During a routine checkup, a patient states that she is unable to take the prescribed antihistamine because of one of its most common adverse effects. The nurse suspects that which adverse effect has been bothering this patient?

Correct Answer: C

Rationale: The correct answer is C: Drowsiness. Antihistamines are known to cause drowsiness as a common adverse effect due to their sedative properties. This is why the patient may be unable to take the medication. Choices A, B, and D are incorrect because constipation and abdominal cramps are not common adverse effects of antihistamines, and decreased libido is not typically associated with this type of medication.

Correct Answer: C

Rationale: The therapeutical dose is the amount of a substance required to produce the desired effect in most patients. This is because it aims to provide optimal benefits with minimal side effects. Choice A is incorrect as it refers to a subtherapeutic dose. Choice B is incorrect as it describes a toxic dose. Choice D is incorrect as it does not accurately define a therapeutical dose.

Correct Answer: B

Rationale: Step-by-step rationale for why B (Lidocaine) is the correct answer: 1. Lidocaine has a longer duration of action compared to Procaine and Mepivacaine. 2. Bupivacaine is a long-acting local anesthetic, but it has a longer duration of action than Lidocaine. 3. Therefore, among the given choices, Lidocaine is the long-acting agent with a duration of action longer than Procaine and Mepivacaine. Summary: A: Bupivacaine - Incorrect, longer-acting than Lidocaine. C: Procaine - Incorrect, shorter-acting than Lidocaine. D: Mepivacaine - Incorrect, shorter-acting than Lidocaine.

Correct Answer: B

Rationale: The correct answer is B: Mydriasis. Cholinesterase inhibitors cause excessive stimulation of the parasympathetic nervous system, leading to symptoms such as salivation, sweating, bronchial constriction, and GI symptoms. Mydriasis, or pupil dilation, is not a typical initial symptom of cholinesterase inhibitor intoxication. Pupil constriction (miosis) is actually more common due to increased parasympathetic activity. Therefore, mydriasis does not fit the profile of initial symptoms seen in cholinesterase inhibitor intoxication.

Correct Answer: A

Rationale: The correct answer is A because depolarizing agents, like succinylcholine, directly open the nicotinic receptor channel causing prolonged depolarization. Choice B is correct, as depolarizing agents react with the nicotinic receptor to cause depolarization. Choice C is incorrect because desensitization and flaccid paralysis are associated with non-depolarizing agents. Choice D is incorrect because cholinesterase inhibitors can reverse non-depolarizing blockade by preventing acetylcholine breakdown.