Which of the following adverse effect can occur even after the offending drug has been withdrawn a long time back ?
**Core Concept**
The question is testing the concept of drug-induced tardive dyskinesia, a condition characterized by involuntary, repetitive body movements that can occur after long-term use of neuroleptic drugs. Tardive dyskinesia is a classic example of a tardive effect, a type of adverse effect that persists even after the causal drug has been discontinued.
**Why the Correct Answer is Right**
Tardive dyskinesia is thought to result from long-term blockade of dopamine receptors in the basal ganglia, leading to an imbalance between dopamine and acetylcholine signaling. This blockade can cause irreparable damage to the brain, resulting in persistent motor symptoms even after the offending drug has been withdrawn. The pathophysiology of tardive dyskinesia is complex and involves multiple neurotransmitter systems, including dopamine, acetylcholine, and GABA.
**Why Each Wrong Option is Incorrect**
* **Option A:** Anaphylaxis is a severe, immediate hypersensitivity reaction that occurs within minutes of exposure to an allergen. It is not a tardive effect and does not persist after the offending drug has been withdrawn.
* **Option B:** Withdrawal symptoms, such as those seen in benzodiazepine or opioid dependence, occur when a person attempts to stop taking a drug after prolonged use. They are not a tardive effect and typically resolve within a short period after drug discontinuation.
* **Option C:** Hypersensitivity reactions, such as drug rash or serum sickness, are immune-mediated adverse effects that occur in response to a specific drug. They are not a tardive effect and typically resolve after the offending drug has been withdrawn.
**Clinical Pearl / High-Yield Fact**
Tardive dyskinesia can be irreversible and may persist even after the offending drug has been withdrawn for many years. It is essential to monitor patients for signs of tardive dyskinesia, especially those taking long-term neuroleptic medications.
**Correct Answer: C. Hypersensitivity reactions are not a tardive effect and typically resolve after the offending drug has been withdrawn.**