Emulgels have emerged as a promising drug delivery system for the delivery of hydrophobic drugs. Mentha oil and clove oil were used as penetration enhancers. The emulsion was prepared and it was incorporated in gel base. The formulations were evaluated for rheological studies, spreading coefficient studies, bioadhesion strength, skin irritation studies, in vitro release, ex vivo release studies, anti-inflammatory activity and analgesic activity. Formulation F2 and F4 showed comparable analgesic and anti-inflammatory activity when they compared with marketed diclofenac sodium gel.
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Microemulsions were characterized for optical birefringence, globule size, polydispersity andconductivity. All microemulsion were stable, transparent, oil in water type and in globulesize range of The prepared emulgels were evaluated for pH, drug content,viscosity, in vitro drug release study using dialysis membrane, and skin irritationtest. The pH and drug content of emulgels was in acceptable range of topical application. The viscosity was increased as the proportion of tween and ethyl oleate increased.
The in vitro release of valdecoxib was also increased as the proportion of tween increased. All the emulgels were free from skin irritation and were stable at room temperature.
From the study it can be concluded that microemulsion based emulgel formulation containing tween PG in the proportion of was the best formulation. A , Imam S. Preparation and Evaluation of Valdecoxib Emulgel Formulations. Biomed Pharmacol J ;1 1. Microemulsion has several advantages such as enhanced drug solubility, good thermodynamic stability, ease of manufacturing and enhancement effect on transdermal delivery over conventional formulation Lawrence and Rees, ; Gasco, An additional advantage of these microemulsion-based gels is that drugs that with poor solubility in water and ethanol can be incorporated into these systems in sufficient quantity to enhance drug delivery.
Valdecoxib was used as a highly lipophilic model drug in the present study. Valdecoxib is a nonsteroidal anti-inflammatory drug that acts by inhibition of cycloxygenase II COX-II and is used in the treatment of inflammation and arthritis. The adverse effects are GI disturbances and hypertension after oral use. In the present study, an attempt has been made to develop emulgel formulations of valdecoxib so as to reduce adverse effects and to enhance percutaneous absorption.
Ethyl oleate was purchased from Loba Chemie, Mumbai. All other chemicals were of analytical grade. Click here to View figure. To find out the suitable oil which can be used as the oil phase in microemulsion and provide excellent skin permeation rate of valdecoxib, the solubility of valdecoxib in various oils including IPM, OA and EO was measured.
The solubility of valdecoxib in oily mixtures containing ratio of oil: tween PG was also measured. The equilibrated sample was centrifuge to remove the excess amount of valdecoxib undissolved and filtered through a membrane filter. Finally diluted with methanol and the concentration of valdecoxib was determined by UV-visible spectrophotometer at nm.
These phase diagrams were prepared with the , and weight ratios of tween to PG respectively. The mixtures of oil, surfactant and co-surfactant at certain weight ratios were diluted with water drop-wise, under moderate magnetic stirring.
After being equilibrated, the mixtures were assessed visually anddetermined as being microemulsions, crude emulsions or gels. The microemulsion was checked both visually and using crosspolarizers for optical isotropy to confirm absence of other phases.
Weighed quantity of carbopol was soaked in the microemulsion system by stirring to disperse the carbopol in the microemulsion and finally neutralize with sufficient triethanolamine amine to obtained emulgels. For determination of drug content, about one gram of the gel was weighed in a mL volumetric flask and dissolved in methanol; it was diluted appropriately and analyzed on a Shimadzu UV-Visible spectrophotometer at nm.
CP In vitro release study of valdecoxib from emulgel was done by using modified beaker method. The diffusion medium used was ml distilled water containing 0. The cellophane membrane acts as a barrier between the gel phase and distilled water containing 0. A quantity of 1 ml sample was withdrawn from receptor fluid at the time interval of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 hours.
The released drug was estimated by using Shimadzu UV-visible spectrophotometer at nm. To develop microemulsion formulations, the optimum oil needs to be chosen. The solubility of valdecoxib in various oils and in oily mixtures is shown in Table 1. Hence oleic acid was not used in the present study. Ethyl oleate shows next highest solubility in the series and also in oily mixture containing tween and PG. Solubility of valdecoxib in oily mixture increases due to the solubilization effect of tween and further PG reduces the interfacial tension which helps in solubilization of valdecoxib in oily phase.
The pseudoternery phase diagrams with various weight ratios of tween PG is depicted in Figure 1. The transparent microemulsion region was observed visually and also by using cross polarizer.
Only those systems, which appeared black when visualized through cross polarizer, were deemed to be within the microemulsion region. The rest of the region on the phase diagram represents turbid and conventional emulsion.
Various microemulsions were selected from , and phase diagrams and the drug was incorporated. The various characterization parameters of microemulsions aredepicted in Table 2.
The optical birefringence studies suggested that all the microemulsions were found to be isotropically clear. All the microemulsions had small average droplet diameters between In MC series the droplet size was small which may be due to large amount of surfactant. From overall result the microemulsions containing ratio of tween to PG shows small droplet size. Small droplet size was preferred in term of skin penetration.
The polydispersity index was 0. All the microemulsions showed high conductivity values of All the prepared microemulsions were then incorporated in 0. All the emulgels were clear and transparent in appearance. The various evaluation parameters of emulgels are represented in Table 4. The pH of all emulgels was found between 5.
All the prepared emulgel formulations showed uniformity in drug content and were within permissible range indicating the uniformity of the drug dispersion in the emulgels. All formulated valdecoxib emulgels showed an increase in the viscosity as the amount of oil was increased and also the proportion of tween increased. The increase in viscosity was due to decrease in the aqueous phase of emulgel.
In the skin irritation study as represented in Table 5, the emulgel formulations showed no skin irritation even after 72 hours with zero scoring for erythema which indicates better skin acceptability for topical applications. The in vitro permeation of valdecoxib from different emulgels was affected by many parameters like globule size, viscosity, amount of oil and proportion of tween to PG.
In MB series of emulgels, MB1 showed maximum percent drug release. The reason is same as that of MA series. This was due to highest proportion of tween as a surfactant, which acts as a permeation enhancer, and also the globule size was less compared to MA and MB series and hence small globule size was preferred in terms of skin penetration. The viscosity of MC series was high as compared to MA and MB series but due to the reasons said above, the release was more.
From the study it can be concluded that microemulsion based emulgel formulation containing Tween PG in the proportion of was the best formulation. Hence microemulsion based gels could be successfully used as a vehicle for topical delivery of Valdecoxib. Mumbai for providing gift sample of drug. This work is licensed under a Creative Commons Attribution 4.
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