Study of herbal bioenhancers on various characteristics of isoniazid and rifampicin microspheres

Abstract

Background: Bioenhancers are agents when combined with an active drug lead to potentiate the pharmacological effect of the drug but themselves are not having any therapeutic effect. Recent development in bioavailability enhancement of drugs by herbal compounds has produced a new shift in the way of therapeutics. Bioenhancers improve permeability and influence bioavailability of the drug for therapeutic efficacy which may result into decrease in dose ensuring therapeutic availability. The major problems associated with the anti-TB drug therapy include loss of efficacy through bacterial resistance, side effects, and low patient compliance. In the cited research work, we have attempted to solve the above mentioned problems by simultaneous use of both the concepts of microsphere drug delivery (higher bioavailability) and herbal bioenhancers (improved bioavailability).Methods & Materials: Methods: Complex coacervation and modified emulsion method.Material: Isoniazid and rifampicin as a model drug used in TB therapy. Hydro-alcoholic extracts of Carum carvi and Ocimum sanctum were used as bioenhancer.Results: The in-vitro drug release of isoniazid and rifampicin from formulations where bioenhancer extract is used was found to be about 85-90% in 12 hrs. While the same was about 45-50% in case of formulations where bioenhancers were not used. Other parameters like percentage bioadhesion, permeability study using intestinal sac method etc. were also studied.Conclusion: For microspheres prepared by both complex coacervation and modified emulsion methos, the particle size was uniform and found to be less than 130 micron in size; the particle size may alter on addition of bioenhancer extract to the formulations. The drug encapsulation efficiency was found to be in the range of 43-67% (increased on addition of bioenhancer in the formulations). The percentage bioadhesion of the microsphere where bioenhancers were used found to increase by 20% as compared to basal value (upto 67% from 42%). The in-vitro release study by USP paddle apparatus and the most important results from the in-vitro release study relates to the very significant enhancement in drug release (45 to 90% for microspheres prepared by modified emul-sion method and 47 to 90% complex coacervation method), due to presence of bioenhancers alone and in combination.