The following pharmacological definition has been taken from the Pharmacology and Experimental Therapeutics Department Glossary at Boston University School of Medicine.
The ability of a population, an individual or a tissue, relative to the abilities of others, to respond in a qualitatively normal fashion to a particular drug dose. The smaller the dose required to produce an effect, the more sensitive is the responding system. A patient would be considered abnormally sensitive to aspirin if a small fraction of the normal analgesic dose gave adequate pain relief; or, were an abnormally large dose of aspirin required to afford pain relief, the subject would be said to be “insensitive” to aspirin. Conversely, the drug would appear to be extraordinarily potent or impotent in such a patient. If a patient manifested an allergic response after raking aspirin, he would be considered hypersensitive to aspirin, regardless of whether the aspirin afforded him relief from pain, and regardless of the size of the dose required to elicit the allergic response. Such a patient might be simultaneously hypersensitive to aspirin, and insensitive to aspirin, acting as an analgesic agent.
Every subject is sensitive to a drug; the question of importance is “how sensitive?” In any event sensitivity is a property ascribed to the organism; potency is a property ascribed to the drug. Hypersensitivity is a property ascribed to a subject in a particular immunologic state.
Sensitivity may be measured or described quantitatively in terms of the point of intersection of a dose-effect curve with the axis of abscissal values or a line parallel to it; such a point corresponds to the dose just required to produce a given degree of effect (see Threshold”). In analogy to this, the “sensitivity” of a measuring system is defined as the lowest input (smallest dose) required to produce a given degree of output (effect).
The copyright of the text is hold by Trustees of Boston University. Permission has been granted for its use in this blog.