Does cisapride (Prepulsid) and terazosin (Sinalfa) have antagonising effects on micturition frequen

Fråga: Does cisapride (Prepulsid) and terazosin (Sinalfa) have antagonising effects on micturition frequency? If so, what drug is recommended instead of cisapride? A 45-year-old man who is treated with cisapride for nausea and terazosin for increased micturition frequency due to benign prostate hypertrophy with initial good effect but he now thinks the micturition frequency has increased.

Sammanfattning: The effect of terazosin on the micturition frequency may sometimes be antagonised by cisapride, as cisapride, as an adverse effect, can increase the micturition frequency. Metoclopramide and terazosin could be a better combination, as metoclopramide has no documented influence on micturition frequency.

Svar: Terazosin, an alfa-1-adrenoreceptor antagonist, can be used to reduce micturition frequency in patients with benign prostate hyperplasia by its inhibiting effect on prostatic smooth muscle contraction.

Cisapride, a 5-HT3 receptor antagonist and 5-HT4 receptor agonist, causes stimulation of gastric motility and emptying. Cisapride may cause, as an adverse effect, an increase in micturition frequency according to FASS (1). The mechanism behind this is unclear.

Metoclopramide, a D2-dopamin receptor antagonist, also has a stimulating effect on gastric emptying via an unclear mechanism. Metoclopramide has no adverse effects concerning micturition frequency according to FASS and there exist no case reports of metoclopramide causing increased micturition frequency in SWEDIS (Swedish Adverse Drug Reactions Advisory Committee database) (2). A search in pharmacological handbooks describes no influence by metoclopramide on micturition frequency. There exists one case report of metoclopramide causing urinary incontinence, possibly due to relaxing effect on the urethral sphincter (3). Therefore maybe metoclopramide could be a better choice when combined with terazosin.