Diphenhydramine - perhaps known most commonly as its brand name formulation Benadryl - is a first-generation H1 receptor antihistamine that is used extensively for the treatment of seasonal allergies, insect bites and stings, and rashes [L5263, L5266, L5269, F3379]. However, it also has antiemetic, antitussive, hypnotic, and antiparkinson properties [L5269, F3352]. As histamine receptors exist both peripherally and in the central nervous system, diphenhydramine has been shown to cause sedation due to its competitive antagonism of histamine H1 receptors within the central nervous system [L5263, L5266, L5269, F3379, A174541]. While its use in allergy therapy can sometimes fall out of favor due to its sedative effect, diphenhydramine has been repurposed for use within many non-prescription over-the-counter sleep aids and cough-and-cold medications that have been marketed for "night time" use [L5263, L5281, L5287]. Diphenhydramine is also used in combination with [DB14132] as the anti-nausea drug [DB00985] where it is utilized primarily for its antagonism of H1 histamine receptors within the vestibular system [A1540]. Diphenhydramine has also been shown to be implicated in a number of neurotransmitter systems that affect behaviour including dopamine, norepinephrine, serotonin, acetylcholine, and opioid [A1539]. As a result, diphenhydramine is being investigated for its anxiolytic and anti-depressant properties.
Synonyms
β-dimethylaminoethyl benzhydryl ether
2-(benzhydryloxy)-N,N-dimethylethylamine
2-diphenylmethoxy-N,N-demthylethanamine
Diphenhydramine salicylate
α-(2-dimethylaminoethoxy)diphenylmethane
O-benzhydryldimethylaminoethanol
Diphenhydramine
Diphenhydramine hydrochloride
Diphenhydramine methylbromide
Difenhidramina
Diphenhydraminum
Diphenhydramine citrate
N-(2-(diphenylmethoxy)ethyl)-N,N-dimethylamine
β-dimethylaminoethanol diphenylmethyl ether
Indication
Diphenhydramine is a first-generation histamine H1 receptor antagonist (H1 antihistamine) that is widely available as a non-prescription, over-the-counter (OTC) medication. As an OTC medication, diphenhydramine is typically formulated as tablets and creams indicated for use in treating sneezing, runny nose, itchy/watery eyes, itching of nose or throat, insomnia, pruritis, urticaria, insect bites/stings, allergic rashes, and nausea [L5263, L5266, L5269, F3379, A174541]. Additionally, when the use of oral diphenhydramine is impractical, there are also prescription-only formulations such as diphenhydramine injection products that are effective in adults and pediatric patients (other than premature infants and neonates) for: i) the amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after acute allergic reaction symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated [F3352]; ii) the active treatment of motion sickness [F3352]; and iii) use in parkinsonism when oral therapy is impossible or contraindicated, as follows: parkinsonism in the elderly who are unable to tolerate more potent agents; mild cases of parkinsonism in other age groups, and in other cases of parkinsonism in combination with centrally acting anticholinergic agents [F3352].
Categories
Agents producing tachycardia
Amines
Aminoalkyl Ethers
Anesthetics
Anesthetics, Local
Anti-Allergic Agents
Anticholinergic Agents
Antiemetics
Antihistamines for Systemic Use
Antihistamines for Topical Use
Antipruritics, Incl. Antihistamines, Anesthetics, Etc.
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682
