7.4.1 Drugs for urinary retention
Drugs for urinary retention (due to benign prostatic hyperplasia)
First-choice: Tamsulosin 400micrograms m/r capsules
Second-choice: Alfuzosin XL 10mg m/r tablets
Tamsulosin and alfuzosin XL are alpha1-selective alpha-blockers. Alpha-blockers relax smooth muscle in benign prostatic hyperplasia (BPH) improving obstructive symptoms and urinary flow rate. Alpha-blockers reduce blood pressure, monitor BP in hypotensive patients or those already on antihypertensive therapy as dose reduction may be required.
5α-reductase inhibitors are used in the treatment of BPH. They reduce prostate size, reducing obstructive symptoms and increasing urinary flow rate. For information on the use of 5α-reductase inhibitors in the treatment of BPH see 6.4.2.
Doxazosin (tablets) is an alpha1-selective alpha-blockers which may be of particular value in patients with BPH who require concurrent treatment for hypertension.
Distigmine bromide (tablets) is a muscarinic drug which improves voiding efficiency by increasing detrusor muscle contraction. It is also used to treat patients with an upper motor neurone neurogenic bladder.
PRESCRIBING POINTS FOR DRUGS FOR URINARY RETENTION
- Alpha-blocking drugs may cause a wide range of side-effects including sedation and hypotension. Special care (and reduced dosage) is needed when initiating them in the elderly, in renal and, possibly, hepatic impairment, and in patients receiving antihypertensives. They may also cause drowsiness and affect the ability to drive or operate machinery.
- Men should be warned regarding retrograde ejaculation, which can occur with alpha-blocker usage.
- Anti-muscarinic medication should not be used in men at risk of urinary retention without specialist advice.
- Distigmine bromide tablets should be given on an empty stomach, half an hour before breakfast.