Planta Med 2013; 79 - PK40
DOI: 10.1055/s-0033-1352300

Evaluation of dissolution properties of silymarin capsules at different pH values

A Uzunovic 1, S Pilipovic 1, A Elezovic 1, A Sapcanin 2, O Rahic 2
  • 1Agency for Medicinal Products and Medical Devices, Titova 9, 71000, Sarajevo, Bosnia and Herzegovina
  • 2Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, 71000, Sarajevo, Bosnia and Herzegovina

Milk thistle (Silybum marianum L.) is a medicinal plant widely used in traditional medicine. Silibinin is the major and most active component present in silymarin, a polyphenolic flavonoid isolated from milk thistle. The aim of the present work is to compare the influence of surfactant or acidity varying on dissolution profiles of silymarin capsules, obtained from one producer, label claim 100 mg of silibinin. Silibinin working standard was provided by Sigma-Aldrich (Buchs, Switzerland). Differences in the dissolution properties of silymarin capsules were determined in four dissolution media: 0.5% sodium lauryl sulphate (SDS) in water, simulated gastric fluid pH 1.2, phosphate buffer pH 4.5 and phosphate buffer pH 6.8. Fixed volumes of the dissolution medium were withdrawn at 15, 30, 45 and 60 minutes. Dissolution tests were performed on the USP Apparatus 2 (Dissolution tester ERWEKA DT 800; rotating speed 100 rpm at 37 ± 0.50C, 900 mL) [1]. HPLC method proposed by Wu et al. was used for the determination of the amount of the active ingredient released [2]. HPLC was performed with a mobile phase composed of 0.01 M monosodium phosphate buffer pH 5.45 ± 0.05:acetonitrile (50:50v/v), and peaks were detected at 288nm. Degassed and diluted samples were analysed on LiChrospher® C18 column (250 × 4.0 mm, 5 µm), at 24 ± 10C and 1.0 mLmin-1 flow rate. The dissolved amounts of silibinin at the end of testing were in the range of 1.4 ± 0.2% at pH 1.2 to 40.1 ± 5.3% at 0.5% SDS. The results of dissolution studies are summarized in Figure 1. On the basis of our results, it can be concluded that presence of surfactant or physiological variation of pH of the gastrointestinal tract could influence dissolution rate of silibinin from silymarin capsules.

Fig. 1: Comparative display of dissolution profile for silymarin capsules

References:

[1] Campodonico, A. et al. (2001) Drug Dev Ind Pharm 27(3): 261 – 265.

[2] Wu, J.-W. et al. (2007)J Pharm Biomed Anal 45:635 – 641.