Active Transport

Passage of substances through cellular or subcellular membranes against the concentration gradient using transport proteins, either by coupling to an energy-providing reaction (e.g. ATP cleavage) or to the opposite concentration gradient of another substance.

Through active transport, a drug can pass through the cell membrane independently of the concentration ratios and change from one compartment to another. The active transport is made possible by a carrier which works dependent on energy or ATP. Active transport is rather rare in the resorption (uptake in the intestine) of drugs, but in the excretion in the kidney the body uses the energy-dependent secretion in the tubule lumen to help.