[Maprotiline versus fluvoxamine: comparison of their effects on the hypothalamo-hypophyseal-thyroid axis]

The TRH test has been used in psychiatry these last 20 years. One of the most promising results is that concerning the possibility to use it to identify the best moment to stop a treatment after clinical recovery of the depressive episode. For that it is necessary to demonstrate an absence of intrinsic action of antidepressants on the HPT axis physiology. This overt, randomized study has compared the actions on T3, T4, basal TSH and its response to the TRH test after 75 mg/day of maprotiline and 100 mg/day of fluvoxamine, both administrated in depressed patients during 28 days. Forty patients (20 men and 20 women) were studied, 20 patients per treatment. The inclusion criteria were those of DSM III-R for major depression and dysthymia as well a minimum score of 25 at MADRS scale. Blood samples for T3, T4 and basal TSH dosages were made before TRH intranasal administration (2 mg) at days 1 and 28 of the treatment. We haven't observed any difference before treatment between the 2 groups for clinical and biological studied parameters. After treatment both antidepressants produced equivalent improvement of depression evaluated by MADRS (fluvoxamine:dMADRS = 16.95 +/- 7.11; maprotiline: dMADRS = 17.10 +/- 6.84. t = 0.07, NS). T3 and T4 variations between the beginning and the end of the study weren't also significantly different between the 2 groups. Basal TSH was increased in the maprotiline group but decreased in the fluvoxamine group resulting in a significant difference (fluvoxamine: dTSH = 0.31 +/- 0.76 mUI/l. Maprotiline : dTSH = -0.23 +/- 0.66 mUI/l. t = 2.40, p < 0.02). The TSH response to TRH was decreased in the fluvoxamine group (ddTSH = 0.24 +/- 6.65 mUI/l. dAUC = 103.98 +/- 596.84 mUI/l) while it was increased in the maprotiline group (ddTSH = -3.59 +/- 5.88 mUI/l. dAUC = -355.80 +/- 505.67 mUI.min/l). The difference between the 2 treatments was not significant when evaluated by ddTSH (t = 1.53, NS) but it became significant if evaluated by dAUC (t = 2.63, p < 0.01). As we could demonstrate an absence of influence of the clinical evolution between both groups in the hormonal variations observed, we concluded to a intrinsic difference action on HPT axis between fluvoxamine and maprotiline. This difference could be linked to the different aminergic action of these 2 antidepressants.