6.3. A. Microemulsions (135-143)
Microemulsions are clear, stable, isotropic mixtures of oil, water, and surfactant, frequently in combination with a cosurfactant 135-137. Microemulsions have several advantages such as enhanced drug solubility, good thermodynamic stability, and higher transdermal permeability over conventional formulations 138,139. Many studies reported the use of microemulsions as topical drug delivery vehicles showed their ability to improve transdermal and dermal delivery properties 140-141. Microemulsions have several permeation enhancement mechanisms such as increase in concentration gradient and thermodynamic activity toward the skin 142.
1. Determination of saturation solubility
The solubility of mepivacaine in various oils was determined by adding excess amount of drug to 4 g of oil in capped glass test tubes. The tubes were equilibrated at 37°C for 72 h in a thermostatically controlled water bath shaker. The suspensions were centrifuged at 6,000 rpm for 15 min followed by filtration of the obtained supernatant through 0.45 μm Millipore membrane filters.
2. Construction of Microemulsion Phase Diagrams
The oil phase studied included lemon oil, oleic acid, benzyl alcohol, or …show more content…
In vitro permeation study : The permeation and the diffusion of mepivacaine from prepared microemulsions were evaluated using Franz diffusion cells (surface 2 cm2 receiver liquid volume 7 mL) in a 370C thermostatic bath. The receiver liquid contains phosphate buffer of pH = 7.4. It was used a cellulose acetate membrane with the pore size of 0.45µm as diffusion barrier. This membrane was hydrated for 24 hours with phosphate buffer pH=7.4. The donor compartment contains 0.1083 gm of microemulsion. It was collected 1.5mL of sample at every hour from the receiver compartment and it was established the amount of mepivacaine delivered and diffused. After each sample was collected the same volume of phosphate buffer solution in the receiver compartment was
Microemulsions are clear, stable, isotropic mixtures of oil, water, and surfactant, frequently in combination with a cosurfactant 135-137. Microemulsions have several advantages such as enhanced drug solubility, good thermodynamic stability, and higher transdermal permeability over conventional formulations 138,139. Many studies reported the use of microemulsions as topical drug delivery vehicles showed their ability to improve transdermal and dermal delivery properties 140-141. Microemulsions have several permeation enhancement mechanisms such as increase in concentration gradient and thermodynamic activity toward the skin 142.
1. Determination of saturation solubility
The solubility of mepivacaine in various oils was determined by adding excess amount of drug to 4 g of oil in capped glass test tubes. The tubes were equilibrated at 37°C for 72 h in a thermostatically controlled water bath shaker. The suspensions were centrifuged at 6,000 rpm for 15 min followed by filtration of the obtained supernatant through 0.45 μm Millipore membrane filters.
2. Construction of Microemulsion Phase Diagrams
The oil phase studied included lemon oil, oleic acid, benzyl alcohol, or …show more content…
In vitro permeation study : The permeation and the diffusion of mepivacaine from prepared microemulsions were evaluated using Franz diffusion cells (surface 2 cm2 receiver liquid volume 7 mL) in a 370C thermostatic bath. The receiver liquid contains phosphate buffer of pH = 7.4. It was used a cellulose acetate membrane with the pore size of 0.45µm as diffusion barrier. This membrane was hydrated for 24 hours with phosphate buffer pH=7.4. The donor compartment contains 0.1083 gm of microemulsion. It was collected 1.5mL of sample at every hour from the receiver compartment and it was established the amount of mepivacaine delivered and diffused. After each sample was collected the same volume of phosphate buffer solution in the receiver compartment was