Cimetidine Pharmacology

Cimetidine

About Cimetidine
Histamine H2-receptor antagonist, Antiulcer.
Mechanism of Action of Cimetidine
Cimetidine is a H2 (Histamine) receptor antagonist.Histamine is the most potent stimulus of acid secretion and acts as the common mediator. H2 receptor is a G-protein coupled receptor. It induces adenylate cyclase which converts ATP to cyclic AMP. This cyclic AMP acts on proton pump and exchange extracellular potassium ion for intracellular hydrogen ion across the parietal cell membrane. Cimetidine reversibly competes with Histamine for binding to H2 receptors on the basolateral membrane of parietal cells and predominantly inhibits basal acid secretion.
Pharmacokinets of Cimetidine
Absorption: It is rapidly absorbed after oral administration. Distribution: Distributed to body tissues in unbound form. Metabolism: Small amount of Cimetidine undergoes metabolism in the liver. Excretion: It is excreted mainly in urine.
Onset of Action for Cimetidine
60 - 90 minutes
Duration of Action for Cimetidine
4- 6 hours
Half Life of Cimetidine
2 hours
Side Effects of Cimetidine
1.Headache
2.Dizziness
3.Diarrhoea
4.Myalgia
5.Arthralgia
6.Fatigue
7.Blood dyscrasias
8.Rash
9.Hypersensitivity reactions
10.Gynaecomastia (long term use)
Contra-indications of Cimetidine
1.Hypersensitivity to Cimetidine
Special Precautions while taking Cimetidine
1.Hepatic impairment
2.Renal impairment
3.Cardiovascular diseases
4.Debilitated patients
Pregnancy Related Information
Use with caution
Old Age Related Information
Use with caution.
Breast Feeding Related Information
Use with caution.
Children Related Information
Use with caution.
NEONATES: contraindicated
Indications for Cimetidine
1.Duodenal ulcer
2.Zollinger- Ellison syndrome
3.Benign gastric ulcer
4.Gastroesophageal reflux
5.Acid indigestion, Heart burn, Sour stomach
6.Peptic oesophagitis, Stress ulcers, Upper gastrointestinal bleeding
Interactions for Cimetidine
Increases the efficacy of the following drugs by reducing their hepatic metabolism: Benzodiazepines, Caffeine, Calcium channel blockers, Carbamazepine, Chloroquine, Pentoxifylline, Phenytoin, Propranolol, Quinidine, Quinine, Sulfonylureas, Theophyllines, Triamterene, TCAs,
Warfarin.
Decreases the efficacy of the following drugs by decreasing their absorption: Ferrous salts, Indomethacin, Ketoconazole, Tetracyclines.
Following agents decreases the absorption of cimetidine: Antacids, Anticholinergics, Metoclopramide.
Cigarette smoking: Reverses cimetidine induced inhibition of nocturnal gastric and secretion.
Digoxin, Fluconazole: Decreased efficacy of digoxin & flunconazole.
Narcotic analgesics: Toxic effects increased by cimetidine.
Procainamide: Efficacy enhanced by cimetidine.
Succinylcholine: Neuromuscular blockade increased by cimetidine leading to prolonged respiratory depression.
Typical Dosage for Cimetidine
Adult: 400 mg 1 - 4 times depending on the indication
Duodenal ulcer: 800 mg at bed time for 8 weeks
Zollinger- Ellison syndrome: 1200mg / day in 4 divided doses; dose can be increased if necessary to a maximum up to 2400 mg / day
Benign gastric ulcer: 800 mg at bed time for at least 6 weeks.
Gastroesophageal reflux: 1600 mg / day in 2 - 4 divided doses to be taken before meals and at bed time.
Acid indigestion, Heart burn, Sour stomach: 200 mg / day to be taken at bed time dose can be increased up to maximum of 400 mg / day
Peptic oesophagitis, Stress ulcers, upper gastrointestinal bleeding: Dose: 250 - 500 mg 4 times daily.
Children: 5 - 10 mg / kg 4 times daily.
Schedule of Cimetidine
H
Storage Requirements for Cimetidine
Store at 15 - 30 degree C in a tightly closed container.
Effects of Missed Dosage of Cimetidine
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Cimetidine
Give supportive measures and symptomatic treatment. Drug can be removed from the body by inducing emesis and or by gastric lavage. Activated charcoal is given to reduce the absorption of the drug. Tachycardia can be treated with Propranolol. Haemodialysis can be done if necessary.

Home Delivery for Cimetidine in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including cimetidine.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for cimetidine and other medicines and health products. Home delivery services for cimetidine may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take cimetidine only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for cimetidine before they complete the sale. You can get this information while placing the order for cimetidine with the pharmacy.

Cimetidine is a generic medicine name and there are several brands available for it. Some of the brands for cimetidine might be better known than cimetidine itself. If the pharmacy that's willing to deliver medicines to your home doesn't have cimetidine in stock, you can ask for one of the branded alternatives for cimetidine.