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Keywords:

  • amitriptyline;
  • computer;
  • dose regimen;
  • individualization;
  • modified Bayesian method

Abstract  The most efficient method for amitriptyline dose individualization has not been established as yet. For this purpose the authors developed and clinically assessed the modified Bayesian method supported by original basic computer program. Twenty-one male and 39 female subjects (32–65 years old), with major depressive disorder (International Classification of Diseases, 10th revision), were randomly assigned and single-blinded to take individualized (experimental group, n = 30) or empiric (control group, n = 30) doses of amitriptyline for 8 weeks. Both treatments were effective. However, the mean daily doses (112.25 ± 29.85 vs 124.50 ± 32.25 mg/day) and plasma concentrations of amitriptyline plus nortriptyline (145.43–161.95 vs 157.63–197.84 ng/mL) were lower in the experimental group (P < 0.05). Total Hamilton Rating Scale for Depression scores at baseline, 14th, 28th, 42nd and 56th day were significantly lower in experimental (mean ± SD: 26.73 ± 3.92, 18.73 ± 4.01, 11.76 ± 4.43, 9.73 ± 3.89, 8.60 ± 3.72) than in control patients (27.56 ± 4.28, 20.23 ± 4.23, 14.56 ± 3.96, 11.56 ± 4.06, 10.70 ± 4.30). Clinical Global Impression Scale severity of illness scores in the experimental (5.76 ± 0.62, 4.90 ± 0.84, 3.53 ± 1.30, 2.53 ± 1.30, 2.10 ± 1.32) and the control group (5.96 ± 0.80, 5.03 ± 0.80, 4.33 ± 0.92, 3.26 ± 1.20, 2.83 ± 1.41), as well as global improvement and therapeutic effect scores, also favored individualized regimen. The adverse effects were less frequent in the experimental group. It is concluded that the modified Bayesian method is more effective and safe than empiric treatment.