Clarithromycin

Clarithromycin

Class:Antibiotic,macrolide

Mechanism of action

Exerts its antibacterial action by binding to 50s ribosomal subunit resulting in inhibition of protein synthesis.The 14-OH metabolite of clarithromycinis twice as active as the parent compound against certain organisms.

Pharmacokinetics

Absorption:highly stable in the presence of gastric acid(unlike erythromycin).Distribution:widely distributes into most body tissues with the exception of the CNS.Metabolism:partially converted to the microbiologically active metabolite,14-OH clarithromycin.Bioavailability:50 percent;food delays but does not affect extent of bioavailability;Tmax:2-4 hours.Half life:5-7 hours.Elimination:primarily renal excretion;clearance approximates normal GFR.

Indications

Upper and lower respiratory tract infections.skin and soft tissue infections.disseminated for localized mycobacterial infections.disseminated mycobacterium avium complex infection in HIV-infected patients.

Precautions

Clarithromycin principally excreted by the liver.therefor,caution should be exercised in administering the antibiotic to patients with moderate to severe renal impairment.

Warnings

The physician should not prescribe clariyhromycin to pregnant women without carefully weighing the benefits against risk,particularly during the first 3 month of pregnancy.

Side effects

Nausea,dyspepsia,abdominal pain,vomiting,diarrhea,headache,taste perversion and transient elevation of liver enzymes.

Pregnancy

Pregnancy risk factor C.

Drug interactions

Valproate,theophylline,carbamazepine,cisapride,alprazolam,astemizole,cilostazol,oral anticoagulant(e.g warfarin),quinidine,pimozide and terfenadine.

Dosage

The recommended daily dosage in adult is one 250 mg twise daily.In more severe infections,the dosage can be increased to 500 mg twice daily for 6-14 days.The recommended dosage for IV is 1.0 g daily,divided into two equal doses,each infused after further dilution with an appropriate IV diluents,over a 60 minute time period.In children the recommended dosage is 20 mg/kg/day in two divided doses.

Brands

Tabs.Arithro 250,500 mg,Tabs.Claritek 250,500 mg.Tabs.Klaricid 250,500 mg.Tabs.Ultima 250,500 mg.