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In pharmacology, the term ceiling effect refers to the property of increasing doses of a given medication to have progressively smaller incremental effect (an example of diminishing returns). Mixed agonist-antagonist opioids, such as nalbuphine, serve as a classic example of the ceiling effect; increasing the dose of a narcotic frequently leads to smaller and smaller gains in relief of pain. In many cases, the severity of side effects from a medication increases as the dose increases, long after its therapeutic ceiling has been reached. The term is defined as "the phenomenon in which a drug reaches a maximum effect, so that increasing the drug dosage does not increase its effectiveness." Sometimes drugs cannot be compared across a wide range of treatment situations because one drug has a ceiling effect. Sometimes the desired effect increases with dose, but side-effects worsen or start being dangerous, and risk to benefit ratio increases.This is because of occupation of all the receptors in a given specimen. ==See also== *Agonist–antagonist opioids *Buprenorphine *Codeine *Dose–response relationship *Pain ladder *Weber–Fechner law 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ceiling effect (pharmacology)」の詳細全文を読む スポンサード リンク
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