A 27-year-old man treated with risperidon (Risperdal) described difficulties in emptying the bladde

Fråga: A 27-year-old man treated with risperidon (Risperdal) described difficulties in emptying the bladder. The dose was 2 mg daily. The symptoms continued with increased dose and treatment was discontinued 4 months later. An urologist diagnosed atony of the bladder. Has dysfunction of the urinary bladder been described in patients treated with risperidone?

Sammanfattning: Symptoms related to bladder dysfunction are described and can be explained by risperidone´s pharmacological properties of blocking muscarin and alfa-1 receptors in the bladder.

Svar: Urinary incontinence is an uncommon adverse reaction described in patients treated with risperidone (1). Two cases of enuresis and three cases of urinary incontinence are reported in SADRAC and were evaluated to be possibly related to intake of risperidone. In three of the cases the adverse reaction disappeared after discontinued treatment (2).

A total of 500 cases of urinary disorders in patients treated with risperidone have been reported to the WHO database of adverse reactions. Among these there are 42 cases of urinary retention. Other diagnoses which could be related to atony of the bladder included fluid overload (4) and micturition disorder (83). Urinary incontinence (207) was reported as well. Although the information content of the WHO reports is not sufficiently detailed to allow cause-effect relationship in each case, the total number of reports indicates that bladder dysfunction is a drug induced adverse-effect in patients treated with risperidone.

Neuroleptics are well known to cause urinary dysfunctions. Risperidone has a low affinity to cholinergic receptors and at a sufficiently high concentration the drug can achieve the same degree of receptor blockade as a drug of relatively high affinity to the receptor (1,3). Some important functions of this receptor is the control of micturition and a blockade of the receptors can result in urinary retention. Risperidone has also a relatively high binding affinity for alfa-1 and alfa-2 receptors and is an antagonist on both receptors (3). A blockade of alfa-1 receptors could contribute to the reported cases of incontinence and enuresis since the blockade antagonises contraction of trigonal muscle, the internal sphincter of the bladder and may therefore cause leakage of urine. Therapeutic or adverse effects of blockade of the alfa-2 receptors are not known (3).