Pharmacology, Pharmacokinetics, and Therapeutics in Obstetrics and Gynaecology — WACS Viva & Clinical Scenarios (Basic Sciences in Obstetrics and Gynaecology)

Exam-style pharmacology, pharmacokinetics, and therapeutics in obstetrics and gynaecology viva scenarios with examiner probes and model answers for Obstetrics…

Scenarios covered

• SCENARIO 1: A 28-year-old primigravida at 32 weeks gestation requires therapeutic drug monitoring for a medical disorder. Detail the maternal physiological changes during pregnancy that modify drug absorption, apparent volume of distribution, plasma protein binding, hepatic biotransformation, and renal clearance. Explain how these pharmacokinetic alterations necessitate dosage adjustments for renally excreted antibiotics and highly protein-bound anticonvulsants.
• SCENARIO 2: Evaluate the physicochemical and biological determinants governing transplacental drug transfer across the syncytiotrophoblast. Contrast the specific structural malformations and timing of drug exposure for classic teratogens, including angiotensin-converting enzyme inhibitors, sodium valproate, warfarin, and thalidomide, detailing their underlying cellular toxicity mechanisms.
• SCENARIO 3: Compare the intracellular second-messenger pathways, receptor targets, physiological onset, and cardiovascular adverse effect profiles of oxytocin, methylergometrine, prostaglandin F2-alpha (carboprost tromethamine), and misoprostol in active management of the third stage of labour and postpartum haemorrhage. Contrast these with the cellular mechanisms of tocolytic agents, specifically nifedipine, atosiban, and indomethacin.
• SCENARIO 4: Outline the mechanism of action, therapeutic plasma range, excretion pathways, and toxicity manifestations of magnesium sulfate when administered for seizure prophylaxis in severe pre-eclampsia and eclampsia. Explain the pharmacological profiles, maternal-fetal hemodynamic impacts, and contraindications of first-line maternal antihypertensive agents, including labetalol, hydralazine, and immediate-release oral nifedipine.
• SCENARIO 5: Describe the pharmacodynamics and clinical indications of selective oestrogen receptor modulators (clomifene citrate, tamoxifen), antiprogestins (mifepristone), and antifibrinolytics (tranexamic acid) in benign gynaecological practice. Contrast the cellular mechanisms of action, dose-limiting toxicities, and cell-cycle specificities of platinum analogues (carboplatin, cisplatin) and taxanes (paclitaxel) utilised in gynaecological oncology.