Preparation of a Delayed Releasing Device of Hydroxypropyl MethylcelluJose Phthalate MacrocapsuJes Containing Peppermint Oil

In this study, pH-sensitive macrocapsules containing peppermint oil (PO) were prepared using a new emulsification/polymer precipitation technique. An aqueous alkaline solution of hydroxypropyl methylcellulose phthalate (HPMCP) was used to emulsify PO in water (OfW) . This emulsion was then added dropwise to a solution of citric acid to result in a solid dispersion of macrocapsules. Screening studies showed that three different factors including the polymer and the acid concentrations, as well as the essential oil to water (OfW) ratio have considerable effects on the encapsulation process. Different formulations of macrocapsules were prepared and characterized in terms of PO loading, encapsulation efficiency, and release using GC-FID analysis. A 2level factorial design with 4-centre points was then used to optimize PO loading and encapsulation efficiency against the above mentioned parameters. Optical microscopy showed a polydispersed O/W emulsion, whereas the macrocapsules were uniformly dispersed with mean diameter of 1 mm. The prepared macrocapsules could protect PO from acidic condition of stomach and release it in a simulated intestinal fluid .