A 6-year-old child who has chickenpox also has a fever of 102.9 F (39.4 C). The child’s mother asks the nurse if she should use aspirin to reduce the fever.
What is the best response by the nurse?

Choice A rationale:

Phenytoin is an anticonvulsant drug used in the prophylaxis and control of various types of seizures. It has a narrow therapeutic index, which means that the safe and toxic plasma levels of the drug are very close to each other. This characteristic makes the dosing of phenytoin challenging, as even small deviations from the recommended therapeutic range can lead to suboptimal treatment or adverse effects. Therapeutic effect without clinical signs of toxicity occurs more often with serum total concentrations between 10 and 20 mcg/mL34. Therefore, clinicians are advised to initiate therapeutic drug monitoring in patients who require phenytoin.

Choice B rationale:

The statement that phenytoin has a low chance of being effective is incorrect. Phenytoin is a widely used and effective anticonvulsant. It works by slowing down impulses in the brain that cause seizures. It is used to control seizures but does not treat all types of seizures. The effectiveness of phenytoin is not determined by its narrow therapeutic index but by its pharmacological action in the brain.

Choice C rationale:

The assertion that there is no difference between safe and toxic plasma levels of phenytoin is incorrect. There is indeed a difference between the safe (therapeutic) and toxic levels of phenytoin. The therapeutic range for phenytoin is typically between 10 and 20 mcg/mL34. Levels above this range can lead to toxicity, while levels below this range may not provide the desired therapeutic effect.

Choice D rationale:

The statement that a very small dosage of phenytoin can result in the desired therapeutic effect is not entirely accurate. While it’s true that phenytoin is effective in controlling seizures, the dosage required to achieve this effect is not necessarily “very small”. The usual adult dose for seizures is 100 mg orally 3 times a day. The dosage may need to be adjusted based on individual patient factors and response to therapy. Therefore, it’s not accurate to generalize that a “very small” dosage will result in the desired therapeutic effect for all patients.

Choice A rationale:

A WBC count of 16,000/mm is higher than the normal range of 5,000 to 10,000 cells/mm. This indicates that the body is fighting an infection, which is a common reason for prescribing Vancomycin. Therefore, a high WBC count could indicate a therapeutic response to the medication as it suggests that the body’s immune system is actively fighting the infection.

Choice B rationale:

A BUN level of 42 mg/dl is higher than the normal range of 7 to 20 mg/dL3456. Elevated BUN levels can indicate kidney damage or disease, which is not a desired therapeutic response to Vancomycin. Vancomycin can be nephrotoxic, and its use requires careful monitoring of kidney function. Therefore, a high BUN level does not indicate a therapeutic response to the medication. Choice C rationale:

A blood pressure reading of 95/64 is considered normal. Maintaining normal blood pressure is important for overall health and can indicate that the patient’s body is responding well to the medication. Therefore, a blood pressure reading within the normal range could indicate a therapeutic response to Vancomycin.

Choice D rationale:

A body temperature of 101.8F is considered a fever14. Fever is a common response to infection and can indicate that the body is fighting off an infection, which is a common reason for prescribing Vancomycin. Therefore, a high body temperature could indicate a therapeutic response to the medication as it suggests that the body’s immune system is actively fighting the infection.