Tachyphylaxis

Tachyphylaxis

Tachyphylaxis is a medical term describing a rapidly decreasing response to a drug following administration of the initial doses.

Examples

Examples of tachyphylaxes are the following:

*Nitroglycerine demonstrates tachyphylaxis, requiring drug-free intervals when administered transdermally
*Repeated doses of ephedrine may display tachyphylaxis, since it is an indirectly acting sympathomimetic amine which will deplete noradrenaline from the nerve terminal. Thus repeated doses result in less noradrenaline being released than the initial dose.
*Nicotine may also show tachyphylaxis over the course of a day, although the mechanism of this action is unclear.
*Hydralazine displays tachyphylaxis if given as a monotherapy for antihypertensive treament. It is administered with a beta-blocker with or without a diuretic.
*Metoclopramide is another example.
*Dobutamine, a direct-acting beta agonist used in congestive heart failure, also demonstrate tachyphylaxis.
*Desmopressin used in the treatment of type 1 von Willebrand disease is generally given every 12-24 hours in limited numbers due to its tachyphylactic properties.
*Hormone replacement when used in menopausal women in the form of oestrogen and progesterone implants is cited as potentially leading to tachyphylaxis, but that citation is based on a single study done in 1990cite web |url=http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=240075 |title=nal.usda.gov |format= |work= |accessdate=] and no followup research is available to support this interpretation. LSD-25 and Psilocybin containing mushrooms also demonstrate tachyphylaxis very rapidly. e.g. it may be impossible to 'trip' two days in a row. Some people are able to 'trip' by taking up to 3x the dosage, some users may not be able to negate tachyphylaxis at all until a period of days has gone by.

References

ee also

*desensitization
*physiological tolerance
*physical dependence
*Mithridatism

See Lehne, R. 2007, PHARMACOLOGY FOR NURSING CARE, Saunders/Elsevier, St. Louis, p.79 for more info.

External links

*


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