Cimetidine (sye-met’i-deen) is a histamine H2 receptor antagonist that is used to inhibit stomach acid production and is used in the treatment of gastroesophageal reflux disease and peptic ulcer disease. It is most commonly known under the brand name, Tagamet (GlaxoSmithKline Inc). It has been suggested as having a use in some dermatological conditions (eg verruca). Cimetidine, was first marketed in 1976 and became the first of the so-called ‘blockbuster’ drugs. It is available over-the-counter and on prescription. Cimetidine has been advocated for some dermatological conditions (eg verruca)
Mechanism of Action:
Cimetidine blocks the action of histamine at the histamine H2 receptors of the parietal cells in the stomach, decreasing the production of stomach acid.
It also blocks the activity of cytochrome P-450.
Brand names: Tagamet, Peptol, Cimetidine, Acid Reducer and others.
Chemical Formula: C10H16N6S
Pharmacokinetics:
Bioavailability is 60–70% and protein binding is 13–25%. It is metabolised in the liver.
The onset of action is within 30 minutes and the duration of action is 4–8 hours.
Elimination half-life is 2 hours.
Excretion is via the urine.
Side effects:
Diarrhea; skin rash; dizziness; fatigue; constipation; muscle pain, confusion, headache
Interactions:
Cimetidine has a large number of potential drug interactions as it inhibits the cytochrome P450 enzymes.
Contraindications:
Hypersensitivity.
Related Topics:
H1 Antagonists
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