The evidence for using hyoscine N-butylbromide (Buscopan^®) in ureteric obstruction

Hyoscine butylbromide is used regularly in some countries to treat a variety of urologic conditions, by virtue of its spasmolytic effect on the smooth musculature of the urinary tract 1, either as monotherapy or part of a combined approach, with controversial results. An evidence-based approach is required to clarify the role of hyoscine in the management of acute urinary obstruction. Hyoscine butylbromide is a quaternary ammonium compound with anticholinergic properties. It exhibits high affinity for muscarinic receptors and also binds to nicotinic receptors. Inhibition of cholinergic transmission in the abdominal and pelvic parasympathetic ganglia produces the spasmolytic effect in the smooth muscle of gastrointestinal, biliary, urinary tract and female genital organs. It is usually administered parenterally, as oral bioavailability is low, with plasma concentrations measured below the limit of quantitation 1. Also described as scopolamine butylbromide and butylscopolamine, hyoscine is available both as a prescription drug and as an over-the-counter medicine worldwide. It is extensively used in many fields of medicine, especially gastroenterology, anaesthesia and in chronic pain management; yet, the evidence for its specific use and suitability in urology are limited. Ureteric colic is generated by hyperperistalsis of the obstructed ureter and modulated by alpha-receptors (contraction), beta-receptors (relaxation) and prostaglandins (PG F2a: contraction, PGE1/E2: relaxation). Increases in collecting system pressure and ureteral wall tension are also proposed mechanisms. This effect is augmented by the resulting inflammation and oedema caused by stone impaction and by increasing ureteral peristalsis as a direct consequence of an obstructing calculus 2. All these changes constitute the pharmacologic targets of the various medications used in management. The role of butylscopolamine in facilitating ureteral stone passage by acting as a muscle relaxant has been investigated and the results do not support the theory. In vitro, hyoscine did not prove effective in relaxing isolated human ureteric smooth muscle 3. The drug had virtually no lasting effect on the ureter nor did it help the passing of stones by reducing friction in vivo in an experimental rabbit model (LE: 2b) 4. In the study by Gurbuz et al., the stone expulsion rate was higher in the groups of patients treated with different doses of alpha 1-adrenergic blockers than in the groups that received hyoscine (LE: 1b) 5. Studies in 10 patients with neurogenic bladder treated regularly with the drug showed a significant mean increase in bladder capacity and reduced spasm amplitude. This decrease in intravesical pressure was believed to have a secondary effect on pain and spasticity of the urinary system as a whole (LE: 2b) 6. However, the results from three double-blind clinical trials showed no pain relief with hyoscine monotherapy during or after extracorporeal shock-wave lithotripsy (LE: 1b) 7. The addition of hyoscine to opioids in managing renal colic was not found to be effective, although it is widely used in palliative chronic pain management. In a placebo-controlled study of 178 patients by Tomiak et al., no reduction in the need for opioids was confirmed (LE: 1b) 8, a finding further supported in a Cochrane systematic review (LE: 1a) 9. Data from prospective and double-blind randomised studies are suggestive of some effect of HBB in prolonging analgesia when combined with non-steroid anti-inflammatory drugs (NSAIDs). In a double-blind study of hyoscine with dipyrone vs. fluriproben, the synergistic action proved to be effective in providing significant pain relief, although it was suggested that the NSAIDs act more quickly with a longer duration (LE: 1b) 10. Although hyoscine butylbromide is still used often in the management of urological conditions, where urinary tract smooth muscle spasm is thought to be part of the pathophysiological process, its use appears to follow non-peer reviewed protocols based on empiric recommendations. There is good quality evidence that demonstrate no advantage over established forms of analgesia, nor in combination with opioids for treating acute renal colic. When compared with NSAIDs, the onset of and duration of analgesia is superior with the latter to that of hyoscine alone. There appears to be a time dependent relation to pain reduction following parenteral administration, but this needs to be confirmed by more prospective randomised cohorts. None.