Drugs are metabolized mainly by the liver via Phase I or Phase II reactions. The purpose of both of these types of reactions is to:

Correct Answer: C

Rationale: The correct answer is C: Change drug molecules to a form that an excretory organ can excrete. Phase I and Phase II reactions in the liver modify drugs to make them more water-soluble and easily excreted by the kidneys or liver. Phase I reactions typically involve oxidation, reduction, or hydrolysis to introduce or unmask functional groups, while Phase II reactions conjugate the drug with polar molecules like glucuronide or sulfate. This transformation makes the drug more suitable for elimination through urine or bile. Choice A is incorrect because Phase I and II reactions do not necessarily inactivate prodrugs, but rather prepare them for elimination. Choice B is incorrect because altering drug properties to cross membranes is typically not the primary purpose of drug metabolism. Choice D is incorrect because increasing ionization and polarity may not always be the goal of drug metabolism, but rather enhancing excretion through conjugation reactions.

Correct Answer: C

Rationale: Rationale: 1. Phase I metabolism involves enzymes like cytochrome P450, requiring proteins as cofactors. 2. Protein malnutrition reduces enzyme production, hindering the oxidative-reductive process. 3. Iron is necessary for cytochrome P450 activity, so iron deficiency impairs drug metabolism. 4. Option C is correct as both protein malnutrition and iron deficiency inhibit Phase I metabolism. Summary: - Choice A is incorrect because protein malnutrition affects enzyme production. - Choice B is incorrect because iron deficiency hampers cytochrome P450 activity. - Choice D is incorrect as both elements are essential for Phase I drug metabolism.

Correct Answer: D

Rationale: The correct answer is D because drug antagonism refers to the situation where one drug diminishes the effect of another drug when taken together. This occurs when the drugs have opposing actions on the body or compete for the same receptors. In contrast: A: Major physiological psychological dependence is related to addiction, not drug antagonism. B: The modification of drug effects by concurrent administration of another drug is known as drug interaction, not antagonism. C: The ability to be metabolized before another dose is administered is not related to drug antagonism.

Correct Answer: D

Rationale: The correct answer is D, Glucose. Glucose is a small molecule that is primarily absorbed in the small intestine through active transport mechanisms, where most nutrient absorption occurs. The small intestine has a larger surface area and more specialized transport mechanisms for nutrient absorption compared to the stomach. A, Sodium bicarbonate, is mainly absorbed in the stomach as it helps neutralize stomach acid. B, Ascorbic acid, is primarily absorbed in the stomach and the small intestine. C, Salicylic acid, is absorbed in the stomach and upper small intestine. Therefore, D is the most likely substance to be absorbed in the intestines rather than the stomach.

Correct Answer: C

Rationale: Step 1: Drugs metabolized by CYP 3A4 can induce its own metabolism, increasing clearance. Step 2: This induction can also affect other drugs metabolized by CYP 3A4, leading to decreased levels. Step 3: Therefore, choice A is correct. Step 4: Additionally, if CYP 3A4 is inhibited by a drug, it can lead to decreased metabolism of other drugs. Step 5: This inhibition can result in increased levels of the affected drugs. Step 6: Hence, choice B is also correct. Step 7: Combining the effects of induction and inhibition, both choices A and B are true, making choice C the correct answer.