Gastrointestinal therapeutics
Practice questions with explanations

C. Non-selective beta-blockers such as propranolol or carvedilol

Non-selectivity is essential: beta-1 blockade reduces cardiac output while unopposed alpha activity in the splanchnic circulation causes vasoconstriction and reduced portal inflow, and cardioselective agents lack the second mechanism. Carvedilol adds alpha-1 blockade and lowers portal pressure further. Caution applies in advanced disease with refractory ascites.

C. Age, alarm features and local prevalence, with a test and treat approach appropriate for younger patients without alarm symptoms

Test and treat avoids endoscopy in younger patients without alarm features, while those with dysphagia, weight loss, bleeding, anaemia or new symptoms over 50 need direct visualisation. Testing requires the patient to have stopped a proton pump inhibitor for two weeks and antibiotics for four to avoid false negatives.

C. It is a mu agonist acting on gut opioid receptors, and P-glycoprotein pumps it out of the brain

Loperamide slows transit through enteric mu receptors, allowing more water reabsorption. It is a P-glycoprotein substrate and is efficiently excluded from the central nervous system, which is why it is available without prescription. That protection fails in massive overdose, where central opioid effects and dangerous cardiac conduction abnormalities occur, a recognised problem in misuse.