Formulation and evaluation of acyclovir microemulsions

Certain oils and surfactants were screened to select the most suitable ones for the preparation of microemulsions. Labrafil M 1944 CS, Labrafil M 2125 CS and Capryol 90 were selected as oils while Tween 80 was selected as a surfactant. Tween 80 was mixed with n-butanol [n-Bu] at different w/w ratios [K[m]] 1:2, 1:1, 2:1 and 3:1 as surfactant to cosurfactant [S/CoS] respectively. Pseudoternary phase diagrams were constructed using the selected oils [Labrafil M 1944 CS, Labrafil M 2125 CS and Capryol 90] with the different K[m] ratios. Microemulsion formulations were prepared using Labrafil M 1944 CS, Tween 80 and n-Bu with K[m] 2:1. The physicochemical characteristics involving viscosity, refractive index [RI], conductivity and pH were determined for these systems. In addition, the solubility of acyclovir in the prepared microemulsion systems [MEs] was measured. Acyclovir was incorporated to three MEs [ME[10], ME[50] and ME[80]] representing three different regions in the phase diagram; water in oil [w/o], bicontinuous [Bc] and oil in water [o/w] respectively. All of the prepared formulations were subjected to thermodynamic stability studies. The droplets size, polydispersity index [PDI] and zetapotential [ZP] of both before and after drug incorporation were determined. Acyclovir release from drug loaded MEs was determined and the kinetic of the release data was calculated. The conductivity and viscosity results proved the presence of three regions in the phase diagram [w/o, Bc and o/w]. The refractive index showed that the prepared MEs were transparent and isotropic. All the formulations were thermodynamically stable. The droplet size of drug loaded MEs was higher than that of corresponding unloaded ones but all have droplet size in nano range. PDI was found to be less than 0.5 and ZP in the range of-0.101 to 2.5 mV. Release of acyclovir from ME[80] [0.1, 1.99, 17.98 and 79.92 w/w for acyclovir, oil, S/CoS and water respectively] was the highest among the other ones, Model of non-Fickian "anomalous" transport release was the mechanism of drug release from the selected MEs. In conclusion, stable isotropic microemulsion systems using Labrafil M 1944 CS, Tween 80 and n-butanol as oil, surfactant and cosurfactant respectively with K[m] 2:1 could be formulated. The viscosity and electric conductivity results proved the presence of three areas; w/o, Bc and o/w in phase diagram. Acyclovir could be loaded into different microemulsion systems. The percent drug release increased by increasing the water content of microemulsion

Formulation and evaluation of metronidazole bioadhesive matrices for treatment of periodontitis

Metronidazole [Mz] [an anaerobic antibacterial agent] was incorporated into different bioadhesive matrices including gels and films using carbopol 934p [4%], chitosan [3%] and hydroxypropyl methyl cellulose [HPMC] [3%]. Penetration enhancers including menthol [1%] or oleic acid [OA] [5%, 10%] were incorporated in such formulations. The bioadhesive forces of the prepared matrices were determined and expressed as detachment stresses [Dyne/cm[2]]. Permeability of Mz across ear rabbit skin and enhancement ratios [ER] were studied. The effects of selected Mz formulations on the healing rate of experimentally induced periodontitis in guinea pigs were estimated and histologically compared between treated and control groups. The obtained results showed that the gel formulations containing carbopol 934p exhibited maximum bioadhesive force with detachment stress equals to 66.98x10[2] dyne/cm[2] followed by those containing chitosan [42.45x10[2] dyne/cm[2] and HPMC [26.41x10[2] dyne/cm[2]. There was a statistically significant difference [P<0.05] between the detachment stresses of gel formulations containing penetration enhancers and the corresponding ones without penetration enhancer. HPMC based films had bioadhesive force [19.33, 16 and 13.67x10[2] dyne/cm[2] higher than those based on chitosan [5.33 and 7.33x10[2] dyne/cm[2]. Also, it was noticed that the chitosan gel containing 1% menthol had the highest ER [5.13] among other gel formulations. On the other hand, chitosan based film containing 5% OA has the highest ER [1.73] among films. The effects of the selected formulations on the healing periodontal wound showed that bioadhesive chitosan gel containing menthol had accelerated the periodontal wound healing more than chitosan based film containing oleic acid