The development and in vitro evaluation of herbal pellets coated with Eudragit FS 30.

The objective of this study was to prepare pellets of thyme (Thymus vulgaris L.), stinging nettle (Urtica dioica L.) and sage (Salvia officinalis L.) dry extracts by extrusion-spheronization technique to improve technological properties and investigate dissolution profiles of pellets covered different levels of pH-sensitive polymer Eudragit (R) FS. Optimal sample of pellets were prepared using microcrystalline cellulose and lactose as excipients and demonstrated excellent technological quality properties such as Hausner ratio (1.07 +/- 0.11) and compressibility index (6.73 +/- 0.94%) value, spericity (0.87 +/- 0.001) and friability (0.22 +/- 0.08 N). Pellets were coated by 10-35% (w/w) of Eudragit (R) FS. Dissolution studies showed that less than 20% of coating could not prevent dissolution of phenols in pH 1.2, 20% Eudragit (R) FS coating is enough to prevent herbal extract against dissolution in the stomach. There were observed no statistical significant differences between 20% and 25% or higher amount of coating polymer to a dissolution of phenols in low pH.