A patient who has started drug therapy for tuberculosis wants to know how long he will be on the medications. Which response by the nurse is correct?

Correct Answer: C

Rationale: The correct answer is C: “You should expect to take these drugs for as long as 24 months.” This is the correct response because drug therapy for tuberculosis typically lasts for 6 to 9 months for drug-sensitive TB and up to 24 months for drug-resistant TB. It is important to complete the full course of treatment to ensure complete eradication of the bacteria and prevent relapse. Choice A is incorrect because relying solely on symptoms to determine the duration of treatment may lead to premature discontinuation of therapy. Choice B is incorrect as drug therapy is not based on waiting for resistance to develop. Choice D is incorrect because drug therapy for tuberculosis is not lifelong in most cases, except for certain scenarios of drug-resistant TB.

Correct Answer: B

Rationale: The correct answer is B: Procaine. Procaine has a shorter duration of action compared to the other choices. This is because procaine is an ester-type local anesthetic, which undergoes rapid hydrolysis by plasma cholinesterase, resulting in a shorter duration of action. In contrast, lidocaine, bupivacaine, and ropivacaine are amide-type local anesthetics, which are metabolized more slowly, leading to longer durations of action. Therefore, procaine is the local anesthetic with the shortest duration among the options provided.

Correct Answer: C

Rationale: Acetylcholine is not used in clinical practice because it is very rapidly hydrolyzed by the enzyme acetylcholinesterase. Upon administration, it quickly breaks down before exerting its desired effects. This rapid hydrolysis limits its therapeutic efficacy, making it unsuitable for clinical use. Other choices (A, B, D) are incorrect as acetylcholine's lack of use is primarily due to its rapid degradation, not its toxicity, high doses requirement, or costliness.

Correct Answer: C

Rationale: Certainly! The correct answer is C: Homatropine. Homatropine is an antimuscarinic drug that works by blocking muscarinic receptors in the eye, causing dilation of the pupil (mydriasis). This effect is useful in ophthalmology for procedures requiring dilation of the pupil for examination or surgery. Now, let's analyze why the other choices are incorrect: A: Pilocarpine is a muscarinic agonist that constricts the pupil. B: Neostigmine is an acetylcholinesterase inhibitor used to increase muscle contractions. D: Ipratropium is an anticholinergic drug primarily used for bronchodilation in conditions like asthma and COPD. In summary, Homatropine is the correct choice as it is the antimuscarinic drug used for mydriasis, while the other options have different mechanisms of action and purposes.

Correct Answer: B

Rationale: Correct Answer: B (Increase peripheral arterial resistance) Rationale: Nonselective beta receptor agonists stimulate beta-1 and beta-2 receptors. Activation of beta-1 receptors on the heart increases cardiac output (A). Activation of beta-2 receptors in peripheral arteries causes vasodilation, leading to a decrease in peripheral arterial resistance (C). Mean arterial pressure is determined by cardiac output and peripheral resistance, so decreasing peripheral resistance would not directly lead to a decrease in the mean pressure (D). Therefore, the correct answer is B because nonselective beta receptor agonists do not increase peripheral arterial resistance.