Clarithromycin
Mechanism :
Clarithromycin is a macrolide antibiotic.
It is first metabolized to 14-OH clarithromycin, which is active and works synergistically with its parent compound. Like other macrolides, it then penetrates bacteria cell wall and reversibly binds to domain V of the 23S ribosomal RNA of the 50S subunit of the bacterial ribosome, blocking translocation of aminoacyl transfer-RNA and polypeptide synthesis. Clarithromycin also inhibits the hepatic microsomal CYP3A4 isoenzyme and P-glycoprotein, an energy-dependent drug efflux pump.
Indication :
- Pertussis
- Mycobacterium avium complex
- Community acquired pneumonia, sinusitis, bronchitis, skin infections
- Mycoplasma pneumonia
Contraindications :
Contraindicated in patients with known hypersensitivity to clarithromycin, or any other macrolide.
Dosing :
15 mg/kg/day PO in 2 divided doses for 7-10 days.
Maximum dose: 500 mg/dose.
Adverse Effect :
Nausea, vomiting, abdominal pain, diarrhea, anorexia, altered taste sensation, stomatitis, glossitis, anxiety, dizziness, insomnia, altered liver function tests.
Interaction :
Theophylline: Increase in serum theophylline levels and potential theophylline toxicity.
Oral anticoagulants: Increased anticoagulant effects
Ergotamine or Dihydroergotamine: Acute ergot toxicity characterized by severe peripheral vasospasm and dysesthesia.
Terfenadine, Astemizole and Cisapride: Risk of cardiac arrhythmias.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 30-50 | Dose as in normal renal function |
| 10-30 | Oral: 250–500 mg every 12 hours. IV: 250–500 mg every 12 hours |
| <10 | Oral: 250–500 mg every 12 hours. IV: 250–500 mg every 12 hours. |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Dialysed. Dose as in GFR<10 mL/ min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–30 mL/min |
Hepatic Dose :
No dosage adjustments are recommended.