Pharmacogenetics of the safety of phenazepam in alcohol withdrawal syndrome: haplotype and combinatorial analyses of polymorphic variants in the pharmacokinetic factor genes

Phenazepam is a benzodiazepine tranquilizer that is widely used in Russia. The drug is metabolized by cytochrome P450 3A (CYP3A) isozymes. Since their substrates have an affinity for P-glycoprotein, the polymorphic variants in the ABCB1 gene may affect the safety of this drug.

Objective: to analyze associations between the CYP3A5, CYP2C9, CYP2C19, CYP2D6 and ABCB1 gene polymorphisms and the safety of phenazepam treatment for alcohol withdrawal syndrome (AWS).

Patients and methods. The investigation enrolled 102 patients diagnosed with uncomplicated AWS (IDC-10 code F10.30). All the patients were followed up for 6 days within which they took phenazepam. 5-ml venous blood samples were collected from each patient for genotyping. The carriage of  CYP3A4*22, CYP3A5*3, CYP2C19*2, CYP2C19*17, CYP2C9*2, ABCB1 3435C>T, 1236C>T, and  2677G>T/A polymorphic variants was determined by a real-time polymerase chain reaction assay. Therapy safety was evaluated using the UKU Side-Effect Rating Scale on day 6. Statistical analysis was carried out with SPSS Statistics 21.0. Haplotype and combinatorial analyses were performed using SNPStats.

Results and discussion. The greater subjective severity of adverse reactions (ARs) was shown for the homozygotes of ABCB1 1236C>T CC (odds ratio (OR), 2.154; 95% confidence interval (CI), 1.271–3.650; p=0.014) and ABCB1 2677G>T GG (OR, 2.154; 95% CI, 1.271–3.650; p=0.014). On the contrary, a combinatorial analysis revealed the role of ABCB1 3435C>T, 1236C>T, and 2677G>T polymorphic alleles as predictors for the greater subjective severity of ARs. The following statistically significant polymorphic variant combinations were ABCB1 3435-1236–2677 and T-T-T-CYP3A5*3 isozymes (OR=5.03; 95% CI, 1.65–15.34; p=0.0056); T-T-T-CYP2C9*1 (OR=3.61; 95% CI, 1.31–9.92; p=0.015); T-T-T-CYP2C19*1 (OR=2.52; 95% CI, 1.05–6.08; p=0.042). Attention disorders were also established to be associated with the carriage of T-T-T-CYP2D6*1 (OR=2.58; 95 CI, 1.08–6.13; p=0.035).

Conclusion. The carriage of ABCB1 3435-2677-1236 (T-T-T) haplotype is significantly associated with the greater severity of ARs in phenazepam-treated patients with AWS.

1. Ladyzhenskii MYa, Gorodnichev AV, Kostyukova EG. Benzodiazepine anxiolytics: demand are they today? Sovremennaya terapiya psikhicheskikh rasstroistv. 2014;(2):20-5. (In Russ.).

2. Fukasawa T, Suzuki A, Otani K. Effects of genetic polymorphism of cytochrome P450 enzymes on the pharmacokinetics of benzodiazepines. J Clin Pharm Ther. 2007 Aug;32(4): 333-41.

3. Ham AC, Ziere G, Broer L, et al. CYP2C9 Genotypes Modify Benzodiazepine-Related Fall Risk: Original Results From Three Studies With Meta-Analysis. J Am Med Dir Assoc. 2017 Jan;18(1):88.e1 88.e15.

4. Whirl-Carrillo M, McDonagh EM, Hebert JM, et al. Pharmacogenomics Knowledge for Personalized Medicine. Clin Pharmacol Ther. 2012 Oct;92(4):414-7. doi: 10.1038/clpt.2012.96.

5. Ivashchenko DV, Rudik AV, Poloznikov AA, et al. Which cytochrome P450 does metabolize Phenazepam? Step by step in silico, in vitro and in vivo studies. Drug Metab Pers Ther. 2018 Jun 27;33(2):65-73. doi: 10.1515/dmpt-2017-0036.

6. Ivashchenko DV, Ryzhikova KA, Sozaeva ZhA, et al. Impact of CYP3A5, CYP2C9, CYP2C19, and CYP2D6 Polymorphisms on Phenazepam Safety in Patients with Alcohol Withdrawal Syndrome. Vestnik RAMN. 2018;73(3):206-14. (In Russ.).

7. de Jonge H, Elens L, de Loor H, et al. The CYP3A4*22 C>T single nucleotide polymorphism is associated with reduced midazolam and tacrolimus clearance in stable renal allograft recipients. Pharmacogenomics J. 2015 Apr;15(2):144-52. doi: 10.1038/tpj.2014.49. Epub 2014 Oct 7.

8. Kuehl P, Zhang J, Lin Y, et al. Sequence diversity in CYP3A promoters and characterization of the genetic basis of polymorphic CYP3A5 expression. Nat Genet. 2001 Apr;27(4):383-91.

9. Werk AN, Cascorbi I. Functional gene variants of CYP3A4. Clin Pharmacol Ther. 2014 Sep;96(3):340-8. doi: 10.1038/clpt.2014.129. Epub 2014 Jun 13.

10. Hiratsuka M. Genetic Polymorphisms and in Vitro Functional Characterization of CYP2C8, CYP2C9, and CYP2C19 Allelic Variants. Biol Pharm Bull. 2016;39(11):1748-1759.

11. Fricke-Galindo I, Cespedes-Garro C, Rodrigues-Soares F, et al. Interethnic variation of CYP2C19 alleles, 'predicted' phenotypes and 'measured' metabolic phenotypes across world populations. Pharmacogenomics J. 2016 Apr; 16(2):113-23. doi: 10.1038/tpj.2015.70

12. Zanger UM, Schwab M. Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variation. Pharmacol Ther. 2013 Apr; 138(1):103-41. doi: 10.1016/j.pharmthera.2012.12.007. Epub 2013 Jan 16.

13. Lerena A, Naranjo ME, Rodrigues-Soares F, et al. Interethnic variability of CYP2D6 alleles and of predicted and measured metabolic phenotypes across world populations. Expert Opin Drug Metab Toxicol. 2014 Nov;10(11):1569-83. doi: 10.1517/17425255.2014.964204.

14. Wolking S, Schaeffeler E, Lerche H, et al. Impact of Genetic Polymorphisms of ABCB1 (MDR1, P-Glycoprotein) on Drug Disposition and Potential Clinical Implications: Update of the Literature. Clin Pharmacokinet. 2015 Jul; 54(7):709-35. doi: 10.1007/s40262-015-0267-1.

15. Kwan P, Brodie MJ. Early identification of refractory epilepsy. N Engl J Med. 2000 Feb 3; 342(5):314-9.

16. Cascorbi I, Haenisch S. Pharmacogenetics of ATP-binding cassette transporters and clinical implications. Methods Mol Biol. 2010;596:95-121

17. Candiotti K, Yang Z, Xue L et al. SingleNucleotide Polymorphism C3435T in the ABCB1 Gene is Associated with Opioid Consumption in Postoperative Pain. Pain Med. 2013 Dec;14(12):1977-84. doi: 10.1111/pme.12226. Epub 2013 Aug 19.

18. Aronica E, Sisodiya SM, Gorter JA. Cerebral expression of drug transporters in epilepsy. Adv Drug Deliv Rev. 2012 Jul;64(10): 919-29. doi: 10.1016/j.addr.2011.11.008. Epub 2011 Nov 29.

19. Haerian BS, Lim KS, Tan CT, et al. Association of ABCB1 gene polymorphisms and their haplotypes with response to antiepileptic drugs: a systematic review and meta-analysis. Pharmacogenomics. 2011 May;12(5):713-25. doi: 10.2217/pgs.10.212. Epub 2011 Mar 11.

20. Sole X, Guino E, Valls J, et al. SNPStats: a web tool for the analysis of association studies. Bioinformatics. 2006 Aug 1;22(15):1928-9. Epub 2006 May 23.