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Contents lists available at ScienceDirect

European Journal of Pharmaceutical Sciences journal homepage: www.elsevier.com/locate/ejps 5 6 3 4 7 8 9 10 11 12 13 1 2 5 8 16 17 18 19 20 21 22 23 24 25 26 27

Permeability test for transdermal and local therapeutic patches using Skin PAMPA method } Tóth a, Réka Balogh a, Mária Budai-Szu } cs b, Erzsébet Csányi b, Gábor Vizserálek a, Szilvia Berkó b, Gergo Bálint Sinkó a,c, Krisztina Takács-Novák a,⇑ a

}gyes Endre Street, H-1092 Budapest, Hungary Department of Pharmaceutical Chemistry, Semmelweis University, 9 Ho Department of Pharmaceutical Technology, University of Szeged, 6 Eötvös Street, H-6720 Szeged, Hungary c SinkoLAB Scientific, 23 Bécsi Street, H-9400 Sopron, Hungary b

a r t i c l e

i n f o

Article history: Received 16 March 2015 Received in revised form 23 April 2015 Accepted 6 May 2015 Available online xxxx Keywords: Permeability Skin PAMPA Transdermal drug delivery Transdermal patch Artificial membrane permeability assay

a b s t r a c t Using the skin as absorption site presents unique advantages that have facilitated the progression of transdermal drug delivery in the past decades. Efforts in drug research have been devoted to find a quick and reproducible model for predicting the skin permeation of molecules. The Parallel Artificial Membrane Permeability Assay (PAMPA) has been extended for prediction of transdermal permeation by developing the ‘‘skin-mimetic’’ artificial membrane. The present study aims to extend the Skin PAMPA method for testing transdermal and local therapeutic patches. The original method was modified and seven commercially available transdermal and local therapeutic patches with four different active pharmaceutical ingredients (nicotine, fentanyl, rivastigmine and ketoprofen) were studied. Data were compared to the declared delivery rates that are indicated by the manufacturers. Ex vivo permeation study was also performed in order to compare the permeated amount of the released drugs obtained by the two methods. The flux across the artificial membrane as well as the human skin (ex vivo) has been calculated and compared to the in vivo flux deduced from the labelled delivery rate and the active area of the patches. The results suggest that Skin PAMPA system can serve as a useful tool for evaluation and classification of the transdermal patches. Ó 2015 Published by Elsevier B.V.

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1. Introduction

48

History of transdermal drug delivery (TDD) has been facing back to the early 50s (Hadgraft and Lane, 2005). In the early days, this method of drug administration was limited to few compounds formulated in ointments, gels, creams and medicinal plasters. The first pharmaceutical transdermal patch developed by Alza Corporation indicated the benefits and applicability of this administration method for further development in this field (Thomas and Finnin, 2004). Beside the transdermal patches that provide a systemic effect of the selected drugs, numerous local therapeutic patches are also available. The TDD is a very convenient and advantageous alternative for drug administration. Recently published reviews summarized the benefits of TDD, as: the drug levels can be maintained within the therapeutic window during the whole period of the administration; the pre-systemic first-pass effect can be avoided which can result in higher bioavailability and fewer adverse effects than in the case of oral administration; the drug

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⇑ Corresponding author.

administration can be stopped instantly in situations where drug input is no longer desirable; it allows a reduced frequency of dosing which is particularly favorable for compounds with short biological half-life (Guy, 2009; Prausnitz and Langer, 2008; Wiedersberg and Guy, 2014). However, TDD is affected by limitations as well that are due to the primary function of human skin. The outermost layer, the stratum corneum is a strong, protective barrier for a broad range of xenobiotics, therefore TDD is suitable only for very potent active pharmaceutical ingredients (API) that are able to overcome this complex structure (Thomas and Finnin, 2004; Wiedersberg and Guy, 2014; Hadgraft, 2004). To support the development of TDD, evaluation of skin permeation rates has become crucial both in pharmaceutical and cosmetic research. Numerous methods have been described previously in the literature to predict and estimate the permeation through human skin (Zendzian, 2000; Salerno et al., 2010; Franz, 1975; Khan et al., 2005; Frum et al., 2007; Lee et al., 2010; Potts and Guy, 1992). These models are generally labor intense, suffered from poor reproducibility and cause huge intra- and inter-laboratory variation in permeability results (Howes et al., 1996).

E-mail address: [email protected] (K. Takács-Novák). http://dx.doi.org/10.1016/j.ejps.2015.05.004 0928-0987/Ó 2015 Published by Elsevier B.V.

Please cite this article in press as: Vizserálek, G., et al. Permeability test for transdermal and local therapeutic patches using Skin PAMPA method. Eur. J. Pharm. Sci. (2015), http://dx.doi.org/10.1016/j.ejps.2015.05.004

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The Parallel Artificial Membrane Permeability Assay (PAMPA) which has been first described by Kansy et al. (1998) has provided a suitable platform to develop a fast, cost-efficient and high throughput technology called Skin PAMPA (Sinko et al., 2012). This is an in vitro, 96-well plate based method containing a completely artificial membrane which can mimic the barrier properties of stratum corneum. Skin PAMPA membrane has been created using ceramide-analog compound that mimics the features of ceramides in the lipid matrix, cholesterol and free fatty acids. Its high prediction capability has been demonstrated; therefore it appears to be a useful tool for preliminary absorption prediction. Recent studies have investigated the skin permeability of API’s in solute phase and in different semi-solid formulations (gel, ointment and cream) (Sinko et al., 2012; Vizserálek et al., 2013; Sinkó et al., 2014); however it would be very essential for pharmaceutical and cosmetic industries to further extend the application potential of the Skin PAMPA method to study the permeability of the compounds from patches. The aim of our current work is to extend the original Skin PAMPA method to test transdermal and local therapeutic patches. We have investigated seven marketed products containing nicotine, fentanyl, ketoprofen and rivastigmine. The data obtained by PAMPA method and Franz diffusion cell measurement have been compared. Our study aims to examine whether the Skin PAMPA can classify the behavior of the transdermal patches and can provide enough information about the permeation of the released drugs. This would be very valuable for further development of transdermal products.

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2. Materials and methods

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2.1. Materials

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Table 1 indicates the list of the selected transdermal and local patches. The Skin PAMPA sandwiches (P/N: 120657), the hydration solution (P/N: 120706) and the stirring bars (P/N: 110211) were purchased from Pion, INC. The UV plates were from Greiner Bio-one (UV-star micro plate, clear, flat bottom, half area). The manufacturer-calibrated pipettes (EDP-3 and pipet lite series) were purchased from Mettler-Toledo. Standard Britton-Robinson (BR) buffers were made in-house, and 0.2 M sodium-hydroxide was used to adjust the pH 7.4 to serve the acceptor solution for PAMPA measurements. Phosphate buffer solution (PBS; pH = 7.4) for ex vivo permeation study was also made in-house. The pH values were measured using Meterlab PHM 220 pH meter (Radiometer AnalyticalÒ). Nicotine solution, fentanyl citrate, rivastigmine hydrogen tartrate and ketoprofen as model compounds for calibration of the quantitative analysis were purchased from Sigma–Aldrich. The deionized water was prepared with a Milli-Q Direct 8 Millipore system. Methanol (gradient grade for liquid chromatography) (106007) was purchased from Merck Millipore.

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2.2. PAMPA method

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The traditional PAMPA method was modified for transdermal patch testing. The schematic view of the method is demonstrated in Fig. 1. The Skin PAMPA sandwiches were used after an overnight hydration (Hydration Solution, Pion, INC, P/N: 120706). The bottom part (the original donor compartment) of the Skin PAMPA sandwich has been replaced with a deep well reservoir to provide enough space for patches. Patches were applied as they are without any chemical treatment to serve as donor phase. They are applied in whole pieces on the bottom side of filter of the acceptor plate. The top plate was filled with 250 lL of fresh acceptor solution (BR buffer, pH 7.4), and the stirring bars were also applied in every single well to avoid the effect of the unstirred water layer. The Gut-Box™ from Pion, INC was used for stirring. The resultant system was incubated at room temperature. Acceptor solution was sampled after 0.5, 1, 3 and 6 h of incubation. Measurements with longer incubation period were performed in the cases of patches containing fentanyl and rivastigmine. In these experiments, acceptor solution was sampled after 12 and 24 h of incubation as well. UV spectrophotometry (nicotine, rivastigmine and ketoprofen) (Section 2.3) and LC–MS (fentanyl) (Section 2.4) were used to analyze the concentration of the samples.

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2.3. Sample analysis using UV spectrophotometry

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The amount of the nicotine, rivastigmine and ketoprofen in the acceptor phase were determined by UV spectrophotometry. After every single incubation period, 150 lL of the acceptor compartment (BR buffer, pH 7.4) was transferred to UV plates, and the absent volume of the receiving medium was replaced with fresh acceptor solution. UV absorption (230–500 nm) was measured with Tecan Infinite M200 driven by Magellan 6 software (Tecan). Calibration for the quantitative analysis was performed using nicotine, rivastigmine and ketoprofen standard compounds. The calibration curves (Lambert–Beer law: A = e c l) were prepared using six dilutions in BR buffer with pH 7.4. The relevant parameters of the calibration process, like wavelength, linearity range, extinction coefficient (e) and determination coefficient (R2) are indicated in Table 2. Calibration curves were calculated by least-square linear regression analysis.

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2.4. Sample analysis using LC–MS method

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The concentration of the fentanyl in the acceptor phase was determined by HPLC–MS in selective ion monitoring (SIM) mode based on previous literature method (Koch et al., 2004). HPLC analysis was performed by an Agilent 1260 Infinity LC system in conjunction with an Agilent 6460 triple-quadrupole mass spectrometer. Chromatography was carried out using a Zorbax Eclipse Plus C18 (4.6  100 mm, 3.6 lm) column with a mobile phase of methanol, aqueous formic acid (90:10 v/v), (50:50 v/v)

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Table 1 Some relevant information about the examined transdermal and local patches. Active pharmaceutical ingredient (API)

Amount of API (mg)

Area of the patch (cm2)

Declared delivery rate (mg/h)

Duration of application (h)

Product

Manufacturer

Nicotine

23.62 78.00 17.50 23.12

13.5 15.0 10.0 42.0

0.94 0.58 0.29 0.10

16 24 24 72

McNeil AB GSK Consumer Healthcare Novartis Hungary Ltd. Sandoz Hungary Ltd.

16.50

30.0

0.10

72

9.00 20.00

5.0 70.0

0.19 £

24 £

NicoretteÒ NiquitinÒ NicotinellÒ Fentanyl SandozÒ FentanylratiopharmÒ ExelonÒ KeplatÒ

Fentanyl

Rivastigmine Ketoprofen

Teva Pharmaceutical Industries Ltd. Novartis Europharm Ltd. Hisamitsu

£: no data available.

Please cite this article in press as: Vizserálek, G., et al. Permeability test for transdermal and local therapeutic patches using Skin PAMPA method. Eur. J. Pharm. Sci. (2015), http://dx.doi.org/10.1016/j.ejps.2015.05.004

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Fig. 1. The schematic view of Skin PAMPA method. The original sandwich is shown on panel (a); the modified system on panel (b). On panel (c) a photo shows how the patch is applied to the filter of the acceptor phase.

Table 2 Calibration data for UV analysis of nicotine, rivastigmine and ketoprofen. Compound

kmax (nm)

Linearity range (mM)

e (M 1)

R2

Nicotine Rivastigmine Ketoprofen

261 264 260

0.0415–0.8320 0.2200–3.3100 0.0320–0.1250

2846 432.83 13028.34

0.9999 0.9998 0.9923

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with a flow rate of 0.5 mL/min at 25 °C. The mass spectrometer was operated in conjunction with a Jet Stream electrospray ion source in positive ion mode. MS was set to monitor in SIM mode at m/z 337 [M + H]+. Optimized parameters were the following: fragmentor voltage: 145 V; dwell time 200 ms; delta EMV 10 V. Flow and temperature of the drying gas (N2) in the ion source: 10 L/min and 300 °C; pressure of the nebulizer gas (N2): 45 psi; capillary voltage: 4000 V; sheath gas flow and temperature: 11 L/min and 250 °C. Mass spectra were processed using Agilent MassHunter B.04.00 software. The HPLC–MS method was validated according to the ICH guideline Q2 (R1) (Q2 (R1), 2005). Calibration curves were prepared using six concentrations between 1 and 500 ng/mL. Calibration curves were calculated by least-square linear regression analysis. Intra- and inter-day relative standard deviation (low, mid and high concentrations of the standards in three parallel runs on the same day and on three successive days) was less than 2.65% and 5.15%, respectively.

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2.5. Ex vivo permeation study

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The ex vivo permeability studies were performed with a vertical Franz diffusion cell system (Hanson Microette TM Topical & Transdermal Diffusion Cell System, Hanson Research Corporation, Chatsworth, CA, USA). The patch was placed as a donor phase on human epidermis supported on Porafil membrane filter (cellulose

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acetate; pore diameter 0.45 lm, Macherey–Nagel, INC). The effective diffusion surface area was 1.33 cm2. PBS (pH 7.4) was used as the acceptor phase to ensure sink conditions. The rotation of the magnetic stirring bars was set to 450 rpm. Experiments were performed at 37 °C for 24 h. Acceptor solution has been sampled after 0.5, 1, 3, 6, 12 and 24 h of incubation. Samples of 0.8 mL were taken from the acceptor phase by the autosampler (Hanson Microette Autosampling System, Hanson Research Corporation, Chatsworth, CA, USA) and replaced with fresh receiving medium. The quantitative measurements of active agents were carried out using UV spectrophotometry. UV absorption (230–500 nm) was measured with Thermo Scientific Evolution 201 UV–Visible Spectrophotometer.

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2.6. Preparation of human epidermis by a heat-separated technique

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The human skin samples were originated from several 35–40 years old Caucasian female patients who had undergone abdominal plastic surgery. The thickness of epidermis was not determined, but skin samples were from abdominal region where the thickness of epidermis is about 0.1 mm. This procedure was approved by the Ethical Committee of the University of Szeged, Albert Szent-Györgyi Clinical Centre (Human Investigation Review Board). Immediately after excision, the subcutaneous fatty tissue was removed and the skin was stored frozen at 20 °C. For the permeation study, the skin was thawed, and the epidermis was separated from the underlying dermis using a heat separation technique based on a procedure reported by Kligman and Christophers (1963). Individual portions were immersed in water at 60 °C for 90 s. Following removal of skin from the water, it was placed stratum corneum side up on a filter paper, and the

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epidermis (comprising the stratum corneum and viable epidermis) was gently removed from the underlying dermis with the use of forceps. The dermis was discarded and the epidermal membrane was floated on the surface of PBS (pH = 7.4) for at least 20 min. After this hydration process the preparation was placed on a supporting Porafil membrane.

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3. Results

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Six marketed transdermal patches and a commercially available local therapeutic patch containing a non-steroidal anti-inflammatory drug have been selected for this study (Table 1). The transdermal and local patches have been produced by various manufacturers, and they contain four different API’s (nicotine, fentanyl, rivastigmine and ketoprofen). Some relevant information of the patches (amount of API, area of the patch, declared delivery rate, duration of application, etc.) are also summarized in Table 1. Three samples were measured for each product, which covered different amount of the wells up to the active area of the patches. The average permeated amounts were calculated from the concentration of the acceptor phases. The results are deduced from the permeated amount of API’s and the permeation surface of every single well (0.3 cm2) and they are expressed in mg/cm2 unit. The standard deviations are demonstrated in the figures. The PAMPA experiments were performed on ready to use Skin PAMPA plates with the required technical modification described above (Section 2.2) and shown in Fig. 1. Ex vivo permeation studies with vertical Franz diffusion cell system were also carried out in order to compare with the data obtained by PAMPA method. The incubation time of the investigations was 6 h, but in cases of the patches with fentanyl and rivastigmine it was lengthened to 12 and 24 h, respectively. The measurements were performed with same incubation time range in both methods. Permeability profiles (permeated amount vs. time curve) determined by Skin PAMPA and Franz diffusion cell technique are shown on the same figures (left and right panels, respectively). The permeability profiles of the patches containing fentanyl are shown in Fig. 2a and b. They have been produced by different manufacturers but their declared delivery rates are the same. The sample analysis in the acceptor phase was performed by LC–MS technique (Section 2.4) because of the small amount of drug delivered. Ex vivo permeation study has not been carried out in the case of these products, as these patches are not recommended to be cut in the leaflet for patient and the whole patches cannot be applied onto the Franz diffusion cell. The red dots and black solid lines demonstrate the data measured by Skin PAMPA, and the blue dashed lines indicate the declared delivery rates of the patches. The next investigated patch contains rivastigmine, a CNS acting drug used for the treatment of dementia in Alzheimer’s or Parkinson’s diseases. The permeability profiles of this patch were studied by both Skin PAMPA and ex vivo permeation method and are shown in Fig. 3a and b. Longer incubation period (24 h) was selected during these measurements. Data are compared to the declared delivery rate indicated by the manufacturers. Fig. 4a–c panels show the results of three patches containing nicotine as active agent obtained by Skin PAMPA method, and d– f panels represent the data of the same patches measured by Franz diffusion cell. The permeability profiles of the three products are demonstrated with red dots and black solid lines. These data are compared with the declared delivery rates estimated by the manufacturers of the transdermal patches (blue dashed lines). A local therapeutic patch with ketoprofen as active ingredient has been also studied in this work (Fig. 5a and b). Declared delivery rate is not available for this patch.

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Fig. 2. The permeability profiles of transdermal patches with nicotine obtained by in vitro and ex vivo method. The red dots and black solid lines demonstrate the measured data, and the blue dashed lines indicate the declared delivery rates of the patches. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

The flux across the artificial membrane (in vitro; JPAMPA) as well as the human skin (ex vivo; JFranz) has been calculated and data are summarized in Table 3. The flux data were obtained from the slope of concentration versus time profile in the receiver compartment, and expressed in lg cm 2 h 1 unit. For the linear regression analysis, the linear range of the incubation period from 1 to 6 h was selected, and this range was used to calculate the flux data of the compounds. The in vivo flux values (Jin vivo) are deduced from the labeled delivery rate and active area of the patch, and expressed in lg cm 2 h 1 unit (Table 3).

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4. Discussion

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The aim of transdermal patch testing is to evaluate the performance of the patch as transdermal therapeutic system (and not just to determine the permeability of API); therefore the data obtained by PAMPA method must be compared with some relevant parameters which can represent the complex operation of the examined products. For this purpose, the fundamental comparison was offered by the declared delivery rates of the active agent from the examined transdermal patches. These parameters are indicated by the manufacturers in all cases with the exception of the local therapeutic patch KeplatÒ. Further useful comparison was provided by ex vivo Franz diffusion cell studies performed also in this work.

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Fig. 3. The permeability profiles of transdermal patches containing fentanyl measured by Skin PAMPA system. The red dots and black solid lines demonstrate the measured data, and the blue dashed lines indicate the declared delivery rates of the patches. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

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According to our results (Figs. 2–4), the established permeability profiles (solid lines) in all cases were higher than the expected curves (dotted lines). This phenomenon can be caused by the ‘‘edge-effect’’ well known and described in the literature (Hadgraft et al., 1991; Olivier et al., 2003). The edge-effect means a lateral diffusion within the adhesive layer or matrix of the patch that increases virtually the assay surface if the total surface of the patch is not covered by the assay cells. This effect can appear in both Franz cell assay and in PAMPA technique and in any other in vitro or ex vivo method as well, and cause a tendentious, systematic (approximately 10–30%) error that can be taken into account. However, the diffusivity of the compounds within the adhesive layer is not known precisely, thus the numerical correction of this deviation is quite challenging. If the structure of the patch is known by the investigators and the patch can be cut, than the overestimation can be avoided by cutting the patch to the proper size. Since the aim of the present study was not practically influenced by the edge-effect, we did not correct the experimental permeability values. Slightly higher standard deviation can be observed occasionally at the PAMPA method than the Franz cell technique. It can be caused by the differences of the two procedures. The patches applied on the PAMPA plates can cover from 6 to 80 single wells based on the size of the different products. The average permeated amounts are calculated from the data of every covered well; therefore the standard deviation can increase comparing to the error of the Franz cell measurements. On the other hand, the higher standard deviation may also be caused by the inhomogeneous dispersion of API’s on the surface of the patches, which may not influence the therapeutic effect of the examined products.

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4.1. Comparison of permeability measured by two methods

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The permeability profiles of patch containing rivastigmine measured by two different methods (Fig. 3a and b) are practically identical. However, the permeated amount of the API is significantly higher at both methods than it can be expected from the declared data. The discrepancy is bigger than the above mentioned edge-effect may cause and probably is due to the presence of one or more penetration enhancers in the patch. Ò Ò Ò Three nicotine patches (Niquitin , Nicotinell and Nicorette ) from different manufacturers were studied. The best agreement of permeability profiles between the PAMPA and Franz diffusion Ò cell methods was found at Nicotinell (Fig. 4b and e). The adhesive layer of this patch can be saturated by the drug; therefore an

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excessive release and permeation can be seen at the beginning of incubation, but after this initial part, the permeation kinetic is nicely following the declared delivery rate. In the case of the other Ò nicotine patches (NiquitinÒ and Nicorette ), there is no initial excessive release probably because of the lack of saturation in the adhesive layer, and indicating the different structure of the patch matrix. In these experiments significant difference can be observed between the permeability profiles of the same patch in Ò the two methods. The permeability is overestimated for Niquitin Ò by the Franz cell method (Fig. 4d), and for Nicorette by Skin PAMPA technique (Fig. 4c). It can be supposed that the auxiliaries used in these patches have different impact on the artificial membrane and the real skin. Detailed interpretation requires further investigations. After the transdermal patch testing, a local therapeutic patch called KeplatÒ with ketoprofen was studied (Fig. 5a and b). In this case, self-evidently, declared delivery rate is not indicated by the manufacturer. The area of this patch is 70 cm2 which is significantly higher than the previously discussed patches; therefore it covered more than 80 individual wells on the top of the PAMPA plates during the measurements. Higher standard deviation can be observed which may be caused by the facts detailed previously.

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4.2. Classification of the patches based on the estimated flux values

383

Significant differences can be observed between the fluxes of the API’s for TDD across human skin from the extremely permeable nicotine to compounds which have very low permeability (e.g. buprenorphine) (Wiedersberg and Guy, 2014). Thus, various formulation techniques can be required to maintain the drug level in therapeutic window. Table 4 indicates the maximum thermodynamic driving force (Jmax) of the examined API’s (nicotine, fentanyl and rivastigmine). These data represent the potential maximum flux through human skin. The ratio of the labeled in vivo delivery rates (Jin vivo) and Jmax can provide information about the behavior of the products. The transdermal patches examined in this study can represent three individual cases based on the Jin vivo/Jmax ratio of the drugs in the products. If all transdermal systems were formulated to provide the maximum thermodynamic driving force for passive diffusion across the skin, the Jin vivo/Jmax ratios should be equal to 1 (e.g. patches with fentanyl as active compound, first group). In the second group, the transdermal patch with rivastigmine as active compound has lower Jmax than the achieved Jin vivo. This situation supposes the presence of penetration enhancers in the patch. Third, nicotine

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Fig. 4. The permeability profiles of transdermal patches with rivastigmine obtained by in vitro and ex vivo method. The red dots and black solid lines demonstrate the measured data, and the blue dashed lines indicate the declared delivery rates of the patches. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

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has high permeation capacity, so the Jmax significantly exceeds the achieved delivery rates. The transdermal patches for smoking cessation have assumed a degree of rate control to avoid a potentially high drug level in patient (Wiedersberg and Guy, 2014). Table 4 also indicates the deduced JPAMPA/Jmax ratios which show, that the modified PAMPA method for transdermal patch testing is able to separate the three individual groups detailed previously. In these ratios, JPAMPA values are calculated as the average data from the individual in vitro fluxes for the different API’s (Table 3). The transdermal patches containing fentanyl represent the first group. The JPAMPA/Jmax ratio is 1.83 compared to the Jin vivo/Jmax ratio 1.10. This agreement in the magnitude of values indicates good

correlation between the in vitro measurements and the in vivo circumstances. As a representative of the second group (Jin vivo/Jmax  1), ExelonÒ with rivastigmine was selected. The JPAMPA/Jmax ratio was found 14.23 which value is higher than the theoretical one, Jin vivo/Jmax ratio 4.00. The difference may be caused by the effect of penetration enhancer on artificial membrane as detailed previously. The transdermal patches with nicotine as active compound serve the third group in this study having Jin vivo/Jmax  1. Good agreement was found in this case (JPAMPA/Jmax: 0.06 vs Jin vivo/Jmax: 0.03). This means that the modified PAMPA method can also

Please cite this article in press as: Vizserálek, G., et al. Permeability test for transdermal and local therapeutic patches using Skin PAMPA method. Eur. J. Pharm. Sci. (2015), http://dx.doi.org/10.1016/j.ejps.2015.05.004

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Fig. 5. The permeability profiles of the patches with ketoprofen measured by in vitro and ex vivo method. The measured data are demonstrated with red dots and black solid lines. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Table 3 The flux value of active pharmaceutical ingredient of patches across the artificial membrane and human skin; the in vivo flux declared by the manufacturer. Compound/patch

In vitro JPAMPA (lg cm Ò

Nicotine/Nicorette Nicotine/NiquitinÒ Nicotine/NicotinellÒ Fentanyl/Fentanyl SandozÒ Fentanyl/Fentanyl-ratiopharmÒ Rivastigmine/ExelonÒ Ketoprofen/KeplatÒ

In vivoa

Ex vivo 2

h

1

)

191.16 43.20 42.20 4.60 4.90 135.20 5.50

SD

JFranz (lg cm

11.51 2.35 5.57 0.91 0.28 7.82 0.02

90.80 134.60 45.30 £ £ 142.30 16.20

2

h

1

)

SD

Jin

1.75 7.85 5.29 £ £ 15.68 0.94

69.40 38.90 29.20 2.40 3.30 38.30 £

vivo

(lg cm

2

h

1

)

£: no data available. a Deduced from the labeled delivery rate and active area of the patch.

Table 4 The in vivo fluxes (Jin vivo) and the in vitro fluxes (JPAMPA) compared to the potential maximum flux of the selected drugs. Drug Nicotine Fentanyl Rivastigmine a

Jin vivo (lg cm 45.83 2.85 38.30

2

h

1 a

)

Jmax (lg cm 1425 2.6 9.5

2

h

1 c

)

Jin vivo/ Jmax

JPAMPA/ Jmaxb

0.03 1.10 4.03

0.06 1.83 14.23

Average in vivo fluxes of the transdermal patches with the selected API’s (individual data in Table 3). b Average in vitro fluxes (JPAMPA) were used for calculation (individual data in Table 3). c Wiedersberg and Guy (2014): S. Wiedersberg and R.H. Guy, J. Controlled Release, 190 (2014) 150–156.

provide useful information about the transdermal products, where the active compound is highly permeable such as nicotine. The measured flux values (JPAMPA and JFranz) and the deduced flux from the declared delivery rates (Jin vivo) can demonstrate the ability of the Skin PAMPA method to classify the behavior of transdermal patches. For this purpose, the logarithmic values of the fluxes are summarized in Fig. 6. According to our results, the obtained and the deduced flux data are in same order of magnitude in all three cases. Therefore, both Skin PAMPA as an in vitro technique and the vertical Franz diffusion cell as an ex vivo method are useful tools for transdermal patch testing. However, the plate based artificial membrane method provides better reproducibility, lower cost and higher throughput.

Fig. 6. The measured in vitro (JPAMPA), ex vivo (JFranz) flux and declared delivery rate (Jin

vivo)

values of tested transdermal patches.

Please cite this article in press as: Vizserálek, G., et al. Permeability test for transdermal and local therapeutic patches using Skin PAMPA method. Eur. J. Pharm. Sci. (2015), http://dx.doi.org/10.1016/j.ejps.2015.05.004

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The present study has demonstrated the usage of Skin PAMPA skin permeation model system for transdermal and local therapeutic patch testing. The permeability profiles obtained by PAMPA and Franz diffusion cell methods were in good agreement in most cases. This system is also affected by the edge-effect similarly to most of the available in vitro permeation models but this fact has no influence on the applicability of the modified PAMPA method for the purposes described in this work. The method is suitable for patch testing, because it reflects well the permeability differences between drugs; the deviating behavior of various patches and it is able to classify them based on the flux ratio. Our results suggest that Skin PAMPA system can serve as a useful tool for rapid evaluation of transdermal patches and can be recommended for the permeation studies during the development process of the transdermal therapeutic systems.

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Please cite this article in press as: Vizserálek, G., et al. Permeability test for transdermal and local therapeutic patches using Skin PAMPA method. Eur. J. Pharm. Sci. (2015), http://dx.doi.org/10.1016/j.ejps.2015.05.004

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Permeability test for transdermal and local therapeutic patches using Skin PAMPA method.

Using the skin as absorption site presents unique advantages that have facilitated the progression of transdermal drug delivery in the past decades. E...
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