Which organ is primarily responsible for detoxifying chemicals and metabolizing drugs?

The liver is the primary organ responsible for detoxifying chemicals and metabolizing drugs. It performs a variety of critical functions essential for maintaining overall health. The liver processes the blood coming from the digestive tract, filtering out toxins, and breaking down substances like alcohol and medications. This organ contains specialized cells known as hepatocytes, which carry out metabolic processes that convert toxins into harmless substances or prepare them for excretion.

By changing the chemical composition of drugs, the liver helps to regulate drug levels in the bloodstream, ensuring that medications are effective without accumulating to dangerous levels. Furthermore, it produces important substances such as bile, which helps in the digestion of fats.

In contrast, while the kidneys play a significant role in filtering waste products from the blood and are crucial for excreting toxins via urine, their primary function is not drug metabolism but rather waste elimination. The spleen is involved in blood filtration and immune functions, and the pancreas primarily focuses on producing enzymes for digestion and hormones like insulin for blood sugar regulation. Therefore, the liver's unique combination of detoxification and metabolic capabilities makes it the correct answer for this question.