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Rahma A, Gu J, Lane ME. In vivo permeation of 2-phenoxyethanol in human skin. Eur J Pharm Sci 2024:106889. [PMID: 39187094 DOI: 10.1016/j.ejps.2024.106889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/25/2024] [Accepted: 08/23/2024] [Indexed: 08/28/2024]
Abstract
A number of baby wipe formulations contain 2-phenoxyethanol (PE) as a preservative and cetylpyridinium chloride (CPC) as a surfactant with antimicrobial activity. Previously, we reported the skin absorption of PE in porcine skin and human skin in vitro. In the present work, the permeation of PE from preparations with CPC and without CPC was investigated in human skin in vivo. The studies were conducted using Confocal Raman Spectroscopy (CRS) and tape stripping (TS) methods. The CRS studies showed that the area under the curve (AUC) of PE for the formulation with and without CPC were not significantly different (p > 0.05). The TS data indicated no significant difference in the amounts of PE recovered from tapes 1-6 for the preparation with and without CPC (p > 0.05). When comparing the in vitro and in vivo data, a correlation was observed between the cumulative amount of PE permeated through human skin in vitro at 24 h and the AUC as measured by CRS (r2 = 0.97). In addition, the cumulative amount of PE permeated through human skin in vitro at 24 h was found to correlate with the amount of PE recovered from tape 1 to 6 in vivo (r2 = 0.95). Both CRS and TS techniques demonstrated limitations in assessing the distribution of PE and CPC in the skin in vivo, primarily attributed to the Raman signal intensities of compounds under investigation and the variability in the amount of SC collected by TS. Despite the limitations of CRS and TS, the results from the present study add further insights to the in vitro permeation data. Additionally, the findings of the present study encourage the further development and application of CRS for non-invasive evaluation of topical skin formulations in vivo.
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Affiliation(s)
- Annisa Rahma
- School of Pharmacy, University College London, 29 - 39 Brunswick Square, London WC1N 1AX, United Kingdom; School of Pharmacy, Institut Teknologi Bandung, Ganesa 10, Bandung 40132, Indonesia.
| | - Jingyi Gu
- School of Pharmacy, University College London, 29 - 39 Brunswick Square, London WC1N 1AX, United Kingdom.
| | - Majella E Lane
- School of Pharmacy, University College London, 29 - 39 Brunswick Square, London WC1N 1AX, United Kingdom.
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2
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Paz-Alvarez M, Fung Tang C, Pudney PD, Lane ME. Rational development of topical climbazole formulations. Int J Pharm 2024; 653:123886. [PMID: 38331330 DOI: 10.1016/j.ijpharm.2024.123886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/03/2024] [Accepted: 02/04/2024] [Indexed: 02/10/2024]
Abstract
Dandruff, or pityriasis capitis simplex, is a common scalp condition associated with excessive flaking and scaling of the epidermal tissue. Other features include irregular corneocyte turnover, irritation, itching and an impaired skin barrier function. Previously we reported the characterization of climbazole (CBZ), an antifungal agent used in the management of dandruff. Skin permeation of CBZ from neat solvents was also investigated. In the present work we evaluated CBZ permeation in human skin in vitro from more complex formulations that better represent products used by consumers. The various systems studied were composed of propylene glycol (PG), Transcutol®P (TC), octyl salicylate (OSal) and isopropyl alcohol (IPA). As well as measurement of skin uptake and penetration of CBZ, where possible, the skin retention and permeation of the various solvents was also determined. All vehicles promoted skin permeation of CBZ but no significant differences in amount permeated were evident between the binary vehicles (PG:TC, TC:OSal) and the ternary vehicle studied (PG:IPA:OSal). The binary vehicles generally promoted more skin uptake of CBZ compared with the neat solvents (PG, TC, OSal) studied previously. Permeation and skin extraction of CBZ from the PG:TC vehicles increased with increasing PG content; a similar trend was evident for the PG:IPA:OSal systems. New methods were developed and validated for measurement of PG, TC and OSal. Analysis of the individual solvents indicated that PG permeation was also independent of the amounts of other solvents in the binary or ternary systems. Consistent with previous findings higher proportions of TC permeated compared with PG for the PG:TC binary systems; TC also permeated the skin more rapidly than PG from these vehicles. For OSal, skin extraction was generally higher for TC:OSal compared with the PG:IPA:OSal vehicle. However, increasing the content of OSal did not appear to influence CBZ skin uptake nor permeation. Interestingly, the effects of the various PG:TC vehicles on CBZ skin delivery contrast with results we previous reported for the same systems for a different active. This confirms that with reference to skin permeation, formulation effects and/or skin penetration enhancement should be expected to vary and may not be predicted for specific vehicles.
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Affiliation(s)
| | - Chun Fung Tang
- UCL School of Pharmacy, 29-39 Brunswick Square WC1N 1AX, London, UK
| | - Paul D Pudney
- Strategic Science Group, Unilever R&D, Colworth Science Park MK44 1LQ, Sharnbrook, Bedford, UK
| | - Majella E Lane
- UCL School of Pharmacy, 29-39 Brunswick Square WC1N 1AX, London, UK
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3
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Iliopoulos F, Tu D, Pence IJ, Li X, Ghosh P, Luke MC, Raney SG, Rantou E, Evans CL. Determining topical product bioequivalence with stimulated Raman scattering microscopy. J Control Release 2024; 367:864-876. [PMID: 38346503 DOI: 10.1016/j.jconrel.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 02/19/2024]
Abstract
Generic drugs are essential for affordable medicine and improving accessibility to treatments. Bioequivalence (BE) is typically demonstrated by assessing a generic product's pharmacokinetics (PK) relative to a reference-listed drug (RLD). Accurately estimating cutaneous PK (cPK) at or near the site of action can be challenging for locally acting topical products. Certain cPK approaches are available for assessing local bioavailability (BA) in the skin. Stimulated Raman scattering (SRS) microscopy has unique capabilities enabling continuous, high spatial and temporal resolution and quantitative imaging of drugs within the skin. In this paper, we developed an approach based on SRS and a polymer-based standard reference for the evaluation of topical product BA and BE in human skin ex vivo. BE assessment of tazarotene-containing formulations was achieved using cPK parameters obtained within different skin microstructures. The establishment of BE between the RLD and an approved generic product was successfully demonstrated. Interestingly, within the constraints of the current study design the results suggest similar BA between the tested gel formulation and the reference cream formulation, despite the differences in the formulation/dosage form. Another formulation containing polyethylene glycol as the vehicle was demonstrated to be not bioequivalent to the RLD. Compared to using the SRS approach without a standard reference, the developed approach enabled more consistent and reproducible results, which is crucial in BE assessment. The abundant information from the developed approach can help to systematically identify key areas of study design that will enable a better comparison of topical products and support an assessment of BE.
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Affiliation(s)
- Fotis Iliopoulos
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA
| | - Dandan Tu
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA
| | - Isaac J Pence
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA
| | - Xiaolei Li
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA
| | - Priyanka Ghosh
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring 20993, MD, USA
| | - Markham C Luke
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring 20993, MD, USA
| | - Sam G Raney
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring 20993, MD, USA
| | - Elena Rantou
- Office of Biostatistics, Office of Translational Sciences, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring 20993, MD, USA
| | - Conor L Evans
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA.
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4
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Yu HL, Goh CF. Glycols: The ubiquitous solvent for dermal formulations. Eur J Pharm Biopharm 2024; 196:114182. [PMID: 38224756 DOI: 10.1016/j.ejpb.2024.114182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 01/17/2024]
Abstract
Glycols stand out as one of the most commonly employed safe and effective excipients for pharmaceutical and cosmeceutical products. Their widespread adoption can be attributed to their exceptional solvency characteristics and their ability to interact effectively with skin lipids and keratin for permeation enhancement. Notably, propylene glycol enjoys significant popularity in this regard. Ongoing research endeavours have been dedicated to scrutinising the impact of glycols on dermal drug delivery and shedding light on the intricate mechanisms by which glycols enhance skin permeation. This review aims to mitigate the discordance within the existing literature, assemble a holistic understanding of the impact of glycols on the percutaneous absorption of active compounds and furnish the reader with a profound comprehension of the foundational facets pertaining to their skin permeation enhancement mechanisms, while simultaneously delving deeper into the intricacies of these processes.
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Affiliation(s)
- Hai Long Yu
- Discipline of Pharmaceutical Technology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Choon Fu Goh
- Discipline of Pharmaceutical Technology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia.
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5
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Ando K, Sugiyama I, Sadzuka Y. Preparation of Transdermal Gel Containing l-Theanine for the Potential Treatment of Premenstrual Syndrome: A Preclinical Study. WOMEN'S HEALTH REPORTS (NEW ROCHELLE, N.Y.) 2024; 5:193-200. [PMID: 38435100 PMCID: PMC10908322 DOI: 10.1089/whr.2023.0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 01/13/2024] [Indexed: 03/05/2024]
Abstract
Background Premenstrual syndrome (PMS) is experienced by many women who suffer from either its psychological or physical symptoms. Current treatment is limited to symptomatic therapy or oral contraceptives. On the other hand, l-theanine, which has a relaxant effect, has been reported to be useful for PMS, but its short half-life when administered orally makes it less effective. Permeability and properties of transdermal gel containing l-theanine were evaluated as a preclinical study of PMS symptoms relief formulation. Materials and Methods Lyogel composed of stearic acid, stearyl alcohol, and propylene glycol was selected. The ratio of these components and the preparation method were investigated. Permeation of Strat-M membranes was evaluated by using Franz cells (in vitro). Moreover, lyogel was applied to institute of cancer research mice's backs for 10 days to examine the permeability of l-theanine. Results l-Theanine solution did not permeate the Strat-M membrane at all in the permeation study, but lyogel allowed l-theanine to permeate. When the composition of lyogel was 4.4:11.1:296 (mmol) for stearic acid, stearyl alcohol, and propylene glycol, l-theanine absorption through Strat-M membrane was better. In skin permeation study using mice, l-theanine was detected in the serum, that is, it was proven that l-theanine penetrated the skin. Conclusion The preparation of transdermal gels contained l-theanine was investigated as a preclinical study. The skin permeability of semisolid formulations of hydrophobic ointments, hydrophilic ointments, oily creams, creams, and lyogel containing theanine was compared and found that lyogel was the best. The composition of lyogel was also studied to obtain a formulation with good application comfort. Although it is suggested that this lyogel could be tested in clinical studies to determine whether it is effective for relief of PMS symptoms, lyogel may be suitable as an easy-to-use l-theanine-containing formulation for women that can relieve PMS symptoms.
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Affiliation(s)
- Kaana Ando
- Division of Pharmaceutical and Health Sciences, Graduate School of Pharmaceutical Science, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan
| | - Ikumi Sugiyama
- Division of Pharmaceutical and Health Sciences, Graduate School of Pharmaceutical Science, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan
- Department of Advanced Pharmaceutics, School of Pharmacy, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan
| | - Yasuyuki Sadzuka
- Division of Pharmaceutical and Health Sciences, Graduate School of Pharmaceutical Science, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan
- Department of Advanced Pharmaceutics, School of Pharmacy, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan
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6
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Kovács A, Falusi F, Gácsi A, Budai-Szűcs M, Csányi E, Veréb Z, Monostori T, Csóka I, Berkó S. Formulation and investigation of hydrogels containing an increased level of diclofenac sodium using risk assessment tools. Eur J Pharm Sci 2024; 193:106666. [PMID: 38081373 DOI: 10.1016/j.ejps.2023.106666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 01/21/2024]
Abstract
Transdermal delivery of active ingredients is a challenge for pharmaceutical technology due to their inadequate penetration properties and the barrier function of the skin. The necessity of painless, effective, topical therapy for the aging population is growing, and a variety of diclofenac sodium-containing semi-solid preparations are available to alleviate the symptoms of these ailments. Our purpose was to formulate a novel composition with higher drug content to enhance drug release and permeation, thereby providing more effective therapy. Another goal was to maintain the concentration of the organic solvent mixture below 30%, to protect the skin barrier. Firstly, literature and market research were conducted, based on which the appropriate excipients for the target formulation were selected. Solubility tests were conducted with binary and ternary mixtures. As a result, the optimal ternary mixture was chosen. Hydrogels containing 1, 5, and 7% of diclofenac sodium were prepared and the stability of the formulations were studied by microscopic measurements and cytotoxicity test were carried out of the components also. The release and permeation of diclofenac sodium were investigated in different concentrations. It can be concluded that we have succeeded in preparing a topically applicable stable diclofenac sodium hydrogel with higher concentration, drug release, and improved skin permeation than the formulations available on the market.
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Affiliation(s)
- Anita Kovács
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Fanni Falusi
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Attila Gácsi
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Mária Budai-Szűcs
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Erzsébet Csányi
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Zoltán Veréb
- Department of Dermatology and Allergology, Regenerative Medicine and Cellular Pharmacology Laboratory, University of Szeged, Szeged 6720, Hungary; Centre of Excellence for Interdisciplinary Research, Development and Innovation, University of Szeged, Szeged 6720, Hungary; Hungarian Centre of Excellence for Molecular Medicine-USz Skin Research Group, University of Szeged, Szeged 6720, Hungary
| | - Tamás Monostori
- Department of Dermatology and Allergology, Regenerative Medicine and Cellular Pharmacology Laboratory, University of Szeged, Szeged 6720, Hungary; Centre of Excellence for Interdisciplinary Research, Development and Innovation, University of Szeged, Szeged 6720, Hungary
| | - Ildikó Csóka
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary
| | - Szilvia Berkó
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, 6 Eötvös St., Szeged H-6720, Hungary.
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7
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Cheng S, Zhou K, Wang F, Ye Z, Ye C, Lian C, Shang Y, Liu H. Unraveling the Molecular Mechanisms of Alcohol-Mediated Skin Permeation Enhancement: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:594-603. [PMID: 38115608 DOI: 10.1021/acs.langmuir.3c02809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The application of alcohols as permeation enhancers in pharmaceutical and cosmetic formulations has attracted considerable attention, owing to their skin permeation-enhancing effect. Nonetheless, the elucidation of the fundamental mechanisms underlying the skin permeation-enhancing effect remains elusive. In this study, molecular dynamics (MD) simulations were employed to investigate the effect of 1,2-propanediol (1,2-PDO), 1,2-butanediol (1,2-BDO), and ethanol (EtOH) on the stratum corneum (SC) model membrane. The results showed that the effect of alcohols on the SC model membrane displayed a concentration-dependent nature. The alcohols can interact with SC lipids and exhibit a remarkable ability to selectively extract free fatty acid (FFA) molecules from the SC model membrane and make the SC looser. Meanwhile, 1,2-BDO and EtOH can penetrate into SC lipid bilayers at higher concentrations, leading to the formation of continuous hydrophilic defects in SC. The FFA extraction and the formation of continuous hydrophilic defects induced ceramide (CER) tail chains to become more disordered and fluid and also weakened the hydrogen bonding (H-bonding) network among SC lipids. Both the FFA extraction and the continuous hydrophilic defect formation endowed alcohols with the permeation-enhancing effect. The constrained simulations revealed that the free energy barriers decreased for the permeation of the hydrophilic model molecule (COL) across the SC model membranes containing alcohols, particularly for 1,2-BDO and EtOH. The possible permeation-enhancing mechanisms of alcohols were proposed correspondingly. This work not only provided a deep understanding of the transdermal permeation-enhancing behavior of alcohols at the molecular level but also provided necessary reference information for designing effective transdermal drug delivery systems in applications.
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Affiliation(s)
- Shiqiang Cheng
- Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Kangfu Zhou
- Yunnan Botanee Bio-technology Group Co., Ltd., Yunnan 650106, China
| | - Feifei Wang
- Yunnan Botanee Bio-technology Group Co., Ltd., Yunnan 650106, China
- Yunnan Yunke Characteristic Plant Extraction Laboratory Co., Ltd., Yunnan 650106, China
| | - Zhicheng Ye
- Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Chuanjun Ye
- Yunnan Botanee Bio-technology Group Co., Ltd., Yunnan 650106, China
| | - Cheng Lian
- Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yazhuo Shang
- Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Honglai Liu
- Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
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8
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Sohn JS, Choi JS. Development of a tadalafil transdermal formulation and evaluation of its ability to in vitro transdermal permeate using Strat-M® membrane. Eur J Pharm Sci 2024; 192:106615. [PMID: 37863443 DOI: 10.1016/j.ejps.2023.106615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/23/2023] [Accepted: 10/17/2023] [Indexed: 10/22/2023]
Abstract
Tadalafil (TDF) has low water solubility, high intestinal permeability and belongs to the Biopharmaceutics Classification System (BCS) Class II. Due to high intestinal permeability, only oral administration (tablets) and oral thin film formulations have been developed. Therefore, it is necessary to develop various formulations, such as external formulations and transdermal absorption formulations requested by patients. The purpose of this study is to improve the solubility and skin permeability of TDF, and to develop a novel transdermal formulation with secured stability over time. The research strategy is to determine solvents that will improve TDF solubility and to screen substances that will enhance TDF permeability. Skin penetration tests were simulated by using a Strat-M® membrane in Franz diffusion cell systems. The optimal formulation (F1, consisting of TDF/HDTMA-Br at a ratio of 1:10 [weight/weight] in DPG) observed the highest permeability compared to all formulations in PBS (pH 7.4). Changes in thermal property of F1 formulation was observed and maintained its stability over 12 months including drug content (μg/mL), appearance, pH, and permeation (μg/cm2). In conclusion, DPG played a supported role in improving both TDF solubilization and permeability, whereas HDTMA-Br played a key role in enhancing permeability. It is thought that these results will be supplemented in the future to conduct research and experiments on humans.
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Affiliation(s)
- Jeong Sun Sohn
- College of General Education, Chosun University, Gwangju 61452, Republic of Korea
| | - Jin-Seok Choi
- Department of Medical Management, Chodang University, 380 Muan-ro, Muan-eup, Muan-gun, Jeollanam-do 58530, Republic of Korea.
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9
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Sohn JS, Choi JS. Development and evaluation of niacinamide transdermal formulation by artificial membrane permeability. Saudi Pharm J 2023; 31:1229-1236. [PMID: 37284416 PMCID: PMC10239687 DOI: 10.1016/j.jsps.2023.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/14/2023] [Indexed: 06/08/2023] Open
Abstract
Despite many efforts to improve the transdermal permeability of drugs, most of them are blocked by the skin barrier. Niacinamide (NAC) is a Biopharmaceutics Classification System class I drug with high aqueous solubility and intestinal permeability. Due to the high solubility and intestinal permeability of NAC, the development of new formulations is insufficient as transdermal, injection etc. Thus, this study aimed to develop the novel NAC formulation with improved skin permeability and secured stability. The NAC formulation approach is to first select a solvent that improves skin permeability, and then select a second penetration enhancer to determine the final formulation. All formulations were evaluated for skin permeability using an artificial membrane (Strat-M®). The optimal formulation (non-ionic formulations (NF1) consisted of NAC/Tween®80 = 1:1 wt ratio in dipropylene glycol [DPG]) showed the highest permeability in all formulations in PBS buffer (pH 7.4). The thermal properties of NF1 were altered. Moreover, NF1 maintained a stable drug content, appearance, and pH value for 12 months. In conclusion, DPG had an excellent effect in increasing the NAC permeation, and Tween®80 played a boosting role. Through this study, an innovative NAC formulation was developed, and good results are expected for human transdermal research.
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Affiliation(s)
- Jeong Sun Sohn
- College of General Education, Chosun University, PhD, Associate Professor, Gwangju 61452, Republic of Korea
| | - Jin-Seok Choi
- Department of Medical Management, Chodang University, Ph. D, Assistant Professor, 380 Muan-ro, Muan-eup, Muan-gun, Jeollanam-do 58530, Republic of Korea
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10
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de Araujo DR, Padula C. Topical Drug Delivery: Innovative Controlled Release Systems. Pharmaceutics 2023; 15:1716. [PMID: 37376164 DOI: 10.3390/pharmaceutics15061716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023] Open
Abstract
One of the most innovative strategies for administrating bioactive molecules is the design of adequate drug delivery systems [...].
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Affiliation(s)
- Daniele Ribeiro de Araujo
- Human and Natural Sciences Center, ABC Federal University, Santo Andre 09210-580, SP, Brazil
- Drugs and Bioactives Delivery Systems Research Group-SISLIBIO, ABC Federal University, Santo Andre 09210-580, SP, Brazil
| | - Cristina Padula
- Department of Food and Drug, University of Parma, Parco Area delle Scienze, 27/a, 43124 Parma, Italy
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11
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Iliopoulos F, Tang CF, Li Z, Rahma A, Lane ME. Confocal Raman Spectroscopy for Assessing Bioequivalence of Topical Formulations. Pharmaceutics 2023; 15:pharmaceutics15041075. [PMID: 37111561 PMCID: PMC10142145 DOI: 10.3390/pharmaceutics15041075] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/21/2023] [Accepted: 03/25/2023] [Indexed: 03/29/2023] Open
Abstract
The evaluation of bioequivalence (BE) for topical dermatological drug products is challenging, and there has been significant interest from regulatory authorities in developing new BE methodologies in recent years. Currently, BE is demonstrated by comparative clinical endpoint studies; these are costly and time-consuming and often lack sensitivity and reproducibility. Previously, we reported excellent correlations between in vivo Confocal Raman Spectroscopy in human subjects and in vitro skin permeation testing (IVPT) with the human epidermis for skin delivery of ibuprofen and a number of excipients. The aim of the present proof-of-concept study was to evaluate CRS as a method to assess BE of topical products. Two commercially available formulations, Nurofen Max Strength 10% Gel and Ibuleve Speed Relief Max Strength 10% Gel, were selected for evaluation. Delivery of ibuprofen (IBU) to the skin was determined in vitro and in vivo by IVPT and CRS, respectively. The formulations examined were found to deliver comparable amounts of IBU across the skin over 24 h in vitro (p > 0.05). Additionally, the formulations resulted in similar skin uptake values measured with CRS in vivo, either at 1 h or 2 h after application (p > 0.05). This is the first study to report the capability of CRS for the demonstration of BE of dermal products. Future studies will focus on the standardisation of the CRS methodology for a robust and reproducible pharmacokinetic (PK)-based evaluation of topical BE.
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12
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Iliopoulos F, Goh CF, Haque T, Rahma A, Lane ME. Dermal Delivery of Diclofenac Sodium-In Vitro and In Vivo Studies. Pharmaceutics 2022; 14:2106. [PMID: 36297542 PMCID: PMC9607602 DOI: 10.3390/pharmaceutics14102106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/25/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022] Open
Abstract
Previously, we reported the use of confocal Raman spectroscopy (CRS) as a novel non-invasive approach to determine drug disposition in the skin in vivo. Results obtained by CRS were found to correlate with data from the well-established in vitro permeation test (IVPT) model using human epidermis. However, these studies used simple vehicles comprising single solvents and binary or ternary solvent mixtures; to date, the utility of CRS for monitoring dermal absorption following application of complex marketed formulations has not been examined. In the present work, skin delivery of diclofenac sodium (DFNa) from two topical dermatological drug products, namely Diclac® Lipogel 10 mg/g and Primofenac® Emulsion gel 1%, was determined by IVPT and in vivo by both CRS and tape stripping (TS) methodologies under similar experimental conditions. The in vivo data were evaluated against the in vitro findings, and a direct comparison between CRS and TS was performed. Results from all methodologies showed that Diclac promoted significantly greater DFNa delivery to the skin (p < 0.05). The cumulative amounts of DFNa which permeated at 24 h in vitro for Diclac (86.5 ± 9.4 µg/cm2) were 3.6-fold greater than the corresponding amounts found for Primofenac (24.4 ± 2.7 µg/cm2). Additionally, total skin uptake of DFNa in vivo, estimated by the area under the depth profiles curves (AUC), or the signal intensity of the drug detected in the upper stratum corneum (SC) (4 µm) ranged from 3.5 to 3.6-fold greater for Diclac than for Primofenac. The shape of the distribution profiles and the depth of DFNa penetration to the SC estimated by CRS and TS were similar for the two methods. However, TS data indicated a 4.7-fold greater efficacy of Diclac relative to Primofenac, with corresponding total amounts of drug penetrated, 94.1 ± 22.6 µg and 20.2 ± 7.0 µg. The findings demonstrate that CRS is a methodology that is capable of distinguishing skin delivery of DFNa from different formulations. The results support the use of this approach for non-invasive evaluation of topical products in vivo. Future studies will examine additional formulations with more complex compositions and will use a wider range of drugs with different physicochemical properties. The non-invasive nature of CRS coupled with the ability to monitor drug permeation in real time offer significant advantages for testing and development of topical dermatological products.
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Affiliation(s)
- Fotis Iliopoulos
- Department of Pharmaceutics, UCL School of Pharmacy, 29–39 Brunswick Square, London WC1N 1AX, UK
| | - Choon Fu Goh
- Discipline of Pharmaceutical Technology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden 11800, Penang, Malaysia
| | - Tasnuva Haque
- Department of Pharmaceutics, UCL School of Pharmacy, 29–39 Brunswick Square, London WC1N 1AX, UK
| | - Annisa Rahma
- Department of Pharmaceutics, UCL School of Pharmacy, 29–39 Brunswick Square, London WC1N 1AX, UK
- Pharmaceutics Department, School of Pharmacy, Institut Teknologi Bandung, Bandung 40132, Indonesia
| | - Majella E. Lane
- Department of Pharmaceutics, UCL School of Pharmacy, 29–39 Brunswick Square, London WC1N 1AX, UK
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13
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Reconstructed Human Epidermis: An Alternative Approach for In Vitro Bioequivalence Testing of Topical Products. Pharmaceutics 2022; 14:pharmaceutics14081554. [PMID: 35893811 PMCID: PMC9331624 DOI: 10.3390/pharmaceutics14081554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 02/04/2023] Open
Abstract
The use of in vitro human skin permeation tests is of value when addressing the quality and equivalence of topical drug products in Europe and the US. Human skin is the membrane of choice for these studies. The use of human skin as a membrane is hindered by limited access, high variability of results, and limited applicability for drugs with low skin permeability. Reconstructed human epidermis (RhE) models are validated as skin surrogates for safety tests and have been explored for percutaneous absorption testing. Clotrimazole poorly permeates human skin and is widely available for topical treatments. In this study, clotrimazole creams were used to test the ability of RhE to be used as biological membrane for bioequivalence testing, based on the Draft Guideline on Quality and Equivalence of Topical Products (CHMP/QWP/708282/2018) using a discriminative and modified in vitro permeation test (IVPT). To fulfill the validation of a discriminatory method, Canesten® 10 mg/g cream was compared with a test product with the same drug strength, along with two “negative controls” dosed at a 50% and 200% drug strength. Products were compared in finite dose conditions, regarding maximal flux (Jmax) and the total amount of drug permeated (Atotal). The results showed the discriminatory power of the method among the three drug strengths with no interference of the placebo formulation. The study design and validation complied with the requirements established in the guideline for a valid IVPT. This new test system allowed for the equivalence comparison between test and comparator product. Higher permeability of the RhE compared to human skin could be observed. This arose as a strength of the model for this modified IVPT bioequivalence testing, since comparing permeation profiles among products is envisaged instead of drawing absolute conclusions on skin permeation extent. These results may support the acceptance of RhE as biological membranes for modified IVPT in bioequivalence testing of topical products.
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14
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Kocsis D, Klang V, Schweiger EM, Varga-Medveczky Z, Mihály A, Pongor C, Révész Z, Somogyi Z, Erdő F. Characterization and ex vivo evaluation of excised skin samples as substitutes for human dermal barrier in pharmaceutical and dermatological studies. Skin Res Technol 2022; 28:664-676. [PMID: 35726964 PMCID: PMC9907592 DOI: 10.1111/srt.13165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 05/03/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Excised animal and human skins are frequently used in permeability testing in pharmaceutical research. Several factors exist that may have influence on the results. In the current study some of the skin parameters that may affect drug permeability were analysed for human, mouse, rat and pig skin. MATERIALS AND METHODS Classic biophysical skin parameters were measured (e.g. pH, hydration, permittivity, transepidermal water loss). Physiological characteristics of the skins were also analysed by confocal Raman spectroscopy, scanning electron microscopy and two-photon microscopy. RESULTS Based on biophysical testing, skin barrier function was damaged in psoriatic mouse skin and in marketed pig skin. Hydration and pH values were similar among the species, but freezing and thawing reduced the water content of the skins and shifted the surface pH to acidic. Aging reduced hydration and permittivity, resulting in impaired barrier function. Mechanical sensitization used in permeability studies resulted in proportional thinning of dead epidermis. DISCUSSION Results indicate that depending on the scientific question it should be considered whether fresh or frozen tissue is used, and for certain purposes rodent skins are well usable. The structure of the skin tissue (ceramide, cholesterol, keratin, natural moisturizing factor or urea) is similar in rats and mice, but due to the higher skin thickness the lipid distribution is different in porcine skin. Psoriasis led to irregular chemical composition of the skin. CONCLUSION A comprehensive evaluation of skin samples of four species was performed. The biophysical and microscopic observations should be considered when selecting drug penetration models and experimental conditions.
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Affiliation(s)
- Dorottya Kocsis
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Victoria Klang
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Eva-Maria Schweiger
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Zsófia Varga-Medveczky
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Anna Mihály
- Institute of Experimental Medicine, H-1094, Budapest, Hungary
| | - Csaba Pongor
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | | | - Zoltán Somogyi
- Department of Pharmacology and Toxicology, University of Veterinary Medicine, Budapest, Hungary
| | - Franciska Erdő
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
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15
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da Costa Bernardo Port B, Schneider-Rauber G, Fretes Argenta D, Arhangelskis M, de Campos CEM, João Bortoluzzi A, Caon T. Effect of Vehicle Composition on the Preparation of Different Types of Dapsone Crystals for Topical Drug Delivery. Mol Pharm 2022; 19:2164-2174. [PMID: 35708215 DOI: 10.1021/acs.molpharmaceut.2c00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Topical formulations composed of API-pure crystals have been increasingly studied, especially in regards to the impact of particle size in penetration efficiency. Less attention, however, has been devoted to the solid-state properties of drugs delivered to the skin. In this study, we address the effect of formulation composition on the crystal form existing in topical products. Dapsone (DAP) gel formulations were prepared by mixing an organic solution containing DAP with an aqueous solution containing polymers and preservatives. The organic solvent was chosen as ethoxydiglycol (DEGEE), polyethylene glycol (PEG), or 1-methyl-2-pirrolidone (MPR) to assess the impact of composition on DAP crystal form. Such solvent variations resulted in different particulate matter. In terms of crystalline nature, the presence of DEGEE in formulations induced the crystallization of DAP hydrate, while PEG cocrystal and a mixture of hydrate and MPR solvate crystallized from the same amounts of PEG and MPR, respectively. Microscopic analysis of the gels showed heterogeneous particles with different characteristics. The behavior of gels after application to the skin was also tested. Interestingly, the different formulations seemed to accumulate in different regions of the skin. This could be the result of the effect of vehicle composition/excipients on the characteristics of the skin, such as hydration. The site-specific accumulation, however, was more pronounced in crystal-loaded gels as opposed to blank formulations. These results indicate that future studies should consider the effect of formulation composition on the API crystal form landscape as part of the strategies used to successfully target drug delivery to the skin.
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Affiliation(s)
| | | | | | - Mihails Arhangelskis
- Faculty of Chemistry, University of Warsaw, 1 Pasteura Street, Warsaw 02-093, Poland
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16
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In vitro human skin absorption of Linalool: effects of vehicle composition, evaporation and occlusion on permeation and distribution. Int J Pharm 2022; 622:121826. [DOI: 10.1016/j.ijpharm.2022.121826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/04/2022] [Accepted: 05/09/2022] [Indexed: 11/21/2022]
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17
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Hummer J, Birngruber T, Sinner F, Page L, Toner F, Roper CS, Moore DJ, Baker MB, Boncheva Bettex M. Optimization of topical formulations using a combination of in vitro methods to quantify the transdermal passive diffusion of drugs. Int J Pharm 2022; 620:121737. [PMID: 35413396 DOI: 10.1016/j.ijpharm.2022.121737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/06/2022] [Accepted: 04/07/2022] [Indexed: 10/18/2022]
Abstract
This paper describes a new approach to the early-stage optimization of topical products and selection of lead formulation candidates. It demonstrates the application of open flow microperfusion in vitro in conjunction with the Franz diffusion cell to compare time-resolved, 24-hour profiles of diclofenac passive diffusion through all skin layers (including the skin barrier, dermis, and subcutis) resulting from nine topical formulations of different composition. The technique was successfully validated for in vitro sampling of diclofenac in interstitial fluid. A multi-compartmental model integrating the two datasets was analyzed and revealed that the passive diffusion of diclofenac through the dermis and subcutis does not correlate with its diffusion through the skin barrier and cannot be predicted using Franz diffusion cell data alone. The combined application of the two techniques provides a new, convenient tool for product development and selection enabling the comparison of topical formulation candidates and their impact on drug delivery through all skin layers. This approach can also generate the experimental data required to improve the robustness of mechanistic PBPK models, and when combined with clinical sampling via open flow microperfusion - for the development of better in vivo-in vitro correlative models.
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Affiliation(s)
- Joanna Hummer
- Joanneum Research Forschungsgesellschaft mbH, Health-Institute for Biomedicine and Health Sciences, Neue Stiftingtalstraße 2, 8010 Graz, Austria
| | - Thomas Birngruber
- Joanneum Research Forschungsgesellschaft mbH, Health-Institute for Biomedicine and Health Sciences, Neue Stiftingtalstraße 2, 8010 Graz, Austria
| | - Frank Sinner
- Joanneum Research Forschungsgesellschaft mbH, Health-Institute for Biomedicine and Health Sciences, Neue Stiftingtalstraße 2, 8010 Graz, Austria
| | - Leanne Page
- Charles River Laboratories, Tranent, Edinburgh, EH33 2NE, UK
| | - Frank Toner
- Charles River Laboratories, Tranent, Edinburgh, EH33 2NE, UK
| | - Clive S Roper
- Roper Toxicology Consulting Limited, 6 St Colme Street, Edinburgh, EH3 6AD, UK
| | - David J Moore
- GSK Consumer Healthcare, 184 Liberty Corner Rd, Warren, NJ 07059, USA
| | - Mark B Baker
- GSK Consumer Healthcare SARL, Route de l'Etraz 2, Case postale 1279, 1260 Nyon 1, Switzerland
| | - Mila Boncheva Bettex
- GSK Consumer Healthcare SARL, Route de l'Etraz 2, Case postale 1279, 1260 Nyon 1, Switzerland.
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18
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Goh CF, Hadgraft J, Lane ME. Thermal analysis of mammalian stratum corneum using differential scanning calorimetry for advancing skin research and drug delivery. Int J Pharm 2022; 614:121447. [PMID: 34998922 DOI: 10.1016/j.ijpharm.2021.121447] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 11/15/2022]
Abstract
For effective topical and transdermal drug delivery, it is necessary for most actives to penetrate and permeate through the stratum corneum (SC). Extensive investigation of the thermal behaviour of mammalian SC has been performed to understand the barrier function of the skin. However, little attention has been paid to the related experimental variables in thermal analysis of the SC using differential scanning calorimetry that may influence the results obtained from such studies. In this review, we provide a comprehensive overview of the thermal transitions of the SC of both porcine and human skin. More importantly, the selection and impact of the experimental and instrumental parameters used in thermal analysis of the SC are critically evaluated. New opportunities for the use of thermal analysis of mammalian SC in advancing skin research, particularly for elucidation of the actions of excipients employed in topical and transdermal formulations on the skin are also highlighted.
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Affiliation(s)
- Choon Fu Goh
- Discipline of Pharmaceutical Technology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.
| | - Jonathan Hadgraft
- Department of Pharmaceutics, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Majella E Lane
- Department of Pharmaceutics, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom.
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19
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Rahma A, Lane ME. Skin Barrier Function in Infants: Update and Outlook. Pharmaceutics 2022; 14:433. [PMID: 35214165 PMCID: PMC8880311 DOI: 10.3390/pharmaceutics14020433] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/23/2022] [Accepted: 01/26/2022] [Indexed: 12/10/2022] Open
Abstract
A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.
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Affiliation(s)
- Annisa Rahma
- Pharmaceutics Department, School of Pharmacy, Institut Teknologi Bandung, Bandung 40132, Indonesia
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK;
| | - Majella E. Lane
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK;
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20
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Kis N, Gunnarsson M, Berkó S, Sparr E. The effects of glycols on molecular mobility, structure, and permeability in stratum corneum. J Control Release 2022; 343:755-764. [PMID: 35150813 DOI: 10.1016/j.jconrel.2022.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/28/2022] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The skin provides an attractive alternative to the conventional drug administration routes. Still, it comes with challenges as the upper layer of the skin, the stratum corneum (SC), provides an efficient barrier against permeation of most compounds. One way to overcome the skin barrier is to apply chemical permeation enhancers, which can modify the SC structure. In this paper, we investigated the molecular effect of three different types of glycols in SC: dipropylene glycol (diPG), propylene glycol (PG), and butylene glycol (BG). The aim is to understand how these molecules influence the molecular mobility and structure of the SC components, and to relate the molecular effects to the efficiency of these molecules as permeation enhancers. We used complementary experimental techniques, including natural abundance 13C NMR spectroscopy and wide-angle X-ray diffraction to characterize the molecular consequences of these compounds at different doses in SC at 97% RH humidity and 32 °C. In addition, we study the permeation enhancing effects of the same glycols in comparable conditions using Raman spectroscopy. Based on the results from NMR, we conclude that all three glycols cause increased mobility in SC lipids, and that the addition of glycols has an effect on the keratin filaments in similar manner as Natural Moisturizing Factor (NMF). The highest mobility of both lipids and amino acids can be reached with BG, which is followed by PG. It is also shown that one reaches an apparent saturation level for all three chemicals in SC, after which increased addition of the compound does not lead to further increase in the mobility of SC lipids or protein components. The examination with Raman mapping show that BG and PG give a significant permeation enhancement as compared to SC without any added glycol at corresponding conditions. Finally, we observe a non-monotonic response in permeation enhancement with respect to the concentration of glycols, where the highest concentration does not give the highest permeation. This is explained by the dehydration effects at highest glycol concentrations. In summary, we find a good correlation between the molecular effects of glycols on the SC lipid and protein mobility, and macroscopic permeation enhances of the same molecules.
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Affiliation(s)
- Nikolett Kis
- Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, 6720 Szeged, Hungary.
| | - Maria Gunnarsson
- Division of Physical Chemistry, Chemistry Department, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
| | - Szilvia Berkó
- Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, 6720 Szeged, Hungary.
| | - Emma Sparr
- Division of Physical Chemistry, Chemistry Department, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
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