The term “chemical antagonism” means that:

Correct Answer: A

Rationale: The correct answer is A. Chemical antagonism refers to the interaction between two drugs where they combine to form an inactive compound. This results in a decrease in the overall pharmacological effect of the drugs. In contrast, options B, C, and D are incorrect because they describe scenarios where the combination of drugs leads to a more active, more water-soluble, or more fat-soluble compound, which would typically result in enhanced pharmacological effects rather than antagonism.

Correct Answer: B

Rationale: The correct answer is B: Secretions. Atropine is used to reduce respiratory secretions before inhaling anesthetics as it helps prevent airway obstruction and aspiration. It does not affect muscle tone or nausea/vomiting. Choice A is incorrect because atropine can actually increase muscle tone. Choice C is incorrect because atropine does not directly address nausea and vomiting. Overall, the main purpose of using atropine in this context is to decrease secretions, making option B the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Ephedrine. Catecholamines are a class of neurotransmitters that include epinephrine, norepinephrine, and isoprenaline. Ephedrine is a sympathomimetic amine, not a catecholamine. Ephedrine acts by stimulating both alpha and beta-adrenergic receptors, while catecholamines specifically act on adrenergic receptors. Therefore, ephedrine does not fit the definition of a catecholamine, making it the correct answer. Epinephrine, norepinephrine, and isoprenaline are all true catecholamines.

Correct Answer: D

Rationale: The correct answer is D: Epinephrine. 1. Epinephrine is the drug of choice in anaphylactic shock due to its alpha and beta-adrenergic effects, which help reverse vasodilation, bronchoconstriction, and increased vascular permeability. 2. Methoxamine (A) acts as a selective alpha-1 adrenergic agonist and may worsen the vasodilation in anaphylactic shock. 3. Terbutaline (B) is a beta-2 adrenergic agonist used in asthma but may not be as effective in reversing the systemic effects of anaphylactic shock. 4. Norepinephrine (C) is a potent vasoconstrictor but lacks the beta-adrenergic effects needed to reverse bronchoconstriction and vascular permeability in anaphylactic shock.

Correct Answer: D

Rationale: The correct answer is D: Hyperglycemia. Beta-blockers can cause bronchoconstriction (Choice A) by blocking beta-2 receptors, leading to airway constriction. They depress myocardial contractility and excitability (Choice B) by blocking beta-1 receptors in the heart. "Supersensitivity" of beta-receptors (Choice C) can occur upon rapid withdrawal of beta-blockers due to upregulation of receptors. However, beta-blockers typically do not cause hyperglycemia (Choice D) as they may actually mask the symptoms of hypoglycemia.