|
Cimetidine
Composition and Description
Cimetidine 200 mg/tablet Round, pale yellow film-coated tablet, bevel-edged,
shallow convex faces.
Cimetidine 400 mg/tablet Oblong, pale yellow film-coated tablet, deep convex
faces and break-bar embossed on one face.
Cimetidine 800 mg/tablet Oblong, pale yellow film-coated tablet with shallow
convex faces, bevel-edged and break-bar embossed on one face.
Actions and Pharmacology
Cimetidine inhibits basal and nocturnal gastric acid secretion by
competitive inhibition of the action of histamine at the histamine
H2-receptors. It also inhibits gastric acid secretion stimulated by food,
betasole, pentagastrin, caffeine, insulin and physiological vagal reflex.
Cimetidine is well absorbed from the gastrointestinal tract and is weakly
bound to plasma proteins. It is partially metabolised in the liver and most
of an oral dose of cimetidine is excreted unchanged in the urine.
Indications
Cimetidine is indicated in the :
- prophylaxis and treatment of duodenal ulcer.
- short-term treatment of active benign gastric ulcer.
- treatment of pathological gastric hypersecretion states, such as Zollinger-Ellison
syndrome.
- treatment of acute
gastroesophageal reflux disease.
- treatment of upper gastrointestinal bleeding.
Contraindications
- Avoid in patients known to be hypersensitive to histamine H2-receptors
antagonists.
- It should not be used in
nursing mothers.
Precautions
- Caution in patients with cirrhosis, history of portal systemic
encephalopathy, hepatic and renal function impairment.
- Safety for use in pregnancy has
not been established.
- Dosage should be reduced in patients with impaired renal function.
- Care should be taken in patients with a history of peptic ulcer,
particularly the elderly.
Main Side/Adverse Effects
Diarrhoea, dizziness, tiredness, rashes. Reversible confusional states,
especially in the elderly or in seriously ill patients such as those with
renal failure, gynaecomastia and impotence have occasionally occurred.
Drug Interactions
Concurrent use with the following drugs requires careful monitoring :
- Theophylline, phenytoin, lidocaine, anti-arrhythmias, benzodiazepines,
some beta-blockers and some vasodilators.
Adjustment to anti-coagulant medications may be necessary during and after
cimetidine therapy to prevent bleeding due to anti-coagulant potentiation.
Overdosage
Clinical features : Allergic reaction, bradycardia or tachycardia,
bronchospasm, confusion, neutropenia or other blood dyscrasias and fever may
occur.
Treat overdosage by emesis or gastric lavage; artificial respiration in the
event of respiratory failure and administration of beta-blocker to control
tachycardia.
Dosage and Administration
Adults (Oral) :
Duodenal or benign gastric ulcer :
A single daily dose of 800
mg at bedtime, or
400 mg twice a day with
breakfast and at bedtime, or
200. mg three times a day with meals and 400 mg at bedtime (1.0 g/day),
or
400 mg four times a day
with meals and at bedtime (1.6 g/day).
Treatment should be given initially for at least four weeks (six weeks in
benign gastric ulcer).
Oesophageal reflux disease : 400 mg four times a day, with meals and at
bedtime, for 4 to 8 weeks.
Gastric hypersecretion states (eg
Zollinger-Ellison Syndrome) : 400 mg four times a day.
The total daily dose should not exceed 2.4 g. Dosage should be reduced in
patients with impaired renal function. Antacids can be made available to all
patients until symptoms disappear.
Children (more than one year old) : Oral, 25 - 30 mg/kg of body
weight per day in divided doses.
Shelf-life
3 years from the date of
manufacture.
Storage
Store below 25°C. Protect from
light and moisture.
Presentation/Packing
Film-Coated Tablet 200 mg x
100's, 500's, 1000's, Blisters of 10 x 10's.
Film-Coated Tablet 400 mg x 100's, 500's, 1000's, Blisters of 10 x 10's.
Film-Coated Tablet 800 mg x 100's, 500's, 1000's, Blisters of 10 x 10's.
|
