The addition of glucuronic acid to a drug:

Correct Answer: B

Rationale: The addition of glucuronic acid to a drug is a process known as glucuronidation, a Phase II metabolism reaction. This conjugation reaction is essential for detoxification and elimination of drugs from the body. By adding glucuronic acid, the drug becomes more water-soluble, facilitating its excretion. Therefore, Option B is correct as it leads to inactivation of the drug. Option A is incorrect as it actually increases water solubility. Option C is incorrect as glucuronidation is a Phase II reaction. Option D is incorrect as the rate of glucuronidation can vary between adults and newborns due to developmental differences.

Correct Answer: D

Rationale: Step 1: Sympathetic and parasympathetic preganglionic neurons are cholinergic, meaning they release acetylcholine. Step 2: In the autonomic nervous system, preganglionic neurons synapse with postganglionic neurons in ganglia. Step 3: Since preganglionic neurons release acetylcholine, they will also release acetylcholine at the synapse in the ganglion. Summary: - Dopamine, serotonin, and GABA are not typically released by sympathetic and parasympathetic preganglionic neurons. - Acetylcholine is the primary neurotransmitter released by cholinergic neurons in the autonomic nervous system, making it the correct choice.

Correct Answer: C

Rationale: - Endorphin is a neuropeptide hormone, not an eicosanoid derived from fatty acids. - Prostacyclin, leukotrienes, and prostaglandins are all eicosanoids produced from fatty acids. - Endorphins are produced in the brain and nervous system, mainly known for their role in pain regulation. - Eicosanoids play roles in inflammation, blood clotting, and regulating blood pressure. - Therefore, the correct answer is C, Endorphin, as it is not an eicosanoid derived from fatty acids.

Correct Answer: B

Rationale: The correct answer is B: Fatty tissue. Drugs with a large volume of distribution (Vd) distribute extensively into tissues, especially those with high lipid content like fatty tissue. Lipophilic drugs tend to accumulate in fatty tissues due to their high lipid solubility. This leads to a higher volume of distribution as the drug is not primarily confined to the blood but distributed into tissues. Choices A, C, and D are incorrect because drugs with a large Vd are not typically confined to the GI tract, interstitial tissue, or intravascular fluid, as they distribute widely throughout the body.

Correct Answer: C

Rationale: The correct answer is C because competitive antagonists compete with the agonist for the same binding site, leading to a decrease in the potency of the drug. This occurs because the antagonist reduces the number of available binding sites for the agonist, requiring a higher concentration of the agonist to achieve the same effect. Option A is incorrect as efficacy is related to the maximal effect of a drug, not affected by competitive antagonists. Option B is incorrect because a leftward shift in the dose-response curve indicates an increase in potency, which is not the case with competitive antagonists. Option D is incorrect because competitive antagonists do affect the agonist dose-response curve by reducing potency.