Preparation of Casting Solution:

The casting solutions were prepared by dissolving appropriate polymers, plasticizer and penetration enhancer in suitable solvents (i.e. methanol and ethanol) using a magnetic stirrer to get uniform dispersion. The drug was added slowly to the solution and dissolved by continuous stirring for 30 minutes.

Casting of Matrices:

Mercury was used as the substrate. Mercury was poured into the petridish. The mould was kept on the surface of mercury with smooth horizontal surface. About 10 ml of the 4% PVA solution was poured on the mercury surface (3.14 cm² area) and dried in oven at 60 for 6 hr. After drying the solution for drug reservoir was poured and dried in oven at 45 for 6 hr. after drying of this layer the solution for rate controlling membrane was poured. The rate of evaporation was controlled by inverting a funnel over the mould. The dried patches thus were cut into required size (2 cm diameter) by cork borer and wrapped in aluminum foil and stored over fused calcium chloride in a desiccator at room temperature for further use.

Evaluation parameters:

Investigation of physicochemical compatibility of drug and polymer Fourier transform-infrared spectroscopy²

The physicochemical compatibility between granisetron hydrochloride and polymers used in the films was stu-died by using Fourier transform-infrared spectroscopy (Perkin Elmer spectrum RX1 FT-IR). The pellatization was done by the KBr pellet method. The FT-IR spectra were recorded in the wavelength region between 4000 and 400 cm-1. The spectra obtained for KTF and physical mixtures of granisetron hydrochloride with polymers were compared.

Film Thickness^2:

The thickness of the formulated film was measured at 3 different points using a screw micrometer and average thickness of three reading was calculated.

Film Weight variation^2:

For each formulation, three randomly selected patches were used. For weight variation test, 3 films from each batch were weighed individually and the average weight was calculated.

Folding endurance²

The folding endurance was measured manually for the prepared films. A strip of film was cut 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/cracking gave the value of folding endurance calculated.

Drug Content²

The patches (1cm²) were cut and added to a beaker containing 100 mL of phosphate buffered saline of pH 7.4. The medium was stirred with magnetic bead. The contents were filtered using whatmann filter paper and the filtrate was examined for the drug content against the reference solution consisting of placebo films (contains no drug) at 302 nm spectrophotometrically

Surface pH³

Surface pH of the patch was determined by allowing them to swell in closed petridish at room temperature for 30 minutes in 0.1 ml of double distilled water. The swollen devices were removed and placed under digital pH meter to determine.

Swelling index²

Swelling index was determined by immersing the patch in a preweighed stainless steel basket in 20 ml of freshly boiled and cooled phosphate buffer ph 7.4 at 370 °C. The weight of the swelled patch was determined at specified time intervals (every 5 minutes). The procedure was continued till there was no increase in the weight. And the relative weight gain (water uptake) was calculated using the following relationship.

Swelling Index = (Wt -Wo/Wo) x 100

Where Wt = weight of patch at time t

Wo = weight of patch at time zero.

Tensile strength⁴

The patch was cut into required size. The apparatus consist of a base plate pullery aligned unit; one aluminum clip was fixed on one end of the base plate to which the insert was clipped. The other end of the patch was clipped to movable aluminum clip. A thread was tied to movable clip and passed over the pullery to which the small pan was attached to hold weights. The weights were gradually added to the pan till the patch was broken. The weight are necessary to break the patch was noted as break force.

Tensile load at break

Tensile strength = --------------------------------

Cross section area

Hardness²

Apparatus consist of a wooden stand of 11 cm height and top area of 16 × 16 cm. A small pan was fixed horizontally on one end of the 2 mm thick iron rod whose other end is reduce to sharp point. A hole of 0.2 cm diameter was made at the centre of the top area of wooden stand for supporting the pan rod. An electric circuit was made through battery in such a way that the bulb lights up only when circuit is completed through the contact of the metal plate and sharp end of the rod. The weights were gradually added to the pan at an interval of 10sec and for the stabilization of force till the bulb was glown. The final weight was considered as measure of hardness.

Percentage moisture content²

The prepared films are to be weighed individually and to be kept in a desiccator containing fused calcium chloride at room temperature for 24 hr. After 24 hr the films are to be reweighed and determine the percentage moisture content from the below mentioned formula:

Percentage moisture content = [initial weight- final weight/ final weight] × 100.

Percentage moisture uptake²

The weighed films are to be kept in desiccators at room temperature for 24 hr containing saturated solution of potassium chloride in order to maintain 84% RH. After 24 hr the films are to be reweighed and determine the percentage moisture uptake from the below mentioned formula:

Percentage moisture uptake = [final weight- initial weight/ initial weight] × 100.

In vitro drug release studies²

Skin permeation studies were performed by using a modified Franz diffusion cell with a receptor compartment capacity of 10 mL. The wistar rat abdominal skin was mounted between the donor and receptor compartment of the diffusion cell. The formulated patches were cut into size of 2 cm² and placed over the drug release membrane and the receptor compartment of the diffusion cell was filled with phosphate buffer pH 7.4. The whole assembly was fixed on a magnetic stirrer, and the solution in the receptor compartment was constantly and continuously stirred using magnetic beads at 50 rpm; the temperature was maintained at 37 ± 0.50°C. The samples were withdrawn at time intervals up to 12 hr, analyzed for drug content spectrophotometrically at 302 nm.

Accelerated stability study²

Stability studies are to be conducted according to the ICH guidelines by storing the TDDS samples at 40±0.5°c and 75±5% RH. The samples were withdrawn at 30days and analyze suitably for weight variation, hardness, thickness, folding endurance and drug content (ICH Q1A [R2] Stability testing new drugs substances and products).

RESULT

Table 2 Evaluation of transdermal patches

Formulation code	Evaluation of parameters
Formulation code	Film thickness (mm)	Weight variation(gm)	Folding endurance	Surface pH	Hardness (mg)
G1	0.103 ± 0.0306	0.0403 ± 0.0015	301 ± 3.00	7.20 ± 0.2	222.33 ± 2.0817
G2	0.187 ± 0.0153	0.052 ± 0.002	319.33 ± 4.1633	7.07 ± 0.5774	239.33 ± 2.0817
G3	0.243 ± 0.0153	0.0727 ± 0.0015	322.33 ± 1.5275	7.27 ± 0.5774	249.67 ± 1.5275
G4	0.360 ± 0.02	0.0673 ± 0.0021	318.67 ± 2.0817	7.10 ± 0.1	274.33 ± 3.7859
G5	0.353 ± 0.0153	0.067 ± 0.001	318.33 ±3 .2146	7.10 ± 0.1	274 ± 3.00
G6	0.307 ± 0.0153	0.0807 ± 0.0015	333.33 ± 4.1633	7.03 ± 0.5774	264 ± 2.00
G7	0.307 ± 0.0252	0.079 ± 0.0026	328.67 ± 4.0415	7.07 ± 0.5774	262.67 ± 0.5774

Table 3 Evaluation of transdermal patches

Formulation code	Evaluation parameters
Formulation code	Tensile strength (kg/mm²)	Swelling index (%)	Drug content (%)	Percentage moisture uptake (%)	Percentage moisture content (%)
G1	0.181 ± 0.0015	281.67 ± 0.5774	85.053 ± 0.0666	2.482 ± 0.0929	3.831 ± 1.1369
G2	0.183 ± 0.001	286 ± 2.6458	86.443 ± 0.1026	2.566 ± 1.1109	1.925 ± 0.0740
G3	0.186 ± 0.0015	297 ± 1.00	87.127 ± 0.1320	2.296 ± 0.8051	1.827 ± 0.7589
G4	0.184 ± 0.0006	309.67 ± 1.5275	86.653 ± 0.1026	1.976 ± 0.8369	2.929 ± 1.4839
G5	0.185 ± 0.0006	310.33 ± 3.0551	87.11 ± 0.03	1.998 ± 0.8938	2.495 ± 0.8874
G6	0.189 ± 0.001	303 ± 2.00	88.343 ± 0.0551	1.662 ± 0.7535	1.651 ± 0.7085
G7	0.188 ± 0.0015	302 ± 2.00	90.307 ± 0.6608	1.692 ± 0.7548	1.267 ± 0.0421

Table 4 In vitro permeation study

*In vitro* permeation study
Time (hr)	% Cumulative drug release (mean ± SD, n=3)
Time (hr)	G1	G2	G3	G4	G5	G6	G7
0	0	0.00	0.00	0.00	0.00	0.00	0.00
1	5.86±1.23	3.54±0.67	3.60±0.45	3.47±0.35	4.04±0.76	3.62±0.78	4.60±0.56
2	12.55±1,22	7.32±0.56	7.64±0.55	7.40±0.47	8.84±0.87	8.18±0.88	9.81±0.67
3	20.08±0.89	11.59±0.45	12.07±0.78	11.62±0.56	14.29±0.56	13.18±0.56	15.74±0.88
4	28.81±0.34	16.17±0.89	16.91±0.69	16.18±0.76	20.32±0.89	18.59±0.45	22.14±0.56
5	38.41±0.56	21.43±0.56	22.54±1.32	21.36±0.56	27.01±0.67	24.60±0.50	29.00±0.56
6	49.19±0.66	26.94±1.23	28.48±1.28	26.96±0.84	34.13±0.56	31.42±0.67	36.48±0.67
7	60.79±0.78	32.87±0.34	34.82±1.22	32.89±0.88	42.27±1.23	38.73±1.31	44.77±1.34
8	73.84±0.45	39.28±0.45	41.68±0.89	39.32±0.65	51.19±1.34	46.81±0.98	53.69±1.22
9	_91.97±0.98	46.35±0.45	48.79±0.67	46.20±0.78	60.42±1.32	55.65±1.23	62.85±0.98
10	-	53.65±0.89	56.14±0.77	53.71±0.76	70.21±0.67	65.04±0.67	72.49±0.67
11	-	61.18±0.95	63.63±0.88	62.07±0.88	80.31±0.76	74.97±0.88	82.57±0.77
12	-	69.06±0.67	71.54±0.56	76.29±1.23	90.69±0.78	85.43±0.67	92.88±1.22

Results are expressed as mean ± SD (n = 3).

DISCUSSION:

The thickness of patches varied from 0.103±0.0306 to 0.360±0.02 mm (see Table 2). Because of casting of the rate-controlling membrane the thickness of patches was increased. A low standard deviation value in the patch thickness measurement confirms uniformity of the patches prepared by solvent evaporation technique. The weight variation of patches varied from 0.0403±0.0015 to 0.0807±0.0015 gm (see Table 2). Because of casting of the rate-controlling membrane the weight of patches was increased. Folding endurance measures the ability of patch to withstand rupture. Folding endurance of the patches varied from 301±3.00 to 333.33±4.1633 (see Table 2). Patch G1 representing the least value. The surface pH of patches varied from 7.03±0.5774 to 7.27±0.5774 (see Table 2). Neutral pH is required for transdermal formulation. So patch G6 and G7 can be considered as desired formulations with respect to surface pH. Hardness of the patches varied from 222.33±2.0817 to 274.33±3.7859 (see Table 2). The swelling index of patches varied from 281.67±0.5774 to 310.33 ±3.0551. Drug content was also found to be uniform among the all formulations and ranged from 85.053±0.0666 to 90.307±0.6608 (see Table 3). The tensile strength measures the ability of a patch to withstand rupture. The tensile strength of patches varied from 0.181±0.0015 to 0.189±0.001 (see Table 3). So patch G6 and G7 can be considered as desired formulations with respect to tensile strength. The percentage moisture content of patches varied from 1.267±0.0421 to 3.831 ±1.1369 (see Table 3). But little moisture content is desirable so as the patches would not become dry and brittle. So patch G7 and G6 can be considered as desired formulations with respect to moisture content. The percentage moisture uptake of patches varied from 1.662±0.7535 to 2.566±1.1109 (see Table 3). High moisture uptake leads to microbial contamination. So patch G6 and G7 can be considered as desired formulations with respect to moisture uptake. The drug release of patches (see Table 4) varied from 69.06% (1.28 mg) to 93.23% (1.73 mg). Drug permeation profiles from different formulations are shown in Figure 5.11. It was found that 93.23% of drug was released within 7 hr from G1 (without the rate-controlling membrane) and followed first-order kinetics.

This means the patch is to be applied several times a day. Therefore rate controlling membranes of Eudragit RL100 and Eudragit RS100 with PVP were cast with the aim to achieve controlled release of granisetron hydrochloride from drug reservoirs of HPMC E5. The cumulative amount of drug permeated after 12 hr from G2 (ERS as the rate controlling membrane) and G3 (ERL as the rate controlling membrane) was found to be 66.06 and 71.54%, respectively. Two surfactants differing in their hydrophile lipophile balance (HLB) number were therefore, considered. The non-ionic surfactants Tween 80 (HLB = 15.0) and Span 80 (HLB = 4.3) were incorporated in the patches to enhance the drug permeation. In vitro permeation studies of patches with enhancers indicate that 76.29, 90.69, 85.43 and 92.88% of the drug permeated at the end of 12 hr from G4, G5 (ERS as the rate-controlling membrane), G6 and G7 (ERL as the rate controlling membrane), respectively. There was improvement in the drug permeability through wistar rat abdominal skin.

CONCLUSION:

Granisetron hydrochloride was used in transdermal patch to prevent chemotherapy induced nausea and vomiting. Transdermal rout was used to avoid the inconvenient of Parenteral and oral rout.

From the preliminary study HPMC E5 (4% m/v) and PEG 400 (30% m/m) used as plasticizer for preparation of dug reservoir and PVA (4% m/v) used for backing membrane. Based on the literature review Eudragit RL 100 and Eudragit RS 100 (2% m/v) used for rate controlling membrane and Tween 80 and Span 80 (1% m/v) used as permeation enhancer.

From the evaluation of the trial and error batches it was found that G7 and G6 show good result in all physicochemical parameters. The effects of non-ionic surfactants Tween 80 and Span 80 on drug permeation were studied. In vitro permeation study of the batches indicated that G7 and G6 shows 92.88% and 85.43% drug release by using the permeation enhancer span 80 and tween 80 respectively. G4 and G5 shows 76.29% and 90.69% drug release by using the permeation enhancer tween 80 and span 80 respectively. The non- -ionic surfactants in the patches increased the permeation rate, Span 80 exhibiting better enhancement relative to Tween 80.

Transdermal patches consisting of the HPMC-drug reservoir with Span 80 as permeation enhancer and rate-controlling membranes of Eudragit RS100 and Eudragit RL100 demonstrated sustained and controlled release of the drug during in vitro permeation studies.

REFERENCES:

1. http://Dailymed.Nlm.Nih.Gov/Dailymed/Druginfo.Cfm?Id=16331.

2. Ashok K.J, Nikhila P, Lakshmana P.S and Gopal V, “Transdermal drug delivery system: an overview”, International Journal Of Pharmaceutical Sciences Review And Research , 2010, 3, pp.51-53

3. Mass G.P, Dearden J.C, Patel H and Cronin M.T.D, “Quantitative structure permeability relationships for percutaneous absorption, toxicology invitro”, International Journal Of Pharmaceutics, 2002, 16, pp.299-317

4. Gawkrodger DJ. Dermatology, An Illustrated Colour Text; 3^rdEdn; Churchill Livingstone, Edinburgh, 2002, pp 10-14.

Received on 24.05.2012 Modified on 19.06.2012

Research J. Pharm. and Tech. 5(7): July 2012; Page 973-977

Formulation	Backing layer (4%, m/V)	Drug reservoir (3%, m/V)	Rate-controlling membrane (2%, m/V)	Permeation enhancer (1%, m/V)
G1	PVA	HPMC E5	-	-
G2	PVA	HPMC E5	ERS	-
G3	PVA	HPMC E5	ERL	-
G4	PVA	HPMC E5	ERS	Tween 80
G5	PVA	HPMC E5	ERS	Span 80
G6	PVA	HPMC E5	ERL	Tween 80
G7	PVA	HPMC E5	ERL	Span 80