Amitriptyline Tables:

Pharmacokinetics

Bioavailability Peak plasma level Plasma half-life Active metabolites Elimination
very variable 30-60% 4 to 8 hours 15 hours (10-28 h)* important* extrarenal
*Nortriptyline, the most important metabolite, has a half-life of 36 hours (18-60 hours). It has a polymorphically controlled metabolism (debrisoquine metabolism). In subjects with a slow metabolism (in Switzerland about 9% of the population) high therapeutic doses can lead to toxic plasma levels very quickly.

Dose
Indication Administration
Initial loading dose
Dose Interval
Maintenance dose
Dose Interval
depression oral 25-50 mg 24 hours* 25-150 mg** 24 hours*
*The daily dose can also be divided in 2 or 3 single doses, as a rule, however, one nightly dose is better tolerated. The treatment should normally last at least six months.
**The necessity of an individual dosage cannot be emphasized enough. In the hospital higher daily doses can be permitted exceptionally (up to 300 mg). Smaller doses are often effective for pain (25 mg/day). Injection of amitriptyline is poorly documented.

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