Pharmacological and Pharmacokinetic effect of a polyherbal combination with Withania somnifera (L.) Dunal for the management of anxiety

Ethnopharmacological relevance: In the Indian system of medicine, Withania somnifera (L.) Dunal, Hemidesmus indicus (R.Br.), Aegle marmelos (L.) Correa, Emblica officinalis Gaertn, Ocimum sanctum (L.) has been mentioned as a remedy for the treatment of anxiety related disorders. Based on their folklore use, a polyherbal combination was derived for the management of anxiety.

Aim of the study: The present study is aimed to find the best polyherbal combination (PHC), in terms of its pharmacological action, out of two PHC, namely PHC1 and PHC3, prepared based on the previous studies conducted and to carry out the pharmacokinetic (PK) study of the best combination (PHC3).

Materials and methods: Pharmacological activities include elevated plus maze model and hole-board test for anti-anxiety screening, gamma amino-butyric acid (GABA_A) measurement in brain tissues and superoxide dismutase, lipid peroxidation and reduced glutathione measurement for anti-oxidant screening.

Results: PHC3 (100mg/kg) produced statistically significant (p<0.05) effect on all the pharmacological outcome measures when compared to alprazolam standard. Therefore, it was chosen for PK study. PK study was carried out using Liquid Chromatography Mass Spectroscopy technique with respect to Withaferin-A. PK parameters such as maximum plasma concentration (C_max), 16.78±5.32ng/ml; time of maximum concentration (T_max), 18±0.12min; half-life (T_1/2) 61.20±9.87min; mean residual time (MRT), 7.53hrs; area under the concentration versus time curve (AUC_0-1), 1678±34.13ng/mL; area under the concentration versus time curve from zero to infinity (AUC_0-∞), 1705±28.87ng/mL; total clearance (CL), 290.67±15.89 mL/min and volume of distribution (V_d) 0.054L were calculated.

Conclusions: The results of the studies revealed that PHC3 possessed significant anxiolytic, anti-oxidant activities and enhanced expression of GABA_A mediated inhibition when compared to PHC1. Withaferin-A in PHC3 exhibited a rapid oral absorption in rat plasma. The findings of this study greatly help to provide useful evidence for the development of suitable formulation using PHC3.

Keywords: Anti-anxiety; Pharmacodynamic; Pharmacokinetics; Polyherbal combination; Withaferin-A.