The FDA has approved an effervescent tablet formulation of acetylcysteine (Cetylev – Arbor) to prevent or lessen hepatic injury after acetaminophen overdose. Acetylcysteine has been available for years in an IV solution (Acetadote, and generics) and an oral solution for the same indication; use of the oral solution has been limited by its unpleasant odor and taste.

A recent article in Circulation reported that acetaminophen (Tylenol, and others; paracetamol outside the US) increased blood pressure in patients with coronary artery disease. This conclusion was based on a randomized, placebo-controlled crossover trial in 33 patients; acetaminophen 1 g three times daily for 2 weeks was associated with statistically significant increases in blood pressure of 2.9 mmHg systolic and 2.2 mmHg diastolic.1

NSAIDs can increase blood pressure; the mechanism is thought to be inhibition of cyclooxygenase leading to decreased renal prostaglandin activity. Acetaminophen also inhibits cyclooxygenase (primarily COX-2) and decreases prostaglandin activity.2

The small increases in blood pressure reported with acetaminophen would probably be inconsequential in low-risk patients, but might be a concern for those with cardiovascular disease. Like most drugs, acetaminophen should be used in the lowest effective doses for the shortest possible time. Mild to moderate pain due to osteoarthritis or headache generally responds to a dose of 650 mg.3

1. I Sudano et al. Acetaminophen increases blood pressure in patients with coronary artery disease. Circulation 2010; 122:1789.

2. B Hinz et al. Acetaminophen (paracetamol) is a selective cyclooxygenase-2 inhibitor in man. FASEB J 2008; 22:383.

3. Drugs for pain. Treat Guidel Med Lett 2010; 8:25.

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Every pharmaceutical drug is a dose-dependent poison. This article describes the clinical presentation and treatment of some dangerous overdoses commonly reported in adults.

Acetaminophen (paracetamol; Tylenol, and others) taken in overdosage can cause severe hepatic injury and death. Acetaminophen poisoning is treated with (N-)acetylcysteine. Available for many years in the US as a solution for inhalation therapy (Mucomyst, and others), it subsequently became available for oral use and was recently marketed in the US for intravenous (IV) use as Acetadote (Cumberland).