Drug metabolism is the enzymatic break down of drugs-a process that takes place in the liver. While drug metabolism can take place at the cellular level, the liver is the major site for this process due to its size-translating to a big supply of enzymes. Drug metabolism is classified as one of the liver’s processes to detoxify the body or get rid of foreign compounds (Law et al., 2014). When the drug reaches the target site and finished working, the remaining amounts may accumulate in the body to levels that may be poisonous or toxic. Drug components are xenobiotics-suggesting that their structure is foreign and strange to the body’s biochemistry. In this regard, the purpose of the enzymatic break down of drugs (drug metabolism), it to transform drug structure into a soluble structure that can be eliminated from the body through bile or urine (Perlis, 2014).
As depicted by the image above, drug metabolism takes place in three major phases or stages. The first phase involves the modification of the drug compounds through introducing a polar head which is reactive. This process may be achieved through oxidation, hydrolysis, reduction and cyclization (Law et al., 2014). On the other hand, the second phase of drug metabolism involves conjugation of the active metabolites created in phase I (Novik et al., 2010). This is purposely intended to increase the molecular weight of these compounds so as to ensure that they are heavy enough, hence cannot penetrate or diffuse through membranes. Conjugation helps in increasing the molecular weight but at the same time, retaining solubility for the purposes of elimination through bile or urine. The final phase of drug metabolism is elimination through bile and urine (Novik et al., 2010).
References
Law, V., Knox, C., Djoumbou, Y., Jewison, T., Guo, A.C., Liu, Y., Maciejewski, A., Arndt, D., Wilson, M., Neveu, V. and Tang, A., 2014. DrugBank 4.0: shedding new light on drug metabolism. Nucleic acids research, 42(D1), pp.D1091-D1097.
Novik, E., Maguire, T.J., Chao, P., Cheng, K.C. and Yarmush, M.L., 2010. A microfluidic hepatic coculture platform for cell-based drug metabolism studies. Biochemical pharmacology, 79(7), pp.1036-1044.
Perlis, R., 2014. Drug Metabolism Animation, Retrieved from https://www.youtube.com/watch?v=a5ZtBnYUEeQ
