Phenylephrine is a medication that is used as a nasal decongestant, used to dilate the pupil, used to increase blood pressure (given intravenously in cases of hypotension, septic shock and anesthesia), used to relieve hemorrhoids and uncomplicated nasal congestion. It is a selective α1-adrenergic receptor agonist with minimal to no beta-adrenergic activity. It causes constriction of both arteries and veins. Phenylephrine can also be taken by mouth, given by injection into a vein or muscle, or applied to the skin.
Common side effects when taken by mouth or injected include nausea, vomiting, headache, and anxiety. Use on hemorrhoids is generally well tolerated. Severe side effects may include a slow heart rate, intestinal ischemia, chest pain, kidney failure, and tissue death at the site of injection. It is unclear whether its use during pregnancy and breastfeeding is safe.
Phenylephrine was patented in 1927 and came into medical use in 1938. It is available as a generic medication. Unlike pseudoephedrine, abuse of phenylephrine is very uncommon. Its effectiveness as a nasal decongestant has been questioned.
Phenylephrine is used as an alternative to pseudoephedrine as a decongestant, whose availability has been restricted due to a potential for use in the illicit synthesis of methamphetamine. Its efficacy as an oral decongestant has been questioned, with several independent studies finding that it provided no more relief to sinus congestion than a placebo.
A 2007 meta-analysis concluded that the evidence for its effectiveness is insufficient, though another meta-analysis published shortly thereafter by researchers from GlaxoSmithKline found the standard 10-mg dose to be more effective than a placebo; however, the fact that GSK markets many products containing phenylephrine has raised some speculation regarding selective publishing and other controversial techniques. A 2007 study by Wyeth Consumer Healthcare notes that 7 studies available in 1976 support the efficacy of phenylephrine at a 10 mg dosage.
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A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter of which has disputed effectiveness). Intranasal corticosteroids can also be used as decongestants and antihistamines can be used to alleviate runny nose, nasal itch, and sneezing. Topical decongestants on topical application as dilute solution (0.05–0.
In rat mesenteric arteries, smooth muscle cells exhibit intercellular calcium waves in response to local phenylephrine stimulation. These waves have a velocity of similar to 20 cells/s and a range of similar to 80 cells. We analyze these waves in a theoret ...
Muscular arteries are able to actively modify their diameter by modulating the tone of the smooth muscle cells located within the arterial wall. A small variation of lumen diameter has a large influence on blood flow as well as on arterial pressure. The ca ...
To investigate the functional role of different alpha1-adrenergic receptor (alpha1-AR) subtypes in vivo, we have applied a gene targeting approach to create a mouse model lacking the alpha1b-AR (alpha1b-/-). Reverse transcription-PCR and ligand binding stu ...