Long-acting microneedle formulations

The minimally-invasive and painless nature of microneedle (MN) application has enabled the technology to obviate many issues with injectable drug delivery. MNs not only administer therapeutics directly into the dermal and ocular space, but they can also control the release profile of the active compound over a desired period. To enable prolonged delivery of payloads, various MN types have been proposed and evaluated, including dissolving MNs, polymeric MNs loaded or coated with nanoparticles, fast-separable MNs hollow MNs, and hydrogel MNs. These intricate yet intelligent delivery platforms provide an attractive approach to decrease side effects and administration frequency, thus offer the potential to increase patient compliance. In this review, MN formulations that are loaded with various therapeutics for long-acting delivery to address the clinical needs of a myriad of diseases are discussed. We also highlight the design aspects, such as polymer selection and MN geometry, in addition to computational and mathematical modeling of MNs that are necessary to help streamline and develop MNs with high translational value and clinical impact. Finally, up-scale manufacturing and regulatory hurdles along with potential avenues that require further research to bring MN technology to the market are carefully considered. It is hoped that this review will provide insight to formulators and clinicians that the judicious selection of materials in tandem with refined design may offer an elegant approach to achieve sustained delivery of payloads through the simple and painless application of a MN patch.

A new engineering process of biodegradable polymeric solid implants for ultra-long-acting drug delivery

We present a long-acting (LA) biodegradable polymeric solid implant (PSI) fabricated using a new process combining in-situ phase inversion and compression. This robust process allows fabrication of solid implants that can have different shapes and sizes, accommodate high drug payloads, and provide sustained drug release over several months. Herein the integrase inhibitor dolutegravir (DTG) was used to develop PSIs for HIV prevention. PSIs were fabricated using a three-step process by (a) phase inversion of DTG-loaded polymer solution to form an initial in-situ forming implant in an aqueous solution, (b) micronization of dried DTG-loaded solid implants, and (c) compression of the micronized DTG-loaded solid implants to form the PSI. High drug loading (up to 85 wt%) was achieved in the PSIs. DTG exhibited minimum burst release in the first 24 h (<6%) and sustained release kinetics over 6 months. The release kinetics of DTG can be fine-tuned by varying drug-loading concentration, the ratio of polymer (poly(lactic-co-glycolic acid), PLGA) to solvent (N-methyl-2-pyrrolidone, NMP) and polymer (PLGA) molecular weight in the precursor solution. The physical/chemical properties of DTG were retained post-storage under accelerated storage conditions (40 °C/75% relative humidity) for 6 months. The versatility of this technology makes it an attractive drug delivery platform for HIV prevention applications.

Archway Randomized Phase 3 Trial of the Port Delivery System with Ranibizumab for Neovascular Age-Related Macular Degeneration

PURPOSE

To evaluate the safety and efficacy of the Port Delivery System with ranibizumab (PDS) for the treatment of neovascular age-related macular degeneration (nAMD).

DESIGN

Phase 3, open-label, randomized, visual acuity assessor-masked noninferiority and equivalence trial.

PARTICIPANTS

Patients with nAMD diagnosed within 9 months of screening previously treated with and responsive to anti-vascular endothelial growth factor therapy.

METHODS

Patients were randomized 3:2 to treatment with the PDS with ranibizumab 100 mg/ml with fixed 24-week (Q24W) refill-exchanges (PDS Q24W) or intravitreal ranibizumab 0.5-mg injections every 4 weeks (monthly ranibizumab).

MAIN OUTCOME MEASURES

Primary end point was change in best-corrected visual acuity (BCVA) Early Treatment Diabetic Retinopathy Study letter (letters) score from baseline averaged over weeks 36 and 40 (noninferiority margin,-4.5 letters; equivalence margin, ±4.5 letters).

RESULTS

Archway enrolled 418 patients; 251 were randomized to and 248 received treatment with the PDS Q24W, and 167 were randomized to and received treatment with monthly ranibizumab. Baseline BCVA was 74.4 letters (PDS Q24W arm) and 75.5 letters (monthly ranibizumab arm; Snellen equivalent, 20/32). Adjusted mean change in BCVA score from baseline averaged over weeks 36 and 40 was +0.2 letters (standard error [SE], 0.5 letters) in the PDS Q24W arm and +0.5 letters (SE, 0.6 letters) in the monthly ranibizumab arm (difference, -0.3 letters; 95% confidence interval, -1.7 to 1.1 letters). PDS Q24W was both noninferior and equivalent to monthly ranibizumab. Of 246 PDS-treated patients assessed for supplemental ranibizumab treatment, 242 (98.4%) did not receive supplemental ranibizumab treatment before the first refill-exchange procedure, including 4 patients who discontinued treatment before the first refill-exchange procedure. Prespecified ocular adverse events of special interest were reported in 47 patients (19.0%) in the PDS Q24W arm and 10 patients (6.0%) in the monthly ranibizumab arm, which included, in the former arm, 4 (1.6%) endophthalmitis cases, 2 (0.8%) retinal detachments, 13 (5.2%) vitreous hemorrhages, 6 (2.4%) conjunctival erosions, and 5 (2.0%) conjunctival retractions. Most ocular adverse events in the PDS Q24W arm occurred within 1 month of implantation.

CONCLUSIONS

Archway met its primary objective and PDS Q24W demonstrated noninferior and equivalent efficacy to monthly ranibizumab, with 98.4% of PDS-treated patients not receiving supplemental treatment in the first 24-week interval.

Acid-triggered degradable polyprodrug with drug as unique repeating unit for long-acting drug delivery with minimal leakage

Acid-triggered degradable polyprodrug P(DOX-AH) was designed for long-acting drug delivery with minimal leakage and enhanced antitumor efficacy. By facile polymerization of doxorubicin (DOX) and N-(tert-butoxycarbonyl)acryloylhydrazine (Boc-AH), P(DOX-AH) with drug as unique repeating unit was obtained, possessing an ultrahigh drug content. It was stable in the neutral media but could degrade completely into DOX-AH in the acidic media without any other by-product. The cleavage of the hydrazone linkage between the DOX-AH repeating units was revealed by the LC-MS/MS analysis. Furthermore, a slow solubility-controlled drug release performance was achieved in the acidic media because of the low solubility of the released DOX-AH. Even with the slow DOX-AH releasing, the enhanced antitumor efficacy was obtained than free DOX in the in vitro cellular experiments. These features demonstrated the promising potential of the proposed polyprodrug for long-acting drug delivery in future tumor chemotherapy.

Biodegradable polymeric solid implants for ultra-long-acting delivery of single or multiple antiretroviral drugs

Lack of adherence is a key barrier to a successful human immunodeficiency virus (HIV) treatment and prevention. We report on an ultra-long-acting (ULA) biodegradable polymeric solid implant (PSI) that can accommodate one or more antiretrovirals (e.g., dolutegravir (DTG) and rilpivirine (RPV)) at translatable human doses (65% wt.) in a single implant. PSIs are fabricated using a three-step process: (a) phase inversion of a drug/polymer solution to form an initial in-situ forming solid implant, (b) micronization of dried drug-loaded solid implants, and (c) compression of the micronized drug-loaded solid powder to generate the PSI. DTG and RPV can be pre-combined in a single PLGA-based solution to make dual-drug PSI; or formulated individually in PLGA-based solutions to generate separate micronized powders and form a bilayer dual-drug PSI. Results showed that in a single or bilayer dual-drug PSI, DTG and RPV exhibited physicochemical properties similar to their pure drug analogues. PSIs were well tolerated in vivo and effectively delivered drug(s) over 180 days with concentrations above 4× PA-IC90 after a single subcutaneous administration. While biodegradable and do not require removal, these PSIs can safely be removed to terminate the treatment if required. The versatility of this technology makes it attractive as an ULA drug delivery platform for HIV and various therapeutic applications.

Long-acting nanoparticle-loaded bilayer microneedles for protein delivery to the posterior segment of the eye

Treatment of neovascular ocular diseases involves intravitreal injections of therapeutic proteins using conventional hypodermic needles every 4-6 weeks. Due to the chronic nature of these diseases, these injections will be administrated to patients for the rest of their lives and their frequent nature can potentially pose a risk of sight-threatening complications and poor patient compliance. Therefore, we propose to develop nanoparticle (NP)-loaded bilayer dissolving microneedle (MN) arrays, to sustain delivery of protein drugs in a minimally invasive manner. In this research, a model protein, ovalbumin (OVA)-encapsulated PLGA NPs were prepared and optimised using a water-in-oil-in-water (W/O/W) double emulsion method. The impact of stabilisers and primary sonication time on the stability of encapsulated OVA was evaluated using an enzyme-linked immunosorbent assay (ELISA). Results showed that the lower primary sonication time was capable of sustaining release (77 days at 28.5% OVA loading) and improving the OVA bioactivity. The optimised NPs were then incorporated into a polymeric matrix to fabricate bilayer MNs and specifically concentrated into MN tips by high-speed centrifugation. Optimised bilayer MNs exhibited good mechanical and insertion properties and rapid dissolution kinetics (less than 3 min) in excised porcine sclera. Importantly, ex vivo transscleral distribution studies conducted using a multiphoton microscope confirmed the important function of MN arrays in the localisation of proteins and NPs in the scleral tissue. Furthermore, the polymers selected to prepare bilayer MNs and OVA NPs were determined to be biocompatible with retinal cells (ARPE-19). This delivery approach could potentially sustain the release of encapsulated proteins for more than two months and effectively bypass the scleral barrier, leading to a promising therapy for treating neovascular ocular diseases.

Trans-urocanic acid enhances tenofovir alafenamide stability for long-acting HIV applications

Long-acting (LA) pre-exposure prophylaxis (PrEP) for HIV prevention is poised to address non-adherence and implementation challenges by alleviating the burden of user-dependent dosing. Due to its potency, tenofovir alafenamide (TAF) is a viable candidate for LA PrEP. However, the inherent hydrolytic instability of TAF presents a challenge for application in LA systems. In this work, we examined the mechanism of TAF hydrolysis in a reservoir-based implant system and characterized TAF degradation kinetics as a function of the solution pH. We determined a pH "stability window" between pH 4.8 - 5.8 in which TAF degradation is substantially mitigated, with minimal degradation at pH 5.3. In a pursuit of a TAF formulation suitable for LA PrEP, we studied trans-urocanic acid (UA) as a buffer excipient. Here we show that UA can maintain the pH of TAF free base (TAFfb) solution inside a surrogate implant model at approximately pH 5.4. Through in vitro analysis, we demonstrated preservation of released TAF purity above 90% for over 9 months. Further, we performed an in vivo assessment of TAFfb-UA formulation in a reservoir-based nanofluidic implant inserted subcutaneously in non-human primates. Preventive levels of tenofovir diphosphate above 100 fmol/106 peripheral blood mononuclear cells were achieved in 2 days and sustained over 35 days. Fluid retrieved from implants after 60 days of implantation showed that UA preserved the aqueous phase in the implant at ~ pH 5.5, effectively counteracting the neutralizing action of interstitial fluids. Moreover, residual TAF in the implants maintained > 98% purity. Overall, TAF-UA represents a viable formulation applicable for LA HIV PrEP.