Medical pharmacology, definition

The method by which the principal intended action is achieved. This is crucial in the definition of a medical device. Typically, the MD function is fulfilled by physical means (including mechanical action, physical barrier, replacement of, or support to, organs or body fimctions). The action of a medicinal product is achieved by pharmacological or immimological means or by metabolism. 

Oral bioavailability is one of principal pharmacokinetic properties in drug discovery. It represents the percentage of an oral dose that is available to produce pharmacological actions, in other words, the fraction of the oral dose that reaches the system circulation in an active form. By the definition, when a drug is administered intravenously, its bioavailability is 100%. However, when a medication is administered via other routes, especially orally, its bioavailability decreases due to incomplete absorption and first-pass metabolism. 

Biomarkers Definitions Working Group 2001 Biomarkers and surrogate endpoints preferred definitions and conceptual framework. Clinical Pharmacology and Therapeutics 69 89-95 Bland J M, Altman D G 2000 Statistical notes. The odds ratio. British Medical Journal 320 1468 Chalmers 11995 What do I want from health research and researchers when I am a patient British Medical Journal 310 1315-1318 Chatellier G et al 1996 The numbers needed to treat a clinically useful nomogram in its proper context. British Medical Journal 312 426-429 Doll R1998 Controlled trials the 1948 watershed. British Medical Journal 317 1217 (and following articles). 

A less wordy definition appears in the Oxford Concise Medical Reference Dictionary as . . . a substance that is combined with a drug to render it suitable for administration for example in the form of pills. Excipients should have no pharmacological actions themselves . There are, however, indications that in certain situations, excipients do interact with the drug... 

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