Tetracaine has all of the following properties EXCEPT:

Correct Answer: B

Rationale: The correct answer is B: Low potency. Tetracaine is a potent local anesthetic with high potency. It has a slow onset, long duration, and high toxicity. Low potency would imply weaker anesthetic effects, which is not true for tetracaine. Other choices are incorrect as tetracaine is known for its strong anesthetic properties.

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.

Correct Answer: D

Rationale: Step-by-step rationale: 1. Tiagabine inhibits the reuptake of GABA, an inhibitory neurotransmitter, reducing excitatory effects of amino acids. 2. This mechanism helps prevent seizures by increasing GABA levels in the brain. 3. Ethosuximide is used for absence seizures, not related to amino acids. 4. Lamotrigine blocks voltage-gated sodium channels. 5. Diazepam enhances the effects of GABA but does not directly inhibit excitatory amino acids.