Adapting Ferritin, a Naturally Occurring Protein Cage, to Modulate Intrinsic Agonism of OX40.

Ferritin is a multivalent, self-assembling protein scaffold found in most human cell types, in addition to being present in invertebrates, higher plants, fungi, and bacteria, that offers an attractive alternative to polymer-based drug delivery systems (DDS). In this study, the utility of the ferritin cage as a DDS was demonstrated within the context of T cell agonism for tumor killing. Members of the tumor necrosis factor receptor superfamily (TNFRSF) are attractive targets for the development of anticancer therapeutics. These receptors are endogenously activated by trimeric ligands that occur in transmembrane or soluble forms, and oligomerization and cell-surface anchoring have been shown to be essential aspects of the targeted agonism of this receptor class. Here, we demonstrated that the ferritin cage could be easily tailored for multivalent display of anti-OX40 antibody fragments on its surface and determined that these arrays are capable of pathway activation through cell-surface clustering. Together, these results confirm the utility, versatility, and developability of ferritin as a DDS.

Finite sample corrections for average equivalence testing.

Average (bio)equivalence tests are used to assess if a parameter, like the mean difference in treatment response between two conditions for example, lies within a given equivalence interval, hence allowing to conclude that the conditions have "equivalent" means. The two one-sided tests (TOST) procedure, consisting in testing whether the target parameter is respectively significantly greater and lower than some pre-defined lower and upper equivalence limits, is typically used in this context, usually by checking whether the confidence interval for the target parameter lies within these limits. This intuitive and visual procedure is however known to be conservative, especially in the case of highly variable drugs, where it shows a rapid power loss, often reaching zero, hence making it impossible to conclude for equivalence when it is actually true. Here, we propose a finite sample correction of the TOST procedure, the α $$ \alpha $$ -TOST, which consists in a correction of the significance level of the TOST allowing to guarantee a test size (or type-I error rate) of α $$ \alpha $$ . This new procedure essentially corresponds to a finite sample and variability correction of the TOST procedure. We show that this procedure is uniformly more powerful than the TOST, easy to compute, and that its operating characteristics outperform the ones of its competitors. A case study about econazole nitrate deposition in porcine skin is used to illustrate the benefits of the proposed method and its advantages compared to other available procedures.

Co-administration of zinc phthalocyanine and quercetin via hybrid nanoparticles for augmented photodynamic therapy.

The photodynamic anticancer activity of a photosensitizer can be further increased by co-administration of a flavonoid. However, this requires that both molecules must be effectively accumulated at the tumor site. Hence, in order to enhance the activity of zinc phthalocyanine (ZnPc, photosensitizer), it was co-encapsulated with quercetin (QC, flavonoid) in lipid polymer hybrid nanoparticles (LPNs) developed using biodegradable & biocompatible materials and prepared using a single-step nanoprecipitation technique. High stability and cellular uptake, sustained release, inherent fluorescence, of ZnPC were observed after encapsulation in the LPNs, which also showed a higher cytotoxic effect in breast carcinoma cells (MCF-7) compared to photodynamic therapy (PDT) alone. In vivo studies in tumor-bearing Sprague Dawley rats demonstrated that the LPNs were able to deliver ZnPc and QC to the tumor site with minimal systemic toxicity and increased antitumor effect. Overall, the photodynamic effect of ZnPc was synergized by QC. This strategy could be highly beneficial for cancer management in the future while nullifying the side effects of chemotherapy.

Ocular Biodistribution of Spironolactone after a Single Intravitreal Injection of a Biodegradable Sustained-Release Polymer in Rats.

Sustained-release formulations for ocular delivery are of increasing interest given their potential to significantly improve treatment efficacy and patient adherence. The objectives of this study were (i) to develop a sustained-release formulation of spironolactone (SPL) using a biodegradable and injectable polymer, hexyl-substituted poly-lactic acid (hexPLA) and (ii) to investigate the ocular biodistribution and tolerability of SPL and its metabolites in rats in vivo over 1 month following a single intravitreal injection (IVT inj). The concentrations of SPL and its two principal active metabolites, 7α-thiomethylspironolactone and canrenone (CAN), in the different ocular compartments were determined at different time points (3, 7, and 31 days after IVT inj) using a validated ultra-high-performance liquid chromatography-mass spectrometry method. Systemic exposure following a single IVT inj of 5% SPL-hexPLA formulation was evaluated by quantifying SPL and its metabolites in the plasma. Ocular tolerability of the formulation was evaluated using in vivo retinal imaging and histology. In vitro release studies revealed a sustained release of SPL from 5% SPL-hexPLA for up to 65 days. In vivo studies showed that SPL and its metabolites were detected in all ocular tissues at 3 and 7 days post-IVT inj. At 31 days post-IVT inj, SPL and CAN were mainly detected in the retina. These results also highlighted the clearance pathway of SPL and its metabolite involving the anterior and posterior routes in the first week (days 3 and 7), then mainly the posterior segment in the last week (day 31). This study showed that a single IVT inj of 5% SPL-hexPLA in rats enabled sustained delivery of therapeutic amounts of SPL for up to 1 month to the retina without systemic exposure. This formulation may be of interest for the local treatment of diseases involving overactivation of the mineralocorticoid receptor in the chorioretina such as chronic central serous chorioretinopathy.

Controlled Iontophoretic Delivery in Vitro and in Vivo of ARN14140-A Multitarget Compound for Alzheimer's Disease.

ARN14140 is a galantamine-memantine conjugate that acts upon both cholinergic and glutamatergic pathways for better management of Alzheimer's disease. Poor oral bioavailability and pharmacokinetics meant that earlier preclinical in vivo studies employed intracerebroventricular injection to administer ARN14140 directly to the brain. The aim of the present study was to evaluate the feasibility of using constant current transdermal iontophoresis for the noninvasive systemic delivery of ARN14140 and to quantify the amounts present in the blood and the brain. Preliminary experiments in vitro were performed using porcine skin and validated with human skin. Cumulative ARN14140 permeation across the skin increased linearly with current density and concentration. Delivery efficiency (i.e., fraction of the amount applied that is delivered) reached an exceptional 76.9%. Statistically equivalent delivery was observed after iontophoresis across human and porcine skin. In vivo studies in male Wistar rats showed that iontophoretic transport of ARN14140 could be controlled using the current density (426.7 ± 42 and 1118.3 ± 73 nmol/cm2 at 0.15 and 0.5 mA/cm2 for 6 h) and demonstrated that transdermal iontophoresis was able to deliver ARN14140 noninvasively to the brain. This is the first report quantifying drug levels in the blood and the brain following transdermal iontophoresis.

Hyaluronic Acid After Subcutaneous Injection-An Objective Assessment.

BACKGROUND: Hyaluronic acid (HA) fillers are the preferred injectable products for aesthetic correction of skin depressions and restoration of facial volume. OBJECTIVE: To investigate the subcutaneous distribution of 3, biophysically distinct, CE-marked and FDA-approved HA fillers. MATERIALS AND METHODS: BELB, JUVV, and RESL were injected ex vivo in porcine and human skin. Immediately after injection, the skin samples were snap-frozen, cross-sectioned, and visualized using stereomicroscopy and full-field optical coherence tomography. Images were compared with histological sections after hematoxylin and eosin staining. RESULTS: Hyaluronic acid fillers were distributed as homogeneous bolus in the ex vivo skin. The injection bulks were found to preserve the fibrous trabecular network, shift the fat lobules, and displace the adjacent adipocyte layers independently of the formulation injected. CONCLUSION: For the first time, the subcutaneous injection of 3 HA fillers with markedly different biophysical properties was systematically investigated by complementary visualization techniques. Despite their different properties, no difference in distribution was found after subcutaneous injection. The global preservation of the hypodermis structure observed was consistent with the good tolerability seen in clinical practice after implantation of the HA fillers in the subcutaneous skin layer.

Topical Administration of Spironolactone-Loaded Nanomicelles Prevents Glucocorticoid-Induced Delayed Corneal Wound Healing in Rabbits.

The objective was to investigate whether mineralocorticoid receptor antagonism using a novel topical micellar formulation of spironolactone could prevent glucocorticoid-induced delayed corneal wound healing in New Zealand white rabbits. Spironolactone micelles (0.1%, w/v) with a mean number weighted diameter of 20 nm were prepared using a pegylated copolymer (mPEG-dihexPLA) and showed a preliminary stability of at least 12 months at 5 °C. Preclinical studies in New Zealand white rabbits demonstrated that the 0.1% spironolactone micellar formulation was well-tolerated since no reaction was observed in the cornea following multiple daily instillation over 5 days. As expected, the preclinical studies also confirmed that dexamethasone significantly delayed epithelial wound healing as compared to untreated control (percentage re-epithelialization after day 4: 84.6 ± 13.9% versus 99.5 ± 1.0% for the control, p < 0.05). However, the addition of the 0.1% spironolactone micellar formulation significantly improved the extent of re-epithelialization, countering the dexamethasone induced delayed wound healing with a percentage re-epithelialization that was statistically equivalent to the control (96.9 ± 7.3% versus 99.5 ± 1.0%, p > 0.05). The biodistribution study provided insight into the ocular metabolism of spironolactone and hence the relative contributions of the parent molecule and its two principal metabolites, 7α-thiomethylspironolactone and canrenone, to the observed pharmacological effects. Comparison of the efficacies of spironolactone and potassium canrenoate (a water-soluble precursor of canrenone) in overcoming the dexamethasone-induced delayed wound healing confirmed that the former had greater efficacy. The results pointed to the greater potency of 7α-thiomethylspironolactone over canrenone as a mineralocorticoid receptor antagonist, which explained its superior ability in countering the glucocorticoid-induced overactivation that was responsible for the delayed wound healing. In conclusion, the preliminary results supported the above-mentioned hypothesis suggesting that coadministration of mineralocorticoid receptor antagonists to patients under glucocorticoid therapy might prevent the deleterious effects of glucocorticoids on complex corneal wound healing processes.

Development and validation of a fast and sensitive UHPLC-ESI-MS method for the simultaneous quantification of spironolactone and its metabolites in ocular tissues.

Glucocorticoids are a mainstay for the treatment of immune-mediated conditions and inflammatory diseases. However, their chronic use causes numerous side-effects including delays in corneal and cutaneous wound healing. This is attributed to off-target agonism of the mineralocorticoid receptor, which can be reduced by co-administration of a mineralocorticoid receptor antagonist such as spironolactone. The aim of this study was to develop a fast, selective and sensitive UHPLC-ESI-MS method for the simultaneous quantification of spironolactone, its active metabolites (7α-thiomethylspironolactone and canrenone), the latter's water-soluble prodrug potassium canrenoate and the synthetic glucocorticoid, dexamethasone, in corneal samples (17α-methyltestosterone served as an internal standard). A one-step extraction procedure using MeOH-H2 O (1:1) was validated and employed to recover the analytes from the corneal tissue. Extracts were centrifuged and the supernatant analyzed under isocratic conditions. Compounds were detected using selected ion recording mode. The method satisfied US Food and Drug Administration guidelines with respect to selectivity, precision and accuracy and displayed linearity from 5 to 1000 ng/mL for all of the analytes. The lower limit of quantitation of the method was 5 ng/mL, making it sufficiently sensitive for quantification of the analytes in samples from in vivo studies.

Fractional Laser Ablation for the Cutaneous Delivery of Triamcinolone Acetonide from Cryomilled Polymeric Microparticles: Creating Intraepidermal Drug Depots.

The efficacy of some dermatological therapies might be improved by the use of "high dose" intraepidermal drug reservoir systems that enable sustained and targeted local drug delivery, e.g., in the treatment of keloids and hypertrophic scars. Here, a fractionally ablative erbium:YAG laser was used to enable "needle-less" cutaneous deposition of polymeric microparticles containing triamcinolone acetonide (TA). The microparticles were prepared using a freeze-fracture technique employing cryomilling that resulted in drug loading efficiencies of ∼100%. They were characterized by several different techniques, including scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. TA was quantified by validated HPLC-UV and UHPLC-MS/MS analytical methods. In vitro release studies demonstrated the effect of polymer properties on TA release kinetics. Confocal laser scanning microscopy enabled visualization of cryomilled microparticles containing fluorescein and Nile Red in the cutaneous micropores and the subsequent release of fluorescein into the micropores and its diffusion throughout the epidermis and upper dermis. The biodistribution of TA, i.e. the amount of drug as a function of depth in skin, following microparticle application was much more uniform than with a TA suspension and delivery was selective for deposition with less transdermal permeation. These findings suggest that this approach may provide an effective, targeted and minimally invasive alternative to painful intralesional injections for the treatment of keloid scars.

Synthesis of 3-azabicyclo[3.2.2]nonanes and their antiprotozoal activities.

Several bicyclic compounds, 3-azabicyclo[3.2.2]nonanes, have been prepared. The new compounds were tested for their activities against one strain of the causative organism of Malaria tropica, Plasmodium falciparum K1, which is resistant against chloroquine and pyrimethamine. In addition, their cytotoxicity and their activity against the pathogen of the East African form of sleeping sickness, Trypanosoma brucei rhodesiense, were investigated. Structure-activity relationships are discussed considering data of readily prepared compounds. For the first time, a distinct in vivo activity was observed against Plasmodium berghei in a mouse model. The active compound was further investigated.

Polymeric micelle nanocarriers for the cutaneous delivery of tacrolimus: a targeted approach for the treatment of psoriasis.

Tacrolimus (TAC) suffers from poor cutaneous bioavailability when administered topically using conventional vehicles with the consequence that although it is indicated for the treatment of atopic dermatitis, it has poor efficacy against psoriasis. The aim of this work was to formulate TAC loaded polymeric micelles using the biodegradable and biocompatible methoxy-poly(ethylene glycol)-dihexyl substituted polylactide (MPEG-dihexPLA) diblock copolymer and to investigate their potential for targeted delivery of TAC into the epidermis and upper dermis. Micelle formulations were characterized with respect to drug content, stability, and size. An optimal 0.1% micelle formulation was developed and shown to be stable over a period of 7 months at 4 °C; micelle diameters ranged from 10 to 50 nm. Delivery experiments using human skin and involving quantification by UHPLC-MS/MS demonstrated that this formulation resulted in significantly greater TAC deposition in skin than that with Protopic (0.1% w/w; TAC ointment), (1.50 ± 0.59 and 0.47 ± 0.20 µg/cm(2), respectively). The cutaneous biodistribution profile of TAC in the upper 400 µm of tissue (at a resolution of 20 µm) demonstrated that the increase in cutaneous drug levels was due to improved TAC deposition in the stratum corneum, viable epidermis, and upper dermis. Given that there was no increase in the amount of TAC in deeper skin layers or any transdermal permeation, the results suggested that it would be possible to increase TAC levels selectively in the target tissue without increasing systemic absorption and the risk of side effects in vivo. Micelle distribution and molecular penetration pathways were subsequently visualized with confocal laser scanning microscopy (CLSM) using a fluorescently labeled copolymer and fluorescent dyes. The CLSM study indicated that the copolymer was unable to cross the stratum corneum and that release of the micelle "payload" was dependent on the molecular properties of the "cargo" as evidenced by the different behaviors of DiO and fluorescein. A preferential deposition of micelles into the hair follicle was also confirmed by CLSM. Overall, the results indicate that MPEG-dihexPLA micelles are highly efficient nanocarriers for the selective cutaneous delivery of tacrolimus, superior to the marketed formulation (Protopic). Furthermore, they may also have significant potential for targeted delivery to the hair follicle.

Cutaneous Delivery and Biodistribution of Cannabidiol in Human Skin after Topical Application of Colloidal Formulations.

The objective of this study was to investigate the cutaneous delivery of cannabidiol (CBD) from aqueous formulations developed for the targeted local treatment of dermatological conditions. CBD was formulated using a proprietary colloidal drug delivery system (VESIsorb®) into an aqueous colloidal solution at 2% (ACS 2%) and two colloidal gels (CG 1% and CG 2%, which contained 1% and 2% CBD, respectively). Two basic formulations containing CBD (5% in propylene glycol (PG 5%) and a 6.6% oil solution (OS 6.6%)) and two marketed CBD products (RP1 and RP2, containing 1% CBD) were used as comparators. Cutaneous delivery and cutaneous biodistribution experiments were performed using human abdominal skin (500-700 µm) under infinite- and finite-dose conditions with 0.5% Tween 80 in the PBS receiver phase. The quantification of CBD in the skin samples was performed using a validated UHPLC-MS/MS method and an internal standard (CBD-d3). The cutaneous deposition of CBD under finite-dose conditions demonstrated the superiority of CG 1%, CG 2%, and ACS 2% over the marketed products; CG 1% had the highest delivery efficiency (5.25%). Cutaneous biodistribution studies showed the superiority of the colloidal systems in delivering CBD to the viable epidermis, and the upper and lower papillary dermis, which are the target sites for the treatment of several dermatological conditions.

Non-Invasive Delivery of Negatively Charged Nanobodies by Anodal Iontophoresis: When Electroosmosis Dominates Electromigration.

Iontophoresis enables the non-invasive transdermal delivery of moderately-sized proteins and the needle-free cutaneous delivery of antibodies. However, simple descriptors of protein characteristics cannot accurately predict the feasibility of iontophoretic transport. This study investigated the cathodal and anodal iontophoretic transport of the negatively charged M7D12H nanobody and a series of negatively charged variants with single amino acid substitutions. Surprisingly, M7D12H and its variants were only delivered transdermally by anodal iontophoresis. In contrast, transdermal permeation after cathodal iontophoresis and passive diffusion was

Enhancing Oral Delivery of Biologics: A Non-Competitive and Cross-Reactive Anti-Leptin Receptor Nanofitin Demonstrates a Gut-Crossing Capacity in an Ex Vivo Porcine Intestinal Model.

Biotherapeutics exhibit high efficacy in targeted therapy, but their oral delivery is impeded by the harsh conditions of the gastrointestinal (GI) tract and limited intestinal absorption. This article presents a strategy to overcome the challenges of poor intestinal permeability by using a protein shuttle that specifically binds to an intestinal target, the leptin receptor (LepR), and exploiting its capacity to perform a receptor-mediated transport. Our proof-of-concept study focuses on the characterization and transport of robust affinity proteins, known as Nanofitins, across an ex vivo porcine intestinal model. We describe the potential to deliver biologically active molecules across the mucosa by fusing them with the Nanofitin 1-F08 targeting the LepR. This particular Nanofitin was selected for its absence of competition with leptin, its cross-reactivity with LepR from human, mouse, and pig hosts, and its shuttle capability associated with its ability to induce a receptor-mediated transport. This study paves the way for future in vivo demonstration of a safe and efficient oral-to-systemic delivery of targeted therapies.

Clinical Perspectives on the Injectability of Cross-Linked Hyaluronic Acid Dermal Fillers: A Standardized Methodology for Commercial Product Benchmarking with Inter-Injector Assessments.

The injectability of cross-linked hyaluronic acid (HA) dermal fillers is influenced by polymer concentration, polymer cross-linking type and degree, the presence of lidocaine or other functional excipients, types of syringes, and injection techniques. Finished product injectability constitutes a critical quality attribute for clinical injectors, as it strongly influences product applicability and ease of use in aesthetic medicine. While injectable product extrusion force specifications are provided by the respective device manufacturers, the qualitative informative value of such datasets is low for injectors wishing to compare product brands and technologies from an injectability standpoint. Therefore, the present study comparatively assessed 28 cross-linked HA dermal fillers (JUVÉDERM®, Restylane®, BELOTERO®, TEOSYAL RHA®, and STYLAGE® brands) using various injectability benchmarking setups for enhanced clinical-oriented relevance. Manual product injections were performed by three specialized and experienced clinicians, whereas automatic product extrusion was performed using a Texture Analyzer instrument. The various hydrogel products were injected into ex vivo human skin and into SimSkin® cutaneous equivalents to appropriately account for injection-related counterpressure. The injectability results revealed important variability between and within product brands, with a strong influence of the local anesthetic lidocaine, HA contents, and needle gauge size. Critical appraisals of the investigated products were performed, notably from manufacturing process-based and clinical ease of application-based standpoints, centered on respective experimental injectability quality levels. Generally, it was confirmed that each HA-based dermal filler product requires specific expertise for optimal injection, mainly due to differing viscoelastic characteristics and injectability attributes. Overall, the present study set forth evidence-based and clinical-oriented rationale elements confirming the importance for injectors to work with injectable products with which they are experienced and comfortable to optimize clinical results.

Controlled iontophoretic transport of huperzine A across skin in vitro and in vivo: effect of delivery conditions and comparison of pharmacokinetic models.

The aim of this study was to investigate constant current anodal iontophoresis of Huperzine A (HupA) in vitro and in vivo and hence to evaluate the feasibility of using electrically assisted delivery to administer therapeutic amounts of the drug across the skin for the treatment of Alzheimer's disease. Preliminary experiments were performed using porcine and human skin in vitro. Stability studies demonstrated that HupA was not degraded upon exposure to epidermis or dermis for 12 h and that it was also stable in the presence of an electric current (0.5 mA · cm(-2)). Passive permeation of HupA (2 mM) was minimal (1.1 ± 0.1 µg · cm(-2)); iontophoresis at 0.15, 0.3, and 0.5 mA · cm(-2) produced 106-, 134-, and 184-fold increases in its transport across the skin. Surprisingly, despite the use of a salt bridge to isolate the formulation compartment from the anodal chamber, which contained 133 mM NaCl, iontophoresis of HupA was shown to increase linearly with its concentration (1, 2, and 4 mM in 25 mM MES, pH 5.0) (r(2) = 0.99). This was attributed to the low ratio of drug to Cl¯ (in the skin and in the receiver compartment) which competed strongly to carry current, its depletion, and to possible competition from the zwitterionic MES. Co-iontophoresis of acetaminophen confirmed that electromigration was the dominant electrotransport mechanism. Total delivery across human and porcine skin was found to be statistically equivalent (243.2 ± 33.1 and 235.6 ± 13.7 µg · cm(-2), respectively). Although the transport efficiency was ∼ 1%, the iontophoretic delivery efficiency (i.e., the fraction of the drug load delivered) was extremely high, in the range of 46-81% depending on the current density. Cumulative permeation of HupA from a Carbopol gel formulation after iontophoresis for 6 h at 0.5 mA · cm(-2) was less than that from solution (135.3 ± 25.2 and 202.9 ± 5.2 µg · cm(-2), respectively) but sufficient for therapeutic delivery. Pharmacokinetic parameters were determined in male Wistar rats in vivo (4 mM HupA; 0.5 mA · cm(-2) for 5 h with Ag/AgCl electrodes) using two-compartment models with either constant or time-variant input rates. A superior fit was obtained using the time-variant model, and the input rate in vivo was significantly greater than that in vitro. Based on these results and the known pharmacokinetics, it was estimated that therapeutic amounts of HupA could be delivered for the treatment of Alzheimer's disease using a reasonably sized patch.

Polymeric micelles for cutaneous delivery of the hedgehog pathway inhibitor TAK-441: Formulation development and cutaneous biodistribution in porcine and human skin.

TAK-441 is a potent inhibitor of the hedgehog pathway (IC50 4.4 nM) developed for the treatment of basal cell carcinoma that is active against the vismodegib-resistant Smoothened receptor D473H mutant. The objective of this study was to develop a micelle-based formulation of TAK-441 using D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) and to investigate its cutaneous delivery and biodistribution. The micelles were prepared using solvent evaporation and incorporation of TAK-441 in the TPGS micelles increased aqueous solubility ∼40-fold. The optimal formulation, a 3% HPMC hydrogel of TAK-441 loaded TPGS micelles, retained ∼92% of the initial TAK-441 content (2.5 mgTAK-441/g) after storage at 4 °C for 6 months. Finite dose experiments using human skin demonstrated that this formulation resulted in significantly greater cutaneous deposition of TAK-441 after 12 h than a non-micelle control formulation, (0.40 ± 0.11 µg/cm2 and 0.05 ± 0.02 µg/cm2, respectively) - no transdermal permeation was observed. The cutaneous biodistribution profile demonstrated that TAK-441 was predominantly delivered to the viable epidermis and upper dermis. Delivery from the HPMC hydrogel formulation resulted in TAK-441 epidermal concentrations that were several thousand-fold higher than the IC50, with almost negligible transdermal permeation, thereby decreasing the risk of systemic side effects in vivo.

Influence of Molecular Structure and Physicochemical Properties of Immunosuppressive Drugs on Micelle Formulation Characteristics and Cutaneous Delivery.

The aim of this study was to investigate whether subtle differences in molecular properties affected polymeric micelle characteristics and their ability to deliver poorly water-soluble drugs into the skin. D-α-tocopherol-polyethylene glycol 1000 was used to prepare micelles containing ascomycin-derived immunosuppressants-sirolimus (SIR), pimecrolimus (PIM) and tacrolimus (TAC)-which have similar structures and physicochemical properties and have dermatological applications. Micelle formulations were prepared by thin-film hydration and extensively characterized. Cutaneous delivery and biodistribution were determined and compared. Sub-10 nm micelles were obtained for the three immunosuppressants with incorporation efficiencies >85%. However, differences were observed for drug loading, stability (at the highest concentration), and their in vitro release kinetics. These were attributed to differences in drug aqueous solubility and lipophilicity. Differences between the cutaneous biodistribution profiles and drug deposition in the different skin compartments pointed to the impact of differences in thermodynamic activity. Therefore, despite their structural similarities, SIR, TAC and PIM did not demonstrate the same behaviour either in the micelles or when applied to the skin. These outcomes indicate that polymeric micelles should be optimized even for closely related drug molecules and support the hypothesis that drugs are released from micelles prior to skin penetration.

Biodistribution of progesterone in the eye after topical ocular administration via drops or inserts.

Progesterone (PG) has been shown to have a slowing effect on photoreceptor cell death in mouse models of retinitis pigmentosa when administered orally. The aim of this study was to investigate whether ophthalmically administered progesterone was able to reach neuroretina and thus, the distribution through ocular tissues of different PG formulations was studied. The effect of different initial PG concentration was also investigated. Different formulations with PG in their composition (drops, a corneal/scleral-insert and scleral-inserts) were prepared and assayed. Using whole porcine eyes, the different formulations were topically administered to the ocular surface. Frozen eyes were dissected, the PG in each tissue was extracted in acetonitrile and the amount of PG quantified by UHPLC-MS/MS. Our results show that after topical administration, PG diffuses from the ocular surface and distributes throughout all tissues of the eye. Lower levels of PG were found in sclera, choroid and neuroretina when PG was applied as drops compared to inserts. Our results also show that an increase in the initial PG concentrations applied, resulted in a statistically significant increase in the amounts of PG in aqueous humour, sclera, choroid and neuroretina.

Injectable Hyaluronan-Based Thermoresponsive Hydrogels for Dermatological Applications.

Most marketed HA-based dermal fillers use chemical cross-linking to improve mechanical properties and extend their lifetime in vivo; however, stiffer products with higher elasticity require an increased extrusion force for injection in clinical practice. To balance longevity and injectability, we propose a thermosensitive dermal filler, injectable as a low viscosity fluid that undergoes gelation in situ upon injection. To this end, HA was conjugated via a linker to poly(N-isopropylacrylamide) (pNIPAM), a thermosensitive polymer using "green chemistry", with water as the solvent. HA-L-pNIPAM hydrogels showed a comparatively low viscosity (G' was 105.1 and 233 for Candidate1 and Belotero Volume®, respectively) at room temperature and spontaneously formed a stiffer gel with submicron structure at body temperature. Hydrogel formulations exhibited superior resistance against enzymatic and oxidative degradation and could be administered using a comparatively lower injection force (49 N and >100 N for Candidate 1 and Belotero Volume®, respectively) with a 32G needle. Formulations were biocompatible (viability of L929 mouse fibroblasts was >100% and ~85% for HA-L-pNIPAM hydrogel aqueous extract and their degradation product, respectively), and offered an extended residence time (up to 72 h) at the injection site. This property could potentially be exploited to develop sustained release drug delivery systems for the management of dermatologic and systemic disorders.