The nurse is reviewing new medication orders for a patient who has an epidural catheter for pain relief. One of the orders is for enoxaparin (Lovenox), a low–molecular-weight heparin (LMWH). What is the nurse’s priority action?

Correct Answer: D

Rationale: The correct answer is D: Contact the prescriber because the LMWH cannot be given if the patient has an epidural catheter. This is the priority action because LMWH use is contraindicated in patients with epidural catheters due to the increased risk of epidural hematoma. Contacting the prescriber ensures patient safety. Choice A is incorrect as giving the LMWH without addressing the contraindication can lead to serious complications. Choice B is unnecessary and delays necessary action. Choice C is incorrect as stopping the epidural medication without addressing the contraindication is not the priority.

Correct Answer: B

Rationale: 1. Liver disorders can lead to a decline in microsomal enzyme activity. 2. Microsomal enzymes play a role in drug metabolism. 3. Reduced enzyme activity can lead to decreased drug metabolism. 4. Decreased drug metabolism can result in an enlarged duration of action. 5. Therefore, in liver disorders, the duration of action of drugs is likely to be enlarged. Summary: A: Incorrect - Decreased duration of action is less likely due to reduced metabolism. C: Incorrect - Activity of microsomal enzymes affects drug metabolism. D: Incorrect - Changes in drug action may be significant due to altered metabolism.

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.