Oxybutynin hydrochloride

Chemical Properties

White to Off-White Solid

Originator

Ditropan, Marion , US ,1975

Uses

An antagonist of M1, M2, & M3 muscarinic acetylcholine receptors

Uses

anticholinergic

Uses

An inhibitor of proliferation and supresses gene expression in bladder smooth muscle cells

Manufacturing Process

A mixture of 394.2 grams of methyl phenylcyclohexylglycolate and 293.1 grams of 4-diethylamino-2-butynyl acetate was dissolved with warming in 2.6 liters of n-heptane. The solution was heated with stirring to a temperature of 60° to 70°C and 8.0 grams of sodium methoxide were added. The temperature of the mixture was then raised until the solvent began to distill. Distillation was continued at a gradual rate and aliquots of the distillate were successively collected and analyzed for the presence of methyl acetate by measurement of the refractive index. The reaction was completed when methyl acetate no longer distilled, and the refractive index observed was that of pure heptane (nD26 = 1.3855). About 3 hours were required for the reaction to be completed.
The reaction mixture was then allowed to cool to room temperature, washed with water, and extracted with four 165 ml portions of 2 N hydrochloric acid. The aqueous extracts were combined and stirred at room temperature to permit crystallization of the hydrochloride salt of the desired product. Crystallization was completed by cooling the slurry in an ice bath, and the product was collected by filtration, pressed dry, and recrystallized from 750 ml of water. Yield of pure crystalline material, 323 grams.

brand name

Ditropan (ALZA).

Therapeutic Function

Spasmolytic

Biological Activity

oxybutynin is an anticholinergic medication used to relieve urinary and bladder difficulties.

Biochem/physiol Actions

Muscarinic acetylcholine receptor antagonist; inhibits proliferation of bladder smooth muscle cells, perhaps by downregulation of growth promoting genes.

Clinical Use

Urinary frequency, urgency and incontinence
Neurogenic bladder instability and nocturnal enuresis

Safety Profile

Poison by ingestion, intravenous, and intraperitoneal routes. An experimental teratogen. Experimental reproductive effects. An eye irritant. Human systemic effects: coma, mydriasis, rate changes. An anticholinergic agent. When heated to decomposition it e

Drug interactions

Potentially hazardous interactions with other drugs
Anti-arrhythmics: increased risk of antimuscarinic side effects with disopyramide.
Other antimuscarinic agents: increased antimuscarinic effects.

Metabolism

Oxybutynin undergoes extensive first-pass metabolism, particularly by the cytochrome P450 isoenzyme
CYP3A4. One of the metabolites, N-desethyloxybutynin is pharmacologically active.
Oxybutynin and its metabolites are excreted in the urine and faeces.