Pharmacology Flashcards

A patient presents with organophosphate poisoning showing excessive salivation, lacrimation, urination, diarrhoea, and miosis. What is the antidote?

Answer: Atropine and pralidoxime

Organophosphate poisoning causes cholinergic crisis by irreversibly inhibiting acetylcholinesterase. Atropine (muscarinic antagonist) treats secretions and bradycardia, while pralidoxime (2-PAM) reactivates acetylcholinesterase if given early (before 'ageing' of the enzyme-inhibitor complex).

A patient on long-term corticosteroids is to undergo surgery. What perioperative consideration is essential?

Answer: Stress-dose steroids (hydrocortisone) perioperatively

Chronic corticosteroid use suppresses the hypothalamic-pituitary-adrenal (HPA) axis. During surgical stress, the adrenal glands cannot mount an appropriate cortisol response, risking adrenal crisis. Stress-dose hydrocortisone (50-100 mg IV) is given perioperatively.

Which antiemetic is the drug of choice for chemotherapy-induced nausea and vomiting?

Answer: Ondansetron

Ondansetron (a 5-HT3 receptor antagonist) is first-line for chemotherapy-induced nausea and vomiting (CINV). It blocks serotonin receptors in the chemoreceptor trigger zone and vagal afferents. For highly emetogenic chemotherapy, it is combined with dexamethasone and aprepitant (NK1 antagonist).

A patient is started on amiodarone for atrial fibrillation. Which organ systems require monitoring due to amiodarone toxicity?

Answer: Thyroid, liver, lungs, and eyes

Amiodarone has a wide toxicity profile requiring monitoring of: thyroid (hypo/hyperthyroidism due to iodine content), liver (hepatotoxicity), lungs (pulmonary fibrosis), eyes (corneal microdeposits, optic neuropathy), and skin (photosensitivity, blue-grey discolouration).

What is the mechanism of action of omeprazole?

Answer: Irreversible proton pump inhibitor

Omeprazole irreversibly inhibits the hydrogen-potassium ATPase (proton pump) on the luminal surface of parietal cells in the stomach. This blocks the final common pathway of acid secretion, providing potent and sustained acid suppression.

A patient develops methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia. What is the drug of choice?

Answer: Vancomycin

Vancomycin is the gold standard treatment for MRSA bacteraemia. It acts by inhibiting cell wall synthesis by binding to D-Ala-D-Ala terminus of peptidoglycan precursors. Trough levels should be monitored (15-20 μg/mL for serious infections). Daptomycin is an alternative.