PHARMACOLOGY

Pharmacotherapeutic Group:  Macrolide Antibiotics

Pharmacodynamic properties: CLARITH reversibly binds to P site of 50S ribosomal subunit of susceptible organisms and inhibit RNA-dependent protein synthesis by stimulating dissociation of peptidyl t-RNA from ribosomes, thereby inhibiting bacterial growth.

Pharmacokinetic properties:

Absorption: Highly stable in gastric acid, rapidly absorbed from the GI tract (oral). Bioavailability: 50%

Distribution: Widely distributed into most body tissues except CNS. Protein bound: 40-50%

Metabolism: Hepatic (extensive), converted to 14- hydroxyclarithromycin and other metabolites.

Excretion: Via the bile into the faeces, via the urine (20-30% as unchanged, 10-15% as 14-hydroxyclarithromycin and other metabolites.
 

Elimination half-life: parent form 3-7 hrs and active metabolite 5-9 hrs

INDICATIONS

 H. pylori infections, acute maxillary sinusitis, pharyngitis, tonsillitis, community acquired pneumonia, chronic bronchitis, SSTI, erythrasma

DOSE

Adult: 500mg twice daily in severe infections for 7-14 days; Paediatric: 7.5-15 mg/kg/day PO divided q12h for 7-4 days

CONTRAINDICATIONS

 Hypersensitivity. Patients receiving terfenadine, astemizole, pimozide, cisapride and ergot derivatives. Pregnancy; history of acute porphyria.

SPECIAL PRECAUTIONS

Renal and hepatic impairment; macrolide cross-resistance; lactation, children.

ADVERSE DRUG REACTIONS

Serious AEs: Pseudomembranous colitis, anaphylaxis, Stevens-Johnson syndrome. General AEs: GI upset, glossitis, stomatitis, altered taste; headache, dizziness, hallucinations, insomnia, other CNS effects; rash; hepatic dysfunction.

DRUG INTERACTIONS

May potentiate oral anticoagulant action. May elevate serum-digoxin concentration. May alter the serum concentration of calcium channel blockers when administrated together. Serious drug interaction:  Increases plasma concentrations of terfenadine or astemizole.

PRESENTATION

Each box is supplied with 10 blisters of 4 tablets in each.