Which drug is a potent uterine relaxant and is rarely used in obstetrics because it can cause increased hemorrhage?

Which drug is a potent uterine relaxant and is rarely used in obstetrics because it can cause increased hemorrhage?

• A. Diazoxide
• B. Nitroprusside
• C. Nifedipine
• D. Labetalol

Answer: (A)

Potent relaxation of uterine smooth muscle can prevent labor but risks postpartum hemorrhage because a uterus that doesn’t contract after delivery can’t compress bleeding vessels in the placental bed. Diazoxide is a powerful vasodilator that also relaxes smooth muscle, including the uterus, so it can cause uterine atony and heavy bleeding after birth. That’s why it’s rarely used in obstetrics despite its antihypertensive effects. The other drugs don’t carry that same risk profile. Nitroprusside is a strong vasodilator for hypertensive emergencies but isn’t used as a tocolytic. Nifedipine, a calcium channel blocker, actually is used to relax the uterus to delay preterm labor, not to promote hemorrhage. Labetalol lowers blood pressure without a primary tocolytic effect.

Potent relaxation of uterine smooth muscle can prevent labor but risks postpartum hemorrhage because a uterus that doesn’t contract after delivery can’t compress bleeding vessels in the placental bed. Diazoxide is a powerful vasodilator that also relaxes smooth muscle, including the uterus, so it can cause uterine atony and heavy bleeding after birth. That’s why it’s rarely used in obstetrics despite its antihypertensive effects.

The other drugs don’t carry that same risk profile. Nitroprusside is a strong vasodilator for hypertensive emergencies but isn’t used as a tocolytic. Nifedipine, a calcium channel blocker, actually is used to relax the uterus to delay preterm labor, not to promote hemorrhage. Labetalol lowers blood pressure without a primary tocolytic effect.