This decline does not occur in Gly-16 individuals. It has been proposed that the tachyphylactic effect of regular exposure to exogenous beta-2 agonists is more apparent in Arg-16 individuals because their receptors have not been downregulated prior to agonist administration. Nicotine
Nicotine may also show tachyphylaxis over the course of a day, although the mechanism of this action is unclear. Other examples
Nitroglycerine (or glyceryl trinitrate) and other nitrovasodilators of the nitrate type demonstrates tachyphylaxis, requiring drug-free intervals of 6 to 8 hours. Hydralazine displays tachyphylaxis if given as a monotherapy for antihypertensive treatment. It is administered with a beta-blocker with or without a diuretic. Metoclopramide
Dobutamine, a direct-acting beta agonist used in congestive heart failure, also demonstrates tachyphylaxis. Desmopressin used in the treatment of type 1 von Willebrand disease is, in general, given every 12–24 hours in limited numbers due to its tachyphylactic properties. Ranitidine, used for acid reflux treatment, can display rapid tachyphylaxis within six weeks of treatment initiation, limiting its long-term use potential. Hormone replacement, when used in menopausal women in the form of estrogen and progesterone implants, is cited as having potential to lead to tachyphylaxis, but that citation is based on a single study done in 1990 and no follow-up research is available to support this interpretation. Intervention and reversal
Intranasal decongestants
Use of intranasal decongestants (such as oxymetazoline) for more than three days leads to tachyphylaxis of response and rebound congestion, caused by alpha-adrenoceptor downregulation and desensitization.
A dermatologist may also prescribe a whitening cream to help treat the hyperpigmentation and return the skin pigmentation back to normal. If the patient does not receive treatment, the affected sites may develop permanent hyperpigmentation or hypopigmentation. History
The photosensitizing effects of plants have been known since antiquity. In Egypt around 2000 B.C., the juice of Ammi majus "was rubbed on patches of vitiligo after which patients were encouraged to lie in the sun." In A.D. 50, the Greek physician Dioscorides observed that pigment would return to patches of vitiligo if "cataplasmed with ye leaves or ye boughes of ye Black Figge," an apparent reference to Ficus carica, the common fig. These ancient practices acknowledged the hyperpigmentation effects now known to accompany phytophotodermatitis. One of the earliest reports of plant-based dermatitis was given by Chaumton in 1815, who noted that the outer rind and root of cow parsnip (a common name for any Heracleum species of plant) contained an acrid sap sufficiently strong to inflame and ulcerate the skin. Similarly in 1887 Sornevin reported that Heracleum sphondylium caused dermatitis. However, neither of these early reports recognized the crucial role of ultraviolet radiation. "Berloque dermatitis" (from the French word "berloque" meaning trinket or charm) is a term coined by Rosenthal in 1925 to describe the pendant-like streaks of pigmentation observed on the neck, face, and arms of patients.