April Journal-2009.p65 - Association of Biotechnology and Pharmacy

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Current Trends in Biotechnology and Pharmacy Vol. 3 (2) 188-196, April 2009. ISSN 0973-8916 192 Fig. 2. In vitro release profiles of atomoxetine hydrochloride from TDDS using Franz diffusion cell. Fig. 4. Ex vivo permeation profiles of atomoxetine hydrochloride from TDDS using Franz diffusion cell. Fig. 3. In vitro release profiles of atomoxetine hydrochloride from TDDS using Franz diffusion cell. Results and Discussion The results of physicochemical characteristics are depicted in Table 2. The weights are ranged from 19.1 ± 2.67 to 24.9 ± 3.76 mg and 19.6 ± 3.78 to 23.1 ± 2.90 for formulation A and B series respectively. Thickness ranged from 125 ± 1 ì to 142 ± 3 ì (A series) and 122 ± 1 ì to 134 ± 3 ì (B series). The weights are found to be high with films prepared with higher proportions of HPMC as Fig. 5. Ex vivo permeation profiles of atomoxetine hydrochloride from TDDS using Franz diffusion cell. one of two polymers. As the proportion of HPMC was decreased, the thickness was also decreased. Good uniformity in drug content was observed and it ranged from 97.1 ± 0.19 mg to 99.4 ± 0.16 mg (A series) and 97.2 ± 0.11 mg to 99.2 ± 0.19 mg (B series). The results of flatness study showed that none of the formulations had the difference in the strip lengths before and after their cuts, thus In vitro and Ex vivo Evaluation
Current Trends in Biotechnology and Pharmacy Vol. 3 (2) 188-196, April 2009. ISSN 0973-8916 indicating 100% flatness. It shows that no amount of constriction in the patches and thus they could maintain a smooth surface when applied onto the skin. The folding endurance was found to be between 209 ± 5.34 to 249 ± 1.00 and it was found to be satisfactory. In vitro release studies The results of in vitro drug release studies from transdermal patches are depicted in Fig 2 and 3. The cumulative percent of drug release from formulations of A-series was 70.70, 91.60, 95.52 and 94.4 respectively from A-1, A-2, A-3 and A-4 and of B-series was 58.02, 63.24, 85.07 and 89.55 respectively from B-1, B-2, B-3 and B-4 (Table 3). The drug release from different formulations was increased in the following order: A-3>A-4>A-2>B-4>B-3>A-1>B-2>B-1. Variable release profiles of A-HCl from different experimental patches composed of various blends of ERL/HPMC and ERS/HPMC were observed. The process of drug release in most controlled release devices is governed by diffusion, and the polymer matrix has a strong influence on the diffusivity as the motion of a small molecule is restricted by the three-dimensional network of polymer chains (24). Release rates were increased when the concentration of HPMC increased in the formulations. This is because as the proportion of this polymer in the matrix increased, there was an increase in the amount of water uptake and hydration of the polymeric matrix and thus more drug was released (25). Formulation A4 showed less drug release compared to formulation A3, this is because the high proportion of HPMC swellable polymer further increases the tartuosity and diffusional path length, resulted in decreased drug release. However the difference was statistically insignifinacant (p>0.05). The data was fitted to different kinetic models to explain drug release mechanism. The 193 results suggested that the drug release followed Higuchi model as it was evidenced from correlation coefficients and indicating that the drug release was taking place by the process of diffusion. The correlation coefficients (0.87 to 0.97 in A4 and A1; 0.86 to 0.98 in B4 to B1) were greater than the correlation coefficients of zero order (0.67 to 0.65 in A4 and A1; 0.68 to 0.88 in B4 to B1) and first order kinetics (0.56 to 0.71 in A4 to A1, 0.57 to 0.72 in B4 to B1). As the concentration of HPMC increases in the formulations Ex vivo skin permeation studies The results of ex vivo permeation of A- HCl from patches are shown in Fig 4 and 5. The cumulative percent of drug permeation from formulations of A-series was 61.94, 75.55, 84.89 and 80.97 respectively from A-1, A-2, A-3 and A-4 and of B-series was 44.4, 45.7, 62.31 and 71.45 respectively from B-1, B-2, B-3 and B-4 (Table 3). The order of drug permeation from different formulations was increased in the following order: A-3>A-4>A-2>B-4>B-3>A- 1>B-2>B-1 Formulations A-3 (84.89 %) and B-4 (71.45 %) showed maximum drug permeation in their respective series with permeability coefficients of 3.43 X10 -2 cm h -1 and 3.02 X 10 -2 cm h -1 (Table 3). The skin permeation profiles of the test formulations were in conformity to the in vitro drug release pattern. The cumulative amount of drug permeated as well as the permeability coefficient (Kp) for TDDS were in the order of A-3>A-4>A-2>A-1 and B-4>B-3>B-2>B-1 for the A and B series, respectively. The results corroborated that higher the drug release from the formulation, higher was the rate and extent of drug permeation. Again the Kp for formulation A-3 was high than B-4 leading to conclusion that ERL 100 and HPMC combination is better than ERS 100 and HPMC as the polymeric precursor for the A-HCl transdermal formulation. As the concentration of hydrophilic polymer was Mamatha et al
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April Journal-2009.p65 - Association of Biotechnology and Pharmacy

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