This study was performed in elderly patients (1) to assess the degree to which CYP2D6 mediated metabolism of debrisoquine at baseline determines plasma concentration to dose quotients for ...nortriptyline or paroxetine after 4 weeks of treatment, and (2) to compare the effects of nortriptyline and paroxetine on debrisoquine metabolism after 6 weeks of treatment. CYP2D6 activity was estimated in 66 subjects (71.4 +/- 7.2 years) before initiating treatment and again after 6 weeks of treatment with either nortriptyline or paroxetine under randomized, double-blind conditions according to a standard protocol. CYP2D6 activity was estimated by the debrisoquine recovery ratio in a 6- to 8-hour urine sample collected after oral administration of 10 mg debrisoquine sulfate. Nortriptyline and paroxetine plasma concentrations were obtained weekly. Baseline debrisoquine recovery ratio values were significantly correlated with the plasma concentration to dose quotient at 4 weeks for both nortriptyline ( = -0.75, = 0.0001, N = 29) and paroxetine ( = -0.50, = 0.003, N = 33). Treatment with either nortriptyline or paroxetine was associated with a significant decrease in the median debrisoquine recovery ratio, reflecting inhibition of CYP2D6 metabolism. The percent decrease associated with nortriptyline was significantly smaller than that with paroxetine ( < 0.0001). None of the patients treated with nortriptyline but 19 of the 32 extensive metabolizers treated with paroxetine were converted to phenotypic poor metabolic status. Our observations of CYP2D6 inhibition are consistent with data and results obtained in younger healthy volunteers. The significant correlations between baseline debrisoquine recovery ratio and the plasma concentrations to dose quotients at 4 weeks for both nortriptyline and paroxetine are consistent with CYP2D6 playing a major role in the metabolism of both drugs. CYP2D6 inhibition by paroxetine, which effectively converted 59% of patients to phenotypic PMs, may be especially relevant for elderly patients given their generally higher concentration of paroxetine.
The authors present data from an open trial of fluvoxamine (median daily dosage: 200 mg) in the treatment of generalized anxiety disorder, panic disorder, and obsessive-compulsive disorder in 19 ...older outpatients (mean age = 66.8). Of the 12 subjects completing the 21-week trial, 8 achieved a good response (50% reduction in symptom measures) and 7 were rated as much or very much improved. Fluvoxamine pharmacotherapy also had a significant effect in reducing comorbid depressive symptoms and in increasing levels of functioning. These data support the effectiveness of fluvoxamine in older subjects with anxiety disorders (particularly generalized anxiety disorder) and warrant further double-blind, placebo-controlled evaluation. (J Geriatr Psychiatry Neurol 2000; 13:43—48).
Speed of response is an important clinical issue in the treatment of depressed elderly patients. Our objective was to compare rapid response rates in a study combining therapeutic sleep deprivation ...(TSD) with paroxetine with two earlier randomized, double-blind studies in late-life depression, one of paroxetine versus nortriptyline and another of nortriptyline versus placebo. We measured depressive symptoms with the 17-item Hamilton Rating Scale of Depression (HRSD), defining rapid response as an HRSD ≤ 10 by 2 weeks. With combination therapy (TSD + paroxetine), 9 of 13 patients (69%) experienced a rapid response. In the nortriptyline versus paroxetine study, nor triptyline brought about rapid response in 12 of 37 (32%) and paroxetine in 11 of 43 patients (26%). In the third study, rapid response to nortriptyline occurred in 10 of 41 patients (24%) and to placebo in 6 of 39 patients (15%). The overall chi square, including the rate of rapid response to placebo, was 14.87 (P = .005). The chi square on the four active treatment groups, excluding placebo, was 10.28 (P = .016). This preliminary observation suggests that combined therapy with TSD plus paroxetine may be twice as successful at achieving rapid response in elderly depressed patients than conventional monotherapy with medication or placebo. A prospective, placebo-controlled evaluation of this dual therapy is warranted. (J Geriatr Psychiatry Neurol 1999; 12:67-71).
