How do kidney and liver function affect the way drugs are removed from the body?

The liver and kidneys are the primary organs responsible for the metabolism and excretion of drugs from the body. When these organs function optimally, they ensure that drugs are processed and removed at an appropriate rate to maintain a safe therapeutic balance.1

The Role of the Liver

The liver is a critical site for drug metabolism, where enzymes catalyze chemical transformations—such as oxidation or reduction—to alter a drug's biological activity. These processes typically convert drugs into metabolites that are less lipid-soluble, making them easier for the body to eliminate through the urine. Reduced liver function can slow this metabolic process, potentially causing drugs to remain in the system longer and increasing the risk of toxicity.21

The Role of the Kidneys

The kidneys are the main route for drug excretion. They filter plasma through the glomeruli, allowing drug molecules to enter the renal tubules for potential reabsorption or elimination in the urine. Some drugs are also actively secreted into the tubules. Impaired kidney function, such as in chronic kidney disease, reduces the body's ability to eliminate waste and drugs, which can lead to dangerous accumulations in the blood.3415