Content Analysis and Stability Evaluation of Selected Commercial Preparations of St. John's Wort

Abstract

Content analysis and stability studies were performed for the commercial products of St. John's wort. Six marketed formulations were analyzed for their hypericin and pseudohypericin content. These products were standardized to contain 0.3% hypericin. Results revealed total hypericin as 7.72–38.57% of the labeled claim with varying concentrations of pseudohypericin. Stability studies were carried out under three different storage conditions: 1) 25 ± 2°C, 60 ± 5%RH for six months, 2) 40 ± 2°C, 75 ± 5%RH for six months, and 3) 50°C for one month. Tablet formulations were also analyzed for their hardness and friability. Stability studies revealed significant decrease in the content of the marker compounds with time.

Key Words:

• St. John's wort
• Commercial tablets and capsules
• Content analysis
• Stability
• HPLC

Notes

*For one particular stability storage condition, p-values are based on the comparison of amount of hypericin/pseudohypericin remaining at 1, 2, 3 or 6 months to that of zero time.

^†Except values—for example, for formulation A at 40 ± 2°C/75 ± 5% RH, residual concentration of hypericin remaining at 1 month (compared to 0 time) is not in the range of the mentioned p-values. Amongst different formulations, except values are for different time points.