Question:
In poisoning with which of the following is central respiratory depression not a feature?
In poisoning with which of the following is central respiratory depression not a feature?
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Which one causes convulsions rather than CNS depression?
Updated On: Jun 25, 2026
- Strychnine
- Opium (opioids)
- Barbiturates
- Datura (atropine-type)
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The Correct Option is A
Solution and Explanation
Step 1: Define the question. We need the poison that does not cause central respiratory depression. Several listed agents are classic CNS depressants; one is a CNS stimulant/convulsant.
Step 2: Strychnine mechanism. Strychnine antagonises glycine at spinal inhibitory (Renshaw) synapses, causing uncontrolled motor neuron firing - violent tonic convulsions, opisthotonus and risus sardonicus. It is a stimulant; it does not depress the central respiratory centre. (Death is from asphyxia due to sustained spasm of respiratory muscles, a peripheral mechanical effect, not central depression.) Hence respiratory depression is not a feature.
Step 3: Why the others depress respiration. Opium/opioids directly suppress the brainstem respiratory centre (the leading cause of opioid death). Barbiturates are potent CNS depressants causing dose-dependent respiratory centre depression. Datura (atropine/hyoscine) in severe toxicity produces central depression, coma and respiratory depression after the initial excitatory anticholinergic phase.
Step 4: Conclude. Strychnine is the convulsant that lacks central respiratory depression.
Key fact: Strychnine is a glycine antagonist causing convulsions, not central respiratory depression.
Step 2: Strychnine mechanism. Strychnine antagonises glycine at spinal inhibitory (Renshaw) synapses, causing uncontrolled motor neuron firing - violent tonic convulsions, opisthotonus and risus sardonicus. It is a stimulant; it does not depress the central respiratory centre. (Death is from asphyxia due to sustained spasm of respiratory muscles, a peripheral mechanical effect, not central depression.) Hence respiratory depression is not a feature.
Step 3: Why the others depress respiration. Opium/opioids directly suppress the brainstem respiratory centre (the leading cause of opioid death). Barbiturates are potent CNS depressants causing dose-dependent respiratory centre depression. Datura (atropine/hyoscine) in severe toxicity produces central depression, coma and respiratory depression after the initial excitatory anticholinergic phase.
Step 4: Conclude. Strychnine is the convulsant that lacks central respiratory depression.
Key fact: Strychnine is a glycine antagonist causing convulsions, not central respiratory depression.
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