(BANM, US Adopted Name, rINNM)
International Nonproprietary Names (INNs) in main languages (French, Latin, and Spanish):
Pharmacopoeias. In Europe and Japan.
European Pharmacopoeia, 6th ed. (Pirenzepine Dihydrochlonde Monohydrate Pirenzepine Hydrochloride BP 2008). A white oryellowish crystalline powder. Freely soluble in water very slightly soluble in dehydrated alcohol practically insoluble in dichloromethane slightly soluble in methyl alcohol. A 10% solution in water has a pH of 1.0 to 2.0. Protect from light.
Adverse Effects and Precautions
Dry mouth and blurred vision have been reported but the risk of antimuscarinic effects (see Atropine Sulfate) may be reduced. Pirenzepine should be used with caution in patients with renal impairment, particularly those with end-stage renal failure.
Effects on the blood. Thrombocytopenia in one patient and agranulocytosis in another was probably associated with the use of pirenzepine.
As for antimuscarinics in general (see Atropine Sulfate).
Pirenzepine is absorbed from the gastrointestinal tract but the bi-oavailability is reported to be only about 20 to 30%, and is decreased to about 10 to 20% when taken with food. Very little pirenzepine is metabolised. About 10% of an oral dose is excreted unchanged in the urine, the remainder being excreted in the faeces.
Pirenzepine has an elimination half-life of about 12 hours and is about 12% bound to plasma proteins. Diffusion across the blood-brain barrier is poor and only minimal amounts are present in breast milk.
Renal impairment. The renal clearance and total plasma clearance of pirenzepine may be significantly reduced in patients with renal impairment, with clearance decreasing proportionately with the degree of renal impairment. The half-life of pirenzepine is increased with reported values ranging from 14 to 20 hours. Plasma concentrations of pirenzepine may be reduced by up to about 50% during haemodialysis.
Uses and Administration
Pirenzepine is a selective M1 tertiary amine antimuscarinic that displays a preferential action on the gastric mucosa thus causing a reduction in the secretion of gastric acid it also reduces the secretion of pepsin. At therapeutic doses it has few other antimuscarinic actions.
Pirenzepine hydrochloride has been used in the management of peptic ulcer disease in a usual oral dose of 50 mg two or three times daily for 4 to 6 weeks. It has also been given by slow intravenous injection in doses of up to 60 mg daily.
Myopia. Pirenzepine ophthalmic gel has been investigated in children for its potential in slowing the progression of myopia. In a study involving 353 children with myopia, pirenzepine 2% gel given once or twice daily into the lower eyelid for 1 year was associated with reduced progression: at 12 months myopia had progressed by a mean of 0.7 and 0.47 dioptres in children assigned to once and twice daily dosage respectively, compared with 0.84 dioptres in those given placebo. The gel was generally well tolerated, the most frequent adverse effects being development of papillae or follicles, or abnormalities of accommodation such as mydriasis or cycloplegia. Of 55 patients who failed to complete the study, 31 did so as a result of adverse effects.
Czech Republic: Gastrozepin
Germany: Gastricur Gastrozepin Ulcoprotect
Italy: Frazim Gastropiren
Argentina: Duo Vizerul