0071643192.pdf

TOXICOLOGY

■ Theophylline:While it was once a very popular therapy for asthma and

COPD, newer, safer, and more selective medications are more common

now. This agent is still used in neonatal apnea and bradycardia.

■ Theobromine: Found in chocolate and various teas

MECHANISM/TOXICITY

■ Mechanism of toxicity is not fully understood but includes:

■ Triggers release of preformed epinephrine and norepinephrine →

adrenergic receptor stimulation and hypokalemia

■ Phosphodiesterase inhibition

■ Adenosine receptor antagonism

SYMPTOMS/EXAM

■ Severe N/Vin majority of patients

■ CNS stimulation ranging from elevated mood to nervousness, agitation,

and seizures

■ Cardiovascular stimulation with tachycardia, hypertension, and dysrythmias

■ At high concentrations: Peripheral vasodilation and hypotension

DIAGNOSIS

■ Usually clear from history and exam

■ Serum theophylline levels, repeated every 2–4 hours until peak and

decline

■ In chronic ingestions, severe symptoms may occur at significantly lower

levels.

■ Caffeine may cross react with the theophylline assay in overdose.

TREATMENT

■ Supportive and symptomatic therapy

■ Most patients autodecontaminate with profuse vomiting.

■ Multiple-dose activated charcoal: To both decrease absorption and increase

elimination

■ Whole-bowel irrigation: For large ingestion of sustained release

preparations

■ Charcoal hemoperfusion or hemodialysis for severe toxicity

■ Benzodiazepines for CNS stimulation

OPIATES

The opioid toxidrome may result from exposure to any of the following:

■ Prescription medications (eg, fentanyl, methadone, oxycodone)

■ Over-the-counter medications (eg, diphenoxylate, dextromethorphan)

■ Illicit drugs (eg, heroin)

MECHANISM/TOXICITY

■ Stimulate opiate receptors in the CNS