A patient Rajnish having depressive disorder has taken 25 times the normal dose of amitriptyline. Which of the following is not likely to be observed in this patient ?
**Core Concept**
Amitriptyline is a tricyclic antidepressant (TCA) that works by inhibiting the reuptake of serotonin and norepinephrine, thereby increasing their concentration in the synaptic cleft. However, at high doses, amitriptyline can cause anticholinergic effects due to its blockade of muscarinic receptors, leading to various systemic symptoms.
**Why the Correct Answer is Right**
In a patient who has taken a toxic dose of amitriptyline, one would expect to observe anticholinergic effects such as:
* Dry mouth (due to decreased salivation)
* Blurred vision (due to mydriasis)
* Constipation (due to decreased gut motility)
* Tachycardia (due to blockade of vagal tone)
* Confusion and disorientation (due to central anticholinergic effects)
**Why Each Wrong Option is Incorrect**
**Option B:** Hyperthermia is unlikely to be observed in this patient. Amitriptyline can cause hypotension and decreased vasomotor tone, which would lead to vasodilation and potentially decreased body temperature.
**Option C:** Myocardial infarction is unlikely to be observed in this patient with acute amitriptyline overdose. While TCAs can cause QT prolongation, the primary concern in acute overdose is anticholinergic toxicity, not cardiac ischemia.
**Option D:** Seizure is unlikely to be observed in this patient with acute amitriptyline overdose. While TCAs can cause seizures at high doses, this is more commonly seen with bupropion or other drugs that have a lower therapeutic index.
**Clinical Pearl / High-Yield Fact**
In cases of TCA overdose, it's essential to remember the "triple threat" of anticholinergic, cardiac, and central nervous system toxicity. A high index of suspicion and prompt recognition of these symptoms can guide management and improve patient outcomes.
**Correct Answer:** B.