Stability and bioequivalence studies of two marketed formulations of coenzyme Q10 in beagle dogs

Abstract

Coenzyme Q10 (CoQ10), a highly lipophilic compound present in the inner mitochondrial membrane, is essential for production of cellular energy in the form of ATE CoQ10 is used as an antioxidant and also in the treatment of various cardiovascular disorders. The relative bioavailabilities of powder filled capsule (I) and oil-based formulation (II) of CoQ10 were compared in beagle dogs in an open, randomized, multiple dose, cross-over design. Poor and slow absorption characteristics were observed for both the formulations. The AUC, C(max), and T(max) for formulation I and II are comparable (p<0.05) where the values for formulation I are 22.84±6.3 μg ml-1 h, 0.51±0.11μ/ml, and 6.1±2.0 h whereas the values for formulation II are 24.32±5.6 μg ml-1 h, 0.55±0.16 μg/ml, and 6.6±2.3 h, respectively. Stability of CoQ10 at various temperature and humidity conditions and its photostability were studied. Various antioxidants were evaluated to determine the type and amount of antioxidant(s) required to improve the stability of CoQ10. Large extent of degradation was observed at 45°C and 55°C. The effect of humidity conditions on degradation was insignificant. Among the various antioxidants studied, mixture of ascorbic acid (5%) and EDTA (0.1%) offered better protection than phenolic antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), or propyl gallate (PG). Further, increasing concentrations of phenolic antioxidants (from 0.1 to 0.3%) accelerated the degradation.