Inter-subject and ethnic differences in paracetamol metabolism

Area of Science:

• Pharmacology
• Metabolism
• Toxicology

Background:

• Paracetamol (acetaminophen) is a widely used analgesic and antipyretic.
• Individual variability in paracetamol metabolism can influence its efficacy and toxicity.
• Ethnic differences in drug metabolism are increasingly recognized.

Purpose of the Study:

• To compare the 24-hour urinary excretion of paracetamol and its metabolites in Caucasian, West African, and East African populations.
• To investigate ethnic and sex-based variations in paracetamol metabolic pathways.

Main Methods:

• A single oral dose of 1.5 g paracetamol was administered to 111 Caucasians, 67 West Africans, and 20 East Africans.
• Urinary excretion of paracetamol and its conjugates (mercapturic acid, cysteine, glucuronide, and sulfate) was quantified over 24 hours.

Main Results:

• Fractional recovery of mercapturic acid and cysteine conjugates was significantly lower in Africans (5.2-4.4%) compared to Caucasians (9.3%).
• Glucuronide conjugate recovery was higher in Africans (58%) than Caucasians (54%), while sulfate conjugation showed no ethnic difference.
• Caucasian females exhibited increased sulfate and reduced glucuronide conjugation compared to males, a trend also observed in Ghanaians.

Conclusions:

• Markedly reduced metabolic activation of paracetamol in African populations suggests potential ethnic differences in susceptibility to hepatotoxicity.
• Variations in paracetamol metabolism may be influenced by genetic or environmental factors, including diet.
• Significant intersubject variation in metabolic activation highlights the importance of understanding individual responses to paracetamol overdosage.