- Diphenhydramine citrate
- Drug Entry
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 9,10,11,17. However, it also has antiemetic, antitussive, hypnotic, and antiparkinson properties 11,16. 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 9,10,11,17,5. 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 9,12,13.
Diphenhydramine is also used in combination with 8-chlorotheophylline as the anti-nausea drug Dimenhydrinate where it is utilized primarily for its antagonism of H1 histamine receptors within the vestibular system 4.
Diphenhydramine has also been shown to be implicated in a number of neurotransmitter systems that affect behaviour including dopamine, norepinephrine, serotonin, acetylcholine, and opioid 3. As a result, diphenhydramine is being investigated for its anxiolytic and anti-depressant properties.
- Accession Number
- Not Available
- CAS Number
- Average: 447.484
- Chemical Formula
- InChI Key
- IUPAC Name
- 2-hydroxypropane-1,2,3-tricarboxylic acid; [2-(diphenylmethoxy)ethyl]dimethylamine
- Predicted Properties
Property Value Source Water Solubility 0.0752 mg/mL ALOGPS logP 3.44 ALOGPS logP 3.65 ChemAxon logS -3.5 ALOGPS pKa (Strongest Basic) 8.87 ChemAxon Physiological Charge 1 ChemAxon Hydrogen Acceptor Count 2 ChemAxon Hydrogen Donor Count 0 ChemAxon Polar Surface Area 12.47 Å2 ChemAxon Rotatable Bond Count 11 ChemAxon Refractivity 79.93 m3·mol-1 ChemAxon Polarizability 29.99 Å3 ChemAxon Number of Rings 2 ChemAxon Bioavailability 1 ChemAxon Rule of Five Yes ChemAxon Ghose Filter Yes ChemAxon Veber's Rule No ChemAxon MDDR-like Rule No ChemAxon