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Baba H, Takahara JI, Yamashita F, Hashida M. Modeling and Prediction of Solvent Effect on Human Skin Permeability using Support Vector Regression and Random Forest. Pharm Res 2015; 32:3604-17. [PMID: 26033768 DOI: 10.1007/s11095-015-1720-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/19/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE The solvent effect on skin permeability is important for assessing the effectiveness and toxicological risk of new dermatological formulations in pharmaceuticals and cosmetics development. The solvent effect occurs by diverse mechanisms, which could be elucidated by efficient and reliable prediction models. However, such prediction models have been hampered by the small variety of permeants and mixture components archived in databases and by low predictive performance. Here, we propose a solution to both problems. METHODS We first compiled a novel large database of 412 samples from 261 structurally diverse permeants and 31 solvents reported in the literature. The data were carefully screened to ensure their collection under consistent experimental conditions. To construct a high-performance predictive model, we then applied support vector regression (SVR) and random forest (RF) with greedy stepwise descriptor selection to our database. The models were internally and externally validated. RESULTS The SVR achieved higher performance statistics than RF. The (externally validated) determination coefficient, root mean square error, and mean absolute error of SVR were 0.899, 0.351, and 0.268, respectively. Moreover, because all descriptors are fully computational, our method can predict as-yet unsynthesized compounds. CONCLUSION Our high-performance prediction model offers an attractive alternative to permeability experiments for pharmaceutical and cosmetic candidate screening and optimizing skin-permeable topical formulations.
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Affiliation(s)
- Hiromi Baba
- Kyoto R&D Center, Maruho Co., Ltd., 93 Awata-cho, Chudoji, Shimogyo-ku, 600-8815, Kyoto, Japan. .,Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida-shimoadachicho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Jun-ichi Takahara
- Kyoto R&D Center, Maruho Co., Ltd., 93 Awata-cho, Chudoji, Shimogyo-ku, 600-8815, Kyoto, Japan
| | - Fumiyoshi Yamashita
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida-shimoadachicho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Mitsuru Hashida
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida-shimoadachicho, Sakyo-ku, Kyoto, 606-8501, Japan.,Institute for Integrated Cell-Material Sciences, Kyoto University, 46-29, Yoshida-shimoadachicho, Sakyo-ku, Kyoto, 606-8501, Japan
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Atobe T, Mori M, Yamashita F, Hashida M, Kouzuki H. Artificial neural network analysis for predicting human percutaneous absorption taking account of vehicle properties. J Toxicol Sci 2015; 40:277-94. [DOI: 10.2131/jts.40.277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
| | | | - Fumiyoshi Yamashita
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Mitsuru Hashida
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University
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Nam SH, Xu YJ, Nam H, Jin GW, Jeong Y, An S, Park JS. Ion pairs of risedronate for transdermal delivery and enhanced permeation rate on hairless mouse skin. Int J Pharm 2011; 419:114-20. [DOI: 10.1016/j.ijpharm.2011.07.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 07/03/2011] [Accepted: 07/17/2011] [Indexed: 12/11/2022]
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Liu P, Cettina M, Wong J. Effects of Isopropanol–Isopropyl Myristate Binary Enhancers on In Vitro Transport of Estradiol in Human Epidermis: A Mechanistic Evaluation. J Pharm Sci 2009; 98:565-72. [DOI: 10.1002/jps.21459] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Funke AP, Günther C, Müller RH, Lipp R. Development of matrix patches for transdermal delivery of a highly lipophilic antiestrogen. Drug Dev Ind Pharm 2003; 29:785-93. [PMID: 12906336 DOI: 10.1081/ddc-120021778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this study was to develop matrix-type transdermal systems (TDSs) containing the highly lipophilic (log P = 5.82) antiestrogen (AE) and the permeation enhancers propylene glycol and lauric acid. For that purpose, permeation of AE from various adhesive matrices through excised skin of hairless mice was evaluated. It was found that pretreatment of the skin with permeation enhancers raised the transdermal flux of subsequently applied antiestrogen. Highest steady-state transdermal fluxes (1.1 microg cm(-2) h(-1)) were obtained from Gelva, polyacrylate adhesive, followed by 0.55 microg cm(-2) h(-1) from Oppanol polyisobutylene, 0.31 microg cm(-2) h(-1) from BIO-PSA silicone, and 0.12 microg cm(-2) h(-1) from Sekisui polyacrylate matrices. In order to develop TDS with high content of fluid permeation enhancer propylene glycol, two different strategies were investigated. One strategy was the addition of hydroxypropyl cellulose (HPC) as thickening agent to Gelva matrices. This allowed for propylene glycol loading levels of up to 30%, resulting in transdermal AE fluxes of 0.09 microg cm(-2) h(-1). On the other hand, a fleece-laminated backing foil was loaded with the described permeation enhancer formulation and laminated with polyacrylate adhesive layer, resulting in transdermal AE fluxes of 0.06 microg cm(-2) h(-1). However, application of these TDSs on skin pretreated with permeation enhancers raised the fluxes to 2.6 microg cm(-2) h(-1) from Gelva/HPC and 0.46 microg cm(-2) h(-1) from fleece/Sekisui.
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Kim JH, Lee CH, Choi HK. Transdermal delivery of physostigmine: effects of enhancers and pressure-sensitive adhesives. Drug Dev Ind Pharm 2002; 28:833-9. [PMID: 12236069 DOI: 10.1081/ddc-120005629] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The purpose of this study was to investigate the effects of various pressure-sensitive adhesives (PSA) on the percutaneous absorption of physostigmine across hairless mouse skin. In addition, the influences of various vehicles and polyvinylpyrrolidone (PVP) on the percutaneous absorption of physostigmine from PSA matrix across hairless mouse skin were evaluated using a flow-through diffusion cell system at 37 degrees C. Physostigmine showed the highest permeability from silicone adhesive matrix, followed by polyisobutylene (PIB), styrene-isoprene-styrene (SIS), acrylic, and styrene-butadiene-styrene (SBS) matrix. Among acrylic adhesives, the permeability of physostigmine was the highest from grafted acrylic adhesive. Polyvinyl pyrrolidone inhibited the crystallization of physostigmine in the PIB adhesive matrix and enhanced the permeability of physostigmine from the PIB adhesive matrix. When esters of sorbitol and fatty acid, polyethylene glycol (PEG) alkyl esters, and caprylic/capric triglycerides were tested, the more lipophilic was a surfactant, the higher the permeation rate within the same group of surfactants. The enhancement effect of PEG derivatives was lower than that of non-PEG derivatives. Among non-linear fatty acid derivatives, linoleate derivatives showed higher permeability of physostigmine than oleate derivatives. This study showed that several non-ionic surfactants, including PEG-20 evening primrose glyceride, enhanced the permeation of physostigmine across hairless mouse skin better than oleic acid.
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Affiliation(s)
- Ju-Hyun Kim
- College of Pharmacy, Chosun University, Kwangju, Korea
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Funke AP, Günther C, Müller RH, Lipp R. In-vitro release and transdermal fluxes of a highly lipophilic drug and of enhancers from matrix TDS. J Control Release 2002; 82:63-70. [PMID: 12106977 DOI: 10.1016/s0168-3659(02)00105-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transdermal systems (TDS) are a well-known application form for small, moderately lipophilic molecules. The aim of this study was to investigate the possibility of applying a highly lipophilic drug, the antiestrogen AE (log P=5.82) transdermally by polyacrylate-based matrix TDS. For this purpose, two effects of both drug and enhancer concentration in TDS were investigated: in-vitro release and transdermal permeation of drug and enhancers. In the TDS investigated, in-vitro release as well as in-vitro permeation of AE through excised skin of hairless mice was found to be independent of concentrations of both drug and enhancers. The steady-state fluxes observed were low (about 50-100 ng cm(-2) h(-1)). But skin pretreatment with permeation enhancers resulted in a markedly enhanced permeability (1400 ng cm(-2) h(-1)). Therefore, the permeation of this highly lipophilic drug seems to be limited by the stratum corneum barrier function. In contrast, the transdermal permeation of the enhancers was dependent on the TDS composition. Increase in enhancer content resulted in a higher permeation of enhancers, whereas skin pretreatment did not. In conclusion, it was shown that the highly lipophilic antiestrogen can be administered transdermally by pretreating the skin with the fluid permeation enhancer combination propylene glycol-lauric acid (9+1) and then applying a matrix TDS.
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Funke AP, Schiller R, Motzkus HW, Günther C, Müller RH, Lipp R. Transdermal delivery of highly lipophilic drugs: in vitro fluxes of antiestrogens, permeation enhancers, and solvents from liquid formulations. Pharm Res 2002; 19:661-8. [PMID: 12069170 DOI: 10.1023/a:1015314314796] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Highly lipophilic basic drugs, the antiestrogens AE 1 (log P = 5.82) and AE 2 (log P = 7.8) shall be delivered transdermally. METHODS Transdermal permeation of drugs, enhancers, and solvents from various fluid formulations were characterized by in-vitro permeation studies through excised skin of hairless mice. Furthermore, differential scanning calorimetry (DSC) measurements of skin lipid phase transition temperatures were conducted. RESULTS Transdermal flux of highly lipophilic drugs was extraordinarily enhanced by the unique permeation enhancer combination propylene glycol-lauric acid (9 + 1): steady-state fluxes of AE 1 and AE 2 were as high as 5.8 microg x cm(-2) x h(-1) and 3.2 microg x cm(-2) x h(-1), respectively. This dual enhancer formulation also resulted in a marked increase in the transdermal fluxes of the enhancers. Furthermore, skin lipid phase transition temperatures were significantly reduced by treatment with this formulation. CONCLUSION Transdermal delivery of highly lipophilic drugs can be realized by using the permeation enhancer combination propylene glycol-lauric acid. The extraordinary permeation enhancement for highly lipophilic drugs by this formulation is due to mutual permeation enhancement of these two enhancers and their synergistic lipid-fluidising activity in the stratum corneum.
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Affiliation(s)
- Adrian P Funke
- Pharmaceutical Development, Schering AG, Berlin, Germany
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Rowland CA, Chilcott RP. The electrostability and electrically assisted delivery of an organophosphate pretreatment (physostigmine) across human skin in vitro. J Control Release 2000; 68:157-66. [PMID: 10925124 DOI: 10.1016/s0168-3659(00)00242-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Physostigmine is a tertiary carbamate that is utilised as a pretreatment against organophosphate intoxication. Oral delivery of physostigmine is not practical due to high first pass metabolism and short elimination half life. Transdermal administration of physostigmine may circumvent such problems. The aim of this study was to assess the electrostability of physostigmine and the feasibility of electrically assisted transdermal drug delivery of physostigmine through isolated human skin in vitro. Buffered solutions of physostigmine (free base, salicylate and sulphate) were electrostable under conditions of iontophoresis and electroporation as measured by HPLC, although instability of the chloridised silver electrodes was observed. Physostigmine sulphate was chosen for further study as it appeared to prevent degradation of the electrodes. Under conditions of iontophoresis (0.8 mA cm(-2), applied for 5- or 2.5-min durations for a maximum period of 45 min over 8 h), the total quantity of physostigmine sulphate that penetrated was 6.5+/-2.3% and 3.9+/-1.7% (pH 5.0 and pH 5.5) of the total applied dose (2 mg). Physostigmine did not penetrate the skin when electroporated at a frequency of 0.1 Hz or 10 Hz (100 V, 1 ms pulse width, duration 1 s, repetition 5-10 s), but significant amounts were delivered at a frequency of 100 Hz, being 11.3+/-2.9% and 5.8+/-2.5% of the applied dose (pH 5.0 and pH 5.5, respectively). These data indicate that iontophoretic and electroporative drug delivery of physostigmine sulphate was buffer-dependent, an effect tentatively attributed to a combination of co-ion competition, mono/di-cation ratio and applied charge effects.
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Affiliation(s)
- C A Rowland
- Department of Biomedical Sciences, CBD Porton Down, Wiltshire SP4 0JQ, Salisbury, UK
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Gorukanti SR, Li L, Kim KH. Transdermal delivery of antiparkinsonian agent, benztropine. I. Effect of vehicles on skin permeation. Int J Pharm 1999; 192:159-72. [PMID: 10567747 DOI: 10.1016/s0378-5173(99)00305-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The influence of pH and various lipophilic and hydrophilic vehicles on the epidermal permeation of benztropine (BZ) free base and its mesylate salt were studied in vitro using the hairless mouse (HLM) and human cadaver (HC) skin membranes. The pH-partition behavior of BZ base (pK(a)=10) was examined using n-octanol and Britton-Robinson buffers over the pH range of 5-12. Unexpectedly, the ionized species of BZ yielded a high partition coefficient (log K(octanol/water)=2. 14), which was reflected by its relatively high skin permeability (P=1.6x10(-2)cm h(-1)). BZ base delivered from a lipophilic vehicle with a solubility parameter range of 7.1-10.3 (cal cm(3))(1/2) exhibited a significantly enhanced rate of permeation as compared to that attained from a hydrophilic vehicle of solubility parameter range between 12.5-23.4 (cal cm(3))(1/2). Among the neat solvents examined, a lipophilic carrier, isopropyl myristate (IPM) provided the most enhancing effect on the permeation of BZ base. In addition, the neat IPM carrier offered the maximum BZ base flux of 150 microg per cm(2) h(-1) across HC skin, which was approximately 16 times greater than the target delivery rate of BZ from a 10-cm(2) device. In comparison, BZ base exhibited a 2-60 times greater flux than BZ mesylate when delivered from the neat solvents. However, interestingly enough, the binary cosolvents consisting of IPM and short-chain alkanols such as ethanol (EtOH), isopropanol (iPrOH), and tertiary butanol (tBtOH), in particular a 2:8 combination, produced a marked synergistic enhancement of BZ flux from the mesylate salt, whereas a retarding effect was noticed for the permeation of BZ base. The enhancement potency for the BZ mesylate permeation increased linearly with the carbon number of the branched alcohols present in the binary mixtures. A tBtOH-IPM (2:8) combination produced the highest BZ flux from the mesylate salt, i.e. , 2016 mg per cm(2) h(-1), which was 100-fold greater than from water and 44-540-fold greater than the individual neat solvents, respectively. The observed permeation enhancement of BZ mesylate by the alkanol-IPM mixtures was probably as a result of a combination of decreasing barrier ability of the stratum corneum by the binary vehicles and moderately partitioning BZ mesylate through the viable epidermis/dermis.
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Affiliation(s)
- S R Gorukanti
- Drug Delivery Systems Research Laboratory, College of Pharmacy and Allied Health Professions, St. John's University, Jamaica, NY 11439, USA
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Liu CH, Ho HO, Hsieh MC, Sokoloski TD, Sheu MT. Studies on the in-vitro percutaneous penetration of indomethacin from gel systems in hairless mice. J Pharm Pharmacol 1995; 47:365-72. [PMID: 7494184 DOI: 10.1111/j.2042-7158.1995.tb05812.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The influence of co-solvents on the in-vitro percutaneous penetration of indomethacin from gel systems was studied using a simplex lattice experimental design. Gel formulations were prepared by gelling the vehicle mixture of water, either alcohol or isopropanol and either propylene glycol or PEG 400 with 1% w/w Carbomer 940. Hairless mouse skin was employed as the barrier in a Franz-type diffusion cell. The penetration rates at steady state for seven formulations were fitted to a polynomial equation based on this simple lattice method and a three-dimensional plot was constructed. The formulation having the maximal penetration rate was determined to be the vehicle with a solvent ratio of water: alcohol: propylene glycol equal to 15:33:52, and which possessed a solubility parameter of 15 and a drug solubility of around 10 mg mL-1. When the solubility parameter of the vehicle was > 15, the drug solubility increased. However, the penetration rate decreased with an increasing solubility parameter. For those vehicles with a solubility parameter < 15, both the drug solubility and the penetration rate decreased with a decrease in the solubility parameter. There was shown to be an approximately 20-fold increase in the relative enhancement factor when using both alcohol and isopropanol, but only a threefold increase for both propylene glycol and PEG 400, when compared with water.
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Affiliation(s)
- C H Liu
- School of Pharmacy, China Medical College, Taichung, Taiwan
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Enhanced transdermal delivery of estradiol in vitro using binary vehicles of isopropyl myristate and short-chain alkanols. Int J Pharm 1995. [DOI: 10.1016/0378-5173(94)00253-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Michael-Baruch E, Shiri Y, Cohen S. Alkali halide-assisted penetration of neostigmine across excised human skin: a combination of structured water disruption and a Donnan-like effect. J Pharm Sci 1994; 83:1071-6. [PMID: 7983588 DOI: 10.1002/jps.2600830803] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The penetration of neostigmine across excised human skin mounted in flow-through diffusion cells, delivered from a 0.28 M aqueous solution, was below detection limits. The presence of either NaCl or LiCl in the donor solution caused significant fluxes of neostigmine, with permeability coefficients (Kp's) in the range of 10(-6) cm min-1. Paradoxically, low concentrations of NaCl or LiCl (0.25 and 0.5 M) were more effective in this respect than the 1 M solution, which was the least effective concentration in the range of 0.25-3 M. Thus, the dependence of the experimental Kp values on inorganic ion concentration followed a biphasic course, suggesting the participation of two distinctive mechanisms in the penetration-enhancement process. The early phase corresponding to 0.25 and 0.5 M NaCl or LiCl is being partly ascribed to a decrease in the viscosity of lamellar water caused by the influx of the respective hydrated ions, hydration of LiCl or NaCl being more extensive at low alkali halide concentration that at higher ones (reference cited). The late phase corresponding to 2 and 3 M LiCl and NaCl is partly ascribed to a Donnan-like effect whereby the presence of a large excess of poorly diffusible common ion (Na+ or Li+) enhances the partitioning into the skin of the more diffusible ion, in this case neostigmine cation. The presence of inorganic ions at different concentrations had no effect on the partial molal volume of neostigmine bromide (Vi infinity = 223.5 cm3 mol-1), which was practically the same for all concentrations of either LiCl and NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- E Michael-Baruch
- Department of Physiology & Pharmacology, Tel Aviv University, Sackler School of Medicine, Israel
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Singh S, Singh J. Transdermal drug delivery by passive diffusion and iontophoresis: a review. Med Res Rev 1993; 13:569-621. [PMID: 8412408 DOI: 10.1002/med.2610130504] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- S Singh
- Department of Pharmaceutics, Institute of Technology, Banaras Hindu University, Varanasi, India
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Maitani Y, Coutel-Egros A, Obata Y, Nagai T. Prediction of skin permeabilities of diclofenac and propranolol from theoretical partition coefficients determined from cohesion parameters. J Pharm Sci 1993; 82:416-20. [PMID: 8468687 DOI: 10.1002/jps.2600820416] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cohesion parameters of diclofenac and propranolol were determined experimentally. The theoretical partition coefficient (Ps,v) was calculated from the activity coefficient (gamma) and the cohesion parameters of the solvent (delta 1 = delta v), solute (delta 2), and skin (delta s). By using the extended Hildebrand solubility equation, the potential energy of solute-solvent interaction in a given solution was considered to have the gamma value derived from solubility data of diclofenac and propranolol in ethanol-aqueous buffer. Values for experimental permeability coefficients (Kp), which were determined from flux and solubility, were compared with values for the respective Ps,v. For a solvent that consists of ethanol-aqueous buffer exhibiting cohesion parameters in the range of delta v = 18-24 (cal/cm3)1/2, the fluxes increased and the Kp decreased because of the similarity in cohesion parameters of these solvents to the solute. The difference between Ps,v and experimental Kp suggests that ethanol in the solvent affects the membrane and diclofenac and propranolol penetrate through the membrane, possibly solvated by ethanol.
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Affiliation(s)
- Y Maitani
- Department of Pharmaceutics, University of Hoshi, Tokyo, Japan
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Coutel-Egros A, Maitani Y, Veillard M, Machida Y, Nagai T. Combined effects of pH, cosolvent and penetration enhancers on the in vitro buccal absorption of propranolol through excised hamster cheek pouch. Int J Pharm 1992. [DOI: 10.1016/0378-5173(92)90052-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Pardo A, Shiri Y, Cohen S. Partial molal volumes and solubilities of physostigmine in isopropanol:isopropyl myristate solvents in relation to skin penetrability. J Pharm Sci 1991; 80:567-72. [PMID: 1941550 DOI: 10.1002/jps.2600800615] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Partial molal volumes (Vi infinity) of physostigmine, ranging from 232.9 to 239.8 cm3.mol-1, and its mole fraction solubilities (Xi), ranging from 0.051 to 0.009, were determined at 25 degrees C in solutions of isopropanol (IPA), isopropyl myristate (IPM), and their mixtures. An inverse relation was found between Vi infinity and Xi. At solubility----0, Vi infinity----240.6 (by extrapolation). The experimentally derived liquid molal volume in the standard state, Vi degrees (231.1), of physostigmine was lower than its lowest Vi infinity (value 232.9) in the series tested. Virtual cohesion parameters (lambda i) and excess free energies (delta EGi) of physostigmine in the various solutions were estimated from the partial molal volumes, assuming regular solution behavior. For each solution, the free energy (-RT In Xi) of the drug was estimated from its solubility. An increase in the virtual cohesion parameter and a decrease in the excess free energy and the free energy was found with an increase in volume fraction of IPA in the mixed solvent. The increase in lambda i over the invariant cohesion parameter, delta i (10.2), reflects a compensation effect needed to maintain the geometric mean assumption of Regular Solution Theory. Deviation from the theoretically expected linearity between -RT In Xi and delta EGi of physostigmine is ascribed to the existence of solvated molecules distinct from unsolvated molecules of physostigmine. The highest permeability coefficient of the delivery of physostigmine through excised human skin from IPA:IPM mixtures was seen from the mixture exhibiting the highest solvation effect, giving additional evidence that physostigmine penetrates through the skin, possibly in combination with IPA.
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Affiliation(s)
- A Pardo
- Department of Physiology and Pharmacology, Tel Aviv University, Sackler School of Medicine, Israel
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