[1] Med Univ Varna Prof Dr Paraskev Stoyanov, Fac Pharm, Dept Pharmacol Toxicol & Pharmacotherapy, Varna, Bulgaria
[2] Med Univ Varna Prof Dr Paraskev Stoyanov, Fac Pharm, Dept Biol, Varna, Bulgaria
[3] Med Univ Varna Prof Dr Paraskev Stoyanov, Fac Med, Dept Gen & Clin Pathol Forens Med & Deontol, Div Gen & Clin Pathol, Varna, Bulgaria
[4] Med Univ Prof Dr Paraskev Stoyanov, Fac Pharm, Dept pharmacol Toxicol & Pharmacotherapy, 84 Tzar Osvoboditel Str, Varna 9000, Bulgaria