Amitriptyline

General information

Indicated for: Depression; also used off-label for neuropathic pain and migraine prophylaxis.

Dosing & forms

• Forms/strengths: —
• Frequency: —
• Food: —
• Typical range: 75–150 mg/day (divided or nightly)

Mechanism (brief)

Tricyclic antidepressant; serotonin and norepinephrine reuptake inhibition with strong anticholinergic effect.

Metabolism & Half‑life

• Metabolism: CYP2D6 and CYP2C19 to nortriptyline.
• Half‑life: ~21–24 h.

Therapeutic Drug Monitoring (TDM)

Recommended: Yes

Reference range: Combined amitriptyline + nortriptyline 80–200 ng/mL.

Monitoring highlights

• Weight/BMI, fasting glucose/lipids — Baseline and periodically
• Anticholinergic effects (constipation, urinary retention, confusion) — Each visit

Sources

• Amitriptyline label — DailyMed (2025)