CYP3A subfamily activity affects the equilibrium concentration of Phenazepam® in patients with anxiety disorders and comorbid alcohol use disorder.

Phenazepam® is prescribed to relieve anxiety and sleep disorders during alcohol withdrawal, although it is associated with undesirable side effects. Aim: To demonstrate changes in the safety and efficacy profiles of Phenazepam in patients with anxiety disorders and comorbid alcohol use disorder. Materials & methods: A total of 94 Russian patients with alcohol use disorder received 4.0 mg of Phenazepam per day in tablets. We used a urinary 6-beta-hydroxycortisol/cortisol ratio to evaluate CYP3A activity. Results: A statistically significant inverse correlation between Phenazepam plasma concentration and CYP3A activity was found (r = -0.340 and p = 0.017). Correlation between the concentration/dose ratio and phenotyping results was also statistically significant (r = 0.301 and p = 0.026). Conclusion: The safety and efficacy of Phenazepam depend on CYP3A genetic polymorphisms.