Cimetidine

Cimetidine

Class:Antipeptic ulcerants

Mechanism of action

Competitive inhibition of histamine at H2 receptors of the gastric parietal cells resulting in reduced gastric acid secretion,gastric volume and hydrogen ion concentration reduced.

Pharmacokinetics

Onset of action:1 hour.peak serum concentration:1 hour after oral dose.Duration 6 hours.Distribution:crosses the placenta;appears in breast milk.Protein binding 20 percent.Bioavailability:60 to 70 percent.Elimination :principally as unchanged drug by the kidney;some excretion in bile and feces.

Indications

Treatment of acute gastritis,which can manifest as heartburn,epigastric pain,hyperacidity,dyspepsia or acute aggravation of chronic gastritis.

Precautions

Exclude malignancy in gastric ulcer.use in pregnancy should be avoided unless essential for patient's benefit.Dosage to be reduced in patients with severely impaired renal funtion.

Side effects

Diarrhea,dizziness,rash,tiredness;reversible gynecomastia has been reported;reversible liver damage,acute pancreatitis,thrombocytopenia,agranulocytosis,headache,myalgia,arthralgia,dysrhythmias and anaphylaxis;also aplastic anemia,very rarely alopecia,isolated increases of plasma creatinine and serum transamine.

Pregnancy

Pregnancy risk factor B

Drug interactions

Cimetidine may prolong the clearance of warfarin-type anticoagulants,phenytoin,theophylline and nifedipin.Patient receiving such drugs should be monitored ,as dosage reduction may be necessary.

Dosage

200 mg (10 ml) twice a day after breakfast and at bed time.

Brands

Tabs.Cimet 400 mg,Tabs.Tagamet 200 mg.