acetylsalicylic acid

Aspirin (Acetylsalicylic Acid)

Overdose may result from accidental ingestion by young children; in adults, overdose is frequently suicidal. The major untoward consequences are metabolic with few morphologic changes. At first respiratory alkalosis develops, followed by metabolic acidosis that often proves fatal before anatomic changes can appear. Ingestion of as little as 2 to 4 gm by children or 10 to 30 gm by adults may be fatal, but survival has been reported after doses five times larger.

Chronic aspirin toxicity (salicylism) may develop in persons who take 3 gm or more daily, the dose required to treat chronic inflammatory conditions. Chronic salicylism is manifested by headache, dizziness, ringing in the ears (tinnitus), difficulty in hearing, mental confusion, drowsiness, nausea, vomiting, and diarrhea.

The central nervous system changes may progress to convulsions and coma. The morphologic consequences of chronic salicylism are varied. Most often there is an acute erosive gastritis , which may produce overt or covert gastrointestinal bleeding and lead to gastric ulceration. A bleeding tendency may appear concurrently with chronic toxicity, because aspirin acetylates platelet cyclooxygenase and blocks the ability to make thromboxane A2, an activator of platelet aggregation. Petechial hemorrhages may appear in the skin and internal viscera, and bleeding from gastric ulcerations may be exaggerated.

Proprietary analgesic mixtures of aspirin and phenacetin or its active metabolite, acetaminophen, when taken for a span of years, have caused renal papillary necrosis, referred to as analgesic nephropathy.