Drug-induced bladder and urinary disorders. Incidence, prevention and management

The bladder is vulnerable to the adverse effects of drugs because of its complex control and the frequent excretion of drug metabolites in the urine. Incontinence results when bladder pressure exceeds sphincter resistance. Stress incontinence because of sphincter weakness occurs with antipsychotics and alpha-blockers, especially in women. Urge incontinence and irritative symptoms may be caused by drugs. Anticholinergics, anaesthetics and analgesics cause urinary retention because of failure of bladder contraction. They are more likely to cause retention in men because of prostatic enlargement. Cyclophosphamide and tiaprofenic acid can cause chemical cystitis, and should be withdrawn if a patient develops irritative symptoms or haematuria. Cyclophosphamide may also induce bladder tumours. Adverse effects of cyclophosphamide can be reduced with prophylactic administration of mesna and adequate hydration. Mitomycin, doxorubicin or bacillus Calmette-Guerin (BCG) instilled locally to treat bladder tumours can cause cystitis, contracture and calcification. Their administration should be limited to 1 hour per week for a maximum of 8 weeks. Retroperitoneal fibrosis and urine discolouration may be caused by drugs. Ureteric calculi may result from any drug causing nephrolithiasis.