Which of the following is not a therapeutic use of adrenaline:

Correct Answer: C

Rationale: The correct answer is C: To treat hypertension. Adrenaline, also known as epinephrine, is not typically used to treat hypertension because it can worsen high blood pressure due to its vasoconstrictive effects. Adrenaline is used to prolong the action of local anesthetics (A), stop epistaxis (B), and treat anaphylaxis (D) due to its ability to constrict blood vessels and increase heart rate in emergency situations.

Correct Answer: D

Rationale: Step 1: Alpha methyl dopa is a centrally acting antihypertensive medication. Step 2: It is a prodrug that is converted to alpha-methyl norepinephrine in the brain. Step 3: This metabolite stimulates alpha2 receptors in the brain, leading to decreased sympathetic outflow. Step 4: Decreased sympathetic outflow results in decreased peripheral vascular resistance and ultimately decreases blood pressure. Summary: Option D is correct because alpha methyl dopa decreases blood pressure by acting centrally on alpha2 receptors. Options A, B, and C are incorrect as alpha methyl dopa does not inhibit decarboxylase enzyme, increase renin, or stimulate alpha2 receptors centrally.

Correct Answer: D

Rationale: The correct answer is D: Stimulate uterine contraction. Selective β2 agonists primarily target β2 receptors in the lungs, leading to bronchodilation. They have minimal effect on β1 receptors, thus do not significantly impact heart rate or blood pressure. However, β2 receptors in the uterus can cause uterine relaxation, not contraction. Therefore, selective β2 agonists do not stimulate uterine contractions. Choices A, B, and C are incorrect as they align with the typical effects of selective β2 agonists.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Adrenaline is not given orally because: A) It is inactivated in the gut mucosa due to enzymatic breakdown, B) Local vasoconstriction inhibits absorption into the bloodstream, and C) It is rapidly inactivated in circulation by enzymes like catechol-O-methyltransferase and monoamine oxidase. Therefore, administering adrenaline orally would result in poor absorption and rapid degradation, making it ineffective.

Correct Answer: C

Rationale: Correct Answer: C Rationale: 1. Phenylephrine is a vasoconstrictor that raises blood pressure. 2. Increased blood pressure activates the baroreceptor reflex. 3. Baroreceptor reflex detects elevated blood pressure and sends signals to the brain. 4. The brain then signals the heart to slow down, thus normalizing the rapid heart rate in PSVT. Summary: A: Blocking beta-receptors would have the opposite effect, as beta-blockers slow down the heart rate. B: Stimulating norepinephrine release would increase heart rate, not slow it down. D: ACh esterase is involved in the breakdown of acetylcholine, not relevant to the mechanism of action of phenylephrine in PSVT.