Vasoconstrictors are less effective in prolonging anesthetic properties of:

Correct Answer: B

Rationale: The correct answer is B, Bupivacaine. Bupivacaine is a long-acting local anesthetic with intrinsic vasoconstrictive properties, so using additional vasoconstrictors may not significantly prolong its anesthetic effects. Procaine (A), Lidocaine (C), and Mepivacaine (D) do not have intrinsic vasoconstrictive properties, so adding vasoconstrictors can help prolong their anesthetic effects.

Correct Answer: B

Rationale: The correct answer is B: Tubocurarine. Tubocurarine has the potential to cause the greatest release of histamine among the choices. This is because tubocurarine is a non-depolarizing neuromuscular blocking agent that can directly stimulate histamine release from mast cells, leading to histamine-related adverse effects like hypotension and bronchospasm. Succinylcholine (A) mainly activates nicotinic acetylcholine receptors, while Pancuronium (C) and Rocuronium (D) are less likely to cause significant histamine release compared to Tubocurarine.

Correct Answer: B

Rationale: The correct answer is B: It is used to treat bronchospasm. Dobutamine is a beta1-selective synthetic catecholamine used for its positive inotropic effects in conditions like heart failure. Choice A is correct as dobutamine is beta1-selective. Choice C is incorrect as dobutamine can increase atrioventricular conduction. Choice D is incorrect as dobutamine can cause changes in heart rate and systolic pressure. Therefore, the correct answer is B because dobutamine is not used to treat bronchospasm.

Correct Answer: D

Rationale: Propranolol is a non-selective beta-blocker, used in cardiovascular diseases, hyperthyroidism, and migraine headache. However, it is contraindicated in bronchial asthma due to its potential to induce bronchoconstriction. Propranolol can worsen asthma symptoms by blocking beta-2 receptors in the lungs, leading to bronchoconstriction and exacerbation of asthma. Therefore, the correct answer is D. Choices A, B, and C are incorrect as propranolol is commonly used for these conditions due to its beneficial effects on heart rate, blood pressure, and migraine prevention.

Correct Answer: C

Rationale: The correct answer is C because hypnotic benzodiazepines are known to decrease both REM and slow wave sleep in a dose-dependent manner. This is due to their ability to suppress rapid eye movement (REM) sleep and slow wave sleep stages. Benzodiazepines have a sedative effect on the central nervous system, leading to a reduction in overall sleep quality and disruption of normal sleep architecture. Choice A is incorrect because benzodiazepines do not increase REM or slow wave sleep. Choice B is incorrect because benzodiazepines do alter sleep patterns. Choice D is incorrect as it states an increase in REM sleep, which is not true for benzodiazepines.