A client taking atorvastatin develops an increased serum creatine phosphokinase (CK) level. The nurse should assess the client for the onset of which problem?

Choice A reason: This is the best option to measure the peak and trough levels of vancomycin, as it reflects the highest and lowest concentrations of the drug in the blood. The peak level indicates the efficacy and potential toxicity of vancomycin, while the trough level indicates the clearance and potential subtherapeutic effect of vancomycin. The peak level should be drawn immediately after completion of the IV dose, as it takes about 30 minutes for vancomycin to reach its maximum concentration in the blood. The trough level should be drawn 30 minutes before the next administration of the medication, as it represents the lowest concentration of vancomycin in the blood before it is replenished by another dose.

Choice B reason: This is not a good option to measure the peak and trough levels of vancomycin, as it may not capture the true highest and lowest concentrations of the drug in the blood. The peak level may be lower than expected, as it takes about 30 minutes for vancomycin to reach its maximum concentration in the blood. The trough level may be higher than expected, as it is drawn too close to the next administration of the medication.

Choice C reason: This is not a good option to measure the peak and trough levels of vancomycin, as it does not reflect the highest and lowest concentrations of the drug in the blood. The peak level is drawn too early, as vancomycin has not reached its maximum concentration in the blood yet. The trough level is drawn too late, as vancomycin has already started to decline in the blood.

Choice D reason: This is not a good option to measure the peak and trough levels of vancomycin, as it may miss the highest and lowest concentrations of the drug in the blood. The peak level is drawn too late, as vancomycin may have already started to decline in the blood. The trough level is drawn too early, as vancomycin may have not reached its minimum concentration in the blood yet.

Choice A reason: Telling the client to notify the nurse if the pain is not relieved is an important nursing action, but it is not the highest priority. The nurse should assess the client's pain level before and after administering the medication, and evaluate its effectiveness. If the pain is not relieved, the nurse should report it to the prescriber and consider other interventions.

Choice B reason: Advising the client that the medication should start to work in about 30 minutes is an informative nursing action, but it is not the highest priority. The nurse should educate the client about the expected onset, peak, and duration of action of the medication, and how to take it safely and effectively. However, this does not address any immediate risks or needs of the client.

Choice C reason: Administering a stool softener/laxative at the same time as the analgesic is a preventive nursing action, but it is not the highest priority. The nurse should anticipate and prevent potential side effects of the medication, such as constipation, which can be caused by codeine. However, this does not address any urgent or emergent issues of the client.

Choice D reason: Instructing the client to request assistance when ambulating to the bathroom is the highest priority nursing action, as it addresses a serious safety concern of the client. The nurse should protect the client from falls and injuries, which can be caused by codeine's sedative and drowsy effects. The nurse should also monitor the client's respiratory rate and level of consciousness, as codeine can cause respiratory depression and altered mental status.