Azithromycin
Mechanism :
It is a macrolide antibiotic used for the treatment of respiratory and skin infections. It inhibits the ribosomal synthesis of the bacteria. It is a broad-spectrum antibiotic with increased action against the gram-negative bacteria. It is the preferred drug against urethritis caused by chlamydia trachomatis. It has fewer side effects as compared to erythromycin and requires a shorter course as the drug is widely distributed in tissues with a very long half-life.
Indication :
- Pertussis
- Penicillin allergic rheumatic fever prophylaxis
- Campylobacter
- Uncomplicated genital infections
- Drug resistant enteric fever.
- Chlamydial Trachomatis Infection
- Cat Scratch Disease
- Mycobacterium avium complex
- Chancroid
- Babesiosis
- Yersinia pseudotuberculosis infections
- Mycoplasma pneumonia
Contraindications :
Contraindicated in patients with known hypersensitivity to azithromycin, or any other macrolide and in hepatic disease. Use with caution in renal failure.
Dosing :
10 mg/kg/dose PO once daily for 3-5 days Max: 500 mg/day.
Endocarditis prophylaxis:
15 mg/kg PO 30-60 mins before procedure. Max: 500 mg/dose.
Mycobacterium avium complex:
Primary Prophylaxis: 20 mg/kg PO weekly; do not exceed 1200 mg or 5 mg/kg/day once a day; do not exceed 250 mg/day.
Secondary prophylaxis: 5 mg/kg/day PO once a day; do not exceed 250 mg/day in combination with
ethambutol with or without
rifabutin.
Treatment: 10 mg/kg/day PO OD for 1 month (Max: 500 mg/day) along with other TB agents.
Chancroid/Non gonococcal urethritis/Cervicitis:
Single 20 mg/kg dose. Maximum dose of 1 gm.
Typhoid:
20 mg/kg/day PO per day for 7 days.
Chlamydial infections:
Infants: 20 mg/kg/day PO OD for 3 days.
Children <8 years or <45 kg: 20 mg/kg/day PO OD for 1 day. Max dose: 1 gm.
Children >8 years or >45 kg: 1 gm PO single dose.
Adverse Effect :
Abdominal pain, nausea, vomiting, diarrhea, rashes. increase in transaminase levels and/or alkaline phosphatase levels, transient neutropenia, cholestatic jaundice and reversible hearing loss.
Interaction :
Nelfinavir: Increased azithromycin serum concentrations. Close monitoring for known side effects of azithromycin, such as liver enzyme abnormalities and hearing impairment is warranted
Warfarin: Associated with increased anticoagulant effects.
Digoxin: Elevated digoxin concentrations.
Ergotamine or Dihydroergotamine: Acute ergot toxicity characterized by severe peripheral vasospasm and dysesthesia.
Terfenadine, Cyclosporine, Hexobarbital And Phenytoin: Elevated concentrations.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in normal renal function |
| HD | Unknown dialysability. Dose as in normal renal function |
| HDF/High flux | Unknown dialysability. Dose as in normal renal function |
| CAV/VVHD | Unknown dialysability. Dose as in normal renal function |
Hepatic Dose :
Since liver is the principal route of elimination for azithromycin, the use of azithromycin should be undertaken with caution in patients with significant hepatic disease. In case of liver dysfunction on treatment, discontinue the drug.