A 45-year-old man with irritable bowel syndrome experiences abdominal pain and bloating and is prescribed a medication to relieve smooth muscle spasm. Which drug would most likely be prescribed?

• A. Hyoscine
• B. Mebeverine
• C. Diphenhydramine
• D. Loperamide

Answer: (B)

Relieving abdominal cramping in IBS comes from using an antispasmodic that relaxes intestinal smooth muscle. Mebeverine works directly on gut smooth muscle to reduce spasms and pain, with minimal systemic absorption and fewer overall side effects, and it tends to spare normal gut movements. That gut-selective, direct action makes it a preferred choice for smoothing out the spasms that drive the symptoms.

Hyoscine can also help with cramps, but it acts as an antimuscarinic and often causes systemic anticholinergic side effects like dry mouth, constipation, and blurred vision, which can limit its use. Diphenhydramine is an antihistamine with anticholinergic effects and isn’t used for IBS spasm. Loperamide slows intestinal transit rather than specifically addressing muscle spasms, so it’s not the best option for cramping relief.