Safety Assessment of Acyl Glucuronides-A Simplified Paradigm

Area of Science:

• Drug metabolism and pharmacokinetics
• Toxicology
• Chemical reactivity of drug metabolites

Background:

• Acyl glucuronides are reactive metabolites of carboxylic acid-containing drugs.
• Concerns exist regarding their safety, but direct evidence is limited.
• Species differences, instability, and rearrangement complicate safety assessments.

Purpose of the Study:

• To discuss alternative mechanisms of drug-induced toxicity.
• To propose a novel approach for comparing acyl glucuronide exposure between humans and preclinical species.
• To aid in the safety qualification of acyl glucuronide metabolites.

Main Methods:

• Review of existing literature on acyl glucuronide reactivity and toxicity.
• Discussion of alternative toxicity mechanisms.
• Proposal of a quantitative approach to estimate total body burden of circulating acyl glucuronides.

Main Results:

• Acyl glucuronides can exhibit structure-dependent reactivity.
• Traditional safety assessment methods are challenged by acyl glucuronide properties.
• A practical method is proposed to compare human and animal exposure to acyl glucuronides.

Conclusions:

• Alternative mechanisms to acyl glucuronide reactivity may cause adverse drug reactions.
• The proposed approach facilitates comparative assessment of systemic exposure to acyl glucuronides.
• This method can improve the preclinical safety evaluation of drugs containing carboxylic acid moieties.