Stereoselectivity in pharmacodynamics and pharmacokinetics

Area of Science:

• Pharmacology and Medicinal Chemistry
• Drug Development and Safety

Background:

• Stereoisomers of bioactive compounds, including pharmaceuticals and pesticides, often exhibit significantly different biological activities.
• Typically, only one enantiomer (the eutomer) provides the desired therapeutic effect, while the other (the distomer) acts as 'isomeric ballast'.
• The distomer can contribute to or be the primary cause of adverse effects associated with racemic mixtures.

Purpose of the Study:

• To highlight the critical importance of stereoisomerism in drug action and safety.
• To emphasize the need to minimize 'isomeric ballast' and reduce the overall xenobiotic load.
• To address the underestimation of racemic product implications in scientific literature and marketing.

Main Methods:

• Review of pharmacological principles concerning stereoisomerism.
• Analysis of case studies involving racemic drugs like labetalol and medroxalol.
• Discussion of the concept of 'isomeric ballast' and its impact on efficacy and safety.

Main Results:

• The eutomer is primarily responsible for therapeutic efficacy, while the distomer often causes undesired effects.
• Racemic mixtures introduce an 'isomeric ballast' that increases the xenobiotic load without contributing to therapeutic benefit.
• The implications of using racemic drugs are frequently overlooked in research and commercialization.

Conclusions:

• Minimizing or eliminating the distomer is essential for reducing adverse effects and improving therapeutic outcomes.
• Avoiding 'isomeric ballast' is a fundamental requirement for safer and more effective drug utilization.
• Further research and regulatory attention are needed to address the widespread use of racemic products.