- Photooxidation mechanism of levomepromazine in different solvents
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Unwanted photoinduced responses are well-known adverse effects of most promazine drugs, including levomepromazine (LPZ, Levoprome or Nozinan). This drug is indicated in psychiatry primarily for the treatment of schizophrenia and other schizoaffective disorders. Levomepromazine's particular sedative properties make it especially fit for use in psychiatric intensive care. Nevertheless, it is photolabile under UV-A and UV-B light in aerobic conditions resulting in the formation of its sulfoxide. The LPZ photochemistry in acetonitrile (MeCN) is completely different from that in methanol (MeOH) and phosphate buffer solutions (PBS, pH = 7.4). The major photoproduct in PBS and MeOH under aerobic conditions is levomepromazine sulfoxide (LPZSO), although the amount is considerably higher in the aqueous environment. The corresponding main photoproduct in MeCN could not be characterized. The destruction quantum yields of LPZ in PBS, MeOH and MeCN are 0.13, 0.02 and -3, respectively. It is further demonstrated that LPZSO does not form by the reaction of singlet oxygen with ground-state LPZ. This oxidation product is actually produced by the reaction of the cation radical of LPZ (LPZ·+) with molecular oxygen. This cation radical in turn, is produced by an electron transfer process between the 3LPZ* and ground-state molecular oxygen.
- Pinero-Santiago, Luis E.,Garcia, Carmelo,Lhiaubet-Vallet, Virginie,Trzcionka, Jerome,Oyola, Rolando,Torres, Karen,Leguillu, Jaysika,Miranda, Miguel A.
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p. 1479 - 1489
(2013/11/19)
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- Photochemistry and in vitro phototoxicity studies of levomepromazine (methotrimeprazine), a phototoxic neuroleptic drug
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The neuroleptic drug levomepromazine (1, previously known as methotrimeprazine) is photolabile under UV-A and UV-B light in aerobic conditions. Irradiation of a methanol solution of this drug produces one photoproduct, resulting from the oxidation of 1 to its sulfoxide parent. It is demonstrated that photodegradation occurs via type II mechanism involving irreversible trapping of self-photogenerated singlet molecular oxygen. 1 shows a photohemolytic effect on human erythrocytes and photoinducers lipid peroxidation.
- Vargas, Franklin,Carbonell,Camacho
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p. 315 - 319
(2007/10/03)
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- Convenient oxidation of phenothiazine salts to their sulfoxides with aqueous nitrous acid
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A simple method is reported for the preparation of gram quantities of phenothiazine sulfoxides by aqueous nitrous acid oxidation of phenothiazines at room temperature. The chiral levomepromazine gave rise to diastereoisomeric products analogous to those reported for thioridazine sulfoxidation.
- Owens,Juenge,Poklis
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p. 334 - 336
(2007/10/02)
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