Solvent dependence of the photophysical properties of 2-chlorothioxanthone, the principal photoproduct of chlorprothixene.

2-chlorothioxanthone (CTX) is used as photoinitiator for the reticulation of synthetic resins and for the preparation of pharmaceuticals. It was previously determined that CTX is the primary photoproduct of z-chlorprothixene (CPTX) when irradiated at 313 nm and is formed in an autocatalyzed reaction through an energy-transfer mechanism (Piñero et al. [2009] Photochem. Photobiol., 85, 895-900). In this work, the photophysical properties of CTX were measured in acetonitrile/water solutions to determine if their magnitude can affect the side effects of CPTX. The results show that CTX has higher absorption coefficients in the visible region (400-420 nm) and higher triplet quantum yields than its parent compound. Similar to TX, both properties strongly depend on the solvent polarity/hydroxylicity. The quantum yield of the triplet intermediate is very close to the value of the phenothiazine triplets. The phenothiazines are the most phototoxic antidepressants. Therefore, given the appropriate microenvironment, the photosensitization side effects of CPTX can be intensified on the production of CTX.

Phenolic metabolites of chlorprothixene in man and dog.

From urine and feces of dogs and urine of patients given chlorprothixene (CPT) per os, metabolites were extracted without or with enzymatic deconjugation and separated by repeated TLC. Purified compounds were characterized by UV, NMR, and mass spectrometry, by color reactions, and by chemical interconversions. Both species excreted 6- and 7-hydroxy-CPT besides the sulfoxide and demethylated analogues. In urine, the phenols were largely present as conjugates. The major metabolites in dog feces were 5-hydroxy-CPT and its demethylated derivative, whereas 5-hydroxylation was not detected in man. Dog excrete also contained 6-hydroxy-7-methoxy (or 7-hydroxy-6-methoxy)-CPT; further, a 5-hydroxy compound was detected in which the exocyclic double bond was hydrated. In the other metabolites, the Z-configuration of CPT had been retained, but small quantities of E-isomers were formed during isolation. According to preliminary quantitative data, phenols accounted for a small part of extractable metabolites in human urine, whereas they predominated in dog feces.

Presence of chlorprothixene and its metabolites in breast milk.

Chlorprothixene (CPX) and CPX sulphoxide were demonstrated in breast milk from two psychotic mothers taking 200 mg CPX daily. The milk concentrations of CPX were 120 to 260% greater than in plasma. The estimated amounts of drug administered in breast milk to one of the infants were 15 and 26 micrograms/day for CPX and CPX sulphoxide, respectively. Accordingly, the infant dose of the parent compound would be only 0.1% of the maternal dose/kg body weight. It is not likely that CPX or its metabolite would exert any immediate pharmacological effects in the nursing infant. However, the long term effect of low doses of neuroleptic drugs in the developing infants is not yet known.

[Proceedings: Age and sex specificity of organ distribution and metabolism of chlorprothixene and nortriptyline in the rat (author's transl)]. / Alters- und Geschlechtsbhängigkeit der Organverteilung und des Metabolismus von Chlorprothixen und Nortriptylin bei Ratten

Chlorprothixene and its N-desmethyl derivative are found to be present in the brain, liver, kidneys and lungs of young animals in larger quantities and for a longer period of time than in older animals. The N-demethylation rate is significantly higher in the brain, liver, kidney and lungs of older animals than of young animals. In general, female animals show higher levels in the organs. The "youth dependent" hyper-content exceeds that of the older animals by the factor of appr. 2. For nortriptyline there is an inverse ratio, with more nortriptyline and desmethylnortriptyline in the older animals than in the young ones. The organ content is also higher in the females than in the males. The "age-dependent" hyper-content exceeds that of the younger animals by the factor of appr. 2. These results correspond roughly with the differences in toxicity.

[Placental transfer of psychotherapeutics of the thioxanthene type (author's transl)]. / Plazentatransfer von Psychopharmaka der Thioxanthenreihe

The hitherto existing investigations on the placental transfer of psycholeptic drugs mostly do not answer the question whether the active compounds themselves or their metabolites or both get into the fetus. As published informations on this problem partly are contradictory the placental transfer of psycholeptic drugs was investigated with the thioxanthenes flupentixol and chlorprothixen for examples. After oral application to rats on the 15th and 20th days of gestation the intact thioxenthenes themselves as well as their sulfoxides and desalkylated metabolites were detectable in placenta, uterus and fetus. The last mentioned substances and the intact thioxanthenes were determined quantitatively. The concentration (mug/g tissue) in the fetus is lower than in uterus and placenta. The results are discussed.