Preparation and characterization of oxybenzone-loaded gelatin microspheres for enhancement of sunscreening efficacy.

The objective of our present study was to prepare and evaluate gelatin microspheres of oxybenzone to enhance its sunscreening efficacy. The gelatin microspheres of oxybenzone were prepared by emulsion method. Process parameters were analyzed to optimize the formulation. The in vitro drug release study was performed in pH 7.4 using cellulose acetate membrane. Microspheres prepared using oxybenzone:gelatin ratio of 1:6 showed slowest drug release and those prepared with oxybenzone:gelatin ratio of 1:2 showed fastest drug release. The gelatin microspheres of oxybenzone were incorporated in aloe vera gel. Sun exposure method using sodium nitroprusside solution was used for in vitro sunscreen efficacy testing. The formulation C5 containing oxybenzone-bearing gelatin microspheres in aloe vera gel showed best sunscreen efficacy. The formulations were evaluated for skin irritation test in human volunteers, sun protection factor, and minimum erythema dose in albino rats. These studies revealed that the incorporation of sunscreening agent-loaded microspheres into aloe vera gel greatly increased the efficacy of sunscreen formulation more than four times.