Formulation and Evaluation of Transdermal Patches of Nebivolol Hydrochloride

Vijay Singh Jatav¹*, Jitendra Singh Saggu², Ashish Kumar Sharma¹, Anil Sharma¹, Rakesh Kumar Jat¹

¹Gyan Vihar School of Pharmacy, SGVU, Jaipur, India

Lordshiva College of Pharmacy, Sirsa, Haryana, India

ABSTRACT:

Aim:- The present study is to formulate the matrix type transdermal patches of Nebivolol hydrochloride as a model drug with combination of HPMC K100M and ERS-100 to minimize the dose of the drug for lesser side effect.

Method:-Matrix type transdermal patches containing Nebivolol hydrochloride were prepared using two polymers by solvent evaporation technique. Aluminium foil cup method was used as a substrate. Polyethylene glycol (PEG) 400 was used as plasticizer and Dimethyl sulfoxide was used as penetration enhancer.

Major Results:-The physicochemical parameters like weight variation, thickness, folding endurance, drug content, Percentage moisture absorption and Percentage moisture loss were evaluated. All prepared formulations indicated good physical stability and no skin irritation. In-vitro drug release and drug permeation studies of formulations were performed by using Franz diffusion cells. Formulation prepared with hydrophilic polymer containing permeation enhancer showed best in-vitro skin permeation through rat skin (Wistar albino rat) as compared to all other formulations.

Conclusions:- On the basis of in vitro drug release through skin permeation performance, Formulation F1 was found to be better than other formulations and it was selected as the optimized formulation.

KEYWORDS: Nebivolol Hydrochloride, Transdermal patch, polymers, Solvent evaporation technique, Skin permeation

INTRODUCTION:

Most recently, there is an increasing recognition that the skin can also serve as the port of administration for systemically active drugs. In this case, the drug applied topically will be absorbed first into blood circulation and then be transported to target tissues, which could be rather remote from the site of drug application, to achieve its therapeutic purpose⁽¹⁾. Recently, it is becoming evident that the benefits of I.V. drug infusion can be closely duplicated, without its hazards, by using the skin as the port of drug administration to provide continuous transdermal drug infusion into the systemic circulation. One of the approaches of transdermal therapeutic systems is the maintenance of the blood concentration of drug at therapeutic level by means of controlled permeation throughout the skin (therefore avoiding the first-pass effect) during a long period of time and using only one administration ⁽²⁾.

The advantages of delivering drug across the skin for systemic therapy are well documented. some of the main advantages of transdermal drug delivery system are to deliver steady infusion of drug over an extended period of time, to increase the therapeutic value of many drugs by avoiding specific problems associated with the drug e.g. GI irritation, low absorption, decomposition due to hepatic “first pass” effect, formation of metabolites, that cause side effects, short half life necessitating frequent dosing etc. application and removal of transdermal patch produce the optimal sequence of pharmacological effect⁽³⁾. The statical data showed a market of $ 12.7 billion in the year 2005 which is assumed to increase by $ 21.5 billion in the year 2010 and $ 31.5 billion in the year 2015. Almost all the pharmaceutical companies are developing transdermal drug delivery systems⁽⁴⁾.

Nebivolol is a third generation beta-blocker, highly selective for the β₁-adrenoceptors (AR) and endowed with the ability to release nitric oxide from the cardiovascular endothelium⁽⁵⁾. In animal models nebivolol has been shown to induce endothelium-dependent arterial relaxation in a dose dependent manner, by stimulation of the release of endothelial nitric oxide⁽⁶⁾. Nevibolol hydrochloride (M.W. 441.9 g:mol) showed the favourable logarithmic value of partition coefficient (Log P (octanol/water): 3.23; 4.03 (pH 11.8, 23°C). and negligible skin degradation. The plasma half life is about 8-10 hours which make frequently dosing necessary to maintain the therapeutic blood levels of drug for a long term treatment⁽⁷⁾.

MATERIAL AND METHODS:

Materials:

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

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- 8300, Shimadzu Co., Kyoto, Japan) 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 and 400 cm^–1. The spectra obtained for Nebivolol hydrochloride, polymers, and physical mixtures of Nebivolol hydrochloride with polymers were compared.

Preparation of transdermal films:

In the present study, drug loaded matrix type transdermal films of Nebivolol hydrochloride were prepared by solvent evaporation method ^{(8, 9, 10, 11)} 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. 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 petridish. The mould was kept on a horizontal surface. The solution was poured on the foil into a petridish 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.

1. Physical appearance:

All the prepared patches were visually inspected for color, clarity, opaque, transperancy, flexibility and smoothness.

2. Thickness of the films:

Patch thickness was measured using screw gauge at three different places and the mean value was calculated ⁽¹²⁾.

3. Weight uniformity:

The films of different batches were dried at 60^oC for 4 hours before testing. Five patches from each batch were accurately weighed in a digital balance. The average weight and the standard deviation values were calculated from the individual weights⁽¹³⁾.

4. Folding endurance:

A strip of film (2× 2 cm) was cut evenly and repeatedly folded at the same place till it broke. The number of times the film could be folded at the same place without breaking gave the value of the folding endurance ^(14,
15).

5. Drug content:

Transdermal system of specified area (2.64 cm²) was cut into small pieces and taken into a 50 ml volumetric flask and 25 mL of phosphate buffer pH 7.4 was added, gently heated to 45^oC for 15 minutes, and kept for 24 hours with occasional shaking. Then, the volume was made up to 50 ml with phosphate buffer of pH 7.4. Similarly, a blank was carried out using a drug-free patch. The solutions were filtered and the absorbance was measured at 282 nm ⁽¹⁶⁾.

6. Percentage moisture absorption:

The films were weighed accurately and placed in the desiccators containing 100 mL of saturated solution of potassium chloride, which maintains 80-90% RH⁽^{11, 17}⁾. After 3 days, the films were taken out and weighed. The study was performed at room temperature.

The percentage moisture absorption was calculated using the formula:

% Moisture absorption = (Final weight – Initial weight/ Initial weight) X100

7. Percentage moisture loss:

The films were weighed accurately and kept in a desiccators containing anhydrous calcium chloride ⁽¹⁸⁾. After 3 days, the films were taken out and weighed. The moisture loss was calculated using the formula:

% Moisture loss = (Final weight – Initial weight/ Initial weight) X 100

8. Tensile strength

Tensile strength of the film was determined with Universal strength testing machine (Hounsfield, Slinfold, Horsham, U.K.). The sensitivity of the machine was 1 g. It consisted of two load cell grips. The lower one was fixed and upper one was movable. The test film of size (4 × 1 cm²) was fixed between these cell grips and force was gradually applied till the film broke ⁽¹⁹⁾. The tensile strength of the film was taken directly from the dial reading in kg. Tensile strength is expressed as follows:

Tensile strength = (Tensile load at break / Cross section area)

9. 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⁽¹²⁾. 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 12ml of normal saline. 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.

Table No. 2 Physiochemical evaluation of transdermal patches

Formulation code	F1	F2	F3	F4
Appearance	Thin, transparent and flexible	Thin, transparent and flexible	Thin, opaque and flexible	Thick, not flexible and opaque.
Thickness	0.263±0.67	0.289±0.55	0.301±0.61	0.219±0.75
Weight (mg)	51.01±0.80	52.15±0.68	50.5±0.75	52.02±2.15
Drug content (mg /2. 64 cm²)	3.75±1.08	3.87±0.98	3.61±0.13	3.67±0.28
% Moisture Absorbance	8.728±0.085	7.757±0.099	7.632±0.132	6.939±0.049
% Moisture Loss	3.771±0.055	3.851±0.061	3.376±0.752	2.837±0.152
Folding endurance	>100	>100	>100	>100
Tensile strength kg/cm²	0.95±0.12	0.65±0.18	0.74±0.35	0.53±0.67

Table 3 In vitro drug permeation profile of Nebivolol hydrochloride transdermal patches

Formulation code	Zero order (R²)	First order (R²)	Higuchi (R²)	Korsmeyer-peppas (R²)
F1	0.9094	0.9956	0.9963	0.9948
F2	0.8929	0.9918	0.9878	0.9623
F3	0.8919	0.9749	0.9934	0.9790
F4	0.8655	0.9403	0.9831	0.9870

10. Skin irritation test:

The optimized transdermal formulation was evaluated for skin irritation studies on 12 rats (grouped in 2 and each group having 6 rats). The hairs of the dorsal portion were removed physically with the help of sharp surgical scissors and the skin was washed properly one day prior to use. Group one was supplied with control formulation and group second were supplied with medicated formulation.

Medicated formulation was secured on experimental side using an adhesive tape and non-medicated patch was adhered on the control side of rats. These were covered with occlusive covering to approximate the condition of use. The patches were removed after 7days and each of the area was observed for any sign of erythema or edema⁽^20,²¹⁾. All the experimental protocols involving laboratory animals were approved by the Institutional Animal Ethics Committee (Protocol No: Nebivolol hydrochloride /01/SGVU/2011) ⁽²²⁾.

11. Stability Studies:

Optimized medicated films were subjected to short term stability testing. Films were placed in a glass beaker lined with aluminium foil and kept in a humidity chamber maintained at 40 ± 2 ⁰C and 75 ± 5% RH for 6 month as per ICH guidelines ⁽²³⁾ Changes in the appearance and drug content of the stored films were investigated after storage at the end of every week. The data presented were the mean of three determinations.

RESULTS AND DISCUSSION:

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 (Table no.2) and in vitro drug permeation through albino rat skin (Table no. 3). The physical appearance of the various formulations in terms of their transparency, smoothness, flexibility, stickiness, homogenicity and opaque properties were recorded. The formulation F-1 was found to be thin, transparent and flexible, formulation F-2 was found to be thin, transparent and flexible, formulation 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 0.219 ± 0.75 mm to 0.301 ± 0.61 mm.

Transdermal drug delivery system is a most suitable system for a long term treatment or for a multi dose treatment because transdermal patches are prepared for a long period of time in a single dose providing treatment from a day to even up to seven days. TDDS also increases the bioavailability of drug by avoiding the first pass metabolism and increases the therapeutic efficacy of drug by reaching into the systemic circulation. Polymers HPMC K100M and ERS-100 were selected on the basis of their adhering property and non toxicity. The result of the finding showed excellent adhering property and controlled release. Result from present study concluded that Nebivolol hydrochloride in combination with HPMC K100M, ERS-100 and with incorporation of PEG 400 (30%) and DMSO (20%) produced smooth, flexible and transparent film. FT-IR studies showed characteristic peaks of Nebivolol hydrochloride, confirming the purity of the drug. FT-IR spectral studies indicated there was no interaction between Nebivolol hydrochloride and polymers used (Fig. no. 1).

Fig. 1- FT-IR spectral studies between Nebivolol hydrochloride and polymers used

Nebivolol hydrochloride patches were prepared with combination of these polymers and evaluated it for physical parameters such as thickness, drug content, weight variation, % moisture loss and % moisture absorption. From the results, it was observed that thickness, drug content, weight variation, low moisture loss, low moisture absorption, tensile strength were suitable for maximum stability of the prepared formulations. The drug content of TDDS patches ranged from 3.61±0.13-3.87±0.98 mg. The drug release rate increased when the concentration of hydrophilic polymer was increased. The cumulative percentage drug release for F1 was found to be 91.21 ± 2.14 % at 48 h and for F4 it was found 68.16 ± 5.57 % at 24 h. The formulation, F1 [HPMC K100M, ERS-100 (8:2)] is considered as a best formulation, since it shows maximum in vitro drug release as 91.21 ± 2.14 % at 48 h shown in figure no. 2.

Fig. 2 Comparative drug permeation profile

The drug release kinetics studies showed that the majority of formulations were governed by Higuchi model and mechanism of release was non-Fickian mediated. Higuchi developed an equation for the release of a drug from a homogeneous-polymer matrix-type delivery system that indicates the amount of drug releases is proportional to the square root of time ⁽²⁴⁾. If the release of drug from the transdermal film, when plotted against square root of time, shows a straight line, it indicates that the release pattern is obeying Higuchi’s kinetics. In our experiments, in vitro release profiles of all the different formulations of transdermal patches could be best expressed by Higuchi’s equation, for release of drug from a homogeneous-polymer matrix–type delivery system that depends mostly on diffusion characteristics.

From the in vitro permeation profile data of all the formulations through rat skin, kinetics of drug release were found for zero-order, first-order, Higuchi-type release kinetics and Korsmeyer-Peppas-type release kinetics. The coefficient of correlation (R²) of each of these release kinetics were calculated and compared (Table no.3). The data revealed that the release pattern of selected formulations was best fitted for Higuchi kinetics, as the formulation coefficient values predominate over zero-order, first-order and Korsmeyer-Peppas-type release kinetics, which again confirmed with Higuchi’s equation for the drug release from matrix. Thus, a slow and controlled release as observed is indicating that the drug release mechanism is non- Fickian model, as proposed by Higuchi.

The regression analysis of the in vitro permeation curves were carried out for in vitro permeation studies in rat skin. Among all these formulations, the formulation F-1 showed the maximum % drug cumulative release i.e. 91.21 % up to 48 hours of the study. All the formulations showed Higuchi-type release kinetics, which was diffusion mediated. Regression analyses of the in vitro permeation curves were carried out. The slope of the straight line obtained after plotting the mean cumulative amount released per Cm. Square patch vs. square root of time was taken as the experimental flux for Nebivolol hydrochloride.

No erythema was observed from a primary skin irritation test carried out on rat after the application of transdermal films. The absence of erythema indicated that these polymeric patches of Nebivolol hydrochloride were compatible with skin and hence can be used for the transdermal application shown in figure 3.

Fig. 3 Test Groups after 7 days

Films that were placed in humidity chamber for short time stability studies were withdrawn every week and analysed for their drug content. Percentage drug present in the patches were determined spectrophotometrically. These properties did not change in films during the period of study. Transdermal films containing Nebivolol hydrochloride using HPMC K100M and Eudragit RS100 polymers showed satisfactory characteristics without being drastically influenced by ageing.

CONCLUSION:

In conclusion, controlled release TDDS patches of Nebivolol hydrochloride can be prepared using the polymer combinations, HPMC K100M, ERS-100 (8:2) with PEG 400 and DMSO as plasticizer and enhancer, respectively. The release rate of drug through patches increased when the concentration of hydrophilic polymer was increased. Whereas, the mechanism of drug release of all formulations were non-Fickian. No erythema was observed from a primary skin irritation test and The properties of film did not change during the period of study. Further, in vivo studies have to be performed to correlate with in vitro release data for the development of suitable controlled release patches for Nebivolol hydrochloride.

ACKNOWLEDGEMENT:

Authors are grateful to Zydus Cadila Health Care Limited, Gujarat, for providing gift samples of Nebivolol Hydrochloride and Gyan Vihar School of Pharmacy and research institute, Jaipur for providing necessary lab facilities.

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Received on 22.08.2012

Modified on 01.09.2012

Accepted on 09.09.2012

Research Journal of Pharmaceutical Dosage Forms and Technology. 4(5): September –October, 2012, 272-277

Formulation code	Drug (mg)	Polymers ratio ERS100:HPMC K100M	DMSO	PEG 400	Solvents ratio (Methanol :Chloroform)
F1	100	2:8	20%	30%	3:2
F2	100	4:6	20%	30%	3:2
F3	100	6:4	20%	30%	3:2
F4	100	8:2	20%	30%	3:2