Polymeric Microarray Patches for Enhanced Transdermal Delivery of the Poorly Soluble Drug Olanzapine.

Transdermal drug delivery is an alternative route of administration that offers avoidance of the associated drawbacks of orally and parenterally administered hydrophobics. However, owing to the extremely specific set of physicochemical characteristics required for passive transdermal drug permeation, the development of marketed transdermal products containing poorly soluble drugs has been severely limited. Microarray patches (MAPs) are a type of transdermal patch that differ from the traditional patch design due to the presence of tiny, micron-sized needles that permit enhanced drug permeation on their application surface. To date, MAPs have predominantly been used to deliver hydrophilic compounds. However, this work challenges this trend and focuses on the use of MAPs, in combination with commonly utilized solubility-enhancing techniques, to deliver the hydrophobic drug olanzapine (OLP) across the skin. Specifically, cyclodextrin (CD) complexation and particle size reduction were employed in tandem with hydrogel-forming and dissolving MAPs, respectively. In vivo experimentation using a female Sprague-Dawley rat model confirmed the successful delivery of OLP from hydrogel-forming MAPs (Cmax = 611.13 ± 153.34 ng/mL, Tmax = 2 h) and dissolving MAPs (Cmax = 690.56 ± 161.33 ng/mL, Tmax = 2 h) in a manner similar to that of oral therapy in terms of the rate and extent of drug absorption, as well as overall drug exposure and bioavailability. This work is the first reported use of polymeric MAPs in combination with the solubility-enhancing techniques of CD complexation and particle size reduction to successfully deliver the poorly soluble drug OLP via the transdermal route. Accordingly, this paper provides significant evidence to support an expansion of the library of molecules amenable to MAP-mediated drug delivery to include those that exhibit poor aqueous solubility.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention.

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

Nanocarrier vaccines for SARS-CoV-2.

The SARS-CoV-2 global pandemic has seen rapid spread, disease morbidities and death associated with substantive social, economic and societal impacts. Treatments rely on re-purposed antivirals and immune modulatory agents focusing on attenuating the acute respiratory distress syndrome. No curative therapies exist. Vaccines remain the best hope for disease control and the principal global effort to end the pandemic. Herein, we summarize those developments with a focus on the role played by nanocarrier delivery.

Microneedle array systems for long-acting drug delivery.

The development of microneedles (MNs) assisted drug delivery technologies have been highly active for more than two decades. The minimally invasive and self-administered MN technology bypasses many challenges associated with injectable drug delivery systems, by delivering the therapeutic materials directly into the dermal and ocular space and allowing the release of the active ingredient in a sustained or controlled manner. Different types of MNs (biodegradable solid/dissolving MNs and nanoparticle loaded/coated polymeric MNs or delivery by hollow MNs) have been envisioned for long-acting sustained delivery of therapeutic payloads, with the aim of reducing the side effects and administration frequency to improve the patient compliance. In this review, we covered the different types of MNs loaded with different nano/biotherapeutics for long-acting delivery for a wide range of potential clinical applications. We also outlined the future development scenario of such long-acting MN delivery systems for different disease conditions to achieve improved clinical benefit. Finally, we discussed the challenges lie ahead to realize the full potential of sustained-release long-acting MNs in the clinic.

Enhancing intradermal delivery of tofacitinib citrate: Comparison between powder-loaded hollow microneedle arrays and dissolving microneedle arrays.

Autoimmune-mediated inflammatory skin diseases, such as psoriasis, alopecia areata, and vitiligo, have been reported as the 4th leading cause of nonfatal disease burden worldwide. This is mainly related to the poor quality of life experienced by these patients. Although topical and systemic steroids represent the most common treatment, the variability in success rates and side effects often lead to treatment discontinuation. Recent off-label clinical studies using oral Janus Kinase (JAK) inhibitors (e.g., ruxolitinib, tofacitinib, baraticinib) have shown promising results. However, frequent side effects, such as infections and blood clots have been reported. Therefore, the aim of this research was to enhance the intradermal delivery of tofacitinib citrate with MN arrays. Using crosslinked hydrogels containing modifying agents (urea, sorbitol and sodium chloride), hollow MN arrays were fabricated and then loaded with tofacitinib citrate. Their efficiency in intradermal delivery of tofacitinib was compared with dissolving MN arrays and a control (Aqueous cream BP), using neonatal porcine skin. Despite the fact that the hydrogel was only present on the outer surface, hollow MN arrays showed comparable resistance to compression values and insertion capabilities to dissolving MN arrays. Although hollow MN arrays containing NaCl in the formulation led to slightly higher depositions of tofacitinib in epidermis and dermis of neonatal porcine skin when compared to a control cream, dissolving MN arrays showed superiority in terms of tofacitinib deposition in the dermis. Indeed, at 24 h of the study, control cream and dissolving MN arrays delivered 143.98 ug/cm2 and 835 ug/cm2 of drug in the dermis, respectively, confirming the enhanced intradermal drug delivery capacity of MN arrays and their potential for treatment of autoimmune skin diseases.

Versatility of hydrogel-forming microneedles in in vitro transdermal delivery of tuberculosis drugs.

Current therapy of tuberculosis (TB) has several limitations, such as risk of liver injury and intestinal dysbiosis due to frequent oral administration of antibiotics. Transdermal administration could be used to improve antibiotic delivery for treatment of Mycobacterium tuberculosis infection. Therefore, we developed a novel approach, using hydrogel-forming microneedle (MN) arrays to transdermally deliver TB drugs, namely rifampicin, isoniazid, pyrazinamide and ethambutol, which have different physicochemical properties. These drugs were individually prepared into three types of drug reservoirs, including lyophilised tablets, directly compressed tablets and poly(ethylene glycol) tablets. Formulations of each drug reservoir type were optimised to achieve a rapidly dissolving tablet, and further integrated with hydrogel-forming MN arrays for in vitro permeation studies. Three types of hydrogel formulation were manufactured using different type of polymers and crosslinking processes. These MN arrays were then evaluated in terms of swelling ability, morphology and physical properties. Results of solute diffusion studies showed that drug permeation across the swollen hydrogel membrane was affected mostly by physiochemical properties and functional groups of each drug. In the in vitro studies, the amount of permeated drug through the hydrogel-forming MN arrays across the dermatomed neonatal porcine skin was affected by the drug solubility and reservoir design. The highest permeation of rifampicin (3.64 mg) and ethambutol (46.99 mg) were achieved using MN arrays combined with the poly(ethylene glycol) tablets and directly compressed tablet, respectively. For isoniazid and pyrazinamide, the highest drug permeation was attained using lyophilised reservoir with the amount of drug delivered approximately 58.45 mg and 20.08 mg, respectively. These equate to transdermal delivery of approximately 75% (rifampicin), 79% (isoniazid), 20% (pyrazinamide) and 47% (ethambutol) of the drugs loaded into the reservoirs on average. Importantly, the results of this work have demonstrated the versatility of hydrogel formulations to deliver a TB drug regime using MN arrays. Accordingly, this is a promising approach to deliver high dose of TB drugs.

Novel nanosuspension-based dissolving microneedle arrays for transdermal delivery of a hydrophobic drug.

A nanosuspension (NS) was formulated from the lipophilic molecule cholecalciferol (CL) for enhanced transdermal delivery by embedding this NS into hydrophilic polymer-based dissolving microneedles (DMNs). First, the NS was prepared by sonoprecpitation with different molecular weights of poly (vinyl alcohol) and poly (vinyl pyrrolidone) as stabilizers and using two different solvents for particle size and zeta potential optimization. DMN arrays were then prepared by centrifugation-assisted micromoulding and subsequently dried. Poly (vinyl alcohol) (10 kDa) produced a NS with the lowest particle size ( ~ 300 nm). These particles yielded DMN with good mechanical properties when combined with aqueous blends of high molecular weight poly (vinyl pyrrolidone) (360 kDa). The particle size remained similar before and after MN preparation, as confirmed by scanning electron microscope. The CL was in the amorphous state in the free particles as well as in the DMN and, hence, no characteristic CL peak was observed in differential scanning calorimetry or X-ray diffraction. DMN arrays were found to be strong enough to bear a 32 N force, showed efficient skin insertion, and penetrated down to the third layer (depth ≈ 375 µm) of the validated skin model Parafilm M®. An ex vivo porcine skin permeation study using Franz diffusion cells compared the permeation of CL from CL-NS-loaded DMN arrays and MN-free CL-NS patches. It was observed that CL-NS-loaded DMN arrays showed significantly higher (498.19 µg ± 89.3 µg) ex vivo skin permeation compared with MN-free CL-NS patches (73.2 µg ± 26.5 µg) over 24 h. This is the first time a NS of a hydrophobic drug has been successfully incorporated into dissolving MN and suggest that NS-containing DMN systems could be a promising strategy for transdermal delivery of hydrophobic drugs.

Novel bilayer dissolving microneedle arrays with concentrated PLGA nano-microparticles for targeted intradermal delivery: Proof of concept.

Polymeric microneedle (MN) arrays continue to receive growing attention due to their ability to bypass the skin's stratum corneum barrier in a minimally-invasive fashion and achieve enhanced transdermal drug delivery and "targeted" intradermal vaccine administration. In this research work, we fabricated biodegradable bilayer MN arrays containing nano - microparticles for targeted and sustained intradermal drug delivery. For this study, model drug (vitamin D3, VD3)-loaded PLGA nano- and microparticles (NMP) were prepared by a single emulsion solvent evaporation method with 72.8% encapsulation of VD3. The prepared NMP were directly mixed 20% w/v poly(vinyl pyrrolidone) (PVP) gel, with the mixture filled into laser engineered micromoulds by high-speed centrifugation (30min) to concentrate NMP into MN shafts. The particle size of PLGA NMP ranged from 300nm to 3.5µm and they retained their particle size after moulding of bilayer MN arrays. The relatively wide particle size distribution of PLGA NMP was shown to be important in producing a compact structure in bilayer conical, as well as pyramidal, MN, as confirmed by scanning electron microscopy. The drug release profile from PLGA NMP was tri-phasic, being sustained over 5days. The height of bilayer MN arrays was influenced by the weight ratio of NMP and 20% w/v PVP. Good mechanical and insertion profiles (into a skin simulant and excised neonatal porcine skin) were confirmed by texture analysis and optical coherence tomography, respectively. Ex vivo intradermal neonatal porcine skin penetration of VD3 NMP from bilayer MN was quantitatively analysed after cryostatic skin sectioning, with 74.2±9.18% of VD3 loading delivered intradermally. The two-stage novel processing strategy developed here provides a simple and easy method for localising particulate delivery systems into dissolving MN. Such systems may serve as promising means for controlled transdermal delivery and targeted intradermal administration.