Development and Evaluation of Transdermal Films of Oxybutynin

TS Vaseeha Banu^1* and Som Sukhen²

¹Department of Pharmaceutics, M.M.U College of Pharmacy, K. K. Doddi, Dist- Ramanagara- 571511, Karnataka (India)

²Department of Pharmaceutical Chemistry, M.M.U College of Pharmacy, K. K. Doddi, Dist. Ramanagara- 571511, Karnataka (India)

ABSTRACT:

Oxybutynin is an anticholinergic drug used to treat over active bladder (OAB) which is a chronic and distressing medical condition symptomatised by urinary urgency and frequency and an urge to urinate immediately with or without urinary incontinence. In our present investigation an attempt has been made to formulate transdermal films of Oxybutynin using Hydroxy Propyl Methyl Cellulose (HPMC) and Carbopol 934-P alone and in combination with different ratios along with Propylene Glycol (PG) which can serve as plasticizer cum permeation enhancer. The films were prepared by solvent casting technique. They are evaluated for physical appearance, drug content, thickness, tensile strength, percent elongation, folding endurance, water vapour transmission rate (WVTR) and in vitro drug release through rat abdominal skin using Franz diffusion cell. It was found that HPMC and Carbopol 934- P have good film forming properties. Between the two polymers used results showed that the formulation HC35 was very flexible with highest folding endurance. The drug release for all the formulations, it has been observed that transdermal films of Carbopol 934- P alone i.e. C3 and C2 and HPMC: Carbopol 934- P (1:3) i.e. HC30 and HC 29 shown more than 88% release, which have the best release pattern among all the formulations prepared. Further it was noticed that as the concentration of PG increases the release pattern also increases. In conclusion combination and HPMC and Carbopol 934- P with PG can potentially be optimized to develop and effective transdermal drug delivery system for Oxybutynin.

KEYWORDS: Permeation enhancer, solvent casting, over active bladder.

INTRODUCTION:

A transdermal drug delivery system (TDDS) is a formulation or device which maintains the blood concentration of the drug within the therapeutic window. It is a successful controlled release technology in terms of the number of approved products which are in the market¹ and are going worldwide accolade as evidence by so many scientific documents being published^2-7.

The feasibility of transdermal route for systemic drug delivery has led to the development of TDDS of several drugs it is expected that in near future many more drugs will be included in the list of successful TDDS.

The penetration through stratum corneum is the rate determining step for delivery of most of the drugs into systemic circulation and this led to the considerable activity towards different percutaneous enhancement technologies⁸. In order to permit and absorb sufficient amount of drug to show the therapeutic effect permeation should be enhanced. Many approaches such as use of chemical, physical enhancer have been applied for permeation enhancement of drugs.⁹

The most important advantage of TDDS include reduction of side effects due to optimization of blood concentration-time profile and extended duration of action, which allows greater patient compliance along with the elimination of multiple dosage schedules.

TDDS may also improve the therapeutic value of many drugs by obviating specific problems associated with the drug e.g. gastro intestinal irritation, low absorption, first passes effect and short half life¹⁰.

Overactive bladder (OAB) is a chronic clinical syndrome characterized by urgency, frequency with or without urinary incontinence affecting millions of people worldwide^{11, 12}. For many patients with OAB transdermal therapy is more convenient than oral therapy and the altered drug metabolism offers the advantages of an improved side effect profile and enhanced steady-state plasma concentration¹³. As demonstrated by several investigations in patients Oxybutynin decreases urinary frequency urgency and episode of urge incontinence, in addition to increase in bladder volume at first desire to void, enhancing maximum bladder capacity and reducing maximum detrusor pressure during filling^14-16.

In this study we have attempted to develop TDDS of Oxybutynin by using HPMC and Carbopol-934P alone and in combination in different ratios and concentrations along with hydrophilic plasticizer that is Propylene Glycol (PG) which can also act as permeation enhancer.

MATERIALS AND METHODS:

Oxybutynin was obtained as a gift sample from Jai Radhe sales, Gujarat; Hydroxy propyl methyl cellulose (HPMC) from NR chemicals, Mumbai; Carbopol 934P from Otto Kemie, Mumbai; Propylene glycol (PG) from Rankem, New Delhi and all others ingredients used were of analytical grade.

Table-1: Formulation compositions of transdermal films with HPMC and Carbopol 934P alone containing 3.9 mg of Oxybutynin.

Serial number	Formulation code	HPMC	Carbopol 934P	P G
1	H1	2%	-	20%
2	H2		-	30%
3	H3		-	40%
4	H4	3%	-	20%
5	H5		-	30%
6	H6		-	40%
7	H7	4%	-	20%
8	H8		-	30%
9	H9		-	40%
10	C1	-	2%	20%
11	C2	-		30%
12	C3	-		40%
13	C4	-	3%	20%
14	C5	-		30%
15	C6	-		40%
16	C7	-	4%	20%
17	C8	-		30%
18	C9	-		40%

Preparation of transdermal film:

The method employed for the preparation of the transdermal film is solvent casting technique¹⁷. Table 1 and 2 show compositions of transdermal films of Oxybutynin with HPMC and Carbopol 934P alone and in combination. Polymer was dissolved in the mixture of alcohol-water (1:1). Drug was separately dissolved in 50% alcohol. PG was added to the drug solution and thoroughly mixed by keeping on magnetic stirrer for 30 minutes. Then the drug solution containing PG was added to the polymer solution and the resulting solution was stirred for 30 minutes at room temperature. The prepared solution was casted in petridish and dried at room temperature by covering petridish with inverted funnel to avoid rapid evaporation of the solvent for 48 hours.

Fig 1: Comparative in vitro release study of the formulations H2 and C2

Evaluation of the film:

The evaluation of the film was performed for their physical appearance, weight variation, uniformity of thickness, folding endurance, tensile strength, drug content, water vapour transmission rate (WVTR) and in vitro release studies across the rat abdominal skin.

Fig 2: Comparative in vitro release study of the formulations HC2 and HC29

Fig 3: Comparative in vitro release study of the formulations HC11 and HC20

Table-2: Formulation composition of transdermal films with combination of HPMC and carbopol 934P (HC1 to HC36) containing 3.9 mg of oxybutynin

Formulation code	HPMC : Carbopo l934P (3 : 1)	HPMC : Carbopo l934P (2 : 1)	HPMC : Carbopo l934P (1: 2)	HPMC : Carbopo l934P (1 :3)	Propylene glycol
HC1	2%	-	-	-	20%
HC2		-	-	-	30%
HC3		-	-	-	40%
HC4	3%	-	-	-	20%
HC5		-	-	-	30%
HC6		-	-	-	40%
HC7	4%	-	-	-	20%
HC8		-	-	-	30%
HC9		-	-	-	40%
HC10	-	2%	-	-	20%
HC11	-		-	-	30%
HC12	-		-	-	40%
HC13	-	3%	-	-	20%
HC14	-		-	-	30%
HC15	-		-	-	40%
HC16	-	4%	-	-	20%
HC17	-		-	-	30%
HC18	-		-	-	40%
HC19	-	-	2%	-	20%
HC20	-	-		-	30%
HC21	-	-		-	40%
HC22	-	-	3%	-	20%
HC23	-	-		-	30%
HC24	-	-		-	40%
HC25	-	-	4%	-	20%
HC26	-	-		-	30%
HC27	-	-		-	40%
HC28	-	-	-	2%	20%
HC29	-	-	-		30%
HC30	-	-	-		40%
HC31	-	-	-	3%	20%
HC32	-	-	-		30%
HC33	-	-	-		40%
HC34	-	-	-	4%	20%
HC35	-	-	-		30%
HC36	-	-	-		40%

Weight variation:

A 2cm² uniformly cut film was weighed in digital balance and results are reported in table 3 and 4.

Thickness of the film:

The prepared films were evaluated for the film thickness at various points using screw gauge. The film was kept in between two glass slides of known thickness and the screw gauge was placed at three different positions, then the thickness was measured and the average was calculated. (Table 3 and 4)

Folding endurance:¹⁸

A strip of 2 cm² film was selected for this purpose. The folding endurance was measured manually by repeatedly folding the film at the same point till it breaks. (Table 3 and 4)

Tensile strength:^{19, 20}

The tensile strength of the prepared films was measured using the method by Allen et. al. A simple apparatus designed at laboratory was used to carry out the measurement. A strip of 2.5cm X 5 cm was selected and attached to a clip on one end of the flat wooden surface. The thread was attached carrying a pan at the other end. The points of attachments were kept 0.5 cm from both the sides, so as to get even force distribution and to avoid breaking of film abruptly. The other end of thread carrying the pan was allowed to slide over pulley opposite to fixed end. Weights were added in a pan in increasing order till the point of break up.

Tensile strength = (break force/ a x b) X (1 + ∆L/ L)

a = thickness of strip of film

b = width of the strip of the film

∆L = length at the breaking point

L = length of the film

Percentage elongation:

Percentage elongation was calculated by measuring the increase in length of the film after tensile strength measurement by using the following formula.

Percentage elongation = (L_F- L_O) X 100 / L_O. Where L_F = final length, L_O= initial length.

Water vapour transmission studies:^{18, 21}

For this study vials of equal diameter were used as transmission cells. These cells were washed and dried in an oven. About one gram of fused calcium chloride was taken in the cell and the polymeric patches were fixed over the brim with the help of an adhesive. Then the cells were weighed accurately and kept in a closed dessicator containing saturated solution of potassium chloride (200ml). The humidity inside the dessicator was measured by a Hygrometer and it was found to be 80-90% relative humidity. The cells were taken out and weighed after 2, 8, 12, 24, 48 and 72 h. From the increase in weights, the amount of water vapor transmitted and rate of water transmitted was calculated using the formula, Water Vapor Transmission Rate = W L /S. where W = Gm of water transmitted, L = Thickness of the patch and S = Exposed surface area of the patch.

Table – 3: Physico chemical data of transdermal films of HPMC and Carbopol 934P alone

Formulation code	Polymer concentration	Plasticizer concentration	Physical appearance	Thickness (mm) n=5	Weight (mg) n=5	Drug content (%) n= 5	Tensile Strength Gm/10^2 Cm n=5	Percent elongation n=5	Folding endurance n=5	WVTR g/cm^2/ 72hrs	Invitro release studies (%)
Films prepared only with HPMC
H1	2%	20%	uniform	0.018 ± 0.006	4.958 ± 0.28	96.78 ± 0.78	41.12 ± 0.23	16 ±0.082	159 ±10.8	0.15023	85.45
H2		30%	Uniform	0.017 ± 0.008	4.253 ± 0.26	98.02 ± 0.86	46.29 ± 0.27	16 ±0.078	172 ±13.8	0.16953	86.52
H3		40%	Uniform	0.017 ± 0.005	4.821 ± 0.53	97.45 ± 0.73	46.09 ± 0.78	17 ±0.062	175 ±12.3	0.16854	86.48
H4	3%	20%	Uniform	0.022 ± 0.008	5.223 ± 0.24	95.32 ± 0.72	40.62 ± 0.52	16 ±0.065	185 ±14.5	0.14632	83.34
H5		30%	Uniform	0.020 ± 0.004	5.213 ± 0.82	96.32 ± 0.82	45.73 ± 0.33	17 ±0.097	190 ±17.2	0.14863	84.62
H6		40%	Uniform	0.021 ± 0.002	5.119 ± 0.69	97.69 ± 0.61	47.28 ± 0.75	18 ±0.078	191 ±8.4	0.14742	84.02
H7	4%	20%	Uniform	0.028 ± 0.004	5.420 ± 0.72	96.23 ± 0.59	43.58 ± 0.76	14 ±0.065	200 ±10.5	0.14119	80.45
H8		30%	Uniform	0.025 ± 0.009	5.397 ± 0.49	97.32 ± 0.45	44.92 ± 0.92	16 ±0.064	205 ±12.5	0.14656	81.68
H9		40%	Uniform	0.026 ± 0.006	5.402 ± 0.52	97.52 ± 0.32	48.12 ± 0.35	16 ±0.054	195 ±9.7	0.14842	81.45
Films prepared only with Carbopol 934P
C1	2%	20%	Uniform	0.018 ± 0.008	4.823 ± 0.22	96.45 ± 0.52	43.26 ± 0.56	17± 0.074	172 ±11.2	0.15832	85.68
C2		30%	Uniform	0.016 ± 0.006	4.752 ± 0.56	98.83 ± 0.28	48.45 ± 0.53	19± 0.082	192± 14.8	0.18452	88.35
C3		40%	Uniform	0.016 ± 0.009	4.749 ± 0.68	98.19 ± 0.22	49.56 ± 0.37	19± 0.069	195± 16.3	0.18762	88.82
C4	3%	20%	Uniform	0.020 ± 0.004	4.951 ± 0.52	96.45 ± 0.72	46.32 ± 0.28	20± 0.052	202± 15.3	0.16324	85.24
C5		30%	Uniform	0.018 ± 0.007	4.792 ± 0.28	97.32 ± 0.45	47.57 ± 0.63	19± 0.041	218± 14.8	0.16783	86.19
C6		40%	Uniform	0.019 ± 0.002	4.801 ± 0.36	97.49 ± 0.56	47.42 ± 0.35	18± 0.071	212± 8.6	0.17021	86.21
C7	4%	20%	Uniform	0.023± 0.005	5.011 ±0.45	97.31 ± 0.23	46.59 ± 0.45	19± 0.095	227± 8.9	0.17112	82.84
C8		30%	Uniform	0.022 ± 0.006	4.832 ± 0.72	96.75 ± 0.69	46.82 ± 0.71	18± 0.056	226± 9.5	0.17531	84.45
C9		40%	Uniform	0.022 ± 0.004	4.833 ± 0.86	96.54 ± 0.28	46.91 ± 0.62	19± 0.023	232± 12.5	0.17542	85.72

Table – 4: Physico chemical data of transdermal films of HPMC and Carbopol 934P containing oxybutynin

Formulation code	Polymer concentration	Plasticizer concentration	Physical appearance	Thickness (mm) n=5	Weight (mg) n=5	Drug content (%) n= 5	Tensile Strength Gm/10^2 Cm n=5	Percent elongation n= 5	Folding endurance n= 5	WVTR g/cm^2/ 72hrs	Invitro release studies (%)
Films prepared with HPMC : Carbopol 934 P = 3 : 1
HC1	2%	20%	Uniform	0.016 ± 0.006	4.732 ± 0.058	96.53 ± 0.72	42.32 ± 0.49	15 ± 0.042	162 ±10.2	0.15862	85.45
HC2		30%	Uniform	0.014 ± 0.004	4.652 ± 0.042	98.45 ± 0.68	48.45 ± 0.52	16 ± 0.052	178 ±10.6	0.17028	86.35
HC3		40%	Uniform	0.013 ± 0.008	4.663 ± 0.048	97.32 ± 0.52	48.52 ± 0.75	16 ± 0.062	182 ±5.6	0.17035	86.48
HC4	3%	20%	Uniform	0.019 ± 0.006	5.021 ± 0.032	97.52 ± 0.34	41.58 ± 0.32	17 ± 0.085	190 ±8.2	15142	85.32
HC5		30%	Uniform	0.017 ± 0.005	4.821 ± 0.064	95.83 ± 0.54	47.32 ± 0.61	18 ± 0.074	194 ±6.5	0.15241	86.12
HC6		40%	Uniform	0.017 ± 0.003	4.762 ± 0.052	96.45 ± 0.23	48.54 ± 0.82	18 ± 0.023	197 ±12.3	0.15192	85.81
HC7	4%	20%	Uniform	0.025 ± 0.006	5.234 ± 0.035	97.42 ± 0.45	45.62 ± 0.52	14 ± 0.045	203 ±15.5	0.14523	84.32
HC8		30%	Uniform	0.023 ± 0.009	5.163 ± 0.021	97.32 ± 0.61	46.72 ± 0.56	15 ± 0.065	214 ±13.4	0.14831	85.68
HC9		40%	Uniform	0.022 ± 0.005	5.182 ± 0.018	96.85 ± 0.32	47.45 ± 0.48	15 ±0.071	208 ±12.6	0.15026	86.23
Films prepared with HPMC : Carbopol 934 P = 2 : 1
HC10	2%	20%	Uniform	0.015 ± 0.004	4.532 ± 0.017	98.32 ± 0.54	41.45 ± 0.53	17 ± 0.054	160 ±10.5	0.15561	86.54
HC11		30%	Uniform	0.013 ± 0.009	4.421 ± 0.018	96.52 ± 0.56	46.83 ± 0.25	19 ± 0.024	173 ±12.8	0.16532	87.71
HC12		40%	Uniform	0.012 ± 0.007	4.402 ± 0.024	96.32 ± 0.38	46.72 ± 0.56	19 ± 0.056	179 ±16.2	0.16962	87.58
HC13	3%	20%	Uniform	0.016 ± 0.003	4.852 ± 0.036	98.83 ± 0.21	40.52 ± 0.72	18 ± 0.087	187 ±15.2	0.15432	85.24
HC14		30%	Uniform	0.015 ± 0.006	4.612 ± 0.042	97.58 ± 0.14	45.34 ±0.84	19 ± 0.074	190 ±10.6	0.15564	85.92
HC15		40%	Uniform	0.015 ± 0.003	4.618 ± 0.058	98.32 ± 0.18	46.62 ±0.38	17 ± 0.024	194 ±5.8	0.15472	85.73
HC16	4%	20%	Uniform	0.022 ± 0.002	5.010 ± 0.034	96.72 ± 0.34	44.52 ± 0.25	18 ± 0.065	198 ±15.6	0.14862	84.32
HC17		30%	Uniform	0.020 ± 0.008	4.985 ± 0.069	98.12 ± 0.56	46.32 ± 0.16	19 ±0.024	202 ±14.3	0.14981	85.68
HC18		40%	Uniform	0.019 ± 0.007	4.893 ± 0.034	97.98 ± 0.62	46.82 ±0.32	19 ± 0.067	200 ±12.5	0.15164	85.32
Films prepared with HPMC : Carbopol 934 P = 1 : 2
HC19	2%	20%	Uniform	0.014 ± 0.003	4.542 ± 0.042	97.32 ± 0.32	41.62 ± 0.54	16 ± 0.052	168 ±10.6	0.15452	86.23
HC20		30%	Uniform	0.013 ± 0.007	4.425 ± 0.016	98.45 ± 0.34	46.34 ± 0.62	17 ± 0.047	180 ±9.8	0.16934	87.24
HC21		40%	Uniform	0.013 ± 0.005	4.421 ± 0.012	98.63 ± 0.28	47.48 ± 0.85	18 ± 0.050	186 ±8.6	0.16845	87.58
HC22	3%	20%	Uniform	0.015 ± 0.007	4.892 ± 0.034	97.45 ± 0.45	42.32 ± 0.82	18 ± 0.022	195 ±5.9	0.15954	86.45
HC23		30%	Uniform	0.015 ± 0.008	4.812 ± 0.028	97.32 ± 0.45	44.02 ± 0.92	19 ± 0.012	201 ±10.6	0.16232	86.58
HC24		40%	Uniform	0.014 ± 0.003	4.732 ± 0.015	96.83 ± 0.56	45.15 ±0.34	19 ± 0.045	205 ±9.8	0.16782	87.12
HC25	4%	20%	Uniform	0.020 ± 0.005	5.021 ± 0.063	97.12 ± 0.45	42.82 ± 0.22	18 ± 0.035	208 ±8.6	0.17091	86.32
HC26		30%	Uniform	0.019 ± 0.007	4.923 ± 0.024	99.01 ± 0.38	43.63 ± 0.12	17 ±0.036	220 ±10.2	0.17142	86.45
HC27		40%	Uniform	0.018 ± 0.006	4.981 ± 0.012	98.32 ± 0.75	43.92 ± 0.16	16 ± 0.058	212 ±12.5	0.17256	86.24
Films prepared with HPMC : Carbopol 934 P = 1 : 3
HC28	2%	20%	Uniform	0.014 ± 0.006	4.568 ± 0.018	97.71 ± 0.32	42.85 ± 0.54	16 ± 0.057	174 ±10.6	0.15563	87.32
HC29		30%	Uniform	0.014 ± 0.007	4.559 ± 0.024	96.28 ± 0.45	48.38 ± 0.66	18 ± 0.025	191 ±15.2	0.17024	88.24
HC30		40%	Uniform	0.013 ± 0.006	4.328 ± 0.058	96.78 ± 0.86	48.54 ± 0.32	18 ± 0.047	198 ±9.7	0.17545	88.28
HC31	3%	20%	Uniform	0.016 ± 0.004	4.923 ± 0.034	97.62 ± 0.32	44.12 ±0.16	19 ± 0.067	206 ±8.6	0.16322	86.45
HC32		30%	Uniform	0.015 ± 0.002	4.756 ± 0.018	96.86 ± 0.76	45.83 ± 0.45	18 ± 0.025	210 ±10.6	0.16541	86.81
HC33		40%	Uniform	0.014 ± 0.008	4.693 ± 0.014	97.32 ± 0.61	45.94 ±0.13	18 ± 0.052	212 ±8.9	0.17032	86.72
HC34	4%	20%	Uniform	0.021 ± 0.005	5.218 ± 0.013	98.45 ± 0.45	44.32 ±0.58	19 ± 0.037	219 ±12.6	0.17284	86.23
HC35		30%	Uniform	0.020 ± 0.003	4.982 ± 0.023	95.62 ± 0.38	44.58 ±0.19	17 ± 0.038	229 ±15.3	0.17345	87.12
HC36		40%	Uniform	0.018 ± 0.007	4.723 ± 0.054	96.82 ± 0.12	44.82 ± 0.57	18 ± 0.027	234 ±13.2	0.17536	87.35

Drug content:¹⁸

A film of size 2cm² was cut into small pieces and put in a 100ml buffer (pH 7.4). This was then shaken in a mechanical shaker for 2 hrs to get a homogenous solution and filtered. Then sample solutions from this was prepared by diluting to different concentrations and determined spectroscopically at 344 nm. The determinations were carried out in triplicates and the average of three readings were recorded and reported in table 3 and 4.

In vitro release studies across the rat skin:¹⁷

Permeation studies of the transdermal film were carried out using rat abdominal skin. The Franz diffusion cell assembly having 100 ml capacity in receptor chamber was used. The skin was washed with plenty of water and trimmed in to circular section of about 3 cm diameter. The patch was then placed over the skin facing the stratum corneum side and mounted with cap of the diffusion cell and clamped securely on to the receptor compartment with dermis side of the skin facing the receptor solution containing 100 ml pH 7.4 phosphate buffer solution. The area of the film exposed for release was 2 cm².

The receptor solution was constantly stirred over magnetic stirrer maintaining temperature at 37⁰ ± 1⁰C. At hourly Intervals, 1ml of the sample was withdrawn and replaced immediately with fresh media. Amount of drug in the withdrawn samples was determined spectrophotometrically at 344 nm and reported in table 3 and 4.

RESULTS AND DISCUSSION:

Transdermal film of Oxybutynin prepared by solvent casting technique was found to be satisfactory. Prepared films were thin, flexible, smooth and transparent. The physicochemical evaluation data for the films (Table 3 and 4) reveal that there were no physical changes like appearance, colour and flexibility when the films stored at room temperature. The thickness found to be least for the films prepared with 2% w/v polymer alone with 30% PG. When the polymers used in different ratios it was observed that the thickness of the film decreases with increase in plasticizer concentration. When it comes to the weights of the films there was no significant increase or decrease with respect to the concentration of polymer as well as PG involved. The calibration plot of Oxybutynin was prepared using various standard concentrations. Based on absorbance shown at 344 nm percent drug content for all the formulations (H1 to C9 and C1 to HC36) was calculated and it was found in the range of 95.32% to 99.01%. In case of folding endurance the formulations prepare only with Carbopol 934- P (C1 to C9) shown more values than any other formulation (except HC36), it may be because of more elasticity of Carbopol 934- P than HPMC. The WVTR was found to be least for formulation H 7 and highest for C3. But in a generalized manner it can be stated that the formulations containing only Carbopol 934- P as well as the higher concentration of the former showed more values than other, specially the formulations containing only HPMC. It may be because of the affinity of film towards water which is in the following order- Carbopol 934- P> HPMC (less hydrophilic).

The results of the in vitro release study from different transdermal patch across the rat skin are given in table 3 and 4. The release pattern was found to be more for formulations C3, C2, HC30 and HC29 and less for H8, H9 and H7. Moreover the drug release was found to be increased as the concentration of PG increased from 20% to 30% to 40%. So the role of PG here can be attributed to enhance the permeation of Oxybutynin from the patches.

CONCLUSION:

OAB is a chronic condition that often requires long term treatment to maintain control of symptoms associated with it. Oxybutynin holds good promise for administration via transdermal route for the treatment of OAB. The various physicochemical parameters that were evaluated helped to understand the suitability and usefulness of Oxybutynin to be formulated as a transdermal film with different concentration of polymers with an aim to depict the effect of permeation enhancer that is PG which has been well documented mainly as a plasticizer. From different physicochemical data it is evident in a generalized manner that irrespective of polymer concentration used, as the plasticizer concentration increases the drug release patter through rat abdominal skin also increases. There by it can be concluded that PG which is a well established plasticizer can also be used as a permeation enhancer. Between the two polymers used only 2% Carbopol 934- P with 40% PG shown the best value. Thus there may be an opportunity to modify the formulation composition and permeation enhancer ratio to get the optimum release over a prolonged period of time. Considering the study results polymer based patches containing chemical permeation enhancer that is PG can emerge out as an efficient drug delivery system for the treatment of OAB.

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Received on 11.08.2009

Accepted on 09.12.2009

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Research Journal of Pharmaceutical Dosage Forms and Technology. 2(2): March –April. 2010, 178-183