Photophysical and photochemical behavior of nimodipine and felodipine

Nancy Pizarro, Germán Günther, Luis J. Núñez-Vergara

Resultado de la investigación: Article

16 Citas (Scopus)

Resumen

A different photophysical and photochemical behavior has been found between two second generation antihypertensive 1,4-dihydropyiridines (1,4-DHPs), felodipine and nimodipine. While nimodipine was observed as being more reactive and photolabile in excited state, felodipine showed a major reactivity in its ground state towards an electrophilic transient species like singlet oxygen. Nimodipine had a photodegradation quantum yield of 2.34 × 10-4 in deaereated acetonitrile and 1.81 × 10-2 in deaereated ethanol. The values of the photodegradation quantum yields in aereated solutions were similar. However, felodipine is less photolabile than nimodipine, with a photodegradation quantum yield changing from 1.4 × 10-5 to 7 × 10-6 in the same solvents, probably a consequence of a lowered stability of the zwitterion radical involved in the formation of the photoproduct. In addition, nimodipine and felodipine were able to generate singlet oxygen with quantum yields of 0.085 and 0.003 in benzene, respectively. The results show that tested 1,4-DHPs behave as relatively good scavengers of excited oxygen, with overall rate constant values for nimodipine ranging from 0.38 × 105 M-1 s-1 in chloroform to 9.73 × 105 M-1 s-1 in N,N-dimethylformamide. On the other hand, the rate constants for felodipine ranged from 0.44 × 105 M-1 s-1 in benzene to 19.5 × 105 M-1 s-1 in N,N-dimethylacetamide. In conclusion, the present results indicate that it is difficult to discriminate which specie is responsible for the photoallergic and phototoxic effects previously reported for these drugs, because these effects could be attributed to the participation of zwitterionic radicals in the process of photodegradation and/or its ability to generate singlet oxygen.

Idioma originalEnglish
Páginas (desde-hasta)23-29
Número de páginas7
PublicaciónJournal of Photochemistry and Photobiology A: Chemistry
Volumen189
N.º1
DOI
EstadoPublished - 10 jun 2007

Huella dactilar

Felodipine
Nimodipine
Photodegradation
Quantum yield
Singlet Oxygen
Oxygen
oxygen
Rate constants
Benzene
benzene
zwitterions
Dimethylformamide
Chlorine compounds
Acetonitrile
chloroform
Excited states
Ground state
acetonitrile
drugs
Ethanol

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

Citar esto

Pizarro, Nancy ; Günther, Germán ; Núñez-Vergara, Luis J. / Photophysical and photochemical behavior of nimodipine and felodipine. En: Journal of Photochemistry and Photobiology A: Chemistry. 2007 ; Vol. 189, N.º 1. pp. 23-29.
@article{7f8d7d5b64d84aac8cd68f5e2b0a92aa,
title = "Photophysical and photochemical behavior of nimodipine and felodipine",
abstract = "A different photophysical and photochemical behavior has been found between two second generation antihypertensive 1,4-dihydropyiridines (1,4-DHPs), felodipine and nimodipine. While nimodipine was observed as being more reactive and photolabile in excited state, felodipine showed a major reactivity in its ground state towards an electrophilic transient species like singlet oxygen. Nimodipine had a photodegradation quantum yield of 2.34 × 10-4 in deaereated acetonitrile and 1.81 × 10-2 in deaereated ethanol. The values of the photodegradation quantum yields in aereated solutions were similar. However, felodipine is less photolabile than nimodipine, with a photodegradation quantum yield changing from 1.4 × 10-5 to 7 × 10-6 in the same solvents, probably a consequence of a lowered stability of the zwitterion radical involved in the formation of the photoproduct. In addition, nimodipine and felodipine were able to generate singlet oxygen with quantum yields of 0.085 and 0.003 in benzene, respectively. The results show that tested 1,4-DHPs behave as relatively good scavengers of excited oxygen, with overall rate constant values for nimodipine ranging from 0.38 × 105 M-1 s-1 in chloroform to 9.73 × 105 M-1 s-1 in N,N-dimethylformamide. On the other hand, the rate constants for felodipine ranged from 0.44 × 105 M-1 s-1 in benzene to 19.5 × 105 M-1 s-1 in N,N-dimethylacetamide. In conclusion, the present results indicate that it is difficult to discriminate which specie is responsible for the photoallergic and phototoxic effects previously reported for these drugs, because these effects could be attributed to the participation of zwitterionic radicals in the process of photodegradation and/or its ability to generate singlet oxygen.",
keywords = "1,4-Dihydropyridines, Mechanisms, Photochemistry, Photophysical behavior, Singlet oxygen",
author = "Nancy Pizarro and Germ{\'a}n G{\"u}nther and N{\'u}{\~n}ez-Vergara, {Luis J.}",
year = "2007",
month = "6",
day = "10",
doi = "10.1016/j.jphotochem.2007.01.003",
language = "English",
volume = "189",
pages = "23--29",
journal = "Journal of Photochemistry and Photobiology A: Chemistry",
issn = "1010-6030",
publisher = "Elsevier",
number = "1",

}

Photophysical and photochemical behavior of nimodipine and felodipine. / Pizarro, Nancy; Günther, Germán; Núñez-Vergara, Luis J.

En: Journal of Photochemistry and Photobiology A: Chemistry, Vol. 189, N.º 1, 10.06.2007, p. 23-29.

Resultado de la investigación: Article

TY - JOUR

T1 - Photophysical and photochemical behavior of nimodipine and felodipine

AU - Pizarro, Nancy

AU - Günther, Germán

AU - Núñez-Vergara, Luis J.

PY - 2007/6/10

Y1 - 2007/6/10

N2 - A different photophysical and photochemical behavior has been found between two second generation antihypertensive 1,4-dihydropyiridines (1,4-DHPs), felodipine and nimodipine. While nimodipine was observed as being more reactive and photolabile in excited state, felodipine showed a major reactivity in its ground state towards an electrophilic transient species like singlet oxygen. Nimodipine had a photodegradation quantum yield of 2.34 × 10-4 in deaereated acetonitrile and 1.81 × 10-2 in deaereated ethanol. The values of the photodegradation quantum yields in aereated solutions were similar. However, felodipine is less photolabile than nimodipine, with a photodegradation quantum yield changing from 1.4 × 10-5 to 7 × 10-6 in the same solvents, probably a consequence of a lowered stability of the zwitterion radical involved in the formation of the photoproduct. In addition, nimodipine and felodipine were able to generate singlet oxygen with quantum yields of 0.085 and 0.003 in benzene, respectively. The results show that tested 1,4-DHPs behave as relatively good scavengers of excited oxygen, with overall rate constant values for nimodipine ranging from 0.38 × 105 M-1 s-1 in chloroform to 9.73 × 105 M-1 s-1 in N,N-dimethylformamide. On the other hand, the rate constants for felodipine ranged from 0.44 × 105 M-1 s-1 in benzene to 19.5 × 105 M-1 s-1 in N,N-dimethylacetamide. In conclusion, the present results indicate that it is difficult to discriminate which specie is responsible for the photoallergic and phototoxic effects previously reported for these drugs, because these effects could be attributed to the participation of zwitterionic radicals in the process of photodegradation and/or its ability to generate singlet oxygen.

AB - A different photophysical and photochemical behavior has been found between two second generation antihypertensive 1,4-dihydropyiridines (1,4-DHPs), felodipine and nimodipine. While nimodipine was observed as being more reactive and photolabile in excited state, felodipine showed a major reactivity in its ground state towards an electrophilic transient species like singlet oxygen. Nimodipine had a photodegradation quantum yield of 2.34 × 10-4 in deaereated acetonitrile and 1.81 × 10-2 in deaereated ethanol. The values of the photodegradation quantum yields in aereated solutions were similar. However, felodipine is less photolabile than nimodipine, with a photodegradation quantum yield changing from 1.4 × 10-5 to 7 × 10-6 in the same solvents, probably a consequence of a lowered stability of the zwitterion radical involved in the formation of the photoproduct. In addition, nimodipine and felodipine were able to generate singlet oxygen with quantum yields of 0.085 and 0.003 in benzene, respectively. The results show that tested 1,4-DHPs behave as relatively good scavengers of excited oxygen, with overall rate constant values for nimodipine ranging from 0.38 × 105 M-1 s-1 in chloroform to 9.73 × 105 M-1 s-1 in N,N-dimethylformamide. On the other hand, the rate constants for felodipine ranged from 0.44 × 105 M-1 s-1 in benzene to 19.5 × 105 M-1 s-1 in N,N-dimethylacetamide. In conclusion, the present results indicate that it is difficult to discriminate which specie is responsible for the photoallergic and phototoxic effects previously reported for these drugs, because these effects could be attributed to the participation of zwitterionic radicals in the process of photodegradation and/or its ability to generate singlet oxygen.

KW - 1,4-Dihydropyridines

KW - Mechanisms

KW - Photochemistry

KW - Photophysical behavior

KW - Singlet oxygen

UR - http://www.scopus.com/inward/record.url?scp=34248402886&partnerID=8YFLogxK

U2 - 10.1016/j.jphotochem.2007.01.003

DO - 10.1016/j.jphotochem.2007.01.003

M3 - Article

AN - SCOPUS:34248402886

VL - 189

SP - 23

EP - 29

JO - Journal of Photochemistry and Photobiology A: Chemistry

JF - Journal of Photochemistry and Photobiology A: Chemistry

SN - 1010-6030

IS - 1

ER -