 15–25 kg: 200 mg; 26–35 kg: 300 mg; 36–45 kg: 400 mg. Doses to be taken once daily for 3 days

Oral
Respiratory tract infections
Adult: 500 mg once daily for 3 days. Alternatively, 500 mg as a single dose on the 1st day followed by 250 mg once daily for 4 days.
Child: >6 mth: 10 mg/kg; 15–25 kg: 200 mg; 26–35 kg: 300 mg; 36–45 kg: 400 mg. Doses to be taken once daily for 3 days

Oral
Uncomplicated genital infections due to Chlamydia trachomatis
Adult: 1 g as a single dose.

Oral
Uncomplicated gonorrhoea
Adult: 2 g as a single dose.

Oral
Prophylaxis of disseminated Mycobacterium avium complex (MAC) infections
Adult: 1.2 g once every wk. For treatment or secondary prophylaxis: 500 mg once daily with other antimycobacterials.
Child: >6 mth: 10 mg/kg once daily for 3 days.

Oral
Granuloma inguinale

Adult: Initially, 1 g followed by 500 mg daily. Alternatively, 1 g once a wk for at least 3 wk, until all lesions have completely healed.

Intravenous
Active immunisation against typhoid fever caused by Salmonella typhi

Adult: 500 mg once daily for 7 days.

Tab
May be taken with or without food. (May be taken w/ meals to reduce GI discomfort.)

Susp
May be taken with or without food. (May be taken w/ meals to reduce GI discomfort.)

Cap
Should be taken on an empty stomach. (Take on an empty stomach 1 hour before or 2 hour after meals.)

Caution when used during pregnancy.

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Caution when used during lactation

Acute bacterial sinusitis, acute otitis media, community-acquired pneumonia
Safety and efficacy not established in children younger than 6 mo of age.

Pharyngitis/Tonsillitis
Safety and efficacy not established in children younger than 2 years of age.

Ophthalmic solution
Safety and efficacy not established in children younger than 1 years of age.

IV infusion
Safety and efficacy not established in children younger than 16 years of age.

Information Not Available

Hypersensitivity

Intravenous
Store below 30°C.

Oral
Store below 30°C.

None well documented