Formulation and investigation of hydrogels containing an increased level of diclofenac sodium using risk assessment tools.

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.

In situ gelation of thiolated poly(aspartic acid) derivatives through oxidant-free disulfide formation for ophthalmic drug delivery.

Efficient topical treatment of ocular diseases requires a prolonged residence time of drug formulations. An in situ gelling, mucoadhesive system can provide improved residence time while keeps the installation of the formulation easy and accurate due to its low initial viscosity. We synthesized a two-component, biocompatible water-based liquid formulation showing in situ gelation upon mixing. S-protected, preactivated derivatives of thiolated poly(aspartic acid) (PASP-SS-MNA) were synthesized by coupling the free thiol groups of thiolated poly(aspartic acid) (PASP-SH) with 6-mercaptonicotinic acid (MNA). The amount of protecting groups was 242, 341, and 530 µmol/g depending on the degree of thiolation of PASP. The chemical interaction between PASP-SS-MNA and mucin was proven, indicating the mucoadhesive properties. Disulfide cross-linked hydrogels were formed in situ without an oxidizing agent by mixing the aqueous solutions of PASP-SS-MNA and PASP-SH. The gelation time was controlled between 1 and 6 min, while the storage modulus was as high as 4-16 kPa depending on the composition. Swelling experiments showed that hydrogels with no residual thiol groups are stable in phosphate-buffered saline at pH = 7.4. In contrast, the presence of free thiol groups leads to the dissolution of the hydrogel with a rate depending on the excess of thiol groups. The biological safety of the polymers and MNA was confirmed on Madin-Darby Canine Kidney cell line. Furthermore, a prolonged release of ofloxacin was observed at pH = 7.4 compared to a conventional liquid formulation, supporting the potential of the developed biopolymers in ophthalmic drug delivery.

Development of Capsaicin-Containing Analgesic Silicone-Based Transdermal Patches.

Transdermal therapeutic systems (TTSs) enable convenient dosing in drug therapy. Modified silicone-polymer-based patches are well-controlled and cost-effective matrix diffusion systems. In the present study, we investigated the substance release properties, skin penetration, and analgesic effect of this type of TTS loaded with low-dose capsaicin. Release properties were measured in Franz diffusion cell and continuous flow-through cell approaches. Capsaicin was detected with HPLC-UV and UV spectrophotometry. Raman spectroscopy was conducted on human skin samples exposed to the TTS. A surgical incision or carrageenan injection was performed on one hind paw of male Wistar rats. TTSs were applied to the epilated dorsal skin. Patches were kept on the animals for 6 h. The thermal hyperalgesia and mechanical pain threshold of the hind paws were detected. Patches exhibited controlled, zero-order kinetic capsaicin release. According to the Raman mapping, capsaicin penetrated into the epidermis and dermis of human skin, where the target receptors are expressed. The thermal pain threshold drop of the operated rat paws was reversed by capsaicin treatment compared to that of animals treated with control patches. It was concluded that our modified silicone-polymer-based capsaicin-containing TTS is suitable for the relief of traumatic and inflammatory pain.

Analytical Quality by Design (AQbD) Approach to the Development of In Vitro Release Test for Topical Hydrogel.

The aim of our study was to adapt the analytical quality by design (AQbD) approach to design an effective in vitro release test method using USP apparatus IV with a semi-solid adapter (SSA) for diclofenac sodium hydrogel. The analytical target profile (ATP) of the in vitro release test and ultra-high-performance liquid chromatography were defined; the critical method attributes (CMAs) (min. 70% of the drug should be released during the test, six time points should be obtained in the linear portion of the drug release profile, and the relative standard deviation of the released drug should not be over 10%) were selected. An initial risk assessment was carried out, in which the CMAs (ionic strength, the pH of the media, membrane type, the rate of flow, the volume of the SSA (sample amount), the individual flow rate of cells, drug concentration %, and the composition of the product) were identified. With the results, it was possible to determine the high-risk parameters of the in vitro drug release studies performed with the USP apparatus IV with SSA, which were the pH of the medium and the sample weight of the product. Focusing on these parameters, we developed a test protocol for our hydrogel system.

Investigation of the effect of polymers on dermal foam properties using the QbD approach.

Dermal foams are promising drug delivery systems due to their many advantages and ease of application. Foams are also considered a novelty in the field of dermatology. In particular, they are beneficial for the treatment of skin conditions where patients have highly inflamed, swollen, infected and sensitive skin, as the application of the foam to the skin surface to be treated minimizes the need for skin contact. In order to formulate foams, it is necessary to know which material and process parameters influence the quality characteristics of foams and which methods can be used to study foams; this part of the research is assisted by the QbD approach. By using the QbD concept, it contributed during the development process to ensure quality-based development. With initial risk assessment, the critical material attributes (CMAs) and the critical process parameters (CPPs) were identified to ensure the required critical quality attributes (CQAs). During the initial risk assessment, five high-risk CQAs, namely foam volume stability, foam expansion, cross point, the initial values of the number and size of bubbles, and three medium-risk CQAs, namely spreadability, relative foam density and viscosity of the liquid system were identified and investigated. In this research, different types of polymers (xanthan gum, hydroxyethylcellulose, different types of hyaluronic acids) were used to improve the properties of foam formulations. The formulations containing xanthan gum and high molecular weight hyaluronic acid had good foam properties and will be appropriate delivery systems for an active pharmaceutical ingredient. Overall, the polymer content had a great effect on the properties of the foams. Different polymers affect the properties of foams in different ways. When used in combination, the methods reinforce each other and help to select a formula for dermal application.

Comparison of Synthetic Membranes to Heat-Separated Human Epidermis in Skin Permeation Studies In Vitro.

In recent years, the study of dermal preparations has received increased attention. There are more and more modern approaches to evaluate transdermal formulations, which are crucial in proving the efficacy of a formulation. The aim of this study was to compare permeation across innovative synthetic membranes (Strat-M and Skin PAMPA membranes) and heat-separated human epidermis (HSE, gold standard membrane) using four different dermal formulations. The Strat-M and Skin PAMPA membranes were designed to mimic the stratum corneum layer of the human epidermis. There have also been some publications on their use in dermal formulation development, but further information is needed. Drug permeation was measured using formulations containing diclofenac sodium (two hydrogels and two creams). The HSE, Strat-M, and Skin PAMPA membranes proved to be significantly different, but based on the results, the Strat-M membrane showed the greatest similarity to HSE. The permeation data of the different formulations across different membranes showed good correlations with formulations similar to these four, which allows the prediction of permeation across HSE using these synthetic membranes. In addition, Strat-M and Skin PAMPA membranes have the potential to select and differentiate a dermal formulation containing diclofenac sodium as an early screening model.

Rheological effects of hypertonic saline and sodium bicarbonate solutions on cystic fibrosis sputum in vitro.

BACKGROUND: Cystic fibrosis (CF) is a life-threatening multiorgan genetic disease, particularly affecting the lungs, where recurrent infections are the main cause of reduced life expectancy. In CF, mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein impair transepithelial electrolyte and water transport, resulting in airway dehydration, and a thickening of the mucus associated with abnormal viscoelastic properties. Our aim was to develop a rheological method to assess the effects of hypertonic saline (NaCl) and NaHCO3 on CF sputum viscoelasticity in vitro, and to identify the critical steps in sample preparation and in the rheological measurements. METHODS: Sputum samples were mixed with hypertonic salt solutions in vitro in a ratio of either 10:4 or 10:1. Distilled water was applied as a reference treatment. The rheological properties of sputum from CF patients, and the effects of these in vitro treatments, were studied with a rheometer at constant frequency and strain, followed by frequency sweep tests, where storage modulus (G'), loss modulus (G″) and loss factor were determined. RESULTS: We identified three distinct categories of sputum: (i) highly elastic (G' > 100,000 Pa), (ii) elastic (100,000 Pa > G' > 1000 Pa), and (iii) viscoelastic (G' < 1000). At the higher additive ratio (10:4), all of the added solutions were found to significantly reduce the gel strength of the sputum, but the most pronounced changes were observed with NaHCO3 (p < 0.001). Samples with high elasticity exhibited the greatest changes while, for less elastic samples, a weakening of the gel structure was observed when they were treated with water or NaHCO3, but not with NaCl. For the viscoelastic samples, the additives did not cause significant changes in the parameters. When the lower additive ratio (10:1) was used, the mean values of the rheological parameters usually decreased, but the changes were not statistically significant. CONCLUSION: Based on the rheological properties of the initial sputum samples, we can predict with some confidence the treatment efficacy of each of the alternative additives. The marked differences between the three categories suggest that it is advisable to evaluate each sample individually using a rheological approach such as that described here.

Electrospun Scaffolds in Periodontal Wound Healing.

Periodontitis is a set of inflammatory conditions affecting the tissues surrounding the teeth predominantly sustained by bacterial infections. The aim of the work was the design and the development of scaffolds based on biopolymers to be inserted in the periodontal pocket to restore tissue integrity and to treat bacterial infections. Nanofibrous scaffolds were prepared by means of electrospinning. Gelatin was considered as base component and was associated to low and high molecular weight chitosans and alginate. The scaffolds were characterized by chemico-physical properties (morphology, solid state-FTIR and differential scanning calorimetry (DSC)-surface zeta potential and contact angle), and mechanical properties. Moreover, preclinical properties (cytocompatibility, fibroblast and osteoblast adhesion and proliferation and antimicrobial properties) were assessed. All the scaffolds were based on cylindrical and smooth nanofibers and preserved their nanofibrous structure upon hydration independently of their composition. They possessed a high degree of hydrophilicity and negative zeta potentials in a physiological environment, suitable surface properties to enhance cell adhesion and proliferation and to inhibit bacteria attachment. The scaffold based on gelatin and low molecular weight chitosan proved to be effective in vitro to support both fibroblasts and osteoblasts adhesion and proliferation and to impair the proliferation of Streptococcus mutans and Aggregatibacter actinomycetemcomitans, both pathogens involved in periodontitis.

QbD-Based Investigation of Dermal Semisolid in situ Film-Forming Systems for Local Anaesthesia.

PURPOSE: The aim of our research work was to develop dermally applicable, lidocaine hydrochloride (LID-HCl)-containing semisolid in situ film-forming systems (FFSs) using the Quality by Design (QbD) approach to increase drug permeation into the skin. METHODS: Silicones were used to improve the properties of formulations and to increase the permeation through the skin. The QbD approach was applied to ensure quality-based development. With initial risk assessment, the critical material attributes (CMAs) and the critical process parameters (CPPs) were identified to ensure the required critical quality attributes (CQAs). RESULTS: During the initial risk assessment, four high-risk CQAs, namely in vitro drug release, in vitro drug permeation, drying properties, and mechanical properties, and three medium-risk CQAs, namely pH, viscosity, and film appearance were identified and investigated. Moreover, four high-risk CMAs were also considered during the formulation: permeation enhancing excipients, drying excipients, film-forming excipients, and emollients. During the experiments, LID-HCl influenced these critical parameters highly, thereby reducing the drying time. The formulation containing 25% silicone showed the best mechanical properties (49 mN skin adhesion, 20.3% film flexibility, 1.27 N film burst strength), which could predict better patient adherence. In addition, in vitro permeation studies showed that formulation containing 50% silicone has the fastest permeation rate. The flux of diffused API was 6.763 µg/cm2/h, which is much higher compared to the silicone-free formulation (1.5734 µg/cm2/h), and it can already be observed in the lower part of the dermis in 0.5 hour. CONCLUSION: Our results show that LID-HCl has great influence on the critical parameters of FFSs. The silicone content can improve the applicability of formulations and has a favorable effect on the permeation rate of LID-HCl into the skin.

Novel In Vitro Investigational Methods for Modeling Skin Permeation: Skin PAMPA, Raman Mapping.

The human skin is marked as a standard by the regulatory agencies in the permeation study of dermal formulations. Artificial membranes can substitute human skin to some extent. Academicians and pharmaceutical corporations are focusing their efforts on developing standardized protocols and safe, reliable options to substitute human skin for carrying out permeability studies. Our research aim was to study the applicability of new techniques in the case of different types of dermal formulations. The skin parallel artificial membrane permeability assay (PAMPA) method and Raman mapping were compared to the gold-standard Franz cell method. A hydrogel and two types of creams were investigated as the most generally used dermal preparations. The values of the diffused drug were closer to each other in PAMPA and Franz cell measurement. The diffused amount of drug showed the same order for the different formulations. These results correlate well with the results of Raman mapping. Our conclusions suggest that all early screening examinations can be performed with model tools such as skin PAMPA supplemented with methods like Raman mapping as a semi-quantitative method.

Effects of Formulation Excipients on Skin Barrier Function in Creams Used in Pediatric Care.

Semisolid dosage forms are recommended for the dermal care of babies and children. If we look at the ingredients of these preparations, there are still many cases in which there are substances (occlusive agents, preservatives) that no longer meet certain requirements of the modern age, so it is timely to replace them with other substances. The aim of this work was to formulate a science-based formulation with new components that keep or improve its moisturizing properties, rheological parameters, and microbiological stability. Occlusive oils, like white petrolatum and liquid paraffin and the preservative parabens are traditional ingredients in oil in water creams, were replaced with white beeswax, sunflower oil, and phenoxyethanol, respectively. Cocoa butter, urea, and glycerol were added to improve long-lasting hydration and support the barrier function of the reformulated creams. The rheological properties of the formulations were determined. The effects of the preparations on skin hydration and on the barrier function of the skin were tested. Furthermore, microbiological stability was investigated. The result of the reformulation was an o/w cream that provided a good longer-lasting hydration effect; supported the barrier function of the baby skin without occlusion; and had adequate consistency, easy spreading, a pleasant skin feeling, proper pH, and good microbiological stability.

Development and Characterization of Potential Ocular Mucoadhesive Nano Lipid Carriers Using Full Factorial Design.

Generally, topically applied eye drops have low bioavailability due to short residence time and low penetration of the drug. The aim of the present study was to incorporate dexamethasone (DXM) into nano lipid carriers (NLC), which contain mucoadhesive polymer, in order to increase the bioavailability of the drug. A 23 factorial experimental design was applied, in which the three factors were the polymer, the DXM, and the emulsifier concentrations. The samples were analyzed for particle size, zeta potential, polydispersity index, and Span value. The significant factors were identified. The biocompatibility of the formulations was evaluated with human corneal toxicity tests and immunoassay analysis. The possible increase in bioavailability was analyzed by means of mucoadhesivity, in vitro drug diffusion, and different penetration tests, such as in vitro cornea PAMPA model, human corneal cell penetration, and ex vivo porcine corneal penetration using Raman mapping. The results indicated that DXM can be incorporated in stable mucoadhesive NLC systems, which are non-toxic and do not have any harmful effect on cell junctions. Mucoadhesive NLCs can create a depot on the surface of the cornea, which can predict improved bioavailability.

Comparison of hydrophilic ophthalmic media on silicone oil emulsification.

The aim of this study was to investigate whether and how the biological media which are in contact with silicone oil play a role in the silicone emulsification process. Commercially available Oxane 1300 silicone oil and potential hydrophilic phases of the emulsions in the eye (porcine aqueous humor, porcine vitreous and balanced salt solution) were investigated separately and in a mixture or emulsions by means of surface tension, rheological, zeta potential measurements and microscopic investigation. The surface tension of biological media (vitreous and aqueous humor) was significantly lower than that of non-biological media, especially in the case of aqueous humor, which indicates a remarkable emulsification tendency with these phases. The biological media are able to form both oil-in-water and water-in-oil emulsions, which can be observed in the clinical practice as well. It was established that the vitreous has a more expressed emulsification ability compared with the aqueous humor because smaller and more stable droplets can form with silicon oil when the vitreous is still there. It can be concluded that the vitreous has a higher impact on emulsification than the aqueous medium, which can predict that the vitreous remaining after vitrectomy has a key role in emulsion formation in the eye with silicone oil endotamponade.

Electrospun PLA Fibers Containing Metronidazole for Periodontal Disease.

PURPOSE: Electrospun PLA fiber devices were investigated in the form of fiber mats and disks. Metronidazole was used as an active agent; its concentration was 12.2 and 25.7 wt% in the devices. METHODS: The structure was studied by X-ray diffraction and scanning electron microscopy, drug release by dissolution measurements, while the antimicrobial efficiency was tested on five bacterial strains. RESULTS: The XRD study showed that the polymer was partially crystalline in both devices, but a part of metronidazole precipitated and was in the form of crystals among and within the fibers. Liquid penetration and dissolution were different in the two devices, they were faster in disks and slower in fiber mats, due to the morphology of the device and the action of capillary forces. Disks released the drug much faster than fiber mats. Although the release study indicated fast drug dissolution, the concentration achieved a plateau value in 24 hrs for the disks; the inhibition effect lasted much longer, 13 days for bacteria sensitive to metronidazole. The longer inhibition period could be explained by the slower diffusion of metronidazole located inside the fibers of the device. CONCLUSION: The results suggest that the devices may be effective in the treatment of periodontitis.

Design and Optimization of Nanostructured Lipid Carrier Containing Dexamethasone for Ophthalmic Use.

The aim of this study was to perform a preformulation study of dexamethasone (DXM)-loaded nanostructured lipid carriers (NLCs) for ocular use. Lipid screening was applied to find the most suitable solid and liquid lipids and surfactant for the NLC formulation. The visual observation was proved with XRD measurements for the establishment of the soluble state of DXM. Thermoanalytical measurements indicated that the most relevant depression of the crystallinity index could be ensured when using a 7:3 solid lipid:oil ratio. In order to optimize the NLC composition, a 23 full factorial experimental design was used. It was established that each independent factor (lipid, DXM, and surfactant concentration) had a significant effect on the particle size while in the case of entrapment efficiency, the DXM and surfactant concentrations were significant. Lower surfactant and lipid concentrations could be beneficial because the stability and the entrapment efficacy of NLCs were more favorable. The toxicity tests on human cornea cells indicated good ophthalmic tolerability of NLCs. The in vitro drug release study predicted a higher concentration of the solute DXM on the eye surface while the Raman mapping penetration study on the porcine cornea showed a high concentration of nanocarriers in the hydrophylic stroma layer.

Investigation of Silicone-Containing Semisolid in Situ Film-Forming Systems Using QbD Tools.

The aim of our research work was to develop dermally applicable, semisolid film-forming systems (FFSs) containing silicones, which form a film on the skin in situ, with suitable mechanical properties for skin application. FFSs were developed and investigated by means of the Quality by Design (QbD) methodology. With this QbD approach, the initial risk assessment defines the critical quality attributes (CQAs), the critical material attributes (CMAs) and the critical process parameters (CPPs) to ensure the required quality. Different semisolid systems were formed with or without silicones. During the initial risk assessment, three CQAs, namely skin adhesion, film flexibility and burst strength, were found to be critical attributes, while film appearance, film integrity and the drying time of the semisolid system, were found to be medium attributes. These parameters were investigated. The initial risk assessment also showed that there are three high CMAs: the type of silicones, film-forming excipients, drying excipients, and that there was one medium CMA: viscosity-enhancing excipients. Based on our results, the silicone content had a great effect on the film-forming systems. Different silicones affected the mechanical properties of the films in varying ways, decreased the drying time and showed promising results regarding the drying mechanism.

Nanostructured Lipid Carrier Gel for the Dermal Application of Lidocaine: Comparison of Skin Penetration Testing Methods.

The aim of this research was to investigate the stability of a lidocaine-loaded nanostructured lipid carrier dispersion at different temperatures, formulate a nanostructured lipid carrier gel, and test the penetration profile of lidocaine from the nanostructured lipid carrier gel using different skin penetration modeling methods. The formulations were characterized by laser diffraction, rheological measurements and microscopic examinations. Various in vitro methods were used to study drug release, diffusion and penetration. Two types of vertical Franz diffusion cells with three different membranes, including cellulose, Strat-M®, and heat separated human epidermis were used and compared to the Skin-parallel artificial membrane permeability assay (PAMPA) method. Results indicated that the nanostructured lipid carrier dispersion had to be gelified as soon as possible for proper stability. Both the Skin-PAMPA model and Strat-M® membranes correlated favorably with heat separated human epidermis in this research, with the Strat-M® membranes sharing the most similar drug permeability profile to an ex vivo human skin model. Our experimental findings suggest that even when the best available in vitro experiment is selected for modeling human skin penetration to study nanostructured lipid carrier gel systems, relevant in vitro/in vivo correlation should be made to calculate the drug release/permeation in vivo. Future investigations in this field are still needed to demonstrate the influence of membranes and equipment from other classes on other drug candidates.

Combination of Zinc Hyaluronate and Metronidazole in a Lipid-Based Drug Delivery System for the Treatment of Periodontitis.

BACKGROUND: Despite being a highly prevalent disease and a possible contributor to adult tooth loss, periodontitis possesses no well-established therapy. The aim of the recent study was the development and evaluation of a mucoadhesive monophase lipid formulation for the sustained local delivery of amoxicillin, metronidazole, and/or zinc hyaluronate or gluconate. METHODS: To investigate our formulations, differential scanning calorimetry, X-ray diffraction, swelling, erosion, mucoadhesivity, drug release, and antimicrobial measurements were performed. RESULTS: Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results show that the loaded drugs are in a suspended form, the softening of the formulations starts at body temperature, but a part remains solid, providing sustained release. Swelling of the lipid compositions is affected by the hydrophilic components, their concentration, and the strength of the coherent lipid structure, while their erosion is impacted by the emulsification of melted lipid components. CONCLUSIONS: Results of drug release and antimicrobial effectiveness measurements show that a sustained release may be obtained. Amoxicillin had higher effectiveness against oral pathogens than metronidazole or zinc hyaluronate alone, but the combination of the two latter could provide similar effectiveness to amoxicillin. The applied mucoadhesive polymer may affect adhesivity, drug release through the swelling mechanism, and antimicrobial effect as well.

Development of Topical Nanocarriers for Skin Cancer Treatment Using Quality by Design Approach.

BACKGROUND: One of the most compelling medical challenges of this century is the treatment of cancer and among them, skin cancer is the most common type. Thus, current treatments need to be renewed continuously to handle this challenge. OBJECTIVE: This review presents considerations which can be employed during the development of nanosized formulations dedicated to the topical treatment of skin cancer. We aimed to collect and organize literature data on the treatment options for skin cancer in order to determine the required quality attributes of an effective dermal anticancer formulation. METHOD: With the consideration of the Quality by Design (QbD) approach related to the development of new pharmaceutical formulations, a cost-saving process ensuring a high-quality product taking into account patient expectations, industrial and regulatory aspects can be achieved. Furthermore, this concept is highly recommended by regulatory agencies. RESULTS: Our work discusses the current therapies, active agents, drug carrier systems, and evaluation methods in connection with the treatment of skin cancer and outlines Critical Quality Attributes which need to be considered during the development of a nanosized dermal anticancer formulation. CONCLUSION: The first part of this review summarizes the most important topical treatment therapies for skin cancer and highlights the future therapeutic perspectives, focusing on the benefits of nanotechnology and dermal administration. The second part outlines the critical points of nanosized dermal anticancer formulation development in the view of QbD approach. Our research emphasizes the application of QbD method for a rationalized and more effective anticancer formulation development process.

Papaverine hydrochloride containing nanostructured lyotropic liquid crystal formulation as a potential drug delivery system for the treatment of erectile dysfunction.

PURPOSE: Papaverine hydrochloride (PaHCl) is an old, well-known drug with spasmolytic activity but it has therapeutic effect in erectile dysfunction, too. As an intracavernous injection, it is not used in urologic clinics today because the side effects of the injection are pain, scarring or priapism. Our aim was to develop and test a topical semi-solid preparation containing PaHCl that would provide an alternative administration option by eliminating the undesirable side effects of the injection. MATERIALS AND METHODS: Lyotropic liquid crystal (LLC) systems were formulated as a semi-solid preparation with different concentrations of PaHCl. The characterization of the LLC structure was performed by polarization microscopy using a Leica image analyzer and rheological measurements. The drug diffusion and penetration tests were performed with in vitro synthetic membrane and an ex vivo human epidermis, using Franz diffusion cell to test the skin penetration of PaHCl. Human skin was investigated by Raman microscope to visualize the Active Pharmaceutical Ingredient (API) in different skin layers. RESULTS: The results of diffusion and penetration showed reverse concentration dependency. The in vitro and ex vivo studies correlated with each other and the results of Raman microscopy. The LLC structure influenced the penetration results, the lower viscosity and lamellar structure increased penetration through the skin. CONCLUSION: Based on our results, a PaHCl containing topically used LLC formulation may be a suitable and effective alternative to the injectable formulation.