Stereochemistry of Pharmacologically Active Compounds: A New Paradigm in Environmental Analysis and Risk Assessment

Chirality plays an important role in the life of plants and animals but it is also vital in the agricultural, pharmaceutical and chemical industries. The phenomenon of chirality is also of growing importance in the field of environmental pollution and its effects on human health. Chiral pharmacologically active compounds (PACs) are environmental pollutants. They enter the environment mainly through sewage, waste effluents from manufacturing processes, runoff and sludge. They are bioactive, ubiquitous and persistent with synergistic properties. Surprisingly, the environmental fate and effects of PACs are assessed without taking into consideration their enantiomeric forms. The European Medicines Agency (EMEA) guideline on the Environmental Risk Assessment (ERA) of Medicinal Products for Human Use [1] recommends the estimation of exposure and the prediction of risk calculation for the whole parent compounds only i.e. as a racemate if prescribed as such. Similarly, the EU Directive for ERA for Veterinary Medicinal Products [2] does not require enantiomer-specific tests to be undertaken for veterinary CMPs. Such an approach leads to an underestimation of toxicity of PACs, incorrect environmental risk assessment, and direct risk to the environment and human health, as PACs are likely to be present in the environment in their non-racemic forms. This talk will introduce the phenomenon of chirality in the context of fate and effects of chiral PACs in the environment. Results from monitoring of several wastewater treatment plants and receiving waters will be presented and implications of enantiomer-dependant fate and ecotoxicity of PACs for procedures applied in environmental risk assessment will be explored.

[1] Guideline on the ERA of medicinal products for human use; European Medicines Agency, Doc. Ref. MEA/CHMP/SWP/4447/00
[2] ERA for Veterinary Medicinal Products other than GMO containing and Immunological Products; EU Directive 81/852/EEC