Salicylate

Aspirin is an analgesic, antipyretic, anti-inflammatory drug contained in a large number of preparations. Aspirin is rapidly hydrolysed by hepatic and blood esterases to the pharmacologically-active intermediate, salicylic acid, which has a dose-dependent serum half-life ranging from 3-20 hours. Stimulation of the respiratory centre in the central nervous system and uncoupling of oxidative phosphorylation are direct effects of salicylate that lead to many of the toxic symptoms observed in overdose situations.

Suspected overdose.
Symptoms of salicylate toxicity can include: nausea, vomiting, tinnitus, headache, hyperpnoea, confusion, hyperthermia, slurred speech and convulsions. Acid-base disturbances, such as compensated respiratory alkalosis (mild toxicity) and metabolic acidosis with increased anion gap (severe toxicity), are commonplace.

Dependent on time of dose.