An elderly client was given a dose of Ambien PO at bedtime for sleep and she was wide awake all night instead of going to sleep.
This adverse reaction to a drug could be classified as a/an:

Choice A rationale

A drug allergy is an adverse immune-mediated reaction to a drug, involving antibodies or sensitized lymphocytes. Symptoms can range from rash and itching to anaphylaxis, occurring upon re-exposure. This client's reaction, wakefulness instead of sedation, does not align with typical allergic manifestations involving the immune system.

Choice B rationale

Drug tolerance is a diminished physiological response to a drug after repeated administration, requiring higher doses to achieve the same effect. This develops due to adaptive changes in drug receptors or metabolism. The client's experience of wakefulness, an opposite effect, is not indicative of tolerance to the drug's intended hypnotic action.

Choice C rationale

A toxic effect occurs when drug levels in the body exceed the therapeutic range, leading to harmful effects on organs or systems. This is often dose-dependent and can manifest as organ damage or severe side effects. While adverse, the described reaction of wakefulness is not typically classified as a toxic effect of Ambien.

Choice D rationale

An idiosyncratic reaction is an uncharacteristic or unpredictable response to a drug that is not an allergic reaction and does not involve known pharmacological properties. These reactions are often genetically determined and represent an individual's unique sensitivity. The paradoxical wakefulness from a sedative like Ambien is a classic example of an idiosyncratic drug response.