Cimetidine 800mg Tablets
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Cimetidine 800mg Tablets
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Cimetidine tablets contain 800mg of the active ingredient Cimetidine USP
3 PHARMACEUTICAL FORM
Tablet.
Cimetidine 800 mg Tablets are green elliptical film coated tablets coded CIM on one side and 800 on reverse
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Benign gastric and duodenal ulceration, stomal ulcer, reflux oesophagitis, Zollinger - Ellison syndromes, other conditions where gastric acid reduction is beneficial.
The prophylaxis of gastro-intestinal haemorrhage from stress ulceration in seriously ill patients.
Before general anaesthesia in patients thought to be at risk of acid aspiration (Mendelson’s) syndrome, particularly obstetric patients during labour.
To reduce malabsorption and fluid loss in the short bowel syndrome.
4.2 Posology and method of administration
Adults:
The usual dosage is 400 mg twice a day with breakfast and at bedtime. Duodenal ulceration may be treated with a single daily dose of 800 mg at bedtime. Other effective regimens are 200 mg three times a day with meals and 400 mg at bedtime (1.0 g/day) and, if inadequate, 400mg four times a day (1 .6g/day) with meals and at bedtime.
Treatment should be given initially for at least four weeks (six weeks in benign gastric ulcer) even if symptomatic relief has been achieved sooner.
Treatment may be continued for longer periods in patients who may benefit from reduction of gastric secretion and the dosage may be reduced in those who have responded to treatment, for example to 400 mg at bedtime or 400 mg in the morning and at bedtime.
In patients with benign peptic ulcer disease who have responded to the initial course, relapse may be prevented by continued treatment. Usual dosage for maintenance treatment is 400 mg at bedtime but 400 mg in the morning and at bedtime has also been used. In oesophageal reflux disease, 400 mg four times a day with meals and at bedtime for four to eight weeks is recommended.
In patients with very high gastric acid secretion (e.g. Zollinger-Ellison syndrome) it may be necessary to increase the dose to 400 mg four times a day, or in occasional cases further.
Antacids can be made available to all patients until symptoms disappear.
In the prophylaxis of haemorrhage from stress ulceration in seriously ill patients up to a usual maximum of 2.4 g per day can be given in divided doses to maintain intragastric pH above 4.
In patients thought to be at risk of acid aspiration syndrome an oral dose of 400 mg can be given 90 - 120 minutes before induction of general anaesthesia.
Up to this dose may be repeated (parenterally if appropriate) as required if operation is prolonged. In obstetric patients during labour, an initial oral dose of 400 mg at the start of labour followed by 200 mg every two hours to a maximum of 1.6 g has been used. The usual precautions to avoid acid aspiration should be taken.
In the short bowel syndrome, e.g. following substantial resection for Crohn's disease, the usual dosage can be used.
Use in the elderly:
The normal adult dosage should be used unless renal function is markedly impaired.
Use in children over 1 year:
20 to 30 mg/kg daily in divided doses.
Route of administration:
Oral
4.3 Contraindications
No know contraindications
4.4 Special warnings and precautions for use
Use of cimetidine in treatment for undiagnosed dyspepsia is undesirable because, by ameliorating symptoms and inducing surface healing, it can delay the diagnosis of gastric cancer.
Dosage should be reduced in patients with impaired renal function according to creatinine clearance. The following dosages are suggested:
Creatinine clearance of 0 to 15 mg/minute -200 mg twice a day
15 to 30 ml/minute -200 mg three times a day 30 to 50 ml/minute -200 mg four times a day over 50 ml/minute- normal dosage
Cimetidine is removed by haemodialysis.
In patients on drug treatment or with illnesses that could cause falls in blood count, the possibility that H2- receptor antagonism could potentiate the effect should be borne in mind.
4.5 Interaction with other medicinal products and other forms of interaction
Care should be exercised when cimetidine is given simultaneously with metoprolol, propranolol and labetolol due to the possibility of increased bioavailability of these beta-blockers.
The elimination of diazepam (and its main metabolite desmethyldiazepam) and chlordiazepoxide has been shown to be prolonged in normal subjects and it is prudent that patients should be monitored for excessive sedation when these agents and cimetidine are administered concurrently. Augmentation of sedation should also be monitored when cimetidine and chlormethiazole are used in combination.
Caution is necessary when cimetidine is given simultaneously with anticoagulants owing to reduced rate of metabolism of these agents. Careful monitoring of the coagulation status of the patient is advised. Similarly the metabolism of phenytoin, carbamazepine and theophylline (or aminophylline) can be prolonged with concurrent use of cimetidine, and plasma levels of these drugs should be monitored and dosage reduced as necessary.
Renal clearance of drugs such as procainamide is retarded.
Pregnancy and lactation
4.6
Although tests in animals have not revealed any hazards from the administration of cimetidine during pregnancy or lactation, both these and studies in women have shown that it does cross the placental barrier and is excreted in milk. As with most drugs, the use of cimetidine should be avoided during pregnancy and lactation unless essential.
4.7 Effects on ability to drive and use machines
In view of reported dizziness and tiredness when taking cimetidine patients should be warned of these possibilities and that they may affect their ability to drive or operate machinery.
4.8 Undesirable effects
Diarrhoea, dizziness or rash, usually mild and transient, and tiredness have been reported. Gynaecomastia has been reported and is almost always reversible on discontinuing treatment. Biochemical or biopsy evidence of reversible liver damage has been reported occasionally. Reversible confusional states have occurred, usually in elderly or already very ill patients, e.g. those with renal failure. There have been very rare reports of interstitial nephritis, acute pancreatitis, thrombocytopenia, headache, myalgia and arthralgia, all reversible on withdrawal of treatment. Alopecia has been reported but no causal relationship has been established. Reversible impotence has also been very rarely reported but no causal relationship has been established at usual therapeutic doses. Isolated increases of plasma creatinine have been of no clinical significance.
4.9 Overdose
In acute overdosage the induction of vomiting and / or gastric lavage may be employed together with symptomatic and supportive therapy.
5 PHARMACOLOGICAL PROPERTIES
5.1
Pharmacodynamic properties
Cimetidine is an H2 blocker with reversible competitive antagonism of the actions of histamine. Cimetidine inhibits gastric acid secretion elicited by histamine or other H2 antagonists, it also inhibits the gastric secretion, reduces the volume of juice secreted and its hydrogen ion concentration.
5.2 Pharmacokinetic properties
Cimetidine is reported to be rapidly absorbed from the gastro-intestinal tract with an elimination half life of around 2 - 3 hours. Peak plasma concentrations are attained in about 1 - 2 hours and there is a reported large inter subject variation occurring in Cmax and Tmax and Auc’s.
Over two-thirds of a dose is excreted in the urine within 24 hours, following parenteral administration this is mainly as unchanged cimetidine, but following oral administration a portion is metabolised, mainly to the sulphoxide. Cimetidine crosses the placental barrier and excreted in milk. It does not readily cross the blood-brain barrier.
5.3 Preclinical safety data
Not applicable
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Starch
Povidone
Magnesium Stearate Sodium Starch Glycollate Purified Water
Hydroxypropyl Methyl cellulose Polyethylene Glycol 400
6.2 Incompatibilities
None known.
Shelf life
6.3
Shelf life of product as packaged for sale 3 years from the date of manufacture
Shelf life after dilution or reconstitution according to directions Not applicable
Shelf life after first opening the container 3 years from the date of manufacture
6.4 Special precautions for storage
Store below 25°C.
6.5 Nature and contents of container
Blister packages of PVDC (60gsm) coated PVDX (250p)/Aluminium blisters in the following pack sizes: 30, 50, 100, 250, 500, & 28.
6.6 Special precautions for disposal
No special instructions
7. Marketing Authorisation Holder
Medreich Plc Warwick House Plane Tree Crescent Feltham TW13 7HF
8 MARKETING AUTHORISATION NUMBER(S)
PL 21880/0090
DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
19th January 2005
10
DATE OF REVISION OF THE TEXT
25/06/2013