What mechanism is primarily involved in the elimination of a majority of drugs from the body?

The primary mechanism involved in the elimination of a majority of drugs from the body is metabolism and excretion. This process is critical for the pharmacokinetics of drugs, meaning how the body absorbs, distributes, metabolizes, and finally excretes them.

Metabolism typically occurs in the liver, where enzymes transform lipophilic drug molecules into more hydrophilic metabolites that can be more easily eliminated from the body. This biotransformation can result in active or inactive metabolites. Following metabolism, the resultant substances are usually excreted via the kidneys into urine, although they can also enter the bile and be eliminated through feces.

Excretion itself specifically refers to the removal of these metabolites from the body and is often done via renal pathways. While absorption refers to how drugs enter the systemic circulation, it does not contribute to their elimination. Filtration alone is a process that pertains specifically to the kidneys' function, but does not encompass the entire spectrum of drug elimination which includes both metabolic transformation and subsequent excretion.

Thus, the combination of metabolism and excretion comprehensively explains how most drugs are processed and removed from the body.