- Published on
Toxicology – Sympathomimetic Toxidrome
Sources
Sympathomimetic agents are substances that stimulate the sympathetic nervous system by increasing catecholamine activity. They may act directly on receptors (e.g., alpha- or beta-agonists) or indirectly by increasing catecholamine release, blocking reuptake, or inhibiting breakdown. Common examples include cocaine, amphetamines, MDMA, ephedrine, pseudoephedrine, epinephrine, MAO inhibitors, and synthetic stimulants such as “bath salts” (e.g., mephedrone).
Typical Presentation
Patients typically present in an agitated, hyperactive state. A common scenario involves stimulant use followed by symptoms such as chest pain, anxiety, and marked vital sign abnormalities including hypertension, tachycardia, and hyperthermia.
Clinical Features
This toxidrome reflects a “fight-or-flight” response. Key findings include tachycardia, hypertension, hyperthermia, dilated pupils, diaphoresis, hyperreflexia, and preserved bowel sounds. Patients may also exhibit agitation, pressured speech, paranoia, tremors, teeth grinding (bruxism), chest pain, and rhabdomyolysis. Unlike anticholinergic toxicity, patients are typically sweaty rather than dry.
Mechanism of Action
These agents stimulate the autonomic nervous system either by directly activating adrenergic receptors or indirectly by increasing catecholamine availability through enhanced release, decreased reuptake, or reduced metabolism.
Management
Treatment is largely supportive. Intravenous fluids are administered for hydration and to prevent or treat rhabdomyolysis. Benzodiazepines are first-line therapy for agitation, anxiety, and chest pain. Severe hyperthermia requires rapid cooling measures. Hypertension may be managed with benzodiazepines, vasodilators such as sodium nitroprusside, or alpha-blockers like phentolamine.
Key Points
Sources
Sympathomimetic agents are substances that stimulate the sympathetic nervous system by increasing catecholamine activity. They may act directly on receptors (e.g., alpha- or beta-agonists) or indirectly by increasing catecholamine release, blocking reuptake, or inhibiting breakdown. Common examples include cocaine, amphetamines, MDMA, ephedrine, pseudoephedrine, epinephrine, MAO inhibitors, and synthetic stimulants such as “bath salts” (e.g., mephedrone).
Typical Presentation
Patients typically present in an agitated, hyperactive state. A common scenario involves stimulant use followed by symptoms such as chest pain, anxiety, and marked vital sign abnormalities including hypertension, tachycardia, and hyperthermia.
Clinical Features
This toxidrome reflects a “fight-or-flight” response. Key findings include tachycardia, hypertension, hyperthermia, dilated pupils, diaphoresis, hyperreflexia, and preserved bowel sounds. Patients may also exhibit agitation, pressured speech, paranoia, tremors, teeth grinding (bruxism), chest pain, and rhabdomyolysis. Unlike anticholinergic toxicity, patients are typically sweaty rather than dry.
Mechanism of Action
These agents stimulate the autonomic nervous system either by directly activating adrenergic receptors or indirectly by increasing catecholamine availability through enhanced release, decreased reuptake, or reduced metabolism.
Management
Treatment is largely supportive. Intravenous fluids are administered for hydration and to prevent or treat rhabdomyolysis. Benzodiazepines are first-line therapy for agitation, anxiety, and chest pain. Severe hyperthermia requires rapid cooling measures. Hypertension may be managed with benzodiazepines, vasodilators such as sodium nitroprusside, or alpha-blockers like phentolamine.
Key Points
- Beta-blockers are generally avoided due to the risk of unopposed alpha-adrenergic vasoconstriction.
- Stimulant drugs can be easily manufactured or obtained, contributing to their widespread use.
- Sympathomimetics lower the seizure threshold, increasing the risk of seizures.
0 Comments
