Introduction: Drugs acting on uterus are essential for managing labor, abortion, and preterm birth in clinical practice and pharmacology. This topic covers oxytocics (oxytocin, ergometrine, prostaglandins), tocolytics/uterine relaxants (beta-2 agonists, magnesium sulfate, nifedipine, indomethacin, atosiban), antiprogestins (mifepristone), mechanisms (oxytocin receptor-Gq/IP3-Ca2+, prostaglandin receptors), therapeutic indications, dosing, contraindications, and adverse effects. Understanding receptor pharmacology, drug interactions, and clinical scenarios prepares B.Pharm students for safe drug selection and counselling. These MCQs emphasize mechanism-based reasoning, clinical application, and safety considerations in obstetric pharmacotherapy. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which receptor primarily mediates oxytocin-induced uterine contraction?
- Beta-2 adrenergic receptor
- Oxytocin receptor coupled to Gq
- Mu-opioid receptor
- Calcium-sensing receptor
Correct Answer: Oxytocin receptor coupled to Gq
Q2. Which drug is a uterotonic derived from prostaglandin F2α and commonly used for postpartum hemorrhage and to induce labor?
- Misoprostol
- Dinoprostone
- Carboprost (15-methyl PGF2α)
- Atosiban
Correct Answer: Carboprost (15-methyl PGF2α)
Q3. Which of the following is a contraindication to using prostaglandin E2 (dinoprostone) for cervical ripening?
- Previous cesarean section or major uterine surgery
- Nulliparity
- Gestational diabetes
- Advanced maternal age
Correct Answer: Previous cesarean section or major uterine surgery
Q4. What is the principal mechanism of action of magnesium sulfate as a tocolytic?
- Inhibition of prostaglandin synthesis via COX inhibition
- Calcium channel blockade in uterine smooth muscle
- Competitive antagonism at oxytocin receptors
- Blocking calcium entry and reducing intracellular calcium via antagonism of NMDA receptors and membrane stabilization
Correct Answer: Blocking calcium entry and reducing intracellular calcium via antagonism of NMDA receptors and membrane stabilization
Q5. Which drug is an oxytocin receptor antagonist used for preterm labor in some countries?
- Ritodrine
- Atosiban
- Terbutaline
- Nifedipine
Correct Answer: Atosiban
Q6. Which of the following is the main adverse effect limiting the use of beta-2 adrenergic agonists (e.g., ritodrine) as tocolytics?
- Severe hypotension and reflex bradycardia
- Tocolytic-induced uterine rupture
- Tachycardia, hyperglycemia, pulmonary edema
- Nephrotoxicity
Correct Answer: Tachycardia, hyperglycemia, pulmonary edema
Q7. Indomethacin delays preterm labor by inhibiting which enzyme?
- Phospholipase A2
- Cyclooxygenase (COX)
- 5-alpha reductase
- Monoamine oxidase
Correct Answer: Cyclooxygenase (COX)
Q8. Which uterotonic is preferred for induction of labor because it closely mimics physiological hormone release and can be given IV infusion?
- Ergometrine
- Oxytocin
- Mifepristone
- Dinoprostone
Correct Answer: Oxytocin
Q9. Mifepristone facilitates medical abortion primarily by antagonizing which receptor?
- Estrogen receptor
- Progesterone receptor
- Oxytocin receptor
- Prostaglandin receptor
Correct Answer: Progesterone receptor
Q10. Which drug combination is commonly used for medical termination of early pregnancy?
- Oxytocin plus ergometrine
- Mifepristone followed by misoprostol
- Atosiban followed by nifedipine
- Dinoprostone plus magnesium sulfate
Correct Answer: Mifepristone followed by misoprostol
Q11. Which of the following is a major risk when using indomethacin for tocolysis after 32–34 weeks gestation?
- Fetal ductus arteriosus constriction
- Severe maternal hyperkalemia
- Maternal hypothyroidism
- Placental abruption
Correct Answer: Fetal ductus arteriosus constriction
Q12. Ergometrine (ergonovine) produces sustained uterine contraction via agonism at which receptor type?
- Beta-2 adrenergic receptor
- Alpha-adrenergic and serotonin (5-HT2) receptors
- Histamine H1 receptor
- M3 muscarinic receptor
Correct Answer: Alpha-adrenergic and serotonin (5-HT2) receptors
Q13. Which calcium channel blocker is widely used off-label as a tocolytic to inhibit uterine contractions?
- Amlodipine
- Nifedipine
- Verapamil
- Diltiazem
Correct Answer: Nifedipine
Q14. Which of the following best describes the signaling cascade after oxytocin receptor activation in the myometrium?
- Gs → increased cAMP → relaxation
- Gi → decreased cAMP → relaxation
- Gq → phospholipase C → IP3 → increased intracellular Ca2+ → contraction
- Toll-like receptor → NF-κB activation → contraction
Correct Answer: Gq → phospholipase C → IP3 → increased intracellular Ca2+ → contraction
Q15. Misoprostol is a synthetic analog of which prostaglandin and is used for cervical ripening and abortion?
- PGI2 (prostacyclin)
- PGD2
- Prostaglandin E1 (PGE1)
- Prostaglandin F2α (PGF2α)
Correct Answer: Prostaglandin E1 (PGE1)
Q16. Which adverse effect is most associated with ergometrine use postpartum?
- Severe hypotension
- Hypertension and coronary vasospasm
- Hyperglycemia
- Excessive uterine atony
Correct Answer: Hypertension and coronary vasospasm
Q17. Atosiban is less likely than beta-2 agonists to cause which maternal side effect?
- Tachycardia
- Hypoglycemia
- Pulmonary edema
- Tremor
Correct Answer: Tachycardia
Q18. Which drug is contraindicated for induction of labor in a patient with active genital HSV infection?
- Oxytocin
- Dinoprostone (vaginal prostaglandin)
- Mifepristone
- Carboprost
Correct Answer: Dinoprostone (vaginal prostaglandin)
Q19. Which statement about postpartum hemorrhage management is correct?
- Methylergometrine is preferred in hypertensive patients
- Oxytocin is first-line for uterine atony
- Prostaglandins are ineffective for hemorrhage control
- Beta-2 agonists help contract the uterus to reduce bleeding
Correct Answer: Oxytocin is first-line for uterine atony
Q20. A tocolytic that acts by increasing intracellular cAMP in uterine smooth muscle would most likely be:
- Oxytocin
- Terbutaline (a beta-2 agonist)
- Carboprost
- Ergometrine
Correct Answer: Terbutaline (a beta-2 agonist)
Q21. Which of the following drugs stimulates uterine contractions by increasing prostaglandin synthesis and is used for cervical ripening?
- Nifedipine
- Dinoprostone
- Magnesium sulfate
- Atosiban
Correct Answer: Dinoprostone
Q22. Which monitoring is essential when using magnesium sulfate as a tocolytic or eclampsia therapy?
- Serum sodium and bicarbonate levels
- Deep tendon reflexes, respiratory rate, urine output
- Blood glucose hourly
- ECG for QT prolongation only
Correct Answer: Deep tendon reflexes, respiratory rate, urine output
Q23. Which of the following best explains why nifedipine can relax the myometrium?
- It blocks L-type voltage-gated calcium channels reducing Ca2+ influx
- It increases prostaglandin production
- It antagonizes progesterone receptors
- It stimulates oxytocin release
Correct Answer: It blocks L-type voltage-gated calcium channels reducing Ca2+ influx
Q24. Which agent is used to control bleeding due to uterine atony and is an ergot alkaloid?
- Misoprostol
- Ergometrine (ergonovine)
- Atosiban
- Nifedipine
Correct Answer: Ergometrine (ergonovine)
Q25. Which pharmacologic property of prostaglandin F2α (PGF2α) explains its use in obstetrics?
- Vasodilation of uterine arteries only
- Potent uterine smooth muscle contraction and cervical ripening
- Beta-adrenergic receptor stimulation
- Calcium channel opening in skeletal muscle
Correct Answer: Potent uterine smooth muscle contraction and cervical ripening
Q26. Which tocolytic is associated with neonatal hypoglycemia as a potential adverse effect due to maternal therapy?
- Oxytocin
- Beta-2 agonists (e.g., terbutaline)
- Indomethacin
- Atosiban
Correct Answer: Beta-2 agonists (e.g., terbutaline)
Q27. For pharmacology exams, which statement about misoprostol is true?
- Misoprostol is an oxytocin analog used IV
- Misoprostol causes uterine relaxation by beta receptor activation
- Misoprostol is a PGE1 analog used for cervical ripening and medical abortion
- Misoprostol is contraindicated in all pregnancies
Correct Answer: Misoprostol is a PGE1 analog used for cervical ripening and medical abortion
Q28. Which of the following increases the risk of uterine hyperstimulation when using uterotonics?
- Careful titration of oxytocin infusion
- Concurrent use of prostaglandins and oxytocin
- Lower-than-recommended doses
- Use of calcium channel blockers
Correct Answer: Concurrent use of prostaglandins and oxytocin
Q29. In the management of preterm labor, use of which drug class is avoided after 34 weeks due to fetal risks such as pulmonary hypertension?
- NSAIDs (indomethacin)
- Beta-2 agonists
- Magnesium sulfate
- Calcium channel blockers
Correct Answer: NSAIDs (indomethacin)
Q30. Which pharmacological principle is most important when choosing a uterotonic for a hypertensive patient with postpartum hemorrhage?
- Prefer ergometrine because it lowers blood pressure
- Avoid ergometrine due to risk of hypertension and use oxytocin instead
- Always use prostaglandin F2α first-line in hypertensive patients
- Give beta-2 agonists to increase uterine tone
Correct Answer: Avoid ergometrine due to risk of hypertension and use oxytocin instead
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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