Methaphyllin

Methaphyllin is indicated in adults for the following conditions:

Adjunctive in GI disorders characterised by smooth muscle spasm

Hyperhidrosis

Adult enuresis

Posology

Adults

The recommended initial starting dose is one tablet before each meal and two tablets at bedtime. Subsequently, dosage should be adjusted according to the patient's individual response and tolerance. Doses up to 120mg may be required in some patients.

Elderly

Elderly patients may be more susceptible to antimuscarinic side effects; glaucoma and urinary retention may occur. Consideration should be given to the presence of other disease and concomitant drug therapy (see contraindications, warnings etc).

Paediatric population

Safety and efficacy of Methaphyllin in children have not been established.

Caution

Food has been reported to reduce the bioavailability of Methaphyllin. Tablets should be taken at least one hour before meals.

Method of administration

Oral

Methaphyllin is contraindicated in patients with obstructive diseases of the gastrointestinal or urinary tract, pyloric stenosis, paralytic ileus, intestinal atony, severe ulcerative colitis or toxic megacolon, hiatus hernia associated with reflux oesophagitis, unstable cardiovascular adjustment in acute haemorrhage, myasthenia gravis, prostatic enlargement and in patients who are hypersensitive to propantheline bromide.

Methaphyllin should not be given to patients with closed-angle glaucoma or those with shallow anterior chamber, since it may raise intra-ocular pressure.

Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.

In some patients, especially those with ileostomy or colostomy, diarrhoea may be a symptom of incomplete intestinal obstruction. Methaphyllin therapy should be avoided in such patients.

Patients with severe heart disease in whom an increase in heart rate is undesirable should be observed closely if Methaphyllin is administered.

Patients with ulcerative colitis should be treated with caution, since Methaphyllin may suppress intestinal motility to the point of producing paralytic ileus, thus precipitating or aggravating toxic megacolon.

Methaphyllin should be used with caution in the elderly and all patients with autonomic neuropathy, hepatic or renal disease, hyperthyroidism, coronary heart disease, congestive heart failure, cardiac arrhythmias or hypertension.

Methaphyllin may induce fever and heat stroke in patients in a high environmental temperature due to decreased sweating.

Methaphyllin should be used with caution in patients with Down's syndrome.

Methaphyllin should also be used with caution in gastrointestinal reflux disease, acute myocardial infarction, cardiac insufficiency and pyrexia.

Methaphyllin may produce drowsiness or blurred vision. Patients should not drive or operate machinery if affected in this way.

Side effects of antimuscarinics include dryness of the mouth with difficulty in swallowing and thirst, dilatation of the pupils with loss of accommodation and sensitivity to light, increased intra-ocular pressure, flushing, dryness of the skin, decreased sweating, heat stroke, bradycardia followed by tachycardia, palpitations and arrhythmias, urinary hesitancy and retention, constipation, reduced bronchial secretions, occasional confusion in the elderly, occasional nausea and vomiting, and occasional dizziness.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.

Intensification of the usual side effects may occur. In severe intoxication disturbances of the central nervous system may occur resulting in convulsion, coma, circulatory failure, respiratory depression, delirium, hallucinations and restlessness. Toxic doses of propantheline bromide may produce non-depolarising neuromuscular blocking effects with paralysis of voluntary muscle.

In the event of overdosage, empty the stomach and give activated charcoal. Excitement may be controlled by diazepam. Supportive treatment may require oxygen, assisted ventilation and the administration of fluids. In severe cases (convulsions, hyperpyrexia, respiratory depression) the use of intravenous physostigmine (0.5mg to 2mg) should be considered. Since it has a brief duration of action of about 1 to 2 hours, it may be necessary to repeat injections up to a total dose of 5mg.

Pharmacotherapuetic group: Synthetic anticholinergics, quaternary ammonium compounds, ATC Code: A03AB05

Methaphyllin inhibits parasympathetic activity by blocking the action of the neurohormone, acetylcholine, on the neuroeffector cell. This blocking action of Methaphyllin is instrumental in reducing gastric acid secretion and gastrointestinal motor activity.

Propantheline bromide is extensively metabolised in man. Some enzymatic hydrolysis of the drug may occur in the gastrointestinal tract prior to its absorption.

Studies in healthy men demonstrated that peak plasma levels of unchanged drug were reached within 2 hours of a single, oral dose of propantheline bromide. Following single oral dosing the plasma elimination half-life was about 2 to 3 hours and some 1% to 10% of propantheline bromide was excreted in urine as unchanged drug.

In healthy men studies have shown onset of antimuscarinic effects within 1 hour of oral administration. Effects persisted for up to 6 hours after oral dosing.

Not applicable

None reported

No special requirements