Biodegradation: A Pharmaceutical Journey

Pharmaceuticals are essential to modern healthcare but increasingly represent a pervasive and biologically active class of environmental contaminants. Following administration, many drugs are incompletely metabolised in the human body and are excreted as parent compounds or active metabolites, subsequently entering municipal wastewater treatment plants (WWTPs). Conventional treatment processes only partially remove many pharmaceuticals, resulting in chronic sub-therapeutic exposure of microbial communities which act as both functional agents of biodegradation and sensitive ecological targets. Such exposure alters microbial structure and function, reduces biotransformation capacity, promotes the persistence of recalcitrant compounds such as carbamazepine and diclofenac, and drives the selection and dissemination of antibiotic resistance genes. These effects may propagate across aquatic, terrestrial, agricultural, and food systems via treated effluents and biosolids, linking human medical practices to environmental and public health outcomes. By integrating Pharmaceutical science, wastewater engineering, microbiome ecology, and antimicrobial resistance research, this work frames pharmaceutical pollution as a closed-loop OneHealth challenge.