Hyoscine Butylbromide

Guido N. Tytgat

Abdominal cramping and pain is a frequent problem in the adult population of Western countries, with an estimated prevalence of < or =30%. Hyoscine butylbromide (scopolamine butylbromide) [Buscopan/Buscapina] is an antispasmodic drug indicated for the treatment of abdominal pain associated with cramps induced by gastrointestinal (GI) spasms. It was first registered in Germany in 1951 and marketed in 1952, and has since become available worldwide both as a prescription drug and as an over-the-counter medicine in many countries. This article reviews the pharmacology and pharmacokinetic profile of hyoscine butylbromide, and summarises efficacy and safety data from clinical trials of this drug for abdominal cramping and pain. Pharmacological studies have revealed that hyoscine butylbromide is an anticholinergic drug with high affinity for muscarinic receptors located on the smooth-muscle cells of the GI tract. Its anticholinergic action exerts a smooth-muscle relaxing/spasmolytic effect. Blockade of the muscarinic receptors in the GI tract is the basis for its use in the treatment of abdominal pain secondary to cramping. Hyoscine butylbromide also binds to nicotinic receptors, which induces a ganglion-blocking effect. Several pharmacokinetic studies in humans have consistently demonstrated the low systemic availability of hyoscine butylbromide after oral administration, with plasma concentrations of the drug generally being below the limit of quantitation. The bioavailability of hyoscine butylbromide, estimated from renal excretion, was generally <1%. However, because of its high tissue affinity for muscarinic receptors, hyoscine butylbromide remains available at the site of action in the intestine and exerts a local spasmolytic effect.Ten placebo-controlled studies have evaluated the efficacy and safety of oral or rectal hyoscine butylbromide. Hyoscine butylbromide was considered beneficial in all of these trials, which supports its use in the treatment of abdominal pain caused by cramping. Hyoscine butylbromide is barely absorbed and detectable in the blood and does not penetrate the blood-brain barrier, and is, therefore, generally well tolerated. Few adverse events have been reported; in particular, no significant increases in the incidence of anticholinergic-related adverse effects have been observed. In summary, hyoscine butylbromide appears to be a valuable treatment option for patients with symptoms of abdominal pain or discomfort associated with cramping.