Azithromycin

Indications
Azithromycin is indicated for infections (caused by susceptible organisms) in lower respiratory tract infections including bronchitis and pneumonia, in upper respiratory tract infections including sinusitis and pharyngitis/tonsillitis, in otitis media, and in skin and soft tissue infections. In sexually transmitted diseases in men and women, Azithromycin is indicated in the treatment of non-gonococcal urethritis and cervicitis due to Chlamydia trachomatis.

Therapeutic Class
Macrolides

Pharmacology
Azithromycin is an azalide antibiotic, subclass of the macrolide class of antibiotics. Azithromycin acts by binding to the 50s ribosomal subunit of susceptible organisms and thus interferes with microbial protein synthesis.
Azithromycin demonstrated activity in vitro, against a wide range of gram-positive and gram-negative bacteria including: Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes (Group A) and other Streptococcal species; Haemophilus influenzae and parainfluenzae; Moraxella catarrhalis; anaerobes including Bacteroides fragilis, Escherichia coli, Bordetella pertussis, Bordetella parapertussis, Borrelia burgdorferi, Haemophilus ducreyi, Neisseria gonorrhoeae and Chlamydia trachomatis. Azithromycin also demonstrates activity in vitro against Legionella pneumophila, Mycoplasma pneumoniae and hominis; Campylobacter sp., Toxoplasma gondii and Treponema pallidum.

Dosage
Adult:
500 mg once daily orally for 3 days or 500 mg once on day 1, then 250 mg once on days 2-5 for 4 days.
For sexually transmitted diseases caused by Chlamydia trachomatis in adults, the dose is 1 gm given as a single dose or 500 mg once on day 1, followed by 250 mg once daily for next 2 days may also be given.
Children:
10 mg/kg body weight once daily for 3 days for child over 6 months
200 mg (1 teaspoonful) for 3 days if body weight is 15-25 kg
300 mg (1½ teaspoonfuls) for 3 days if body weight is 26-35 kg; 400 mg (2 teaspoonfuls) for 3 days if body weight is 36-45 kg.
In typhoid fever, 500 mg (21/2 teaspoonfuls) once daily for 7-10 days is given.

Administration
Reconstitution procedure of suspension-
Step 01: Shake the bottle well to loosen the powder.
Step 02: Add boiled and cooled water up to the water mark of the bottle label.
Step 03: Shake until powder is completely mixed with water.
Azithromycin should be taken at least 1 hour before or 2 hours after meal.

Interaction
Azithromycin absorption is reduced in presence of food and antacid. In patients receiving ergot alkaloids Azithromycin should be avoided because of the possibility of ergotism resulting from interaction of Azithromycin with the cytochrome P-450 system. As macrolides increase the plasma concentration of digoxin and cyclosporin, caution should be exercised while co-administration. There have been no drug interactions between Azithromycin and Warfarin, Theophylline, Carbamazepine, Methylprednisolone or Cimetidine.

Contraindications
Azithromycin is contraindicated in patients hypersensitive to Azithromycin or any other macrolide antibiotic. Co-administration of ergot derivatives and Azithromycin is contraindicated. Azithromycin is contraindicated in patients with hepatic diseases.

Side Effects
Azithromycin is well tolerated with a low incidence of side effects. The side effects include nausea, vomiting, abdominal discomfort (pain/cramps), flatulence, diarrhoea, headache, dizziness, and skin rashes and are reversible upon discontinuation of therapy.

Pregnancy & Lactation
Pregnancy Category of Azithromycin is B. Animal reproduction studies have demonstrated that Azithromycin has no evidence of harm to the fetus. There are no adequate and well controlled studies in pregnant women. Since animal reproduction studies are not always predictive of human response, Azithromycin should be used during pregnancy only if adequate alternatives are not available. It is not known whether Azithromycin is secreted in breast milk. So, caution should be exercised when Azithromycin is administered to nursing women.

Precautions & Warnings
As with any antibiotic, observation for signs of superinfection with non-susceptible organisms, including fungi, is recommended. No dose adjustment is needed in patients with renal impairment.

Overdose Effects
There is no data on overdosage with Azithromycin. Typical symptoms of overdosage with macrolide antibiotics include hearing loss, severe nausea, vomiting and diarrhoea. Gastric lavage and general supportive measures are indicated.

Storage Conditions
Keep in a dry place away from light and heat. Keep out of the reach of children.