What describes the process of a drug moving from the blood into tissues and cells?

The process of a drug moving from the blood into tissues and cells is known as distribution. This phase occurs after the drug has been absorbed into the bloodstream and refers to how the drug is dispersed throughout the body. Factors that can affect distribution include blood flow to specific tissues, the drug's ability to cross cell membranes, and the binding of the drug to plasma proteins and tissues. Understanding distribution is crucial in pharmacology as it influences the drug’s therapeutic effect, duration of action, and potential side effects.

Absorption, on the other hand, pertains to the process of a drug entering the bloodstream, while excretion involves the removal of the drug from the body, and metabolism refers to the chemical alteration of the drug within the body. Each of these processes plays a distinct role in drug pharmacokinetics, but distribution specifically denotes the movement from the blood to cells and tissues.