BEHAVIOR OF PHARMACEUTICAL DRUGS (HUMAN AND ANIMAL HEALTH) IN THE ENVIRONMENT

Pharmaceutical drugs (human and animal health) and their precursors or degradates are released to the environment as a result of manufacture, use, and disposal. The potential environmental exposure pathways of these drugs, the description of environmental expo-sure compartments, and the type and nature of studies recommended by the Food and Drug Administration (FDA) (1) to address their behavior in these compartments have been reviewed by Stamm and Velagaleti (2) and Velagaleti (3). The knowledge gained on the partitioning of pharmaceutical drugs in the environmental compartments and their degradation behavior from studies conducted to comply with FDA regulations (1) during the past 10 years has helped the pharmaceutical industry and the FDA regulators define the environmental impacts of these drugs. Based on this knowledge, FDA h a s recently proposed new regulations. Biodegradation, hydrolysis, and photodegradation (direct and indirect) are the processes that contribute to the degradation and depletion processes of the drugs in the environment. Biotransformation, mineralization (biodegradation), and chemical transformation (hydrolysis and photodegradation) are the common mechanisms of such degradative processes. There appears to be a significant variation in the degree of biotransformation and chemical transformation, among various classes of drugs. The amount of drug residues lefi in the environment would depend on the amount of drug produced, the degradation, partial depletion, and dilution processes which help reduce the drug concentration in the environment. Key Words: Human and animal health; Drugs; Environmen