After receiving Nembutal PO at bedtime, a client is wide awake all night instead of going to sleep. What kind of adverse reaction to a drug does this situation represent?

Choice A reason: Toxic effects involve overdose symptoms like coma; staying awake isn’t toxicity, as Nembutal’s sedative intent is reversed, not exaggerated, in this reaction. Choice B reason: Drug allergy causes immune responses (e.g., rash); insomnia isn’t allergic, but a paradoxical effect, differing from hypersensitivity reactions entirely. Choice C reason: Idiosyncrasy is an unexpected reaction; Nembutal, a barbiturate, should sedate, but wakefulness is an abnormal, individual response, fitting this category precisely. Choice D reason: Tolerance reduces efficacy over time; this acute, opposite reaction to a sedative isn’t tolerance, but an immediate, unpredictable drug response.