Procaine has all of the following properties EXCEPT:

Correct Answer: C

Rationale: The correct answer is C: Procaine does not readily penetrate the skin and mucosa. This is because procaine is a local anesthetic with poor lipid solubility, making it less able to penetrate through skin and mucosa efficiently. The other choices are incorrect because: A is correct as procaine contains an ester linkage; B is correct as procaine's metabolic product para-aminobenzoic acid can inhibit sulfonamide action; and D is correct as procaine is relatively short-acting compared to other local anesthetics like lidocaine. Therefore, C is the correct answer as it does not align with the properties of procaine.

Correct Answer: B

Rationale: The correct answer is B: Epinephrine is not synthesized in the nerve endings. It is produced in the adrenal medulla and released into the bloodstream in response to stress. It travels through the blood to target tissues where it interacts with adrenoreceptors, leading to various physiological responses. Epinephrine does not directly interact with nerve endings for synthesis or action. Choices A, C, and D are incorrect because epinephrine is indeed synthesized in the adrenal medulla, transported in the blood to target tissues, and directly interacts with and activates adrenoreceptors, respectively.

Correct Answer: B

Rationale: Rationale: 1. Xylometazoline is an alpha2-selective agonist, which means it selectively activates alpha2 adrenergic receptors. 2. This action leads to vasoconstriction and reduces nasal congestion without affecting blood pressure. 3. Phenylephrine (choice A) is an alpha1-selective agonist, causing increased blood pressure. 4. Ephedrine (choice C) is a mixed agonist affecting both alpha and beta receptors. 5. Epinephrine (choice D) is a non-selective agonist acting on both alpha and beta receptors.

Correct Answer: C

Rationale: The correct answer is C because reserpine actually causes a sympatholytic effect, not a sympathomimetic effect. Reserpine depletes norepinephrine and serotonin stores in the brain, leading to decreased sympathetic activity. Choices A, B, and D are incorrect because reserpine does inhibit the uptake of norepinephrine, decrease cardiac output and peripheral resistance, and deplete catecholamines and serotonin stores in the brain, respectively.

Correct Answer: C

Rationale: The correct answer is C: Phenobarbital. Phenobarbital enhances GABA-mediated inhibition by increasing the duration of GABA-A receptor channel opening, leading to increased chloride ion influx. This enhances inhibitory neurotransmission, reducing neuronal excitability and seizure activity. Ethosuximide (A) works by blocking T-type calcium channels, Carbamazepine (B) by blocking voltage-gated sodium channels, and Lamotrigine (D) by inhibiting sodium channels and reducing glutamate release, none of which directly enhance GABA-mediated inhibition.