What are the four principles of pharmacokinetics?

The four principles of pharmacokinetics are absorption, distribution, metabolism, and excretion.

Absorption refers to the process by which a drug enters the bloodstream after being administered. This can vary depending on the form of the drug and the route of administration, affecting the onset and intensity of its action.

Distribution is the process by which the drug spreads throughout the body's fluids and tissues. Factors influencing distribution include blood flow to tissues, the drug's affinity for tissues, and the presence of barriers, like the blood-brain barrier.

Metabolism involves the chemical alteration of the drug within the body, primarily occurring in the liver. This process can transform the drug into an active metabolite or a form that can be more easily excreted.

Excretion is the process of eliminating the drug from the body, primarily through the kidneys but also via other routes such as bile, sweat, and exhalation. Understanding these processes is crucial for determining the correct dosing, effects, and potential side effects of medications.

Other options introduce terms that are either not fundamental principles of pharmacokinetics, like "toxicity" or "serotonin," or they miss one of the core components of pharmacokinetics, making them unsuitable as correct choices.