A patient has had recent prosthetic heart valve surgery and is receiving anticoagulant therapy. While monitoring the patient’s laboratory work, the nurse interprets that the patient’s international normalized ratio (INR) level of 2.5 indicates that

Correct Answer: B

Rationale: The correct answer is B: the patient’s warfarin dose is at therapeutic levels. An INR level of 2.5 is within the target range for patients on anticoagulant therapy, indicating that the warfarin dose is effective in preventing clot formation. A: Incorrect. An INR of 2.5 is considered therapeutic, so the patient is receiving enough warfarin. C: Incorrect. INR does not reflect heparin levels, so the intravenous heparin dose cannot be determined from this value. D: Incorrect. Similar to choice C, INR does not reflect heparin levels, so the status of the intravenous heparin dose cannot be determined.

Correct Answer: C

Rationale: Conjugation involves attaching a molecule to a drug to increase its solubility for elimination. Hydrolysis is not a conjugation process but rather a breakdown of molecules by water. Glucuronidation, sulfation, and methylation are all types of conjugation reactions. Glucuronidation adds a glucuronic acid, sulfation adds a sulfate group, and methylation adds a methyl group to the drug. So, C is the correct answer as it does not involve drug conjugation.

Correct Answer: D

Rationale: The correct answer is D because most local anesthetic agents consist of all three components: a lipophilic group (often an aromatic ring) for membrane penetration, an intermediate chain (usually containing an ester or amide) for linkage to the lipophilic group, and an amino group for interaction with the sodium channels. A is correct as the lipophilic group aids in crossing the lipid-rich cell membrane. B is correct as the intermediate chain connects the lipophilic group and amino group. C is correct as the amino group interacts with sodium channels to block nerve conduction. Therefore, all three components are essential for the local anesthetic mechanism of action.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Physostigmine is a cholinomimetic agent as it acts by inhibiting acetylcholinesterase, leading to increased acetylcholine levels. 2. Acetylcholine is a neurotransmitter that activates cholinergic receptors, mimicking the effects of the parasympathetic nervous system. 3. Physostigmine is used in conditions like myasthenia gravis and glaucoma to enhance cholinergic activity. 4. Edrophonium is a short-acting acetylcholinesterase inhibitor used for diagnostic purposes, not a direct-acting cholinomimetic. 5. Carbachol is a non-selective cholinergic agonist used in ophthalmology and urology, but not directly related to direct-acting cholinomimetic agents.

Correct Answer: B

Rationale: The correct answer is B because scopolamine is actually more potent than atropine in decreasing bronchial, salivary, and sweat gland secretions. The rationale is that scopolamine, being a tertiary amine, has a greater ability to cross the blood-brain barrier and exert stronger central effects compared to atropine. Scopolamine is also more potent in producing mydriasis and cycloplegia due to its greater affinity for muscarinic receptors in the eye muscles. Additionally, scopolamine has lower effects on the heart, bronchial muscle, and intestines compared to atropine. Therefore, B is the correct choice as scopolamine is not less potent in decreasing bronchial, salivary, and sweat gland secretions.