INTRODUCTION:

Recently, the most common form of delivery of drugs is the oral route. However this system has its oven notable advantage of easy administration, it also has significant drawbacks; namely poor bioavailability due to first pass effect and the tendency to produce rapid both high and low blood level, leading to a need for high and/or frequent dosing, which can be both cost prohibitive and inconvenient.^[1]

Penetration enhancers are the substances that facilitate the absorption of penetrant through the skin by temporarily diminishing the impermeability of the skin. Ideally, these materials should be pharmacologically inert, nontoxic, nonirritating, nonallergenic, and compatible with the drug and excipients, odorless, tasteless, colorless, and inexpensive and have good solvent properties.^[^2,3]

The site of action of the chemical skin penetration enhancers is located in the stratum corneum. ^[4] Chemical enhancers can be divided into two broad categories: Those that change partitioning into the stratum corneum and those that influence diffusion across the stratum corneum ^[5] such as dimethylsulfoxide or DMSO, alcohols. The enhancer should not lead to the loss of body ﬂuids, electrolytes, and other endogenous materials, and skin should immediately regain its barrier properties on its removal. ^[6]

Dimethyl sulphoxides (DMSO) is the most important compound belong to the category of sulfoxide and similar compound enhances the transdermal permeation of a variety of drugs like B- blockers and other antihypertensive drugs.^[^7,8] Dimethyl sulfoxide, or DMSO, all-natural substance derived from wood pulp. Through the normal decomposition of plants DMSO is produced.^[^9]

Dimethyl sulphoxides (DMSO) is one of the earliest and most widely studied penetration enhancers. It is a powerful aportic solvent which hydrogen bonds with itself rather than with water. It is colourless, odourless and is hydroscopic and is often used in many areas of pharmaceutical sciences as a “universal solvent”. DMSO alone has been applied topically to treat systemic inflammation. DMSO works rapidly as a penetration enhancer - spillage of the material onto the skin can be tasted in the mouth within a second. Although DMSO is an excellent accelerant, it does create problems. DMSO changes the stratum corneum keratin from α- helicals to β- sheet confirmations. At concentration > 60% v/v DMSO are needed for optimum enhancement efficacy. ^[10] However, at these relative high concentrations, DMSO can cause erythema and wheal of the stratum corneum. Denaturing of some skin proteins results in erythema, scaling, contact uticaria, stinging and burning sensation. ^[11] Concentration greater than 60% DMSO enhances the ﬂux, there was evidence of its interaction with stratum corneum lipids. It also produces alteration in protein structure, but may also be related to alterations in stratum corneum organization besides any increased drug-partitioning effect. ^[12]

In the present study, transdermal monothilic films of Nebivolol hydrochloride were prepared using various film forming agents and no report are available on the comparative evaluation between with and without permeation enhancer on transdermal patches of Nebivolol hydrochloride.

MATERIAL AND METHODS:

Materials:

Nebivolol hydrochloride was a gift sample from Zydus cadila, Health care ltd., Ahmedabad (Gujrat), and HPMC and Eudragit RS 100 were gift sample from Akums Drugs and Pharmaceutical LTD, Haridwar, Polyethylene glycol 400 (PEG 400) was purchased from Central Drug House Ltd., New Delhi and Dimethyl sulfoxide (DMSO) was purchased from Merck Specialities Pvt., Worli, Mumbai, India.

Preparation of transdermal films:

In the present study, drug loaded matrix type transdermal films of Nebivolol hydrochloride were prepared by solvent evaporation method ^(13,14,15) using different ratios of ERS-100 and HPMC K100M polymers (table 1). The polymers were weighed in requisite ratios by keeping the total polymer weight at 1.0 gm added in solvent mixture (3:2 ratio of chloroform, methanol). Propylene glycol was incorporated as plasticizer and DSMO as penetration enhancer were used in F1 – F4 formulation. The drug was added slowly to the solution and dissolved by continuous stirring for 30 min. For the formulation of transdermal patch, the aluminums foil was spread uniformly on a glass petri dish. The mould was kept on a horizontal surface. The solution was poured on the foil into a petri dish of about 70 cm². The rate of evaporation was controlled by inverting a funnel over the mould. Aluminum foil was used as backing film. The solvent was allowed to evaporate for 24 hrs. The polymer was found to be self adhesive due to the presence of Eudragit polymer along with plasticizer. The patches were cut to give required area and used for evaluation.

PHYSICOCHEMICAL EVALUATION:

Physicochemical properties such as physical appearance, thickness, content uniformity, weight variation, folding endurance, tensile strength and percentage moisture absorption were determined on developed patches.

Investigation of Physicochemical Compatibility of Drug and Polymer:

The physicochemical compatibility between Nebivolol hydrochloride and polymers used in the films was studied by using fourier transform infrared (FTIR Alpha, Bruker, Banglore) spectroscopy. The infrared (IR) spectra were recorded using an FTIR by the KBr pellet method and spectra were recorded in the wavelength region between 4000 cm-1 and 400 cm^–1. The spectra obtained for Nebivolol hydrochloride, polymers, and physical mixtures of Nebivolol hydrochloride with polymers were compared.

DSC studies:

The optimized formulations were subjected to differential scanning calorimeter at a heating rate of 10^oC/min over a tempareture range of 0-300^oC. The sample of pure drug and optimized patches were hermetically sealed in an aluminum pen. Nitrogen gas was purged at the rate of 10 mL/min for maintained inert atmosphere.

In vitro Permeation Study:

The in-vitro permeation study of fabricated transdermal patches of Nebivolol hydrochloride was carried out by using excised rat abdominal skin and franz diffusion cell ^[16]. The skin was sandwiched between donor and receptor compartments of the diffusion cell. The patch of 2.64 cm² was placed in intimate contact with the stratum corneum side of the skin; the top side was covered with aluminum foil as a backing membrane. Teflon bead was placed in the receptor compartment filled with 12 ml of phosphate buffer pH 7.4. The cell contents were stirred with a magnetic stirrer and a temperature of 37±0.5°C was maintained throughout the experiment. Samples of 2ml were withdrawn through the sampling port at different time intervals for a period of 48 h, simultaneously replacing equal volume by phosphate buffer pH 7.4 after each withdrawal. The samples were analyzed spectrophotometrically at 282 nm. Based on the results of in vitro permeation profiles of preliminary batches of Nebivolol hydrochloride transdermal patches the optimum composition of checkpoint batches of Nebivolol hydrochloride transdermal patch was optimized.

Stability Studies of the optimized patch:

Formulation F-1 was then subjected to the accelerated stability studies at temperature of 40±2°C and 75±5% relative humidity (RH) as per the international conference on harmonization (ICH) guidelines (Zone IV) for the period of six months. The optimized patches (formulation F-1) were subjected to accelerated stability studies to evaluate any change in the performance when exposed to accelerated conditions of environment during storage, handling, transport and use. Patches were lined with aluminium foil and packed in plastic covers and kept in desiccator maintained at 75±5% RH at 40±2°C temperature for six months. The hot-air oven was set at temperature 40^oC and the relative humidity (RH) of 75.3% was maintained by using saturated solution of sodium chloride (NaCl). ^[17]

RESULTS:

Evaluation of transdermal patch:

The prepared transdermal patches were evaluated for their physicochemical characteristics such as appearance, weight variation, thickness, % moisture loss, % moisture absorption, folding endurance, drug content, tensile strength and in vitro drug permeation through albino rat skin. The physical appearance of the various formulations in terms of their uniformity, transparency, smoothness, flexibility, stickiness, homogenicity and opaque properties were recorded. The formulation E-1 was found to be Sticky, thin, transparent and flexible, E-2 was found to be Thin, opaque and flexible, E-3 and E-4 was found to be Thick, not flexible and opaque, F-1 was found to be thin, transparent and flexible, formulation F-2 and F-3 was found to be thin, opaque and flexible and formulation F-4 was found to be thick, not flexible and opaque. The formulation F-1 gave the most suitable transdermal film with all desirable physico-chemical properties. The thickness of the patches was varied from 0.211 ± 0.012 mm to 0.301 ± 0.61 mm.

Low standard deviation values in the film thickness measurements ensured uniformity of the patches prepared by solvent evaporation. The weights ranged between 49.16 ± 0.81 mg and 52.49 ± 0.65 mg, which indicates that different batches patch weights, were relatively similar. Folding endurance was found to be >100 that is satisfactory weight of the patches, drug content was found to be 3.61±0.13 mg to 3.87±0.98 mg. The cumulative % drug permeated and % drug retained by the individual path in the in vitro skin permeation studies were based on the mean amount of drug present in the respective patch. The cumulative percentage drug release for E-1, E-2, E-3, E-4, F-1, F-2, F-3 and F-4 was found to be 85.97±3.04%, 63.21±5.70%, 54.06±5.68%, 57.97±6.75%, 91.21 ± 2.14%, 83.16±7.16%, 73.20±7.39 % at 48 h and 68.16±5.57 % at 48 h respectively. The formulation, F1 [HPMC K100M, ERS-100 (8:2)] with DMSO as permeation enhancer is considered as a best formulation, since it shows maximum in vitro drug release as 91.21±2.14 % at 48 h.

The in vitro release profile is an important tool that predicts in advance how a drug will behave in vivo. The results of in vitro skin permeation studies of Nebivolol hydrochloride from transdermal patches are shown in Figures 1. In the present study hydrophobic Eudragit RS100 (ERS100) and hydrophilic hydroxy propyl methyl cellulose (HPMC K100M) polymers are used to prepared patches. Formulation E3 exhibit lowest 54.06±1.789 % of drug release value, while formulation F1 exhibited greatest 91.21±3.39 % of drug release value. The cumulative amount of drug released from formulations containing hydrophilic polymer release drug at faster rate than hydrophobic polymer. The drug release from the patch is ordered as F1>E1>F2>F3>F4>E2>E4>E3. Unlike the formulations F2, F3, F4, E1, E2, E3 and E4, the formulations F1 achieved a high cumulative amount of drug permeation at the end of 48 hours. Based on physiochemical and in vitro release experiments, F1 was chosen for further studies.

DISCUSSION:

A comparative evaluation of the permeability of without penetration enhancer films and the influence of DSMO as penetration enhancer on the film permeability in case was studied. Polymeric films can be prepared by solvent evaporation techniques produces uniform and reproducible films. In each case films were prepared using concentrations 20% of natural enhancer to evaluate the influence of the enhancer on the permeability properties of the film.

The percent penetration was reached to a maximum 92% by the addition of 20% enhancer to Nebivolol hydrochloride formulation with implying the ability of DMSO to increase the drug diffusion by modifying the barrier properties of stratum corneum.

Eudragit RS100 (ERS100) and hydrophilic hydroxy propyl methyl cellulose (HPMC K100M) polymers was used in patch as a rate controlling polymer which was observed to be effective by controlling the release rate of drug up to 48 hours of time period. In order to study the effect of DMSO as penetration enhancer on Nebivolol hydrochloride permeation through albino rat skin, the Nebivolol hydrochloride penetration from formulations with concentrations of penetration enhancer (20%) was determined by excised albino rat skin. From the in vitro permeation profile data of the formulations, the kinetics of drug release were found for the zero order, the first-order shown figure 3, Higuchi-type release kinetic shown figure 2 and Korsmeyer-Peppas type release kinetic shown in figure 4. It could be observed from the figure 1 that the penetration of Nebivolol hydrochloride across rat skin without enhancer was small but was by adding the amount of enhancer with increasing hydrophilic polymers range to the formulations and a maximum 92% drug was penetrated. Similar results were found in an investigative study (Gupta et al., 2009).

The samples were analyzed at zero, 3 months and 6 months as per the ICH guidelines. Changes in the appearance and drug content of the stored films were investigated after storage at the end of every week. The data presented in figue 5 were the mean of three determinations.

CONCLUSION:

Nebivolol hydrochloride transdermal patches was successfully prepared and evaluated with a high in vitro penetration rate. From the above results DMSO was found to be effective enhancer with increasing hydrophilic polymers range for the in vitro skin permeation of Nebivolol hydrochloride. It was also observed that 20% concentration of DMSO was more effective by enhancing penetration of drug through stratum corneum. The properties of film did not change during the period of study. The transdermal Nebivolol hydrochloride patches will be further investigated for in vivo studies in laboratory animals.

REFERENCES:

1. Kumar VS, Niranjan SK, Irchhaiya R, Kumar N, Ali A. A novel transdermal drug delivery system. Int Res J Pharm 3(8);2012:39-44.

2. Hadgraft J, Williams DG, Allan G. Mechanisms of action and clinical effect. In Pharmaceutical Skin Penetration Enhancement, Walters KA, Hadgraft J, Editors., Marcel Dekker: New York, NY, USA, 1993; pp. 175-197.

3. Charoo NA, Shamsher AAA, Kohli K, Pillai K, Rahman K. Improvement in bioavailability of transdermally applied flurbiprofen using tulsi (ocinum sanctum) and turpentine oil. Colloid. Surface. B 65;2008: 300-307.

4. Walker RB, Smith EW. The role of percutaneous penetration enhancers. Adv. Drug Deliver. Rev. 18;1996:295-301.

5. Lizelle TF, Minja G, Jeanetta DP, Josias HH. Transdermal Drug Delivery Enhancement by Compounds ofNatural Origin. Molecules 16;2011:10507-540.

6. Sinha VR, Kaur MP. Permeation Enhancers for Transdermal Drug Delivery. Drug Dev Ind Pharm 26(11);2000:1131–40.

7. Singh J, Tripathi KP, Sakya TR. Effect of penetration enhancers on the in vitro transport of ephedrine through rat skin and human epidermis from matrix based transdermal formulations. Drug Dev Ind Pharm 19;1993:1623.

8. Kai T, Nakazono M, Kurosaki Y, Nakayama T, Kimura T. Keratinized epithelial transport of beta-blocking agents, III : Evaluation of enhancing effect on percutaneous absorption using model lipid liposomes. Biol Pharm Bull 16;1993:801.

9. DMSO General Information, Available from: http://www.herbalremedies.com/dmso-information.html. [Last update on 21 Nov. 2012].

10. Singhla V, Saini S, Singh G, Rana AC, Joshi B. Penetration enhancers: A novel strategy for enhancing transdermal drug delivery. Int Res J Pharm 2(12);2011:32-36.

11. Kavitha K, More RM, Patel DM, Sandeep DS, Ganesh NS. Chemical permeation enhancers for transdermal drug delivery: A brief review Der Pharmacia Lettre 2(6);2010:358-65.

12. Anigbogu AN, Williams AC, Barry BW, Edwards HG. Fourier transform raman spectroscopy of interactions between the penetration enhancer dimethyl sulfoxide and human stratum corneum. Int J Pharm 125(2);1995:265-82.

13. Gupta JRD, Tripathi P, Irchhiaya R, Garud N, Dubey P, Patel JR. Formulation and evaluation of matrix type transdermal patches of Glibenclamide. Int J Pharm Sci Drug Res 1;2009:46-50.

14. Patel HJ, Patel JS, Patel KD. Transdermal Patch for Ketotifen Fumarate (KTF) as Asthmatic Drug. Int J Pharm Tech Res.1;2009:1297-1304.

15. Gannu R, Vamshi VY, Kishan V, Rao YM. Development of Nitrendipine Transdermal Patches: In vitro and Ex vivo Characterization. Curr Drug Deliv.4;2007:69-76.

16. Devi VK, Saisivam S, Maria GR, Deepti PU. Design and Evaluation of Matrix Diffusion Controlled Transdermal Patches of Verapamil Hydrochloride, Drug Dev Ind Pharm. 29(5);2003:495-503.

17. Nyqvist H, Saturated salt solutions for maintaining specified relative humidities. Int J Pharm. Tech and Prod. Mfr. 4;1983:47-48.

Received on 22.11.2012 Accepted on 02.01.2013

Asian J. Res. Pharm. Sci. 3(1): Jan.-Mar. 2013; Page 08-11