OTC Drug Toxicity: Caffeine, Theophylline, and Antihistamine

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What are the proposed mechanisms of toxicity of methylxanthines?

Increased calcium release from intracellular sites, Accumulation of cyclic nucleotides (especially cAMP), Adenosine receptor blockade

How are xanthine derivatives metabolized in the body?

By the liver to methylxanthine and methyluric acid derivatives

Where is caffeine distributed throughout?

Coffee, tea, chocolate, and cola beverages

What causes the nausea and vomiting associated with toxicity of methylxanthines?

Direct stimulation of the chemoreceptor trigger zone Signup and view all the answers

What is the half-life of xanthine derivatives in nonsmokers?

3 to 15 hours Signup and view all the answers

What are the signs and symptoms of caffeine toxicity?

Restlessness, excitement, insomnia, delirium, flashes of light, ringing in the ears, tense and spastic muscles, tachycardia, ventricular fibrillation, convulsions, coma, and death. Signup and view all the answers

What is the peak distribution time for xanthine derivatives when taken orally?

Within two hours Signup and view all the answers

What is the recommended treatment for supraventricular tachycardia due to caffeine toxicity?

Beta-adrenergic antagonists like esmolol or calcium channel blockers. Signup and view all the answers

What is the recommended treatment for theophylline overdose in case of intractable convulsions, persistent hypotension, and uncontrollable arrhythmias?

Haemoperfusion Signup and view all the answers

What are the signs and symptoms of theophylline toxicity?

Convulsions, hypothermia, ataxia, visual hallucinations, cardiac arrhythmias, hypokalaemia, hyperglycaemia, hypercalcaemia, and metabolic acidosis. Signup and view all the answers

What are the signs of antihistamines toxicity?

Tremors, excitable auditory and visual hallucinations, dry mouth, and dry, hot skin. Signup and view all the answers

What are the symptoms associated with caffeine withdrawal?

Headache, anxiety, fatigue, and craving behavior. Signup and view all the answers

What is the recommended treatment for caffeine toxicity related persistent vomiting?

Anti-emetics such as metoclopramide. Signup and view all the answers

How are hypotension refractory to fluids and vasopressors treated in theophylline overdose?

Alpha-adrenergic drugs such as levarterenol. Signup and view all the answers

What are the cardiac effects associated with theophylline toxicity?

Cardiac arrhythmias. Signup and view all the answers

What is the recommended treatment for theophylline toxicity related hyperthermia and rhabdomyolysis?

Dantrolene. Signup and view all the answers

What are the potential complications of potentially lethal ingestions of caffeine?

Cardiac arrhythmias, severe CNS toxicity. Signup and view all the answers

What is the primary symptom of toxicity related to theophylline oral tablets?

Nausea. Signup and view all the answers