**Question:** One of the longer acting analogue among uterine stimulants

**Core Concept:** Uterine stimulants are medications that increase uterine contractions and are used to induce labor or treat uterine hemorrhage. Uterine stimulants include ergot derivatives, prostaglandins, and oxytocin.

**Why the Correct Answer is Right:** Terbutaline (C17H22N2O2) is a selective beta-2 agonist that stimulates the beta-2 receptors in the uterus, leading to increased uterine contractions and is considered longer acting compared to other uterine stimulants.

**Why Each Wrong Option is Incorrect:**

A. Methotrimethylammonium (Option A) is a cardiac stimulant and not a uterine stimulant. It is a local anesthetic used primarily to block cardiac muscle contraction.

B. Albuterol (Option B) is a short-acting beta-agonist used for bronchodilation in asthma treatment, not uterine stimulation.

C. Misoprostol (Option C) is a prostaglandin E1 analogue that is used to induce labor and treat bleeding in the digestive tract. It is not considered longer acting compared to terbutaline.

D. Oxytocin (Option D) is a hormone produced by the posterior pituitary gland that stimulates uterine contractions. It is generally shorter acting compared to terbutaline.

**Clinical Pearl / High-Yield Fact:**

Terbutaline is used to induce labor, treat excessive uterine bleeding, and control postpartum hemorrhage due to its longer acting nature compared to other uterine stimulants. However, its use is often associated with tachycardia, hypotension, and uterine hyperstimulation.

**Correct Answer:** D. Oxytocin (4-hydroxytriptorelin) is a peptide hormone produced by the posterior pituitary gland. It acts as a uterine stimulant by binding to oxytocin receptors in the uterus, leading to increased uterine contractions. Terbutaline is a beta-agonist, not a hormone, and is used to increase uterine contractions. Terbutaline is longer acting than oxytocin, but oxytocin is the correct answer for this question as it is a hormone responsible for uterine contractions. Terbutaline is used in other clinical situations where longer acting uterine stimulation is required.