INTRODUCTION:

Curcuma longa is a perennial herb and member of the Zingiberaceae (ginger) family. Dried Curcuma longa is the source of the spice turmeric. Turmeric is used extensively in the Chinese and Ayurvedic systems of medicine, particularly as an anti-inflammatory agent and for the treatment of flatulence, jaundice, menstrual difficulties, hematuria, hemorrhage, and colic. The best-researched active constituent is curcumin, which comprises 0.3-5.4 percent of raw turmeric ^{1, 2}. Based on early research conducted with cell cultures and animal models, pilot and clinical trials indicate curcumin may have potential as a therapeutic agent in diseases such as inflammatory bowel disease, pancreatitis, arthritis, and chronic anterior uveitis, as well as certain types of cancer ^{3, 4}.The antiinflammatory activity of the curcumin is attributed to its inflammatory mediator inhibitory activity. Curcumin was found to inhibit TNF-α, PGE2 and the expression of COX-2 ⁵

Permeation enhancers are chemicals that interact with the constituents of the biological membrane to increase the drug flux. Human skin is a remarkably efficient barrier that effectively inhibits the efforts to transfer any exogenous compound across it. This barrier property causes difficulties for transdermal delivery of therapeutic agents ⁶.

To-date, a vast array of chemicals has been evaluated as penetration enhancers (or absorption promoters), yet their inclusion in to topical or transdermal formulations is limited since the underlying mechanisms of action of these agents are seldom clearly defined ⁷. The enhancement in the penetration is thought to be acquired by means such as increasing the diffusion coefficient, increasing the drug solubility in the skin and by increasing the degree of saturation ⁸. The usual penetration enhancers used are dimethyl sulphoxide, essential oils, Fatty acids, alcohol, surfactants, pyrrolidones, azones, oxazolidinones, occlusive agents and urea. The skin permeation enhancers have been evaluated already and they were proved to be of commendable efficacy. Researches are being conducted in this field regarding their efficacy and mechanism which would significantly increase the number of drugs suitable for transdermal drug delivery, with the result that skin will become one of major routes of drug administration in the next decade ^{9, 10}.

In this study, an antiinflammatory cream is formulated using turmeric extract. Different formulations are made using various penetration enhancers such as alcohol, dimethyl sulphoxide, tween 80 and occlusive agents. The release of curcumin form each formulation is being evaluated by an in vitro permeation study using pig ear skin as the skin simulatory membrane. The release of curcumin is quantified by curcumin content analysis using UV spectrometry. The effect of different penetration enhancers on curcumin are thus analyzed by comparing the results ^{8, 11}.

Ingredients	Formula 1	Formula 2	Formula 3	Formula 4	Formula 5	Formula 6
Curcuma extract	1	1	1	1	1	1
Tween 80	5	5	5	5	7.5	5
White soft paraffin	25	25	35	25	25	30
Stearyl alcohol	8	8	8	8	8	8
Glycerin	12	12	12	12	12	12
Methyl paraben	0.1	0.1	0.1	0.1	0.1	0.1
Propyl paraben	0.05	0.05	0.05	0.05	0.05	0.05
Butylated hydroxy Toluene	0.02	0.02	0.02	0.02	0.02	0.02
Ethanol	-	5	-	-	-	5
Dimethyl sulphoxide	-	-	-	5	-	2.5
Water	48.83	43.83	38.83	43.83	46.33	36.33

Table 2

FORMULATION	CURCUMIN CONTENT AT DIFFERENT TIME INTERVALS (µg)
FORMULATION	0.5 hr	1 hr	2 hr	3 hr	4 hr
Formula 1	6	18	32	44	60
Formula 2	8	29	55	102	162
Formula 3	8	35	76	111	186
Formula 4	12	24	45	92	150
Formula 5	6	31	63	88	138
Formula 6	9	27	41	78	114

MATERIALS AND METHODS:

CHEMICALS

Turmeric extract was prepared by extracting turmeric rhizomes with methanol for 15 hours using soxhlet apparatus (continuous hot percolation). Tween 80, white soft paraffin, Stearyl alcohol, glycerin, methyl paraben, propyl paraben, butylated hydroxy toluene, alcohol and dimethyl sulphoxide were the different chemicals used for the preparation of the cream. Phosphate buffer of P^H 8 and standard curcumin in different dilutions were used for the in vitro release study.

PREPARATION OF PERMEATION MEMBRANE

Pig ear skin was used as the skin simulatory membrane. Skin from the outer surface of a freshly excised porcine ear was carefully dissected. The skin was shaved to remove the hairs before the preparation. Body fluids were removed by paper or towel. It was stored in the normal saline for preservation. It can be preserved up to 4 days in this state. To counteract microbes, antimicrobial preservatives have been added. The whole skin membrane was removed from the underlying cartilage with the help of a scalpel. The subcutaneous tissues were removed and skin was stored at -4⁰c for the time until use ^{12, 13, 14, 15}.

FORMULATIONS

An O/W formula was created. Six different formulations were created using different penetration enhancers in the formula. Formulation 1 contained 1% turmeric extract with other exipients without any penetration enhancer. Formulation 2 contained 5% ethanol as permeation enhancer. Formulation 3 contained excess amount (35%) of white soft paraffin in the formula as an occlusive agent. in Formulation 4, dimethyl sulphoxide was incorporated as the permeation enhancer. Formulation 5 contained an excess (5%) of tween 80 as surface acting permeation enhancer. Formulation 6 was formulated using a combination of different permeation enhancers such as ethanol, dimethyl sulphoxide and white soft paraffin together for a synergistic activity. The method of preparation employed for the cream formulation is as follows:

The creams were prepared by emulsion method. The ingredients were differentiated in to two phases. The phase 1(aqueous phase) contained the water soluble phase including water, glycerin and methyl paraben. Phase 2(oil phase) contained white soft paraffin, Stearyl alcohol, Propyl paraben, tween 80 and Butylated hydroxy toluene. The ingredients of the phase 1 were added to water and heated. Then glycerin was added to the phase with constant stirring. The phase was heated up to 70⁰C. Phase 2 was prepared by melting white soft paraffin at 70⁰C. Then Stearyl alcohol and tween 80 was added to it with constant stirring. The mixture was stirred continuously until the temperature of 35⁰C was reached.

Then the extract of curcuma longa was added, mixed properly and the cream was cooled by stirring to room temperature. Prepared creams were stored at room temperature in tightly closed plastic containers protected from light ^{16, 17, 18}. The composition of different ingredients used for the different formulations are given in the table 1.

ANALYTICAL PROCEDURE

The curcumin content was analyzed by UV spectrophotometric method (shimadzu 1800 model). The analysis was performed at 429 nm using 50% ethanol as the blank. The sample solutions were taken from the receptor compartment of the Franz diffusion cell. The solutions were diluted with alcohol to make up a 50% alcoholic solution o f the sample. The concentration of the sample solutions were estimated by the standard absorbance Vs concentration graph plotted by using the different dilutions of standard curcumin ^{11, 19, 20}.

PERMEATION STUDY

The permeation studies were carried out in amber glass Franz type diffusion cell with a diffusion area of 1.86 cm². The porcine ear skin samples were placed between the donor and the receptor compartments of the cell, with the dermal side in contact with the receptor medium. The formulation studied (1 g) was placed in the donor compartment and the cell was covered with the aluminium foil. The receptor camber was filled with 15 ml of phosphate buffer of p^H 8 and kept at 32 ± 0.5⁰C by a circulating water jacket. Samples of 1 ml were withdrawn from the receptor compartment at 0.5, 1, 2, 3 and 4 hour and replaced the same volume of phosphate buffer at 32⁰C. Sink conditions were met in all cases ^{12,
13, 14}.

RESULTS:

PERMEATION STUDY

The curcumin penetrated through the skin at different intervals from cream formulations are shown in the table 2. The in vitro release profiles of curcumin from different formulations can be easily compared by these representations. The amount of curcumin permeated at 4 hr ranged between 60 µg (formula 1) and 186 µg (formula 3). In all the cases, the curcumin permeation was enhanced by means of the permeation enhancers; when compared with the control (formula 1). The formula 3 showed the greatest penetration capability with a curcumin content permeation of 186 µg after the time period of 4 hours. The graphical representation of the curcumin permeation is represented in the figure 1.

Figure 1

DISCUSSION:

Different release profiles of curcumin were observed. The control formulation showed the least release rates compared to the formulations incorporated with the penetration enhancers. The highest release was obtained with the use of occlusive agent (white soft paraffin) in the formula. This shows occlusive agents can be of significant value in case of curcumin containing topical preparations.

There was no evidence of phase separation, development of disagreeable odour or change in colour/ consistency in any of the preparations.

REFERENCE:

1. Thorne Research, Inc. Curcuma longa. Alternative Medicine Review Monographs. 2002: 119-125.

2. Committee on Herbal Medicinal products. Assessment report on Curcuma longa (L) rhizoma. European Medicines Agency, Evaluation of Medicines for Human Use. EMEA/HMPC/ 456848/2008.

3. Julie S J. Anti-inflammatory Properties of Curcumin, a Major Constituent of Curcuma longa: A Review of Preclinical and Clinical Research. Alternative Medicine Review. 14 (2); 2009.

4. Sanjay Jain, Satyaendra S, Satish N and Sumbhate S. Recent trends in Curcuma longa Linn. Pharmacognosy Reviews. 1 (1); 2007.

5. Lantz R C, Chen G J, Solyom A M, Jolad S D and Timmermann B N. The effect of turmeric extracts on inflammatory mediator production. Phytomedicine 12(1); 2005: 445–452.

6. Adrian C W and Brian W B. Penetration enhancers. Advanced Drug Delivery Reviews 56 (1); 2004: 603–618.

7. Barrie C F and Timothy M M. Transdermal penetration enhancers: Applications, limitations, and potential. Journal of Pharmaceutical Sciences. 88 (10); 1999: 955.

8. Katrin M, Katrin K, Arti N, Yogeshvar N K and Richard H G. Passive skin penetration enhancement and its quantification in vitro. European Journal of Pharmaceutics and Biopharmaceutics. 52(1); 2001: 103-112.

9. Pathan I B and Setty C M. Chemical Penetration Enhancers for Transdermal Drug Delivery Systems. Tropical Journal of Pharmaceutical Research. 8 (2); 2009: 173-179.

10. Jonathan Hadgraft. Passive enhancement strategies in topical and transdermal drug delivery. International Journal of Pharmaceutics 184 (1999) 1–6.

11. Barik A, Priyadarsini K I and Hari Mohan. Photophysical Studies on Binding of Curcumin to Bovine Serum Albumin. Photochemistry and Photobiology. 77(6); 2003: 597–603.

12. Cristina D R , Telma M K , Renata M R, Vanessa V S, Sonia B, Sawada C H, Massuo J K , Silvia B M. Evaluation of percutaneous absorption of 4-nerolidylcathecol from four topical formulations. International Journal of Pharmaceutics. 249; 2002: 109/116.

13. Fabiana T, Sandra R G, Maria V, and Maria J V. Assessment of in vitro methodologies to determine topical and transdermal delivery of the flavonoid quercetin. Brazilian Journal of Pharmaceutical Sciences. 45 (2); 2009.

14. Saleem M A et al. study on in vitro permeation enhancement of ketoprofen by formation of solid dispersion. International Research Journal of Pharmacy. 2(4); 2011: 134-140.

15. Elvira E, Calpena A C, Josep Q, Obach R and Jose D. Assessment of diclofenac permeation with different formulations: anti-inflammatory study of a selected formula. European Journal of Pharmaceutical Sciences. 19 (1); 2003: 203–210.

16. Ana A M, Elizângela A S, André Luis M C, Ruth R S, Miracy M A, Almir G W and Davi S. Development of Lapachol Topical Formulation: Anti-inflammatory Study of a Selected Formulation. AAPS Pharm Sci Tech. 9 (1); 2008.

17. Jagtap N S, Khadabadi S S, Farooqui I A, Nalamwar V P and Sawarkar H A. Development and evaluation of herbal wound healing formulations. International Journal of Pharmtech Research. 4(1); 2009: 1104-1108.

18. Jurga B, Ruta M, Julija D, Rimantas P, Romualda G, Ruta B, Daiva M, Robertas L ,Genuvaite C, Saule V, Jan M and Zuzana C. Topical application of Calendula officinalis (L.): Formulation and evaluation of hydrophilic cream with antioxidant activity. Journal of Medicinal Plants Research. 5(6); 2011: 868-877.

19. Ferenc Z, Zsolt B and Miklós S. Circular dichroism spectroscopic studies reveal pH dependent binding of curcumin in the minor groove of natural and synthetic nucleic acids. Org biomol chem. 2; 2002: 2902-2910.

20. Curcumin, product information. Cayman chemicals

Received on 05.01.2011 Modified on 20.01.2012

Research J. Pharm. and Tech. 5(3): March 2012; Page 408-410