Q1. An enzyme INHIBITOR added to an existing drug will: A. Lower that drug's level and risk treatment failure B. RAISE that drug's level and risk toxicity C. Have no effect on the level D. Only affect renally cleared drugs ANSWER: B — raise the level. Why: inhibiting the metabolising enzyme slows breakdown, so the drug accumulates. An INDUCER does the opposite: more enzyme, faster metabolism, lower level, treatment failure. LEARNING POINT: INDUCE = REDUCE · INHIBIT = INCREASE.

Q2. Which drug class should generally be AVOIDED in significant renal impairment? A. NSAIDs B. Inhaled corticosteroids C. Topical emollients D. Proton pump inhibitors ANSWER: A — NSAIDs. Why: they reduce renal blood flow by constricting the afferent arteriole, at exactly the time when renal perfusion is already compromised. LEARNING POINT: renally cleared drugs also accumulate and need dose or interval adjustment.

Q3. A man stable on warfarin for four years is given a short course of another drug and develops bruising with a markedly raised INR. His warfarin dose is unchanged. The mechanism is: A. Enzyme INDUCTION B. Enzyme INHIBITION raising the warfarin level C. Poor adherence D. Vitamin K excess ANSWER: B — enzyme inhibition. Why: slowed metabolism raises the warfarin level at an unchanged dose. Four years of stability is what makes the new drug the suspect. LEARNING POINT: warfarin has a narrow therapeutic index — check interactions before adding anything.

Q4. An older woman develops tremor and slowed movement; she is treated for Parkinson's disease, then given an antiemetic for nausea, then falls. The best next step is: A. Add a further drug for the falls B. REVIEW THE WHOLE DRUG CHART for a drug-induced cause C. Arrange brain imaging only D. Increase the Parkinson's treatment ANSWER: B. Why: this is a prescribing cascade. Drug-induced parkinsonism is recognised and reversible, and each subsequent prescription treated the effects of the previous one. LEARNING POINT: ask "could a drug be causing this?" before adding another.

Q5. A 78-year-old on a stable dose of a renally cleared drug becomes confused after several days of vomiting, with a high drug level. The explanation is: A. The prescription was wrong all along B. Reduced renal clearance from dehydration and age has caused ACCUMULATION C. A new allergy D. Enzyme induction ANSWER: B. Why: the dose did not change — the clearance did. This is one of the commonest mechanisms of medication harm in older patients. LEARNING POINT: sick-day guidance and dose review against current renal function prevent it.

Q6. A patient with "penicillin allergy" recorded describes childhood nausea and loose stools. The correct action is: A. Automatically use a broader-spectrum alternative B. Take a proper allergy history and CORRECT THE RECORD C. Record it as anaphylaxis to be safe D. Avoid all antibiotics ANSWER: B. Why: nausea is an intolerance, not an allergy. Mislabelling leads to broader-spectrum, sometimes less effective and more toxic alternatives, and drives resistance. LEARNING POINT: always ask WHAT HAPPENED — genuine anaphylaxis is an absolute contraindication; childhood nausea is not.

Q7. Why is stopping ALL medication in a newly pregnant woman with epilepsy the wrong reflex? A. Antiepileptics are all safe in pregnancy B. UNTREATED maternal illness also harms the fetus — uncontrolled seizures carry real risk C. Drugs never cross the placenta D. Teratogenic risk is greatest in the third trimester ANSWER: B. Why: both reflexes are errors — prescribing without checking, and stopping without weighing. Each drug is reviewed against a current source and against the risk of the untreated condition, with specialist input. LEARNING POINT: teratogenic risk is greatest in the FIRST trimester, often before pregnancy is recognised.