Doxepin vs Metformin
FDA Approved vs FDA Approved
monitor Mechanism-based · 65% Both Doxepin and Metformin enhance GABAergic activity. Combined CNS depression increases risk of excessive sedation, respiratory depression, and impaired coordination. Do not combine with alcohol.
Molecular Data
Doxepin Metformin
Weight 279.38 Da 129.16 Da
Half-life ~15 hours ~5 hours
Type Tricyclic dibenzoxepin derivative (C19H21NO) Biguanide (C4H11N5)
Key Benefits
Doxepin
01 FDA-approved specifically for sleep maintenance insomnia at ultra-low doses (3-6 mg as Silenor)
02 Highly selective H1 antihistamine at low doses, avoiding the side effects of traditional tricyclic antidepressants
03 Non-habit-forming with no dependence, tolerance, or abuse potential
04 No rebound insomnia upon discontinuation, unlike benzodiazepines and Z-drugs
05 Particularly effective for maintaining sleep in the latter half of the night, when many other sleep aids have worn off
06 Extremely well-tolerated side effect profile at ultra-low doses
Metformin
01 Improved insulin sensitivity and glucose regulation
02 Activation of AMPK, the master metabolic energy sensor
03 Potential lifespan extension and delay of age-related diseases (under investigation in TAME trial)
04 Reduced hepatic glucose output (gluconeogenesis suppression)
05 Modest weight loss or weight neutrality compared to other diabetes medications
06 Anti-inflammatory effects through NF-kB pathway suppression
07 Potential anti-cancer properties via mTOR inhibition and AMPK activation
08 Improved lipid profile with modest reductions in LDL cholesterol and triglycerides
Side Effects
Doxepin
Morning drowsiness or grogginess (more common at the 6 mg dose; uncommon at 3 mg)
Dry mouth (mild at ultra-low doses, much less than at antidepressant doses)
Nausea
Upper respiratory tract infection (observed in clinical trials at rates similar to placebo)
Metformin
Gastrointestinal distress (nausea, diarrhea, bloating, abdominal cramping) - most frequent complaint, affects up to 25% of users
Metallic taste in mouth
Decreased appetite
Flatulence and abdominal distension
Loose stools, particularly when initiating therapy or increasing dose
Contraindications
Known hypersensitivity to doxepin or other dibenzoxepines
Concurrent use of MAOIs or use within 14 days of MAOI discontinuation
Untreated narrow-angle glaucoma
Severe urinary retention
Severe hepatic impairment (doxepin is extensively hepatically metabolized)
Severe renal impairment (eGFR below 30 mL/min/1.73m2)
Acute or chronic metabolic acidosis, including diabetic ketoacidosis
Known hypersensitivity to metformin
Acute conditions with potential for tissue hypoxia (decompensated heart failure, respiratory failure, recent MI, sepsis)
Severe hepatic impairment
Excessive alcohol intake (increases risk of lactic acidosis)
Research Evidence
Doxepin Metformin
Status FDA Approved FDA Approved
References 4 studies 5 studies
Latest — 2023
FDA Approved Yes Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.