Protriptyline kinetics.

Area of Science:

• Pharmacokinetics
• Clinical Pharmacology

Background:

• Protriptyline is a tricyclic antidepressant.
• Understanding its pharmacokinetic profile is crucial for therapeutic management.

Purpose of the Study:

• To characterize the pharmacokinetic parameters of protriptyline following a single oral dose.
• To confirm the previously reported long half-life of protriptyline.

Main Methods:

• Single oral dose administration of 30 mg protriptyline hydrochloride to 8 healthy subjects.
• Measurement of plasma protriptyline concentrations over time.
• Calculation of key pharmacokinetic parameters including half-life and volume of distribution.

Main Results:

• Peak plasma protriptyline levels (10.4–22.3 ng/ml) were achieved between 6–12 hours post-dose.
• The mean protriptyline half-life (t1/2) was 74.3 hours (range: 53.6–91.7 hours).
• Estimated first-pass metabolism was low (10–25%), with a mean volume of distribution of 22.5 L/kg.

Conclusions:

• Protriptyline possesses a notably long elimination half-life.
• First-pass metabolism of protriptyline is minimal.
• No correlation was observed between protriptyline and doxepin pharmacokinetics in the studied subjects.