Effect of Salt Form on Gelation and Drug Delivery Properties of Diclofenac-Loaded Poloxamer Gels for Delivery to Impaired Skin

Co-delivery of minoxidil and finasteride via ionic liquid and cyclodextrin-assisted in situ thermosensitive hydrogel for synergistic treatment of androgenic alopecia

Androgenic alopecia (AGA), the most prevalent type of progressive hair loss, currently lacks an effective topical treatment regimen. In this study, we synthesized an ionic liquid (IL) to co-solubilize minoxidil (MXD) and finasteride (FIN) and subsequently formulated them into an in situ thermosensitive ionic liquid/cyclodextrin/poloxamer hydrogel (ICPG), termed M + F@ICPG. M + F@ICPG was developed for the transdermal co-delivery of these two drugs, aiming to provide a multipath therapeutic approach for AGA while avoiding the adverse effects commonly associated with oral FIN and topical MXD tincture. The thermosensitive characteristics, skin penetration, hair follicle (HF) targeting efficiency, biosafety, and in vivo therapeutic efficacy of M + F@ICPG were evaluated using an AGA mouse model. Our results demonstrated that M + F@ICPG was a thermosensitive hydrogel, transitioning from solution to gel upon contact with the scalp. Compared to the FIN suspension and MXD tincture, M + F@ICPG significantly enhanced the skin penetration (∼2.2-fold) and retention (∼8.6-fold) of FIN and increased the relative retention of MXD (∼6.3-fold) in the skin. Moreover, M + F@ICPG exhibited a HF targeting index of 1.74 for MXD and 1.46 for FIN, indicating enhanced drug targeting to HF. M + F@ICPG showed superior in vivo efficacy in terms of hair regeneration, anagen recovery, inflammation mitigation, and microvessel reconstruction. The underlying mechanism was attributed to the upregulation of hair growth genes, downregulation of hair loss genes, and reduction of abnormally elevated inflammatory factors. These findings suggest that this novel M + F@ICPG is a promising topical co-delivery system for the synergistic treatment of AGA.

Alteration of gel point of poloxamer 338 induced by pharmaceutical actives and excipients

Poloxamer 338 is used as versatile thermo-responsive gelling agent in topical and sub-cutaneous applications. Due to application specific needs a gel point below body or even below room temperature is required. The influence of inorganic salts and active pharmaceutical ingredients (APIs) on the gel point was investigated using oscillatory rheology to identify the driving forces and predictors for gel point alteration. While most inorganic salts decreased the gel point, API salts exhibited an increase. Consistent with previous findings, the extent of gel point alteration caused by inorganic salts could be empirically described by the Hofmeister series, primarily influenced by the anion. Notably, this study revealed a concentration-dependent increase in the gel point in the presence of API salts. Moreover, this increase could be accurately predicted in a linear manner by considering the respective logP value. By utilizing the proposed prediction model, the effect of API addition on the gel point can be estimated, facilitating formulation development to achieve the desired gelling behavior for specific applications.

Impact of Formulation and Microneedle Length on Transdermal Metronidazole Permeation through Microneedle-Treated Skin

OBJECTIVE

This study aimed to determine the impact of formulation (gel vs cream) and microneedle characteristics (length, number) on permeation of metronidazole through excised microneedle-treated skin. The long-term goal is to apply these results towards a pharmacokinetic study in human subjects with diverse skin types, using in vitro flux data to determine dosing conditions and ultimately establish in vitro-in vivo correlations.

METHODS

Metronidazole release from 0.75% gel and cream was quantified with flow-through diffusion cells, using a cellulose membrane. Excised porcine skin was treated with stainless steel microneedles (500 or 800 μm length), to create 50 or 100 micropores. Metronidazole gel or cream was applied to microneedle-treated skin and replaced every 48 h for up to 7 days. Metronidazole permeation was quantified using HPLC. Intact skin (no microneedle treatment) served as controls.

RESULTS

Metronidazole release was faster from the gel vs cream. At 7 days there was no difference between gel vs cream in total metronidazole permeated through intact skin. For both formulations, metronidazole permeation was significantly higher (vs intact skin) following microneedle application, regardless of microneedle length or micropore number. Increasing microneedle length and micropore number enhanced MTZ permeation multiple fold for both gel and cream. The greatest enhancement in total permeation for both formulations was achieved with the 800 μm MN, 100 micropore condition.

CONCLUSIONS

Formulation and microneedle conditions both impacted metronidazole permeation. These data will be used to estimate in vivo serum concentrations after applying metronidazole to microneedle-treated skin in humans.

Exploring the Drug-Loading and Release Ability of FucoPol Hydrogel Membranes

The polysaccharide FucoPol has recently been shown to yield hydrogel membranes (HMs) characterized by good mechanical properties, biocompatibility, and anti-inflammatory activity that render them promising biomaterials for use in the biomedical field. Subsequently to such findings, envisaging their development into novel delivery systems for topical applications, in this study, FucoPol HMs prepared by crosslinking the biopolymer with iron cations were loaded with caffeine or diclofenac sodium as model drugs. Two loading methods, namely diffusion and mixing, were applied to evaluate the FucoPol's HM drug-loading capacity and entrapment efficiency. The diffusion method led to a higher caffeine loading (101.9 ± 19.1 mg/g) in the HM1_DCAF membranes, while the mixing method resulted in a higher diclofenac sodium loading (82.3 ± 5.1 mg/g) in the HM1_DDS membranes. The HM1_DCAF membranes were characterized by increased mechanical and rheological parameters, such as their hardness (130.0 ± 5.3 kPa) and storage modulus (1014.9 ± 109.7 Pa), compared to the HM1_DDS membranes that exhibited lower values (7.3 ± 1.2 kPa and 19.8 ± 3.8 Pa, respectively), probably due to leaching occurring during the drug-loading process. The release profiles revealed a fast release of both APIs from the membranes loaded by diffusion, while a prolonged and sustained release was obtained from the membranes loaded by mixing. Moreover, for all API-loaded membranes, the release mechanism followed Fickian diffusion, with the release rate being essentially governed by the diffusion process. These findings, together with their previously shown biological properties, support the suitability of the developed FucoPol HMs to be used as platforms for the topical delivery of drugs.

Phase transitions of aqueous solutions of Pluronic F68 in the presence of Diclofenac Sodium

In recent years, advancements in bioengineering and materials science have witnessed increasing interest in synthetic polymers capable of fulfilling various applications. Owing to their distinctive properties, Pluronics can be used as nano-drug carriers, to deliver poorly water-soluble drugs, and as model systems to study colloidal science by tuning amphiphilic properties. In this work, we investigated the effect of diclofenac sodium on the self-assembly and thermoresponsive crystallization of Pluronic F68 in water solutions, by employing experimental rheology and Nuclear Magnetic Resonance (NMR). We built a complete phase diagram as a function of temperature and concentration for 45 wt% Pluronic F68 with various amounts of diclofenac sodium in water. The morphological transitions were followed as a function of temperature via linear rheology. We extrapolated the transition temperatures - identifying distinct phases - as a function of the drug concentration and proposed an empirical model for their prediction. NMR analysis provided further information on the structural characteristics of the systems, shedding light on the interactions between F68 and diclofenac sodium. Although dealing with a pharmaceutical salt, the study is focused on a colloidal system and its interaction with a binding molecule, that is of general interest for colloidal science.

Spray coverage analysis of topical sprays formed by cold thermoreversible hydrogels

OBJECTIVE

Sprayable hydrogel formulations are promising topical treatments for skin wounds due to their ability to reduce application pain, prolong drug release, and provide moisture to promote skin healing. These viscoelastic materials, however, present challenges in spray ability which can be overcome using a thermoreversible hydrogels sprayed as lower viscosity liquids at cooler temperatures. The purpose of this research was to evaluate the impact of thermoreversible hydrogel formulation and device characteristics on topical spray patterns and to develop metrics to accurately describe surface coverage.

METHODS

Cold solutions of Pluronic F127 were prepared at 15, 17, and 20% (w/w) and tested to determine their rheological properties. Formulations were sprayed from hand-held atomizing pump dispersers under cold conditions and two distinct areas of their spray patterns analyzed: the concentrated core and the full spray pattern. Traditional analysis of spray patterns was conducted to determine major and minor axes, ovality, and total area. In addition, new scripts were developed to evaluate the concentrated core.

RESULTS

The full spray pattern analysis quantified the total area over which the spray would extend a flat surface, while the concentrated core analysis quantified the continuous region where a drug dose would be concentrated. The combination of formulation viscosity, sprayer nozzle, and spray distance produced spray patterns from highly concentrated to highly dispersed. These parameters can be controlled to generate desired hydrogel spray patterns for application on skin surfaces.

CONCLUSION

The developed metrics provide a basis for topical spray analysis that can inform future product performance.