Clinically established biodegradable long acting injectables: An industry perspective

Is Ultrasound as a Milling or Pre-Milling Method to Prepare Aqueous Suspensions an Effective Approach?

High-pressure homogenization is a widely used and acknowledged method to reduce the particle sizes of active pharmaceutical compounds into nanosized range. Thus, the method is associated with limitations, as the compound's initial particle size, since micronized particles are often prerequired to achieve successful size reduction into nanosized range. In this work, the usage of ultrasound as a potential milling or pre-milling technique to decrease particle sizes of different drug compounds varying in deformation properties into micronized range, was investigated.

Development and In Vivo Evaluation of Sustained Release Microparticles Loaded with Levothyroxine for Hypothyroidism Treatment

Hypothyroidism is a chronic condition combated by a daily oral supplementation of levothyroxine. In addition to the need for frequent dosing, oral administration may result in variable absorption of the drug leading to a failure in achieving normal thyroid function. Therefore, the development of a long-acting injectable system capable of delivering the drug is necessary. This work was aimed at developing sustained release microparticles loaded with levothyroxine. The microparticles were produced through the emulsification-solvent evaporation method using 2 grades of biocompatible and biodegradable polyesters: poly(ᴅ,ʟ-lactide-co-glycolide) (PLGA) and poly(ᴅ,ʟ-lactide) (PLA). Both polymers produced microparticles with very similar sizes (1.9 µm) and zeta potential values (around -22.0 mV). However, PLA microparticles had a significantly higher drug loading (6.1% vs. 4.4%, respectively) and encapsulation efficiency (36.8%, vs. 26.1%, respectively) when compared to PLGA counterparts. While both types of microparticles displayed a biphasic release pattern in vitro, a slower rate of release was observed with PLA microparticles. Moreover, a similar biphasic release pattern was found in vivo, with an initial phase of rapid release followed by a slower phase in the subsequent 10 days. These results indicate the possibility of developing levothyroxine loaded polyester microparticles as a potential long-acting thyroid hormone replacement therapy.

Pharmaceutical and biotech industry perspectives on optimizing patient experience and treatment adherence through subcutaneous drug delivery design

Subcutaneous (SC) drug delivery can be a safe, effective alternative to the traditional intravenous route of administration, potentially offering notable advantages for both patients and healthcare providers. The SC Drug Development & Delivery Consortium convened in 2018 to raise awareness of industry challenges to advance the development of patient-centric SC drug delivery strategies. The SC Consortium identified better understanding of patient preferences and perspectives as necessary to optimize SC product design attributes and help guide design decisions during SC product development. This manuscript provides a comprehensive overview of patient-centric factors for consideration in the SC drug delivery design and development process with the aim of establishing a foundation of existing knowledge for patient experiences related to SC drug delivery. This overview is informed by the outcomes of a multi-step survey of Consortium members and key pharmaceutical stakeholders. Framed in the context of the patient's treatment journey, the survey findings offer future perspectives to fill data gaps to advance patient-centric SC drug delivery.

An injectable, nanostructured implant for the delivery of adenosine triphosphate: towards long-acting formulations of small, hydrophilic drugs

While long-acting injectable treatments are gaining increasing interest in managing chronic diseases, the available drug delivery systems almost exclusively rely on hydrophobic matrixes, limiting their application to either hydrophobic drugs or large and hydrophilic molecules such as peptides. To address the technological lock for long-acting delivery systems tailored to small, hydrophilic drugs such as anticancer and antiviral nucleoside/nucleotide analogues, we have synthesized and characterized an original approach with a multi-scale structure: (i) a nucleotide (adenosine triphosphate, ATP) is first incorporated in hydrophilic chitosan-Fe(III) nanogels; (ii) these nanogels are then transferred by freeze-drying and resuspension into a water-free, hydrophobic medium containing PLGA and an organic solvent, N-methyl-2-pyrrolidone. We show that this specific association allows an injectable and homogeneous dispersion, able to form in situ implants upon injection in physiological or aqueous environments. This system releases ATP in vitro without any burst effect in a two-step mechanism, first as nanogels acting as an intermediate reservoir over a week, then as free drug over several weeks. In vivo studies confirmed the potential of such nanostructured implants for sustained drug release following subcutaneous injection to mice hock, opening perspectives for sustained and targeted delivery through the lymphatic system.

Miniaturized screening and performance prediction of tailored subcutaneous extended-release formulations for preclinical in vivo studies

Microencapsulation of active pharmaceutical ingredients (APIs) for preparation of long acting injectable (LAI) formulations is an auspicious technique to enable preclinical characterization of a broad variety of APIs, ideally independent of their physicochemical and pharmacokinetic (PK) characteristics. During early API discovery, tunable LAI formulations may enable pharmacological proof-of-concept for the given variety of candidates by tailoring the level of plasma exposure over the duration of various timespans. Although numerous reports on small scale preparation methods for LAIs utilizing copolymers of lactic and glycolic acid (PLGA) and polymers of lactic acid (PLA) highlight their potential, application in formulation screening and use in preclinical in vivo studies is yet very limited. Transfer from downscale formulation preparation to in vivo experiments is hampered in early preclinical API screening by the large number of API candidates with simultaneously very limited available amount in the lower sub-gram scale, lack of formulation stability and deficient tunability of sustained release. We hereby present a novel comprehensive platform tool for tailored extended-release formulations, aiming to support a variety of preclinical in vivo experiments with ranging required plasma exposure levels and timespans. A novel small-scale spray drying process was successfully implemented by using an air brush based instrument for preparation of PLGA and PLA based formulations. Using Design of Experiments (DoE), required API amount of 250 mg was demonstrated to suffice for identification of dominant polymer characteristics with largest impact on sustained release capability for an individual API. BI-3231, a hydrophilic and weakly acidic small compound with good water solubility and permeability, but low metabolic stability, was used as an exemplary model for one of the many candidates during API discovery. Furthermore, an in vitro to in vivo correlation (IVIVC) of API release rate was established in mice, which enabled the prediction of in vivo plasma concentration plateaus after single subcutaneous injection, using only in vitro dissolution profiles of screened formulations. By tailoring LAI formulations and their doses for acute and sub-chronic preclinical experiments, we exemplary demonstrate the practical use for BI-3231. Pharmacological proof-of-concept could be enabled whilst circumventing the need of multiple administration as result of extensive hepatic metabolism and simultaneously superseding numerous in vivo experiments for formulation tailoring.

Bottom-up production of injectable itraconazole suspensions using membrane technology

Bottom-up production of active pharmaceutical ingredient (API) crystal suspensions offers advantages in surface property control and operational ease over top-down methods. However, downstream separation and concentration pose challenges. This proof-of-concept study explores membrane diafiltration as a comprehensive solution for downstream processing of API crystal suspensions produced via anti-solvent crystallization. It involves switching the residual solvent (N-methyl-2-pyrrolidone, NMP) with water, adjusting the excipient (d-α-Tocopherol polyethylene glycol 1000 succinate, TPGS) quantity, and enhancing API loading (solid concentration) in itraconazole crystal suspensions. NMP concentration was decreased from 9 wt% to below 0.05 wt% (in compliance with European Medicine Agency guidelines), while the TPGS concentration was decreased from 0.475 wt% to 0.07 wt%. This reduced the TPGS-to-itraconazole ratio from 1:2 to less than 1:50 and raised the itraconazole loading from 1 wt% to 35.6 wt%. Importantly, these changes did not adversely affect the itraconazole crystal stability in suspension. This study presents membrane diafiltration as a one-step solution to address downstream challenges in bottom-up API crystal suspension production. These findings contribute to optimizing pharmaceutical manufacturing processes and hold promise for advancing the development of long-acting API crystal suspensions via bottom-up production techniques at a commercial scale.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

Tailoring the use of excipients in bottom-up production of naproxen crystal suspensions via membrane technology

Long-acting crystal suspensions of active pharmaceutical ingredients (API) mostly comprised of an API, a suspension media (water) and excipients and provide sustained API release over time. Excipients are crucial for controlling particle size and to achieve the stability of the API crystals in suspension. A bottom-up process was designed to produce long-acting crystal suspensions whilst investigating the excipient requirements during the production process and the subsequent storage. PVP K30 emerged as the most effective excipient for generating stable naproxen crystals with the desired size of 1 to 15 μm, using ethanol as solvent and water as anti-solvent. Calculations, performed based on the crystal properties and assuming complete PVP K30 adsorption on the crystal surface, revealed lower PVP K30 requirements during storage compared to initial crystal generation. Consequently, a membrane-based diafiltration process was used to determine and fine-tune PVP K30 concentration in the suspension post-crystallization. A seven-stage diafiltration process removed 98 % of the PVP K30 present in the suspension thereby reducing the PVP-to-naproxen ratio from 1:2 to 1:39 without impacting the stability of naproxen crystals in suspension. This work provides insights into the excipient requirements at various production stages and introduce the membrane-based diafiltration for precise excipient control after crystallization.

Prodrugs as empowering tools in drug discovery and development: recent strategic applications of drug delivery solutions to mitigate challenges associated with lead compounds and drug candidates

The delivery of a drug to a specific organ or tissue at an efficacious concentration is the pharmacokinetic (PK) hallmark of promoting effective pharmacological action at a target site with an acceptable safety profile. Sub-optimal pharmaceutical or ADME profiles of drug candidates, which can often be a function of inherently poor physicochemical properties, pose significant challenges to drug discovery and development teams and may contribute to high compound attrition rates. Medicinal chemists have exploited prodrugs as an informed strategy to productively enhance the profiles of new chemical entities by optimizing the physicochemical, biopharmaceutical, and pharmacokinetic properties as well as selectively delivering a molecule to the site of action as a means of addressing a range of limitations. While discovery scientists have traditionally employed prodrugs to improve solubility and membrane permeability, the growing sophistication of prodrug technologies has enabled a significant expansion of their scope and applications as an empowering tool to mitigate a broad range of drug delivery challenges. Prodrugs have emerged as successful solutions to resolve non-linear exposure, inadequate exposure to support toxicological studies, pH-dependent absorption, high pill burden, formulation challenges, lack of feasibility of developing solid and liquid dosage forms, first-pass metabolism, high dosing frequency translating to reduced patient compliance and poor site-specific drug delivery. During the period 2012-2022, the US Food and Drug Administration (FDA) approved 50 prodrugs, which amounts to 13% of approved small molecule drugs, reflecting both the importance and success of implementing prodrug approaches in the pursuit of developing safe and effective drugs to address unmet medical needs.

Microstructure Formation and Characterization of Long-Acting Injectable Microspheres: The Gateway to Fully Controlled Drug Release Pattern

Long-acting injectable microspheres have been on the market for more than three decades, but if calculated on the brand name, only 12 products have been approved by the FDA due to numerous challenges in achieving a fully controllable drug release pattern. Recently, more and more researches on the critical factors that determine the release kinetics of microspheres shifted from evaluating the typical physicochemical properties to exploring the microstructure. The microstructure of microspheres mainly includes the spatial distribution and the dispersed state of drug, PLGA and pores, which has been considered as one of the most important characteristics of microspheres, especially when comparative characterization of the microstructure (Q3) has been recommended by the FDA for the bioequivalence assessment. This review extracted the main variables affecting the microstructure formation from microsphere formulation compositions and preparation processes and highlighted the latest advances in microstructure characterization techniques. The further understanding of the microsphere microstructure has significant reference value for the development of long-acting injectable microspheres, particularly for the development of the generic microspheres.

Is roller milling - the low energy wet bead media milling - a reproducible and robust milling method for formulation investigation of aqueous suspensions?

Long-acting injectables have shown to offer a prolonged release of a drug compound up to several months, providing the opportunity to increase patient compliance for treatment of long-term and chronic conditions. Different formulation technologies have already been utilized for long-acting injectables, and especially aqueous suspensions with crystalline drug particles in the sub-micron range have sparked an interest for future development of long-acting injectables. Wet bead milling is a common top-down process used to prepare nano- and microsuspensions of crystalline drug particles with the addition of surfactants in the dispersion medium, which are working as stabilizers to prevent agglomeration or crystal growth that ultimately may influence the physical stability of nano- and microsuspensions. To examine the reproducibility of the suspensions manufactured and the behavior of their physical stability, i.e., changes in particle sizes over time, low-energy roller mill was utilized for the manufacturing of nano- and microsuspensions in the present study. Investigated formulation parameters was stabilizer type and concentration and milling parameters varied in bead size and duration of milling. The obtained results demonstrated that the physical stability of suspensions containing the two model compounds, cinnarizine and indomethacin, was highly affected by the constitution of surfactant and processing. Various size classes were obtained and accompanied by high variations between the individual samples that indicated uneven and unpredictable milling by the low-energy roller mill, limiting the possibility to prepare reproducible and physical stable suspensions. Short-term stability studies revealed clear tendencies towards reversed Ostwald ripening of suspensions stabilized with poloxamer 188 that contained cinnarizine as the drug compound, and to a smaller extent suspensions containing indomethacin. Furthermore, X-ray Powder Diffraction confirmed no alteration of the drug compounds crystal structure after roller milling for multiple days.

Biodegradable Long-Acting Injectables: Platform Technology and Industrial Challenges

Long-acting injectables have been used to benefit patients with chronic diseases. So far, several biodegradable long-acting platform technologies including drug-loaded polymeric microparticles, implants (preformed and in situ forming), oil-based solutions, and aqueous suspension have been established. In this chapter, we summarize all the marketed technology platforms and discuss their challenges regarding development including but not limited to controlling drug release, particle size, stability, sterilization, scale-up manufacturing, etc. Finally, we discuss important criteria to consider for the successful development of long-acting injectables.

Injectable Biodegradable Silica Depot for Controlled Subcutaneous Delivery of Antisense Oligonucleotides with beyond Monthly Administration

Single-stranded antisense oligonucleotides (ASOs) are typically administered subcutaneously once per week or monthly. Less frequent dosing would have strong potential to improve patient convenience and increase adherence and thereby for some diseases result in more optimal therapeutic outcomes. Several technologies are available to provide sustained drug release via subcutaneous (SC) administration. ASOs have a high aqueous solubility and require relatively high doses, which limits the options available substantially. In the present work, we show that an innovative biodegradable, nonporous silica-based matrix provides zero-order release in vivo (rats) for at least 4 weeks for compositions with ASO loads of up to about 100 mg/mL (0.5 mL injection) without any sign of initial burst. This implies that administration beyond once monthly can be feasible. For higher drug loads, substantial burst release was observed during the first week. The concentrations of unconjugated ASO levels in the liver were found to be comparable to corresponding bolus doses. Additionally, infusion using a minipump shows a higher liver exposure than SC bolus administration at the same dose level and, in addition, clear mRNA knockdown and circulating protein reduction comparable to SC bolus dosing, hence suggesting productive liver uptake for a slow-release administration.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

In Vitro and In Vivo Hydrolytic Degradation Behaviors of a Drug-Delivery System Based on the Blend of PEG and PLA Copolymers

This paper presents the in vitro and in vivo degradation of BEPO, a marketed in situ forming depot technology used for the formulation of long-acting injectables. BEPO is composed of a solution of a blend of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) triblock and diblock in an organic solvent, where a therapeutic agent may be dissolved or suspended. Upon contact with an aqueous environment, the solvent diffuses and the polymers precipitate, entrapping the drug and forming a reservoir. Two representative BEPO compositions were subjected to a 3-month degradation study in vitro by immersion in phosphate-buffered saline at 37 °C and in vivo after subcutaneous injection in minipig. The material erosion rate, as a surrogate of the bioresorption, determined via the depot weight loss, changed substantially, depending on the composition and content of polymers within the test item. The swelling properties and internal morphology of depots were shown to be highly dependent on the solvent exchange rate during the precipitation step. Thermal analyses displayed an increase of the depot glass transition temperature over the degradation process, with no crystallinity observed at any stage. The chemical composition of degraded depots was determined by 1H NMR and gel permeation chromatography and demonstrated an enrichment in homopolymers, i.e., free PLA and (m)PEG, to the detriment of (m)PEG-PLA copolymers in both formulations. It was observed that the relative ratio of the degradants within the depot is driven by the initial polymer composition. Interestingly, in vitro and in vivo results showed very good qualitative consistency. Taken together, the outcomes from this study demonstrate that the different hydrolytic degradation behaviors of the BEPO compositions can be tuned by adjusting the polymer composition of the formulation.

Injectable systems for long-lasting insulin therapy

Insulin therapy is the mainstay to treat diabetes characterizedd by hyperglycemia. However, its short half-life of only 4-6 min limits its effectiveness in treating chronic diabetes. Advances in recombinant DNA technology and protein engineering have led to several insulin analogue products that have up to 42 h of glycemic control. However, these insulin analogues still require once- or twice-daily injections for optimal glycemic control and have poor patient compliance and adherence issues. To achieve insulin release for more than one day, different injectable delivery systems including microspheres, in situ forming depots, nanoparticles and composite systems have been developed. Several of these delivery systems have advanced to clinical trials for once-weekly insulin injection. This review comprehensively summarizes the developments of injectable insulin analogs and delivery systems covering the whole field of injectable long-lasting insulin technologies from prototype design, preclinical studies, clinical trials to marketed products for the treatment of diabetes.

Wet bead milling by dual centrifugation - An approach to obtain reproducible and differentiable suspensions

Aqueous nano- and microsuspensions containing poorly water-soluble, crystalline drug particles have in the recent years sparked an interest for the preparation of long-acting injectables (LAIs), which increase patient compliance for patients treated for long-term or chronic conditions. Nano- and microsuspensions are often prepared by top-down methods, such as wet bead milling, with the addition of stabilizers in the dispersion media, such as surfactants, which influence the particle sizes and physical stability of the suspension. To improve the efficacy of formulation screening for nano- and microsuspensions, dual centrifugation was utilized in this study whereby 40 samples could be manufactured simultaneously to support the formulation definition. Hence, the type and concentration of stabilizer as well as bead size and milling speed was investigated throughout the presented study, but also the ability of the method to produce consistent data was investigated. The obtained results demonstrated that the particle profile obtained after milling was very consistent from run to run and so was the observed stability data, i.e., running n = 1 experiment per combination could clearly be justified as a predictable approach for the formulation screening. The data also showed that the stabilizer, as well as its concentration highly influenced the physical stability of suspensions containing both the two investigated model compounds, i.e., both cinnarizine and indomethacin, where the biggest increase in particle sizes was observed within the first week. For short-term studies, polysorbate 20 was found to be a suitable stabilizer for suspensions of cinnarizine, whereas sodium dodecyl sulphate was more suitable for indomethacin suspensions immediately after the milling even with 1% (w/v) stabilizer solution, but not sufficient for short-term stability due to an insufficient stabilizer concentration. Smaller particles sizes could be achieved by milling the suspensions with the smallest bead sizes and at the highest speed of 1500 rpm without disrupting the crystal structure of the active pharmaceutical ingredient (API), which was confirmed by X-ray Powder Diffraction.

Revolutionizing drug formulation development: The increasing impact of machine learning

Over the past few years, the adoption of machine learning (ML) techniques has rapidly expanded across many fields of research including formulation science. At the same time, the use of lipid nanoparticles to enable the successful delivery of mRNA vaccines in the recent COVID-19 pandemic demonstrated the impact of formulation science. Yet, the design of advanced pharmaceutical formulations is non-trivial and primarily relies on costly and time-consuming wet-lab experimentation. In 2021, our group published a review article focused on the use of ML as a means to accelerate drug formulation development. Since then, the field has witnessed significant growth and progress, reflected by an increasing number of studies published in this area. This updated review summarizes the current state of ML directed drug formulation development, introduces advanced ML techniques that have been implemented in formulation design and shares the progress on making self-driving laboratories a reality. Furthermore, this review highlights several future applications of ML yet to be fully exploited to advance drug formulation research and development.

Role of Modeling and Simulation in Preclinical and Clinical Long-Acting Injectable Drug Development

Innovations in the field of long-acting injectable drug development are increasingly being reported. More advanced in vitro and in vivo characterization can improve our understanding of the injection space and aid in describing the long-acting injectable (LAI) drug's behavior at the injection site more mechanistically. These innovations may enable unlocking the potential of employing a model-based framework in the LAI preclinical and clinical space. This review provides a brief overview of the LAI development process before delving deeper into the current status of modeling and simulation approaches in characterizing the preclinical and clinical LAI pharmacokinetics, focused on aqueous crystalline suspensions. A closer look is provided on in vitro release methods, available biopharmaceutical models and reported in vitro/in vivo correlations (IVIVCs) that may advance LAI drug development. The overview allows identifying the opportunities for use of model-informed drug development approaches and potential gaps where further research may be most warranted. Continued investment in improving our understanding of LAI PK across species through translational approaches may facilitate the future development of LAI drug products.

The Effect of Polymer Blends on the In Vitro Release/Degradation and Pharmacokinetics of Moxidectin-Loaded PLGA Microspheres

To investigate the effect of polymer blends on the in vitro release/degradation and pharmacokinetics of moxidectin-loaded PLGA microspheres (MOX-MS), four formulations (F1, F2, F3 and F4) were prepared using the O/W emulsion solvent evaporation method by blending high (75/25, 75 kDa) and low (50/50, 23 kDa) molecular weight PLGA with different ratios. The addition of low-molecular-weight PLGA did not change the release mechanism of microspheres, but sped up the drug release of microspheres and drastically shortened the lag phase. The in vitro degradation results show that the release of microspheres consisted of a combination of pore diffusion and erosion, and especially autocatalysis played an important role in this process. Furthermore, an accelerated release method was also developed to reduce the period for drug release testing within one month. The pharmacokinetic results demonstrated that MOX-MS could be released for at least 60 days with only a slight blood drug concentration fluctuation. In particular, F3 displayed the highest AUC and plasma concentration (AUC0-t = 596.53 ng/mL·d, Cave (day 30-day 60) = 8.84 ng/mL), making it the optimal formulation. Overall, these results indicate that using polymer blends could easily adjust hydrophobic drug release from microspheres and notably reduce the lag phase of microspheres.

Customizable 3D Printed Implants Containing Triamcinolone Acetonide: Development, Analysis, Modification, and Modeling of Drug Release

Three-dimensional-printed customizable drug-loaded implants provide promising opportunities to improve the current therapy options. In this study, we present a modular implant in which shape, dosage, and drug release can be individualized independently of each other to patient characteristics to improve parenteral therapy with triamcinolone acetonide (TA) over three months. This study focused on the examination of release modification via fused deposition modeling and subsequent prediction. The filaments for printing consisted of TA, ethyl cellulose, hypromellose, and triethyl citrate. Two-compartment implants were successfully developed, consisting of a shape-adaptable shell and an embedded drug-loaded network. For the network, different strand widths and pore size combinations were printed and analyzed in long-term dissolution studies to evaluate their impact on the release performance. TA release varied between 8.58 ± 1.38 mg and 21.93 mg ± 1.31 mg over three months depending on the network structure and the resulting specific surface area. Two different approaches were employed to predict the TA release over time. Because of the varying release characteristics, applicability was limited, but successful in several cases. Using a simple Higuchi-based approach, good release predictions could be made for a release time of 90 days from the release data of the initial 15 days (RMSEP ≤ 3.15%), reducing the analytical effort and simplifying quality control. These findings are important to establish customizable implants and to optimize the therapy with TA for specific intra-articular diseases.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

Solid implantable devices for sustained drug delivery

Implantable drug delivery systems (IDDS) are an attractive alternative to conventional drug administration routes. Oral and injectable drug administration are the most common routes for drug delivery providing peaks of drug concentrations in blood after administration followed by concentration decay after a few hours. Therefore, constant drug administration is required to keep drug levels within the therapeutic window of the drug. Moreover, oral drug delivery presents alternative challenges due to drug degradation within the gastrointestinal tract or first pass metabolism. IDDS can be used to provide sustained drug delivery for prolonged periods of time. The use of this type of systems is especially interesting for the treatment of chronic conditions where patient adherence to conventional treatments can be challenging. These systems are normally used for systemic drug delivery. However, IDDS can be used for localised administration to maximise the amount of drug delivered within the active site while reducing systemic exposure. This review will cover current applications of IDDS focusing on the materials used to prepare this type of systems and the main therapeutic areas of application.

Targeted long-term noninvasive treatment of choroidal neovascularization by biodegradable nanoparticles

Choroidal neovascularization (CNV) is the main cause of vision loss in patients with wet age-related macular degeneration (AMD). Currently, treatment of these conditions requires repeated intravitreal injections, which may lead to complications such as infection and hemorrhage. So, we have developed a noninvasive method for treating CNV with nanoparticles, namely, Angiopoietin1-anti CD105-PLGA nanoparticles (AAP NPs), which targets the CNV to enhance drug accumulation at the site. These nanoparticles, with PLGA as a carrier, can slowly release encapsulated Angiopoietin 1 (Ang 1) and target the choroidal neovascularization marker CD105 to enhance drug accumulation, increases vascular endothelial cadherin (VE-cadherin) expression between vascular endothelial cells, effectively reduce neovascularization leakage and inhibit Angiopoietin 2(Ang 2) secretion by endothelial cells. In a rat model of laser-induced CNV, intravenous injection of AAP NPs exerted a good therapeutic effect in reducing CNV leakage and area. In short, these synthetic AAP NPs provide an effective alternative treatment for AMD and meet the urgent need for noninvasive treatment in neovascular ophthalmopathy. STATEMENT OF SIGNIFICANCE: This work describes the synthesis, injection-mediated delivery, in vitro and in vivo efficacy of targeted nanoparticles with encapsulated Ang1; via these nanoparticles, the drug can be targeted to choroidal neovascularization lesions for continuous treatment. The release of Ang1 can effectively reduce neovascularization leakage, maintain vascular stability, and inhibit Ang2 secretion and inflammation. This study provides a new approach for the treatment of wet age-related macular degeneration.

A Retrospective Analysis of Preclinical and Clinical Pharmacokinetics from Administration of Long-Acting Aqueous Suspensions

Administration of long-acting injectable suspensions is an increasingly common approach to increasing patient compliance and improving therapeutic efficacy through less frequent dosing. While several long-acting suspensions have recently been marketed, parameters modulating drug absorption from suspension-based formulations are not well understood. Further, methods for predicting clinical pharmacokinetic data from preclinical studies are not well established. Together, these limitations hamper compound selection, formulation design and formulation selection through heavy reliance on iterative optimization in preclinical and clinical studies. This article identifies key parameters influencing absorption from suspension-based formulations through compilation and analysis of preclinical and clinical pharmacokinetic data of seven compounds marketed as suspensions; achievable margins for predicting the clinical dose and input rate from preclinical studies as a function of the preclinical species, the clinical injection location and the intended therapeutic duration were also established.

Current State and Opportunities with Long-acting Injectables: Industry Perspectives from the Innovation and Quality Consortium "Long-Acting Injectables" Working Group

Long-acting injectable (LAI) formulations can provide several advantages over the more traditional oral formulation as drug product opportunities. LAI formulations can achieve sustained drug release for extended periods of time, which results in less frequent dosing requirements leading to higher patient adherence and more optimal therapeutic outcomes. This review article will provide an industry perspective on the development and associated challenges of long-acting injectable formulations. The LAIs described herein include polymer-based formulations, oil-based formulations, and crystalline drug suspensions. The review discusses manufacturing processes, including quality controls, considerations of the Active Pharmaceutical Ingredient (API), biopharmaceutical properties and clinical requirements pertaining to LAI technology selection, and characterization of LAIs through in vitro, in vivo and in silico approaches. Lastly, the article includes a discussion around the current lack of suitable compendial and biorelevant in vitro models for the evaluation of LAIs and its subsequent impact on LAI product development and approval.

Prodrug approaches for the development of a long-acting drug delivery systems

Long-acting formulations are designed to reduce dosing frequency and simplify dosing schedules by providing an extended duration of action. One approach to obtain long-acting formulations is to combine long-acting prodrugs (LA-prodrug) with existing or emerging drug delivery technologies (DDS). The design criteria for long-acting prodrugs are distinct from conventional prodrug strategies that alter absorption, distribution, metabolism, and excretion (ADME) parameters. Our review focuses on long-acting prodrug delivery systems (LA-prodrug DDS), which is a subcategory of long-acting formulations where prodrug design enables DDS formulation to achieve an extended duration of action that is greater than the parent drug. Here, we define LA-prodrugs as the conjugation of an active pharmaceutical ingredient (API) to a promoiety group via a cleavable covalent linker, where both the promoiety and linker are selected to enable formulation and administration from a drug delivery system (DDS) to achieve an extended duration of action. These LA-prodrug DDS results in an extended interval where the API is within a therapeutic range without necessarily altering ADME as is typical of conventional prodrugs. The conversion of the LA-prodrug to the API is dependent on linker cleavage, which can occur before or after release from the DDS. The requirement for linker cleavage provides an additional tool to prolong release from these LA-prodrug DDS. In addition, the physicochemical properties of drugs can be tuned by promoiety selection for a particular DDS. Conjugation with promoieties that are carriers or amenable to assembly into carriers can also provide access to formulations designed for extending duration of action. LA-prodrugs have been applied to a wide variety of drug delivery strategies and are categorized in this review by promoiety size and complexity. Small molecule promoieties (typically MW < 1000 Da) have been used to improve encapsulation or partitioning as well as broaden APIs for use with traditional long-acting formulations such as solid drug dispersions. Macromolecular promoieties (typically MW > 1000 Da) have been applied to hydrogels, nanoparticles, micelles, dendrimers, and polymerized prodrug monomers. The resulting LA-prodrug DDS enable extended duration of action for active pharmaceuticals across a wide range of applications, with target release timescales spanning days to years.

Long-acting Parenteral Drug Delivery Systems for the Treatment of Chronic Diseases

The management of chronic conditions often requires patients to take daily medication for an extended duration. However, the need for daily dosing can lead to nonadherence to the therapy, which can result in the recurrence of the disease. Long-acting parenteral drug delivery systems have the potential to improve the treatment of chronic conditions. These systems use various technologies, such as oil-based injectables, PLGA-based microspheres, and in situ forming gel-based depots, to deliver different types of drugs. The use of long-acting parenteral formulations for the treatment of chronic infections such as HIV/AIDS and tuberculosis is a recent development in the field. Researchers are also exploring the use of long-acting parenteral formulations for the treatment of malaria, with the aim of reducing dosing frequency and improving adherence to treatment. This review discusses various aspects of long-acting formulation development, including the impact of the physicochemical properties of the drug, the type of long-acting formulation, and the route of administration. The clinical significance of long-acting formulations and recent advances in the field, such as long-acting nanoformulations and long-acting products currently in clinical trials, have also been highlighted.

Comparison of in vivo behaviors of intramuscularly long-acting celecoxib nanosuspensions with different particle sizes for the postoperative pain treatment

Celecoxib (CXB) has a good analgesic effect on postoperative acute pain, but clinically its compliance is compromised because of frequent administration. Therefore, the development of injectable celecoxib nanosuspensions (CXB-NS) for long-acting analgesic effects is highly desirable. However, how the particle size affects the in vivo behaviors of CXB-NS remains unclear. Herein, CXB-NS with different sizes were prepared by the wet-milling method. Following intramuscular (i.m.) injection in rats (50 mg/kg), all CXB-NS achieved sustained systemic exposure and long-acting analgesic effects. More importantly, CXB-NS showed size-dependent pharmacokinetic profiles and analgesic effects, and the smallest CXB-NS (about 0.5 μm) had the highest C_max, T_1/2, and AUC_0-240h and the strongest analgesic effects on incision pain. Therefore, small sizes are preferred for long action by i.m. injection, and the CXB-NS developed in this study were alternative formulations for the treatment of postoperative acute pain.

Recent advances in long-acting drug delivery systems for anticancer drug

The use of systemic anticancer chemotherapy is intrinsically limited by its toxicity. Whether dealing with small molecules or biopharmaceuticals, after systemic administration, small doses fail to reach effective intratumoral concentrations, while high doses with significant tumor inhibition effects may also drive the death of healthy cells, endangering the patients. Therefore, strategies based on drug delivery systems (DDSs) for avoiding the systemic toxicity have been designed. Due to their ability to protect drugs from early elimination and control drug release, DDSs can foster tumor exposure to anticancer therapeutics by extending their circulation time or steadily releasing drugs into the tumor sites. However, approval of tailored DDSs systems for clinical use is minimal as the safety and the in vivo activity still need to be ameliorated by manipulating their physicochemical characteristics. During the last few years, several strategies have been described to improve their safety, stability, and fine-tune pharmaceuticals release kinetics. Herein, we reviewed the main DDSs, namely polymeric conjugates, nano or microparticles, hydrogels, and microneedles, explored for long-acting anticancer treatments, highlighting recently proposed modifications and their potential advantages for different anticancer therapies. Additionally, important limitations of long-acting anticancer therapies and future technology directions were also covered.

Membrane-Based Solvent Exchange Process for Purification of API Crystal Suspensions

Bottom-up approaches to producing aqueous crystal suspensions of active pharmaceutical ingredients (APIs), such as anti-solvent crystallisation, are gaining interest as they offer better control over surface properties compared to top-down approaches. However, one of the major challenges that needs to be addressed is the removal of organic solvents after the crystallisation step due to strict limitations regarding human exposure. Within this work, we investigated a process concept for the removal of solvent (i.e., ethanol) from the API crystal suspension using membrane-based diafiltration. A four-stage diafiltration process successfully reduced the ethanol concentration in the API (here, naproxen) crystal suspension below 0.5 wt% (the residual solvent limit as per ICH guidelines) with a water consumption of 1.5 g of added water per g of feed. The solvent exchange process had no negative influence on the stability of the crystals in suspension, as their size and polymorphic form remained unchanged. This work is a step towards the bottom-up production of API crystal suspension by applying solvent/anti-solvent crystallisation. It provides the proof of concept for establishing a process of organic solvent removal and offers an experimental framework to serve as the foundation for the design of experiments implementing a solvent exchange in API production processes.

Polyester-based long acting injectables: Advancements in molecular dynamics simulation and technological insights

Long-acting injectable (LAI) delivery technologies have enabled the development of several pharmaceutical products that improve patient health by delivering therapeutics from weeks to months. Over the last decade, due to its good biocompatibility, formulation tunability, wide range of degradation rates, and extensive clinical studies, polyester-based LAI technologies including poly(lactic-co-glycolic acid) (PLGA) have made substantial progress. Herein, we discuss PLGA properties with seminal approaches in the development of LAIs, the role of molecular dynamic simulations of polymer-drug interactions, and their effects on quality attributes. We also outline the landscape of various advanced PLGA-based and a few non-PLGA LAI technologies; their design, delivery, and challenges from laboratory scale to preclinical and clinical use; and commercial products incorporating the importance of end-user preferences.

Long-acting injectable PLGA/PLA depots for leuprolide acetate: successful translation from bench to clinic

The excellent properties of polyesters combined with their ease of synthesis and modification enabled their wide use in the pharmaceutical industry. This has been translated into the approval of several injectable depots for clinical use. Long-acting depots for leuprolide acetate were among the first and most successful examples including Lupron Depot^® and ELIGARD^®. Studying these products is of great interest for researchers in both industry and academia. This will undoubtedly pave the road for the development of new as well as generic long-acting depots for a variety of drugs.

Injectable versatile liquid-solid transformation implants alliance checkpoint blockade for magnetothermal dynamic-immunotherapy

The ongoing circulating energy loss, low reactive oxygen species (ROS) accumulation and poor immunogenicity of tumors make it difficult to induce sufficient immunogenic cell death (ICD) in the tumor immunosuppressive microenvironment (TIME), resulting in unsatisfactory immunotherapy efficacy. Furthermore, for highly malignant tumors, simply enhancing ICD is insufficient for exhaustively eliminating the tumor and inhibiting metastasis. Herein, we propose a unique magnetothermal-dynamic immunotherapy strategy based on liquid-solid transformation porous versatile implants (Fe₃O₄/AIPH@PLGA) that takes advantage of less energy loss and avoids ongoing circulating losses by minimally invasive injection into tumors. In addition, the magnetothermal effect regresses and eliminates tumors that are not limited by penetration to simultaneously trigger 2,2′-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH) decomposition and generate a large amount of oxygen-irrelevant free radicals and heat shock protein (HSP) accumulation by heating, evoking both intracellular oxidative stress and endoplasmic reticulum (ER) stress to induce large-scale ICD and enhance tumor immunogenicity. More importantly, in orthotopic bilateral breast tumor models, a significant therapeutic effect was obtained after combining amplified ICD with CTLA4 checkpoint blockade. The 21-day primary and distant tumor inhibition rates reached 90%, and the underlying mechanism of the effective synergetic strategy of inducing the T-cell-related response, the immune memory effect and TIME reprogramming in vivo was verified by immune cell analyses. This remarkable therapeutic effect provides a new direction for antitumor immunotherapy based on magnetothermally controlled oxygen-independent free radical release.

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Injectable versatile liquid-solid phase transformation Fe₃O₄/AIPH@PLGA gel implants are constructed for the first time.

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The implants triggered magnetothermal dynamic therapy and successfully addressed two key barriers limiting the efficacy of immunogenic cell death (ICD): low reactive oxygen species (ROS) accumulation and poor immunogenicity.

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The implants promoting DC maturation, recognition and presentation of antigens. Combined with CTLA4 blockade, the function of Treg cells was inhibited to transform the “cold” TIME into “hot”.

Long-acting HIV Pre-exposure Prophylaxis (PrEP) approaches: Recent advances, emerging technologies and development challenges

Introduction:

Poor or inconsistent adherence to daily oral pre-exposure prophylaxis (PrEP) has emerged as a key barrier to effective HIV prevention. The advent of potent long-acting (LA) antiretrovirals (ARVs) in conjunction with advances in controlled release technologies has enabled LA ARV drug delivery systems (DDS) capable of providing extended dosing intervals and overcome the challenge of suboptimal drug adherence with daily oral dosing.

Areas covered:

This review discusses the current state of the LA PrEP field, recent advances, and emerging technologies, including ARV prodrug modifications and new DDS. Technological challenges, knowledge gaps, preclinical testing considerations, and future directions important in the context of clinical translation and implementation of LA HIV PrEP are discussed.

Expert opinion:

The HIV prevention field is evolving faster than ever and the bar for developing next-generation LA HIV prevention options continues to rise. The requirements for viable LA PrEP products to be implemented in resource-limited settings are challenging, necessitating proactive consideration and product modifications during the design and testing of promising new candidates. If successfully translated, next-generation LA PrEP that are safe, affordable, highly effective, and accepted by both end-users and key stakeholders will offer significant potential to curb the HIV pandemic.

Repurposing of parenterally administered active substances used to treat pain both systemically and locally

Pain is a constant in our lives. The efficacy of drug therapy administered by the parenteral route is often limited either by the physicochemical characteristics of the drug itself or its adsorption-distribution-metabolism-excretion (ADME) mechanisms. One promising alternative is the design of innovative drug delivery systems that can improve the pharmacokinetics |(PK) and/or reduce the toxicity of traditionally used drugs. In this review, we discuss several products that have been approved by the main regulatory agencies (i.e., nano- and microsystems, implants, and oil-based solutions), highlighting the newest technologies that govern both locally and systemically the delivery of drugs. Finally, we also discuss the risk assessment of the scale-up process required, given the impact that this approach could have on drug manufacturing. Teaser: The management of pain by way of the parenteral route can be improved using complex drug delivery systems (e.g., micro- and nanosystems) which require high-level assessment and shorten the regulatory pathway.

Continuous Processing of Micropellets via Hot-Melt Extrusion

Microparticulate drug delivery systems, e.g., micropellets (MPs), are used in a variety of pharmaceutical formulations such as suspensions, injectable systems, and capsules. MPs are currently manufactured mainly via batch, solvent-based processes, e.g., spray-drying and solvent evaporation-extraction. In this paper, we present a novel, solvent-free, continuous hot-melt extrusion-based approach with an inline cold pelletization step and the potential of unprecedented on-the-fly formulation changes, aiming at producing the smallest particles usable for injectable applications. A biodegradable, crystalline dispersion consisting of poly(DL-lactic acid) (PLA) filled with metformin as the model drug was chosen on purpose to elucidate the broad applicability of the process also to formulations with limited stretchability and complex pelletizability. Next to optical/statistical particle analyses and in-line high-speed camera investigations providing insights into the pelletization process, the injectability of the most promising micropellets was compared to that of one marketed formulation. Fast extrudate haul-off speeds and high numbers of pelletizer knives resulted in particles with a narrow and small particle size distribution with a d₅₀ below 270 µm and aspect ratios close to 1. To omit protruding drug particles to ensure sufficient extrudate stretchability and allow for the smallest MPs, it was found that the d₉₀ of the embedded drug must be significantly below the extrudate diameter. Upon adapting the syringe diameter, the produced micropellets revealed similar injectability parameters to the marketed formulation, showcasing the potential that the proposed setup has for the manufacturing of novel microparticulate formulations.

Surface analysis of sequential semi-solvent vapor impact (SAVI) for studying microstructural arrangements of poly(lactide-co-glycolide) microparticles

Biodegradable poly(lactide-co-glycolide) (PLGA) microparticles have been used as long-acting injectable (LAI) drug delivery systems for more than three decades. Despite extensive use, few tools have been available to examine and compare the three-dimensional (3D) structures of microparticles prepared using different compositions and processing parameters, all collectively affecting drug release kinetics. Surface analysis after sequential semi-solvent impact (SASSI) was conducted by exposing PLGA microparticles to different semi-solvent in the liquid phase. The use of semi-solvent liquids presented practical experimental difficulties, particularly in observing the same microparticles before and after exposure to semi-solvents. The difficulties were overcome by using a new sequential semi-solvent vapor (SSV) method to examine the morphological changes of the same microparticles. The SASSI method based on SSV is called surface analysis of semi-solvent vapor impact (SAVI). Semi-solvents are the solvents that dissolve PLGA polymers depending on the polymer's lactide:glycolide (L:G) ratio. A sequence of semi-solvents was used to dissolve portions of PLGA microparticles in an L:G ratio-dependent manner, thus revealing different structures depending on how microparticles were prepared. Exposing PLGA microparticles to semi-solvents in the vapor phase demonstrated significant advantages over using semi-solvents in the liquid phase, such as in control of exposure conditions, access to imaging, decreasing the time for sequential exposure of semi-solvents, and using the same microparticles. The SSV approach for morphological analysis provides another tool to enhance our understanding of the microstructural arrangement of PLGA polymers. It will improve our comprehensive understanding of the factors controlling drug release from LAI formulations based on PLGA polymers.

Ivermectin: recent approaches in the design of novel veterinary and human medicines

Ivermectin (IVM) is a drug widely used in veterinary and human medicine for the management of parasitic diseases. Its repositioning potential has been recently considered for the treatment of different diseases, such as cancer and viral infections. However, IVM faces some limitations to its formulations due to its low water solubility and bioavailability, along with reports of drug resistance. In this sense, novel technological approaches have been explored to optimize its formulations and/or to develop innovative medicines. Therefore, this review discusses the strategies proposed in the last decade to improve the safety and efficacy of IVM and to explore its novel therapeutic applications. Among these technologies, the use of micro/nano-drug delivery systems is the most used approach, followed by long-acting formulations. In general, the development of these novel formulations seems to run side by side in veterinary and human health, showing a shared interface between the two areas. Although the technologies proposed indicate a promising future in the development of innovative dosage forms containing IVM, its safety and therapeutic targets must be further evaluated. Overall, these approaches comprise tailoring drug delivery profiles, decreasing the risks of developing drug resistance, and supporting the application of IVM for reaching different therapeutic targets.

A long-acting formulation of rifabutin is effective for prevention and treatment of Mycobacterium tuberculosis

Tuberculosis (TB) is a communicable disease caused by Mycobacterium tuberculosis (Mtb) and is a major cause of morbidity and mortality. Successful treatment requires strict adherence to drug regimens for prolonged periods of time. Long-acting (LA) delivery systems have the potential to improve adherence. Here, we show the development of LA injectable drug formulations of the anti-TB drug rifabutin made of biodegradable polymers and biocompatible solvents that solidifies after subcutaneous injection. Addition of amphiphilic compounds increases drug solubility, allowing to significantly increase formulation drug load. Solidified implants have organized microstructures that change with formulation composition. Higher drug load results in smaller pore size that alters implant erosion and allows sustained drug release. The translational relevance of these observations in BALB/c mice is demonstrated by (1) delivering high plasma drug concentrations for 16 weeks, (2) preventing acquisition of Mtb infection, and (3) clearing acute Mtb infection from the lung and other tissues.

Shape-specific microfabricated particles for biomedical applications: a review

The storied history of controlled the release systems has evolved over time; from degradable drug-loaded sutures to monolithic zero-ordered release devices and nano-sized drug delivery formulations. Scientists have tuned the physico-chemical properties of these drug carriers to optimize their performance in biomedical/pharmaceutical applications. In particular, particle drug delivery systems at the micron size regime have been used since the 1980s. Recent advances in micro and nanofabrication techniques have enabled precise control of particle size and geometry-here we review the utility of microplates and discoidal polymeric particles for a range of pharmaceutical applications. Microplates are defined as micrometer scale polymeric local depot devices in cuboid form, while discoidal polymeric nanoconstructs are disk-shaped polymeric particles having a cross-sectional diameter in the micrometer range and a thickness in the hundreds of nanometer range. These versatile particles can be used to treat several pathologies such as cancer, inflammatory diseases and vascular diseases, by leveraging their size, shape, physical properties (e.g., stiffness), and component materials, to tune their functionality. This review highlights design and fabrication strategies for these particles, discusses their applications, and elaborates on emerging trends for their use in formulations.

Smart design of patient centric long-acting products: from preclinical to marketed pipeline trends and opportunities

INTRODUCTION

We see a development in the field of long-acting products to serve patients with chronic diseases by providing benefits in adherence, efficacy and safety of the treatment. This review investigates features of long-acting products on the market/pipeline to understand which drug substance (DS) and drug product (DP) characteristics likely enable a successful patient-centric, low-dosing frequency product.

AREAS COVERED

This review evaluates marketed/pipeline long-acting products with greater than one week release of small molecules and peptides by oral and injectable route of administration (RoA), with particular focus on patient centricity, adherence impact, health outcomes, market trends, and the match of DS/DP technologies which lead to market success.

EXPERT OPINION

Emerging trends are expected to change the field of long-acting products in the upcoming years by increasing capability in engineered molecules (low solubility, long half-life, high potency, etc.), directly developing DP as long-acting oral/injectable, increasing the proportion of products for local drug delivery, and a direction towards more subcutaneous, self-administered products. Among long-acting injectable products, nanosuspensions show a superiority in dose per administration and dosing interval, overwhelming the field of infectious diseases with the recently marketed products.

Recent advances in PLGA micro/nanoparticle delivery systems as novel therapeutic approach for drug-resistant tuberculosis

Tuberculosis is a severe infectious disease caused by Mycobacterium tuberculosis and is a significant public health concern globally. The World Health Organization (WHO) recommends a combination regimen of several drugs, such as rifampicin (RIF), isoniazid (INH), pyrazinamide (PZA), and ethambutol (ETB), to treat tuberculosis. However, these drugs have low plasma concentrations after oral administration and require multiple high doses, which may lead to the occurrence and development of drug-resistant tuberculosis. Micro/Nanotechnology drug delivery systems have considerable potential in treating drug-resistant tuberculosis, allowing the sustained release of the drug and delivery of the drug to a specific target. These system properties could improve drug bioavailability, reduce the dose and frequency of administration, and solve the problem of non-adherence to the prescribed therapy. This study systematically reviewed the recent advances in PLGA micro/nanoparticle delivery systems as a novel therapeutic approach for drug-resistant tuberculosis.

Bridging the gap between fundamental research and product development of long acting injectable PLGA microspheres

INTRODUCTION

Long acting Injectable PLGA microspheres have gained more and more interest and attention in the field of life cycle management of pharmaceutical products due to their biocompatibility and biodegradability. So far, a multitude of trial-and-error experiments at lab scale have been used for establishing the correlation relationship between critical process parameters, critical material attributes and critical quality attributes. However, few published studies have elaborated on the development of PLGA microspheres from an industrial perspective.

AREAS COVERED

In this review, the scale-up feasibility of translational technologies of PLGA microspheres manufacturing have been evaluated. Additionally, state-of-the-art of technologies and facilities in PLGA development have been summarized. Meanwhile, the industrial knowledge matrix of PLGA microspheres development and research are establishing which provide comprehensive insight for understanding properties of PLGA microspheres as controlled/sustained release vehicle.

EXPERT OPINION

There is still big gap between fundamental research in academic institute and product development in pharmaceuticals. Therefore, the difference and connection between them should be identified gradually for better understanding of PLGA microspheres development.

The industrial design, translation, and development strategies for long-acting peptide delivery

INTRODUCTION

Peptides are widely recognized as therapeutic agents in the treatment of a wide range of diseases, such as cancer, diabetes etc. However, their use has been limited by their short half-life, due to significant metabolism by exo- and endo-peptidases as well as their inherent poor physical and chemical stability. Research with the aim of improving their half-life in the body, and thus improving patient compliance (by decreasing the frequency of injections) has gained significant attention.

AREAS COVERED

This review outlines the current landscape and industrial approaches to achieve extended peptide exposure and reduce dosing frequency. Emphasis is placed on identifying challenges in drug product manufacturing and desirable critical quality attributes that are essential for activity and safety, providing insights into chemistry and design aspects impacting peptide release, and summarizing important considerations for CMC developability assessments of sustained release peptide drugs.

EXPERT OPINION

Bring the patient and disease perspective early into development. Substantial advances have been made in the field of sustained delivery of peptides despite their complexity. The article will also highlight considerations for early-stage product design and development, providing an industrial perspective on risk mitigation in developing sustained release peptide drug products.

Current trends in PLGA based long-acting injectable products: The industry perspective

INTRODUCTION

Poly (lactic-co-glycolic acid) (PLGA) has been used in many long-acting drug formulations, which have been approved by the US Food and Drug Administration (FDA). PLGA has unique physicochemical properties, which results in complexities in the formulation, characterization, and evaluation of generic products. To address the challenges of generic development of PLGA-based products, the FDA has established an extensive research program to investigate novel methods and tools to aid product development and regulatory review.

AREAS COVERED

This review article intends to provide a comprehensive review on physicochemical properties of PLGA polymer, characterization, formulation, and analytical aspects, manufacturing conditions on product performance, in-vitro release testing, and bioequivalence. Current research on formulation development as per QbD in vitro release testing methods, regulatory research outcomes, and bioequivalence.

EXPERT OPINION

The development of PLGA based long-acting injectables is promising and challenging when considering the numerous interrelated delivery-related factors. Achieving a successful formulation requires a thorough understanding of the critical interactions between polymer/drug properties, release profiles over time, up-to-date knowledge on regulatory guidance, and elucidation of the impact of multiple in vivo conditions to methodically evaluate the eventual clinical efficacy.

Novel adapter method for in vitro release testing of in situ forming implants

In situ forming implants are injectable liquid formulations which form solid or semisolid depots following injection. This allows for minimally invasive administration, localized drug delivery, and extended drug release. Unfortunately, this drug delivery strategy lacks standardized in vitro dissolution methods due to the difficulties in recreating implant formation in vitro that is biomimicry and with reproducible and controllable shape and dimensions. In the present study, an innovative, adapter-based in vitro release testing method was developed to solve this problem. Two distinctively different in situ forming implants (a risperidone formulation (suspension) consisting of PLGA dissolved in N-methyl pyrrolidone (NMP), where risperidone powder was suspended to form a drug suspension, and a naproxen formulation (solution) consisting of PLGA dissolved in NMP, where naproxen was completely dissolved to form a solution), were used as model in situ-forming implants. The results revealed that the implants formed in the custom-designed adapter with a water-dissolvable polyvinyl alcohol (PVA) film were bio-mimicking and reproducible in both shape and burst release of drug according to rabbit data. For both the suspension and solution formulations, this adapter-based in vitro release testing method resulted in consistent release data. Compared with a direct injection in vitro release testing method, the release profiles generated using the adapter-based method were capable of distinguishing the different release phases (initial release within 24 h, diffusion-facilitated release, and degradation-controlled release). In addition, the adapter-based method could discriminate formulation and dissolution apparatus changes and could be utilized to develop accelerated release testing methods. This adapter-based method has the promise of wide use in release testing of in situ forming implant formulations and has the potential to be used in the development of in vivo-predictive in vitro release methods.

Non-oral routes, novel formulations and devices of contraceptives: An update

Family planning enables society to prevent unintended pregnancies and helps in attaining desired spacing between the pregnancies. It is done with the use of contraceptive methods and infertility treatments. The use of contraceptives serves to ease maternal ill-health and reduce pregnancy-related deaths and helps to decrease the number of unsafe abortions and HIV transmission from mothers to newborns. The most popular contraception method is a daily dose of combined oral contraceptives pills. However, poor compliance and various adverse effects are common problems of oral contraceptives that considerably reduce their long-term use. Thus, several non-oral contraceptive options have been developed for better compliance, reduced side effects and improved therapeutic efficacy. This review presented the non-oral contraceptive formulations given by different routes such as transdermal, nasal, subcutaneous, intramuscular, intrauterine and vaginal routes. These formulations delivering contraceptives, mainly through devices, include transdermal patches and microneedles, nasal sprays, intrauterine devices and intrauterine systems, vaginal rings, contraceptive implants and contraceptive injections, which are unique in their specific advantages and drawbacks.