Adverse drug reactions: drugs causing X — MRCP Part 1 flashcards

Question 1

Name three drugs or drug groups that commonly cause urticaria.

Accepted Answer

Any three: opioids, antibiotics (especially penicillins), ACE inhibitors, aspirin, NSAIDs. — Mechanisms include IgE allergy (penicillins), direct mast-cell release (opioids) and COX inhibition (aspirin, NSAIDs).

Question 2

Name three drugs that can cause thrombocytopenia.

Accepted Answer

Any three: heparin (HIT), quinine, abciximab, NSAIDs, antibiotics (penicillins, cephalosporins, sulphonamides, rifampicin), thiazides, anticonvulsants (carbamazepine, valproate, phenytoin). — Most act by drug-dependent antibodies that destroy platelets.

Question 3

Apart from antithyroid drugs, name three drugs that can cause agranulocytosis.

Accepted Answer

Any three: clozapine, carbamazepine, co-trimoxazole, chloramphenicol, penicillins, mirtazapine, methotrexate. — Patients on these drugs who develop fever or sore throat need an urgent FBC.

Question 4

Name three drug classes that cause impaired glucose tolerance.

Accepted Answer

Any three: beta-blockers, thiazides, antipsychotics, corticosteroids, calcineurin inhibitors (tacrolimus, ciclosporin), interferon-alpha, nicotinic acid. — They reduce insulin secretion or increase insulin resistance.

Question 5

Name three drugs that cause pulmonary fibrosis.

Accepted Answer

Any three: amiodarone, nitrofurantoin, bleomycin, busulfan, methotrexate, ergot-derived dopamine agonists (cabergoline, bromocriptine, pergolide). — Most cause an interstitial pneumonitis that can progress to fibrosis.

Question 6

Which TB drug causes optic neuritis with red–green colour blindness, and what must be checked before starting it?

Accepted Answer

Ethambutol — check visual acuity and colour vision before treatment. — The toxicity is dose-related and usually reversible if the drug is stopped early.

Question 7

Which antiepileptic can cause acute myopia with secondary angle-closure glaucoma?

Accepted Answer

Topiramate. — It causes ciliary body swelling, which shifts the lens forward; sulphonamides can do the same.

Question 8

Name three drugs that cause photosensitivity.

Accepted Answer

Any three: fluoroquinolones (ciprofloxacin), amiodarone, ACE inhibitors/ARBs, thiazides, tetracyclines, sulphonamides, sulfonylureas, NSAIDs. — These absorb UV light and cause phototoxic or photoallergic skin reactions.

Question 9

Name three drug groups that can cause urinary retention.

Accepted Answer

Any three: anticholinergics, tricyclic antidepressants, opioids, antipsychotics, antihistamines, NSAIDs. — Most reduce detrusor contraction through antimuscarinic action; opioids also impair the voiding reflex.

Question 10

Name three drugs that cause peripheral neuropathy.

Accepted Answer

Any three: isoniazid, amiodarone, metronidazole, vincristine, nitrofurantoin, phenytoin. — Most are length-dependent sensory neuropathies, often reversible on stopping.

Question 11

Which first-line TB drug is the most hepatotoxic?

Accepted Answer

Pyrazinamide. — Hepatotoxicity risk is roughly pyrazinamide > rifampicin > isoniazid. Pyrazinamide also causes hyperuricaemia and gout.

Question 12

How is the 'R factor' calculated to classify drug-induced liver injury, and what value means hepatocellular injury?

Accepted Answer

R = (ALT ÷ ULN) ÷ (ALP ÷ ULN). R of 5 or more = hepatocellular; 2 or less = cholestatic; between = mixed. — The pattern points to likely culprits, e.g. paracetamol and isoniazid (hepatocellular) vs co-amoxiclav and flucloxacillin (cholestatic).

Question 13

Name three drugs that can exacerbate psoriasis.

Accepted Answer

Any three: beta-blockers, lithium, antimalarials (chloroquine, hydroxychloroquine), NSAIDs, ACE inhibitors, interferon-alpha. — Withdrawal of systemic corticosteroids can also cause a severe flare (including pustular psoriasis).

Question 14

Which autoantibody is characteristic of drug-induced lupus?

Accepted Answer

Anti-histone antibodies. — Drug-induced lupus rarely affects the kidneys or CNS, and anti-dsDNA is usually negative. Common causes: procainamide, hydralazine, isoniazid, minocycline.

Question 15

Which blood count abnormality is the hallmark of DRESS syndrome?

Accepted Answer

Eosinophilia. — DRESS (drug reaction with eosinophilia and systemic symptoms) causes fever, widespread rash, facial swelling, lymphadenopathy and organ involvement (often hepatitis), typically 2–8 weeks after starting anticonvulsants, allopurinol or antibiotics.

Question 16

Which bladder toxicity does cyclophosphamide cause, and which drug prevents it?

Accepted Answer

Haemorrhagic cystitis — prevented by mesna (with good hydration). — The metabolite acrolein damages the bladder lining; mesna binds acrolein in the urine.

Question 17

Name the two classic dose-limiting toxicities of cisplatin.

Accepted Answer

Nephrotoxicity and ototoxicity (it also causes hypomagnesaemia and peripheral neuropathy). — Doxorubicin, by contrast, is cardiotoxic and bleomycin causes pulmonary fibrosis.

Question 18

Name three long-term adverse effects of phenytoin.

Accepted Answer

Any three: gingival hyperplasia, hirsutism, coarse facies, megaloblastic anaemia (folate deficiency), osteomalacia, peripheral neuropathy. — Phenytoin induces CYP450, which speeds vitamin D breakdown, and impairs folate absorption.

Question 19

Which metabolic cause of encephalopathy can sodium valproate produce, even with normal liver tests?

Accepted Answer

Hyperammonaemia. — Valproate interferes with the urea cycle. Other adverse effects: weight gain, hair loss (regrows curly), tremor, thrombocytopenia, pancreatitis, hepatotoxicity.

Question 20

Which adverse effects of montelukast now carry a boxed warning in the UK?

Accepted Answer

Neuropsychiatric reactions, e.g. sleep disturbance and nightmares, anxiety, depression, agitation or aggression, and rarely hallucinations or suicidal thoughts. — They occur in adults and children. Stop montelukast if new or worsening neuropsychiatric symptoms appear.

Adverse drug reactions: drugs causing X flashcards

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