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.
