A vasoconstrictor does not:

Correct Answer: D

Rationale: The correct answer is D because a vasoconstrictor actually enhances the effects of a local anesthetic by reducing its uptake by the surrounding nerves. This helps to prolong the duration of action of the anesthetic. Choices A and B are incorrect because a vasoconstrictor can retard drug removal from the injection site, which can increase the chance of toxicity. Choice C is incorrect because a vasoconstrictor actually decreases blood levels by constricting blood vessels at the site of administration, which can lead to localized effects.

Correct Answer: D

Rationale: The correct answer is D: Diaphragm. The diaphragm is more resistant to block and recovers rapidly due to its involuntary nature and vital role in breathing. The diaphragm contracts and relaxes continuously, making it more resilient compared to voluntary muscles like the hand, leg, and neck. The other choices are incorrect because voluntary muscles are more susceptible to fatigue and blockage due to their reliance on conscious control and are not essential for immediate survival like the diaphragm.

Correct Answer: C

Rationale: Rationale: Isoproterenol is a non-selective beta-adrenergic agonist that primarily acts on beta-1 and beta-2 receptors. It increases heart rate and contractility, leading to an increase in cardiac output (A) and tachycardia (D). Isoproterenol causes vasodilation, resulting in a fall in diastolic and mean arterial pressure (B). However, it does not cause bronchoconstriction (C) as it stimulates beta-2 receptors leading to bronchodilation. Therefore, the correct answer is C.

Correct Answer: C

Rationale: Rationale: Propranolol is a non-selective beta-blocker that can block beta-2 receptors leading to bronchoconstriction (A). Rapid withdrawal can cause beta-adrenergic receptor supersensitivity (B). Propranolol can cause sedation, sleep disturbances, depression, and sexual dysfunction (D). However, propranolol is associated with hypoglycemia, not hyperglycemia. Therefore, the correct answer is C.

Correct Answer: D

Rationale: The correct answer is D because benzodiazepines, while effective for insomnia, have the potential for psychological and physiological dependence (A), can cause synergistic depression of the central nervous system when combined with other drugs like alcohol (B), and may result in residual drowsiness and daytime sedation (C). Each of these factors poses risks and side effects associated with the use of benzodiazepines for treating insomnia. Therefore, the answer choice D, which includes all of the above factors, is the correct choice.