Formulation and bioavailability studies on orodispersible tablets containing standardized extracts of Glycyrrhiza glabra, Curcuma longa and Piper nigrum

Background

Glycyrrhizin, Curcumin and Piperine indicated good antiasthamatic properties owing to their ability to inhibit airways constriction and anti-inflammatory properties. Orodispersible tablets have advantage of faster drug release and has patient compliance in asthmatic patients.

Hypothesis / Purpose

To develop an orodispersible polyherbal tablets using the standardized extracts of Glycyrrhiza glabra, Curcuma longa and Piper nigrum with respect to glycyrrhizin, curcumin and piperine respectively and evaluate bioavailability of the markers from the formulation.

Methods

Alcoholic extracts of G. glabra, C. longa, and P. nigrum were standardized using HPTLC for glycyrrhizin, curcumin, and piperine content, respectively. The orodispersible tablet formulation was created and standardized for curcumin (50 mg), glycyrrhizin (75 mg), and piperine (2.5 mg) per tablet, using the HPTLC method. The absolute Bioavailability studies were conducted for glycyrrhetinic acid and curcumin in rats by administering pure marker compounds intravenously (2 mg/kg b.w) and orally (10 mg/kg b.w.), followed by determining relative bioavailability through oral administration of the orodispersible tablet formulations.

Results

Orodispersible tablets could be successfully developed using the standardized extracts. The HPTLC bioanalytical method was developed and validated as per M 10 guideline and results were in accordance to specifications. The bioavailability studies in rats indicated absolute bioavailability of Glycyrrhetinic acid and Curcumin to be 20.35 and 2.57% respectively and relative bioavailabilities of orodispersible formulation F1 were found to be 75 and 38.67%.

Conclusion

A standardized orodispersible formulation can be a better option for asthma patients. The low absolute bioavailability of curcumin was significantly (P<0.05) increased in both the formulations F1 and F2. This may be attributed to the extracts containing saponin glycosides like Glycyrrhizin aiding into greater dissolution of curcumin. Formulation with piperine (F1) showed significant increase in bioavailability is due to inhibition of human P-glycoprotein, cytochrome P450 3A4 (CYP3A4) and increase secretion of bile acids.