Development, characterization and acute toxicity study of nanoemulsion containing thymoquinone, hesperetin along with vitamin C for improving oral bioavailability

Thymoquinone, hesperetin and vitamin C are well known for their potential pharmacological properties such as antioxidant, anti-inflammatory, immunomodulatory and antidiabetic activity, etc. Poor oral bioavailability owning to limited aqueous solubility of thymoquinone and hesperetin limits its effective therapeutic delivery.Vitamin C is a water soluble drug but it is degraded by alteration of stomach pH leading to instability.The aim of this study is to develop a combined nanoformulation to enhance the oral bioavailability that can provide synergestic effect.The optimized nanoformulation (NE-17) was found to be clear and transparent with mean particle size 19.96 nm, 22.33 zeta potential, droplet size >60 nm, PDI 0.129, viscosity 9.62, refractive index 1.312 with 98.9% transmittance.In vitro release rate of NE-17 was found to be higher (86.97 ± 2.51%, 87.34 ± 2.29%, 89.24 ± 2.59) in simulated gastric fluid and (90.45 ± 4.009%, 89.81 ± 3.12%, 88.07 ± 2.23%) simulated intestinal fluid than conventional.Oral bioavailability of NE-17 was considered to be highly significant (**p<0.001)with a C max (15.23 ± 0.22 µg/ml, 14.83 ± 0.67 µg/ml, 14.33 ± 0.98 µg/ml), AUC 0-24 (594.01 ± 0.23 µgh/ml, 598.32 ± 0.98 µgh/ ml, 607.09 ± 0.23 µgh/ml,), AUC0- (595.09± 0.87, 645.41 ± 0.91, 798.05 ± 0.43) and t½ (4.9 h, 4.7 h, 5.0 h), respectively.T max was found to be (2.34 ± 0.34 h, 2.12 ± 0.12 h, 2.78 ± 0.12 h) that was highly significant (**p<0.001)when compared with pure drug suspension.In acute toxicity, rats were subjected for a single oral dose (2000 mg/kg body weight) of NE-17 and monitored for 14 days.The results showed no sign of morbidity and mortality in any of the treated groups.Hematological, biochemical and histological assay was found to be normal when compared to control rats.This study result indicates that developed nanoemulsion was safe and improved the oral bioavailability as compared to conventional formulation by exhibited maximum in vitro and in vivo drug release.