For the calculation of the volume of distribution (Vd) one must take into account:

Correct Answer: A

Rationale: The correct answer is A because the volume of distribution (Vd) is a pharmacokinetic parameter that describes the extent of drug distribution in the body. It is calculated by dividing the total amount of drug in the body by the concentration of the drug in the plasma. Therefore, the concentration of a substance in plasma is essential for determining Vd. Choice B (Concentration of substance in urine) is incorrect because Vd is not calculated based on urine concentration but rather on plasma concentration. Choice C (Therapeutical width of drug action) is unrelated to Vd calculation as it refers to the range of drug concentrations in the body that produce the desired therapeutic effect. Choice D (A daily dose of drug) is also incorrect as Vd is not directly calculated from the daily dose but rather from the concentration of the drug in the plasma.

Correct Answer: A

Rationale: Prilocaine is the correct answer as it can cause methemoglobinemia due to its metabolite o-toluidine. This metabolite oxidizes hemoglobin to methemoglobin, leading to reduced oxygen-carrying capacity. Procaine, lidocaine, and ropivacaine do not typically cause methemoglobinemia as they lack the metabolites responsible for this condition. So, prilocaine is the only local anesthetic among the choices that can lead to methemoglobinemia.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Atropine is a non-selective muscarinic antagonist, blocking all muscarinic receptor subtypes (M1, M2, and M3). This is due to its structure and mechanism of action, which allows it to bind and inhibit all types of muscarinic receptors. Atropine's broad action leads to its multiple effects, such as blocking parasympathetic stimulation and increasing heart rate. Choices A, B, and C are incorrect because atropine does not selectively target only one specific muscarinic receptor subtype.

Correct Answer: D

Rationale: Sympathetic stimulation involves the activation of the sympathetic nervous system. Norepinephrine is released from sympathetic nerve terminals, activating adrenoreceptors on postsynaptic sites. Additionally, the adrenal medulla releases epinephrine into the bloodstream. Therefore, all three choices (A, B, and C) are mechanisms through which sympathetic stimulation is mediated. Hence, the correct answer is D. The other choices (A, B, and C) are incorrect as they individually represent different aspects of sympathetic stimulation, but the correct answer encompasses all of them.

Correct Answer: D

Rationale: Step 1: Long-acting decongestants are preferred for sustained relief. Step 2: Xylometazoline has a longer duration of action compared to other choices. Step 3: Epinephrine and norepinephrine are short-acting sympathomimetic agents. Step 4: Phenylephrine is intermediate-acting, not long-acting. Step 5: Therefore, D (Xylometazoline) is the correct choice for long-acting topical decongestant agents.