The route of excretion of a volatile drug will likely be:

Correct Answer: B

Rationale: The correct answer is B: The lungs. Volatile drugs are typically eliminated through exhalation via the lungs due to their ability to evaporate easily into the air. This route is favored for volatile drugs as they can be quickly eliminated through respiration, making it an efficient and rapid process. A: The kidneys primarily excrete water-soluble compounds through urine, not volatile drugs. C: The bile and feces are involved in the excretion of non-volatile, lipophilic drugs, but not volatile drugs. D: The skin is not a primary route of excretion for drugs, especially volatile ones.

Correct Answer: B

Rationale: The correct answer is B because when the peak level for a drug is above the minimum toxic concentration, it indicates that the concentration will produce an adverse response. This is because high drug levels can lead to toxicity and harmful effects on the body. The other choices are incorrect because: A: Concentration will produce therapeutic effects - This is incorrect because being above the minimum toxic concentration means the drug level is too high for therapeutic effects. C: Time between doses must be shortened - This is incorrect as adjusting the time between doses does not address the issue of drug toxicity. D: Duration of action of the drug is too long - This is incorrect because the duration of action does not directly relate to drug toxicity; it is the concentration level that determines toxicity.

Correct Answer: C

Rationale: The correct answer is C: Lipid solubility of the drug. This affects gastric drug absorption because lipid-soluble drugs can easily pass through the lipid bilayer of the cell membrane in the stomach. This allows for faster and more efficient absorption into the bloodstream. Liver enzyme activity (choice A) primarily affects drug metabolism, not absorption. Protein-binding properties (choice B) influence distribution within the body but not absorption. Ability to chew and swallow (choice D) relates to drug administration rather than absorption in the stomach.

Correct Answer: A

Rationale: The correct answer is A because bioavailability is crucial for drugs with narrow therapeutic ranges or sustained release mechanisms as it determines the amount of the drug that reaches the systemic circulation. Choice B is incorrect because different brands of a drug can have varying bioavailability due to differences in formulations. Choice C is incorrect because the frequency of drug administration does not necessarily correlate with bioavailability. Choice D is incorrect as combining an active drug with an inert substance can affect bioavailability, such as altering absorption rates.

Correct Answer: D

Rationale: First, metabolites can be more active than the parent drug due to enhanced pharmacological properties. Second, metabolites can be less active due to decreased potency. Third, metabolites can be deactivated for excretion, preventing any pharmacological effect. Therefore, all options are possible outcomes of drug metabolism by the liver.