​Toxicology – Seizure-Inducing Toxins


Cocaine
Cocaine lowers the seizure threshold through potent stimulation of the central nervous system, similar to other sympathomimetic agents.


Isoniazid
Isoniazid toxicity can cause severe, refractory seizures that are characteristically resistant to standard therapy and require treatment with pyridoxine.


Anticholinergics
Seizures may occur as a late and severe manifestation of anticholinergic toxicity.


Amphetamines
Amphetamines increase catecholamine release and significantly lower the seizure threshold, increasing the risk of seizures.


Organophosphates
These insecticides produce a cholinergic toxidrome and can lead to seizures due to excessive acetylcholine accumulation.


Ethanol Withdrawal
Seizures may develop within 6 to 48 hours after abrupt cessation of alcohol in dependent individuals.


Tricyclic Antidepressants (TCAs)
At high doses, TCAs can induce seizures, often occurring before serious cardiac complications such as arrhythmias or arrest.


Methylanthines
Agents such as theophylline can cause seizures in overdose due to central nervous system stimulation.


Phencyclidine (PCP)
Large doses of PCP may result in severe toxicity, including seizures, hyperthermia, coma, and death.


Lidocaine
Intravenous toxicity from local anesthetics like lidocaine can initially cause seizures, followed by cardiovascular collapse.


Camphor
Camphor exposure, especially in children, can lead to seizures due to increased absorption through ingestion or skin contact.


Sympathomimetics
This class of drugs broadly lowers the seizure threshold through increased adrenergic activity.


Benzodiazepine Withdrawal
Abrupt discontinuation of benzodiazepines can lead to withdrawal symptoms, including seizures. Use of flumazenil may precipitate acute withdrawal in dependent individuals.


Lithium
Severe lithium toxicity may present with neurological complications, including seizures.


Lindane
Lindane, used topically for lice and scabies, can cause seizures when absorbed in excessive amounts, particularly in infants and children.


Lead (Severe Toxicity)
Extremely elevated lead levels can result in neurological toxicity, including seizures.


Treatment
Benzodiazepines such as diazepam or lorazepam are first-line therapy for toxin-induced seizures. If seizures persist, phenobarbital is considered second-line. In refractory cases, propofol with airway protection may be required. Phenytoin and fosphenytoin are generally not effective for toxin-induced seizures. Pyridoxine should be administered when isoniazid or certain mushroom toxicities are suspected.