active principle

active principle

n.

A constituent of a drug, usually an alkaloid or glycoside, on which the characteristic therapeutic action of the substance largely depends.

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active

not passive.

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active principle

the drugs or chemicals in a pharmaceutical preparation that exert an effect pharmacologically; as distinct from the inert fillers, wetting agents and other excipients also often included.

active site

that region of a protein, usually an enzyme, that binds to another molecule such as the substrate of the enzyme.

active transport

the movement of ions or molecules assisted by a carrier protein across the cell membranes and epithelial layers, usually against a concentration gradient, resulting directly from the expenditure of metabolic energy. For example, under normal circumstances more potassium ions are present within the cell and more sodium ions extracellularly. The process of maintaining these normal differences in electrolytic composition between the intracellular fluids is active transport. The process differs from simple diffusion or osmosis in that it requires the expenditure of metabolic energy.

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principle

1. a chemical component.

2. a substance on which certain of the properties of a drug depend.

3. a law of conduct.

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active principle

any constituent of a drug that helps to confer upon it a medicinal property.

reasonable person principle

the basis for many decisions in cases alleging negligence. The court bases its judgment on what it considers a reasonable person, a reasonable veterinarian in our context, would have done in the circumstances. This is the evidence that most expert witnesses are asked to give, evidence about what should be expected of a member of their profession in terms of quality of performance. Called also principle of the reasonable person.