- Effect of CYP2D6 genetic polymorphism on the metabolism of citalopram in vitro
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Genetic polymorphisms of CYP2D6 significantly influence the efficacy and safety of some drugs, which might cause adverse effects and therapeutic failure. We aimed at investigating the role of CYP2D6 in the metabolism of citalopram and identifying the effect of 24 CYP2D6 allelic variants we found in Chinese Han population on the metabolism of citalopram in vitro. These CYP2D6 variants expressed by insect cells system were incubated with 10-1000 μM citalopram for 30 min at 37 °C and the reaction was terminated by cooling to -80 °C immediately. Citalopram and its metabolites were analyzed by high-performance liquid chromatography (HPLC). The intrinsic clearance (Vmax/Km) values of the variants toward citalopram metabolites were significantly altered, 38-129% for demethylcitalopram and 13-138% for citalopram N-oxide when compared with CYP2D6?1. Most of the tested rare alleles exhibited significantly decreased values due to increased Km and/or decreased Vmax values. We conclude that recombinant system could be used to investigate the enzymes involved in drug metabolism and these findings suggest that more attention should be paid to subjects carrying these CYP2D6 alleles when administering citalopram in the clinic.
- Hu, Xiao-Xia,Yuan, Ling-Jing,Fang, Ping,Mao, Yong-Hui,Zhan, Yun-Yun,Li, Xiang-Yu,Dai, Da-Peng,Cai, Jian-Ping,Hu, Guo-Xin
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p. 133 - 138
(2016/04/26)
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- Citalopram hydrobromide: Degradation product characterization and a validated stability-indicating LC-UV method
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Five degradation products (I-V) of citalopram hydrobromide (CTL) were formed under different forced degradation conditions. Products I and II were formed under hydrolytic conditions while product III-V were formed under photolytic conditions. Products II
- Sharma, Manav,Jawa, Parikshit R.,Gill, Ravinder S.,Bansal, Gulshan
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p. 836 - 848
(2012/02/01)
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- Studies on the stereoselective metabolism of citalopram by human liver microsomes and cDNA-expressed cytochrome P450 enzymes
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The involvement of CYP enzymes in the metabolism of citalopram was studied, inclusive the conversion of demethylcitalopram to didemethylcitalopram and the formation of citalopram N-oxide, which both have not been considered previously. Using human mixed liver microsomes and cDNA-expressed CYP enzymes, we confirmed that CYP3A4, 2C19 and 2D6 are involved in the first demethylation step of citalopram, all favouring conversion of the biologically active S-enantiomer. Inhibitor studies indicated that at therapeutic citalopram concentrations CYP3A4 was responsible for 40-50% of demethylcitalopram formation, while the contribution of CYP2C19 increased and that of CYP2D6 tended to decrease with increasing drug concentration, CYP2D6 exclusively mediated the second demethylation step, and citalopram N-oxide was also exclusively formed by CYP2D6. None of the studied CYP enzymes mediated deamination to the propionic acid derivative.
- Olesen, Ole V.,Linnet, Kristian
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p. 298 - 309
(2007/10/03)
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