Formulation and characterization of Cefuroxime Axetil nanoemulsion for improved bioavailability.

Cefuroxime Axetil nanoemulsion was formulated to address the problem of poor oral bioavailability. Formulation was manufactured utilizing Capmul MCM, Soya lecithin, Deoxycholic acid, Pluronic F127 and distilled water. Mean globular size of 121.3 nm was obtained. Drug content of nanoemulsion was found to be 97.12±0.27%(w)/(v). 80.7261% of the drug was diffused from nanoemulsion, as compared with 51.0048% diffused from the plain Cefuroxime axetil suspension. In vivo studies indicated AUC(0-24): 325.3 for nanoemulsion in comparison to AUC(0-24): 165.3 for plain suspension. Therefore a good orally bioavailable formulation was developed successfully.

Cefuroxime Axetil is cephalosporin generally used for lower and upper respiratory tract infections, genito – urinay tract infections, skin and soft tissue infections. It is a prodrug that gets converted into Cefuroxime after oral absorption. The marketed preparation has very poor oral bioavailability (25% – 30%) and is variable with presence or absence of food. The objective of this work was to develop a nanoemulsion formulation to provide a boost to bioavailability of the drug along with faster onset of action.

Materials and Methods

Materials

Cefuroxime Axetil, Soya lecithin (Sigma Aldrich), Capmul MCM (Abitech Corp), Deoxycholic acid (Sigma Aldrich), Pluronic F127 (BASF), Distilled water.

The oil phase consisting of Capmul MCM, Soya lecithin, Deoxycholic acid and Cefuroxime Axetil was heated to 70°C. The aqueous phase comprising of Pluronic F127 and distilled water was also heated to 70°C separately to avoid phase separation during addition. Oil phase was gradually added to aqueous phase under high speed magnetic stirring to form a pre – emulsion. The pre – emulsion was sonicated at 100 W for 9 minutes to get nano – sized emulsion. The prepared nanoemulsion was stored in glass vial until further charactertization.

Gobule size and zeta potential

The mean Globule size and polydispersity index were measured at 25°C by photon correlation spectroscopy (PCS). Each 0.1 ml of sample was diluted to 10 ml with distilled water in order to obtain the optimum scattering intensity. During the measurement, average count rate was maintained between 50 and 500 kcps. The zeta potential was measured by determining electrophoretic mobility of the oil droplets.

Transmission electron microscopy

Morphology and structure of the nanoemulsion were studied using transmission electron microscopy (TEM) operating at 200 kV with resolution of 0.27 nm and magnifications of the order of 750,000X.

Drug content

The amount of Cefuroxime Axetil in the emulsions was assayed by UV Spectroscopic method. Drug content was expressed as a percentage of Cefuroxime Axetil found in the system to the theoretical quantity of the drug added. For estimation, 1.0 ml of nanoemulsion was diluted in methanol and the resulting solution was analyzed at 277 nm in UV-Visible Spectrophotometer.

pH

The pH of lipid nanoemulsion was measured using Digital pH meter.

In vitro diffusion study

2.5 ml of nanoemulsion was taken in dialysis bag. It was then immersed in 100 ml diffusion media [PBS (pH 7.4): Methanol (7:3)]. At predetermined intervals (15 min, 30 min, 1, 2, 3, 4, 5, 6 and 24 hours) of time, 2 ml aliquots were withdrawn from the receptor compartment and subjected to analysis. Fresh buffer was used to replenish the receptor compartment.

In vitro intestinal permeability study

For this study, stomach and small intestine tissue from male Wistar rats were taken. The nanoemulsion sample (2.5 ml containing 40 mg drug) was injected into the lumen of the stomach using a syringe, and the 2 sides of the stomach were tightly closed. The tissue was placed in the organ bath with continuous aeration and a constant temperature of 37°C. The receiver compartment was filled with 30 ml of phosphate-buffered. At predetermined intervals (15 min, 30 min, 1 h. and 2 h.) of time, 2 ml aliquots were withdrawn from the receptor compartment and subjected to analysis. Fresh buffer was used to replenish the receptor compartment. After 2 hours the nanoemulsion was removed from the stomach using a syringe and was then shifted to intestinal tissue and the entire procedure was repeated.

In vivo study

In vivo pharmacokinetic study was done on male wistar rats to compare marketed suspension (control) with equivalent drug strength nanoemulsion formulations (Tests). Results revealed that amount of drug reached into blood was higher with nanoemulsion compared to marketed suspension.

Results and Discussion

The results show that the optimized batch has a mean globular size of 121.3 nm. Zeta potential value of -35.9mV was observed, which is sufficient for stability of nanoemulsion. The negative zeta potential is due to charged induced surfactants utilized in formulation. TEM micrograph further confirmed the nanometric particle size of the nanoemulsion of Cefuroxime Axetil. Drug content of optimized lipid nanoemulsion was found to be 97.12±0.27%w/v. This high drug content could be due to incorporating the drug in the lipid phase. The pH of lipid nanoemulsion was measured using Digital pH meter. Nanoemulsion had a pH between 7.4-7.6, i.e. neutral pH range, which ensures stability of formulation over its shelf life. Comparative diffusion studies were carried out for plain Cefuroxime Axetil suspension and lipid nanoemulsion. After 6 hours of diffusion, 80.7261% of the drug was diffused from the lipid nanoemulsion system, as compared with 51.0048% diffused from the plain Cefuroxime axetil suspension. The total percentage diffusion through the tissue was much higher for the lipid nanoemulsion system than for the Cefuroxime Axetil suspension. In vivo studies indicated better bioavailability for nanoemulsion (AUC0-24:325.3) in comparison to plain suspension (AUC0-24:165.3). The Cmax for nanoemulsion was 59.3 (μg/ml) compared to 37.3 (μg/ml) for plain suspension.

Conclusion

Therefore, in present investigations an attempt was made to curtail the problems associated with currently available Cefuroxime Axetil preparations by preparing stable lipid nanoemulsion formulations. Lipid nanoemulsion of Cefuroxime Axetil was prepared by ultra sonication method, which has been successfully used to reduce oil droplet size of nanoemulsion to below 150nm. Comparative in vitro drug release study, in vitro intestinal permeability study and in vivo study demonstrated that lipid nanoemulsion can significantly improve drug solubilisation and bioavailability of a poorly absorbed drug.