Oxymetazoline, sold under the brand name Afrin among others, is a topical decongestant and vasoconstrictor medication. It is available over-the-counter as a nasal spray to treat nasal congestion and nosebleeds, as eyedrops to treat eye redness due to minor irritation, and (in the United States) as a prescription topical cream to treat persistent facial redness due to rosacea in adults. Its effects begin within minutes and last for up to 6 hours. Intranasal use for longer than three days may cause congestion to recur or worsen, resulting in physical dependence. Oxymetazoline is a derivative of imidazole. It was developed from xylometazoline at E. Merck Darmstadt by Wolfgang Fruhstorfer and Helmut Müller-Calgan in 1961. A direct sympathomimetic, oxymetazoline binds to and activates α1 adrenergic receptors and α2 adrenergic receptors, most notably. One study classified it in the following order: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) >> α(1B), but this is not universally agreed upon. There is little consistency across the (relatively large) number of in-vitro studies with respect to binding affinity/selectivity.
This leads to a disrupted menstrual cycle, infertility, and decreased libido. Causes
Almost all cases of pituitary apoplexy arise from a pituitary adenoma, a benign tumor of the pituitary gland. In 80%, the patient has been previously unaware of this (although some will retrospectively report associated symptoms). It was previously thought that particular types of pituitary tumors were more prone to apoplexy than others, but this has not been confirmed. In absolute terms, only a very small proportion of pituitary tumors eventually undergoes apoplexy. In an analysis of incidentally found pituitary tumors, apoplexy occurred in 0.2% annually, but the risk was higher in tumors larger than 10 mm ("macroadenomas") and tumors that were growing more rapidly; in a meta-analysis, not all these associations achieved statistical significance.The majority of cases (60–80%) are not precipitated by a particular cause. A quarter has a history of high blood pressure, but this is a common problem in the general population, and it is not clear whether it significantly increase the risk of apoplexy. A number of cases has been reported in association with particular conditions and situations; it is uncertain whether these were in fact causative. Amongst reported associations are surgery (especially coronary artery bypass graft, where there are significant fluctuations in the blood pressure), disturbances in blood coagulation or medication that inhibits coagulation, radiation therapy to the pituitary, traumatic brain injury, pregnancy (during which the pituitary enlarges) and treatment with estrogens. Hormonal stimulation tests of the pituitary have been reported to provoke episodes.