Assessment of the antidepressant activity of dothiepin and its metabolites by preclinical tests

Systematic investigation of CD spectra of aryl benzyl sulfoxides interpreted by means of TDDFT calculations

The CD spectra of 13 crystalline aryl benzyl sulfoxides 1a-m with various substituents on the two aromatic rings were recorded in solution and in the solid state. Solution CD spectra were very homogeneous along the series, consisting in most cases of a couplet-like feature in the 200-300 nm region. The red-shifted component of the couplet, corresponding to the sulfoxide-centered n-pi* transition, is always positive for (R) absolute configuration in accordance with Mislow's rule. The presence of a strong electron-withdrawing substituent on the phenyl ring (nitro or ester group) alters the shape of the CD spectrum. CD calculations using the TDDFT method were run for eight representative compounds using DFT-optimized geometries. In all cases, calculated spectra were in very good agreement with experimental ones and allowed for rationalization of the diverse spectral behaviors. It is demonstrated that TDDFT//DFT calculations represent a reliable option for assigning the absolute configuration of this class of compounds whenever crystals suitable for X-ray are not available. Solid-state CD spectra recorded with the KCl pellet technique were in some cases in agreement with those in solution. However, in other cases new and strong CD signals appeared which were interpreted as being due to intermolecular couplings in the crystals.

Effects of dothiepin on nociceptive flexion reflex and diffuse noxious inhibitory controls in humans

The analgesic activity of dothiepin (an antidepressant interacting with serotonin receptors) was studied (double-blind) in humans. A significant increase in nociceptive flexion reflex threshold and subjective pain threshold was observed after a 14-day dothiepin treatment. The effects of dothiepin on diffuse noxious inhibitory controls were also investigated using the cold-pressor test as conditioning stimuli. After dothiepin a reduced inhibition of nociceptive flexion reflex during the cold-pressor test and a significant facilitation immediately after the cold-pressor test were observed, while the subjective pain perception was normally inhibited. Our data suggest a serotonergic modulation of diffuse noxious inhibitory controls in humans.

The excretion of dothiepin and its primary metabolites in breast milk

1. The excretion of dothiepin, nordothiepin, dothiepin-S-oxide and nordothiepin-S-oxide into breast milk was studied in eight women. Exposure to drug was measured in five of their infants, and possible drug-related effects were assessed in all eight infants. 2. Using pre-feed milk samples mean (+/- s.e. mean) milk:plasma (M:P) ratios were 0.78 +/- 0.12, 0.85 +/- 0.16, 1.18 +/- 0.29 and 1.86 +/- 0.29 for dothiepin, nordothiepin, dothiepin-S-oxide and nordothiepin-S-oxide, respectively. In post-feed milk samples, the mean M:P ratio for dothiepin (1.59 +/- 0.32) was significantly greater (P less than 0.05) but M:P ratios for the metabolites were similar. 3. Mean total calculated infant daily doses, (in dothiepin equivalents and as a percent of the maternal dose) were 0.58% for dothiepin, 0.23% for nordothiepin, 2.47% for dothiepin-S-oxide, and 1.17% for nordothiepin-S-oxide. 4. Plasma samples were obtained from five infants. In one, both dothiepin and nordothiepin were below their minimum quantifiable levels (2 micrograms l-1) while in four others both dothiepin-S-oxide and nordothiepin-S-oxide were below their minimum quantifiable levels (10 micrograms l-1). No adverse effects were found in any of the eight infants. 5. Use of dothiepin by depressed mothers is unlikely to be a significant hazard to their breast-feeding infants.

Dothiepin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in depressive illness

Dothiepin is a tricyclic antidepressant that is structurally related to amitriptyline. It appears that the antidepressant activity of dothiepin is mediated through facilitation of noradrenergic neurotransmission by uptake inhibition and possibly also by enhancement of serotoninergic neurotransmission. The overall therapeutic efficacy of dothiepin is very similar to that of amitriptyline. In addition, dothiepin appears to be comparable to imipramine, doxepin, maprotiline, mianserin, fluoxetine, fluvoxamine and trazodone. Dry mouth is the most commonly reported side effect of therapeutic doses but the incidence of this and other anticholinergic side effects is less among patients treated with dothiepin than with amitriptyline. However, the sedative/anxiolytic activity of dothiepin is similar to that of amitriptyline. Dothiepin has not been associated with cardiotoxicity at therapeutic doses. Thus, many years of extensive clinical use have shown that dothiepin is now an established and effective antidepressant in both inpatients and outpatients with depressive symptoms of varying severity and coexisting anxiety. Its therapeutic equivalence to other tricyclics ensures its place as a treatment alternative in these disorders.

Effects of various tricyclic antidepressants on amine uptake

A comparative study of the ability to block the amine pump was carried out on tricyclic antidepressants including dothiepin and northiaden in vivo. Dothiepin was found to prevent the 6-OHDA-induced depletion of cardiac noradrenaline but not the PCA-induced depletion of intracerebral serotonin. Northiaden, an active metabolite of dothiepin, also possessed the same ability with a greater potency than the parent drug. Neither compound affected the biosynthesis of catecholamines and indoleamine. However, neither dothiepin nor northiaden affected 5-HT uptake, as was also observed with imipramine and amitriptyline. These results suggest that the clinical efficacy of dothiepin may be due to inhibition of the amine pump, especially of the catecholamine uptake mechanism, which is qualitatively the same as for imipramine and amitriptyline.