Buy Doxylamine (antihistamine) Cas 469-21-6

Doxylamine is an antihistamine medication used to treat insomnia and allergies, and—in combination with pyridoxine (vitamin B₆)—to treat morning sickness in pregnant women. It is available over-the-counter and is sold under such brand names as Equate or Unisom, among others; and it is used in nighttime cold medicines (e.g., NyQuil) and pain medications containing paracetamol (acetaminophen) or codeine to help with sleep. The medication is delivered chemically by the salt doxylamine succinate and is taken by mouth. Doxylamine and other first-generation antihistamines are the most widely used sleep medications in the world.^[7] Typical side effects of doxylamine include dizziness, drowsiness, grogginess, and dry mouth, among others.^[8][5]

As an antihistamine, doxylamine is an inverse agonist of the histamine H₁ receptor. As a first-generation antihistamine, it typically crosses the blood–brain barrier into the brain, thereby producing a suite of sedative and hypnotic effects that are mediated by the central nervous system.

Doxylamine is also a potent anticholinergic, meaning that it causes delirium at high doses (i.e., at much higher doses than recommended).^[9] Specifically, it is an antagonist of the muscarinic acetylcholine receptors M₁ through M₅. These sedative and deliriant effects have in some cases led to the drug being used recreationally. Doxylamine was first described in 1948 or 1949.^[10]

Doxylamine is an antihistamine used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms. It is also used as a short-term treatment for insomnia.^[11]

The first-generation sedating antihistamines diphenhydramine, doxylamine, and pyrilamine are the most widely used medications in the world for preventing and treating insomnia.^[7] As of 2004, doxylamine and diphenhydramine, which are both over-the-counter medications in some countries, were the agents most commonly used to treat short-term insomnia.^[12] As of 2008 and 2017, over-the-counter antihistamines were not recommended by the American Academy of Sleep Medicine for treatment of chronic insomnia “due to the relative lack of efficacy and safety data”.^[13][14] Neither version of their guidelines explicitly included or mentioned doxylamine, although diphenhydramine was discussed.^[13][14] A 2015 systematic review of over-the-counter sleep aids including doxylamine found little evidence to inform the use of doxylamine for treatment of insomnia.^[5]

A major systematic review and network meta-analysis of medications for the treatment of insomnia published in 2022 found that doxylamine had an effect size (standardized mean difference (SMD)) against placebo for treatment of insomnia at 4 weeks of 0.47 (95% CITooltip confidence interval 0.06 to 0.89).^[15] The certainty of evidence was rated as moderate.^[15] No data were available for doxylamine in terms of longer-term treatment (3 months).^[15] For comparison, the other sedating medicines assessed, doxepin and trimipramine (both of which are tricyclic antidepressants) had effect sizes (SMD) at 4 weeks of 0.30 (95% CI –0.05 to 0.64) (very low certainty evidence) and 0.55 (95% CI –0.11 to 1.21) (very low certainty evidence), respectively.^[15]

Doses of doxylamine that have been used for sleep range from 5 to 50 mg, with 25 mg being the typical dose.^{[16][17][18][19]}