Rice bran wax-a novel excipient for pharmaceutical topical dosage forms
Author(s): Basarkar U. G
The crude rice bran wax was obtained from M/S Bajaj rice mills, Gondia (MS) which was dark brown in color & contains nonwaxy impurities & fixed oil. After purification around 38gm wax obtained which was almost white, light in weight and non-sticky. No instances of skin irritation or sensitization symptoms such as edema / rending of the skin were observed on the skin of Albino rabbits even after 24 hrs. Therefore wax was nontoxic & safe to use in pharmaceutical preparations. In the present study the melting range of rice bran wax was found to be 78–840 which is higher, may reduce the diffusion of drug across the layers of skin. Therefore, in the present study efforts will be made later on to reduce the melting range by addition of low melting point fats like mango kernel fat (M.P. 34.7oC). Solubility studies reveal that the wax is soluble in organic solvents like chloroform & petroleum ether showing typical solubility properties of waxes. Refractive index of a compound gives an idea of purity of the compound & the refractive index of the test sample was found to be 1.44 at 70oc. Sap value of rice bran wax is 68 – 72. The acid value of rice bran wax is 12 – 14. The iodine value of rice bran wax is 9 – 11. From the above data the physicochemical properties of rice bran wax was found to be within the range of other waxes used in topical preparations. Therefore rice bran wax may be utilized as a base in topical preparations. Different topical formulations such as ointments (oleaginous, modified hydrophilic ointment and modified bellers ointment base) were formulated with purified rice bran wax and compared with simple ointment (control) and marketed formulation. All these formulations contain 2% diclofenac sodium. All the formulations were evaluated for p H rheological studies like apparent viscosity, spread ability and diclofenac sodium content. P H of all formulations was found to be 5.98 – 7.30, thus indicating the suitability for application on the skin. Diclofenac sodium content of all the formulations was found to be above 95% indicating the suitability of the method adopted for preparing the formulations. Shelf life and release of diclofenac sodium content in vivo study will be made further.
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