II. Indications
III. Contraindications
- Avoid in age <12 years old
- Concurrent MAO Inhibitor use
- Caution in Narrow Angle Glaucoma
- Caution in Benign Prostatic Hyperplasia with obstruction
IV. Precautions
- Brand-Name Unisom may use Diphenhydramine (Benadryl) instead of Doxylamine for some preparations
V. Mechanism
- First-generation histamine Antagonist (Sedating Antihistamine, Ethanolamine)
- Competitively blocks H1 Receptors at gastrointestinal Smooth Muscle by maintaining the H1 Receptor in the inactive state
- Antiinflammatory properties
- Downregulates precursors involved in Antigen Presentation, chemotaxis, cell adhesion and Cytokine production
VI. Dosing: Doxylamine (Unisom)
- Pregnancy Associated Nausea or Vomiting (Morning Sickness, Hyperemesis Gravidarum)
- Dose: 10 to 12.5 mg orally up to four times daily
- Consider using in combination with Pyrodoxine 10 mg
-
Insomnia
- Dose: 25 mg orally once daily
VII. Dosing: Combination Doxylamine 10 mg and Pyrodoxine 10 mg (Diclegis, previously Bendectin and Diclectin in Canada)
- Dose
- Start with 2 tabs orally at bedtime
- May advance to 1 tab in AM, 1 tab at Noon and 2 tabs at bedtime as needed
- Precautions
- Originally pulled from market due to safety concerns that were unsubstantiated
- Diclegis is very expensive ($570/month) until generic in 2019
- However, generic Doxylamine and Pyridoxine are inexpensive at $20/month
- Bonjesta (extended release Doxylamine 20 mg and Pyridoxine 20 mg)
- Released in 2018, very expensive and no significant added benefit aside from frequency
- References
- (2013) Presc Lett 20(6): 32-3
- (2018) Presc Lett 25(5): 29
VIII. Adverse Effects
- Anticholinergic
- False Positive Urine Drug Screen
- May result in a False Positive test for Methadone or other Opiates, or for Phencyclidine (PCP)
IX. Resources
- Doxylamine (DailyMed)
- Doxylamine and Pyrodoxine delayed release (DailyMed)
X. References
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
Images: Related links to external sites (from Bing)
Related Studies
| doxylamine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| DOXYLAMINE-PYRIDOXINE 10-10 MG | Generic | $2.54 each |
| diclegis (on 3/23/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| DICLEGIS DR 10-10 MG TABLET | Generic | $2.54 each |
Ontology: Doxylamine (C0013092)
| Definition (NCI) | A first generation ethanolamine with antiinflammatory, sedative and antihistamine properties. Doxylamine competitively inhibits the histamine 1 (H1) receptor, thereby preventing the action of endogenous histamine as well as the subsequent release of pro-inflammatory mediators from basophils and mast cells. This agent acts as an inverse agonist that combines with, and stabilizes the inactive form of the H1-receptor, shifting the H1 receptor equilibrium toward the inactive state. This results in downregulation of nuclear factor-kappaB (NF-kappaB) and NF-kappaB dependent antigen presentation, chemotaxis, as well as expression of cell-adhesion molecules and pro-inflammatory cytokines. |
| Definition (MSH) | Histamine H1 antagonist with pronounced sedative properties. It is used in allergies and as an antitussive, antiemetic, and hypnotic. Doxylamine has also been administered in veterinary applications and was formerly used in PARKINSONISM. |
| Concepts | Pharmacologic Substance (T121) , Organic Chemical (T109) |
| MSH | D004319 |
| SnomedCT | 44068004, 412380009 |
| LNC | LP16124-7, MTHU006976 |
| English | Doxylamine, Ethanamine, N,N-dimethyl-2-(1-phenyl-1-(2-pyridinyl)ethoxy)-, Doxylamine [Chemical/Ingredient], doxylamine, DOXYLAMINE, Doxylamine (substance), Doxylamine (product) |
| Swedish | Doxylamin |
| Czech | doxylamin |
| Finnish | Doksyyliamiini |
| Russian | DOKSILAMINSUKTSINAT, DOKSILAMIN, ДОКСИЛАМИН, ДОКСИЛАМИНСУКЦИНАТ |
| Polish | Doksylamina |
| Spanish | doxilamina (sustancia), doxilamina, doxilamina (producto), Doxilamina |
| French | Doxylamine |
| German | Doxylamin |
| Italian | Dossilamina |
| Portuguese | Doxilamina |
