The transdermal drug delivery route is evolving as a potential route due to its advantages of bypassing the hepatic first pass metabolism, decreased side effects and gastrointestinal effects, improve patience compliance as it is a pain-free self-administration for patients, etc. The major setback appearing in this route is the difficulty of the drugs to penetrate through the skin as the stratum corneum (outermost layer of the skin) forms a protective barrier for the underlying tissues from the outer environment. A transdermally delivered drug can only show its action when it can cross the transdermal barrier to reach the systemic circulation and for helping on doing that the penetration enhancer are the agents which increase the permeability of the skin which on return maintains the drug level in the blood. Permeation enhancers can be of a chemical type, natural type, and physical type. The present review describes the natural permeation enhancers can be which be employed for transdermal permeation of drugs.

Objective: To develop a transdermal patch of Indomethacin using patchouli oil as a natural enhancer to increase transdermal permeation of the drug from the matrix system across rat epidermis. Materials and Methods:The chemical characterization of patchouli oil was done by gas chromatography-mass spectrometry. Transdermal patches of indomethacin were formulated after studying the drug-excipient compatibility studies by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). The transdermal patches were evaluated for various physiochemical properties. In-vitro transdermal permeation was carried using modified Keshary-Chein diffusion cell across rat epidermis. FTIR studies of rat epidermis were done to understand the mechanism of the permeation enhancing effect of the oil from the matrix patch. Result:The results of physiochemical parameters of the transdermal patch were found satisfactory. The transdermal flux obtained of the different concentration of patchouli oil tend to increase with increasing concentration of the oil and the maximum transdermal flux of 61.92 ± 0.89 µg/cm 2 /hr was obtained with formulation F7 (containing 1% w/v of patchouli oil) which is similar to the flux of the formulation F2 containing standard enhancer dimethyl sulphoxide. The skin irritation test did not show any edema and the FTIR data of rat epidermis indicated that patchouli oil enhances transdermal permeation of indomethacin by partial extraction of lipids in the stratum corneum. Conclusion:Thus, the results showed a potential enhancing effect of patchouli oil on the transdermal permeation of the model drug indomethacin and may be used as natural permeation enhancer in transdermal drug delivery systems.

The present research work is based on the formulation and evaluation of topical gel of Ibuprofen where Carbopol 940 is used as the polymer. Gels were prepared by dispersing the polymers  in a mixture of water and glycerol with methyl paraben as the preservative and the varying amount of ibuprofen, being kept under magnetic stirring until the homogeneous dispersion was formed. The dispersion was then neutralized and made viscous by the addition of triethanolamine. The Carbopol gels of Ibuprofen were found to be homogenous with good drug loading. The pH of all the gel formulations was found within the neutral pH range which is compatible with skin. And the viscosity of the formulations was found to be feasible for topical drug delivery. The drug content of the three formulations was found in the range of 87.56% to 90.45% which shows efficient drug loading. Results of In vitro drug release study showed that F5 formulation has better diffusion of drug through egg membrane and hence further permeation studies were carried out through rat epidermis. The compatibility study showed that the major peaks in FTIR spectra of the pure drug were found to be intact in their physical mixture. Hence there is no interaction between drug and Carbopol in their physical mixture. Carbopol can be effectively used as the polymer for topical gel preparation. And F5 formulation containing 0.5 % w/w Carbopol 940 may be effectively used as topical transdermal delivery for Ibuprofen. Keywords: Ibuprofen, Transdermal Gel, Drug release, Compatibility study

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