Long-acting injectable formulation technologies: Challenges and opportunities for the delivery of fragile molecules

Exploiting the potential of in situ forming liquid crystals: development and in vitro performance of long-acting depots for peptide drug thymosin alpha 1 subcutaneous administration

The fast-growing filed of long-acting depots for subcutaneous (SC) administration holds significant potential to enhance patient adherence to treatment regimens, particularly in the context of chronic diseases. Among them, injectable in situ forming lyotropic liquid crystals (LCCs) consisting of hexagonal mesophases represent an attractive platform due to their remarkable highly ordered microstructure enabling the sustained drug release. These systems are especially relevant for peptide drugs, as their use is limited by their short plasma half-life and inherent poor stability. In this study, we thus aimed to exploit the potential of a liquid crystalline platform for the sustained release of peptide drug thymosin alpha 1 (Tα1), characterized by a short plasma half-life and with that associated twice-weekly SC administration regimen. We initially selected specified ingredients, with ethanol serving to reduce viscosity and stabilize the peptide drug Tα1, lecithin contributing to LCCs formation and stabilization, and glycerol monooleate or glycerol monolinoleate representing the hexagonal LCCs forming matrix material. The selected studied nonaqueous precursor formulations were characterized by suitable rheological properties for SC injection. A convenient and rapid in situ phase transition of precursor formulations to hexagonal LCCs, triggered by water absorption, was successfully accomplished in vitro. Notably, in situ formed LCCs demonstrated sustained release kinetics of the peptide drug Tα1 for up to 2 weeks of in vitro release testing, offering minimized dosing frequency and thus promoting patient adherence. In summary, the newly developed in situ forming liquid crystalline systems represent prospective injectable long-acting depots for SC administration of the peptide drug Tα1.

Continuous preparation of long-acting hydromorphone PLGA microspheres using an automatic and scalable microfluidic process system

The long-acting hydromorphone loaded poly-lactic-co-glycolic acid (HM-PLGA) microspheres for chronic pain management were developed and prepared using an automatic and scalable microfluidic process system in this study. The system consists of a novel designed micro-mixer for particle generation, syringe and HPLC pumps for continuous dosing, a process Raman spectrometer as process analytical technology (PAT) tool and an automation system for programmable automatic control. With the benefits of the automation and digitalization of the system, a wide range of formulation parameters was investigated for its impact on the properties of the microspheres. The particle size of the HM-PLGA microspheres was tunable with the automatic microfluidic process system. The long-acting injectable homogeneous HM-PLGA microspheres were successfully prepared with maximum drug-loading capacity of 7.71 % and drug encapsulation efficiency of 69.40 %. The physical and chemical properties were characterized using various analytical technologies. Pharmacokinetic experiments in female ICR mice confirmed prolonged exposure in plasma compared to the HM hydrochloride injection. In vivo studies in beagle dogs showed that the HM-PLGA microspheres provided sustained drug release for over 11 days. The results demonstrated the potential of the novel automatic microfluidic process system in the development and continuous manufacturing of the particle size-controllable drug loaded microspheres.

Cotadutide reversible self-assembly based long-acting injectable depot for sustained delivery of GLP-1 glucagon receptor agonists with controlled burst release

Cotadutide (Cota) is a lipidated dual GLP-1 and Glucagon receptor agonist that was investigated for the treatment of various metabolic diseases, it is designed for once daily subcutaneous (SC) administration. Invasive daily injections can result in poor patient compliance with chronic disease, and here, we demonstrate an innovative strategy of encapsulating reversible cota self-assembled fibers within an in-situ forming depot of low molecular weight poly(lactic-co-glycolic) acid (LWPLGA) for sustained delivery GLP-1 and Glucagon receptor agonist with controlled burst release. This could be a suitable alternative to other sustained delivery strategies for fibrillating peptides. We investigated a range of cationic ions (Na+, Ca2+, Zn2+) and studied their influence on the secondary structure, morphology and the monomer release profile of cota fibers. Fibers forming hierarchy structures such as twisted filament and ribbons with beta sheet secondary structure resulted in better controlled burst. The subcutaneous administration of Ca2+ fiber/LWPLGA depot formulation in rats resulted in 60-fold reduction in maximum concentration (Cmax) compared with cota immediate release (IR) SC formulation and a prolonged plasma exposure over a month with plasma half-life extended from the 10 h observed with the cota daily formulation to 100 h. This extended-release formulation also maintains smaller peak and trough fluctuation within therapeutic window, and PK modelling of repeated dose indicates this formulation could enable a possible dose frequency of 14 days in rat with assumed therapeutic concentration (ratios of the maximum concentration and the trough concentration) Cmax/Ctrough window. This new long-acting injectable (LAI) method could open the door to transforming short-life peptides with sub-optimal half-life into candidates for weekly or even monthly dosing regimens, potentially leading to novel drug products with increased patient comfort.

Revolutionizing fixed-dose combinations with long-acting microsphere

Combination therapy, involving the concurrent use of multiple medications, has become crucial for managing complex diseases with diverse pathological mechanisms. Fixed-Dose Combinations (FDCs) are formulated to leverage the synergistic effects of multiple drugs, thereby enhancing therapeutic outcomes. However, conventional FDCs typically maintain therapeutic effects for only up to 24 h and require frequent dosing, which often results in patient non-compliance and inconsistent treatment responses, especially in chronic diseases. This highlights the urgent need for long-acting FDCs that can provide sustained drug release over extended periods-weeks, months, or even years-thereby reducing dosing frequency and enhancing patient adherence. Microspheres, with their ability to encapsulate and release multiple medications in predefined patterns, are highly advantageous for developing long-acting FDC drugs. This review emphasizes the increasing demand for long-acting FDC drugs that ensure sustained drug release, reduce dosing frequency, and ultimately improve patient adherence. We also highlight the potential of microsphere technology, which enables precise encapsulation and sustained release of multiple medications, as a promising approach for revolutionizing long-acting FDCs with enhanced therapeutic outcomes.

Long-acting parenteral formulations of hydrophilic drugs, proteins, and peptide therapeutics: mechanisms, challenges, and therapeutic benefits with a focus on technologies

Despite being the most widely prescribed formulation, oral formulations possess several limitations such as low adherence, low bioavailability, high toxicity (in the case of anticancer drugs), and multiple-time administration requirements. All these limitations can be overcome by long-acting injectables. Improved adherence, patient compliance, and reduced relapse have been observed with long-acting formulation which has increased the demand for long-acting injectables. Drugs or peptide molecules with oral bioavailability issues can be easily delivered by long-acting systems. This review comprehensively addresses the various technologies used to develop long-acting injections with a particular focus on hydrophilic drugs and large molecules as well as the factors affecting the choice of formulation strategy. This is the first review that discusses the possible technologies that can be used for developing long-acting formulations for hydrophilic molecules along with factors which will affect the choice of the technology. Furthermore, the mechanism of drug release as well as summaries of marketed formulations will be presented. This review also discusses the challenges associated with the manufacturing and scale-up of the long-acting injectables.

Evaluating polymer influence on resuspendability of indomethacin suspensions produced by microfluidization

Long-acting injectables improve treatment outcomes for chronic diseases by reducing dosing frequency. Long-acting injectables may be formulated as nano- or microsuspensions produced by wet bead milling and homogenization often facing physical instability. This study investigates different stabilizers' ability to prevent particle growth, caking and the influence on resuspendability. Eight different stabilizers; polysorbate 20 (PS20), polysorbate 80 (PS80), poloxamer 188 (P188), poloxamer 338 (P338), polyvinylpyrrolidone K17 (PVP K17), polyvinylpyrrolidone K30 (PVP K30), vitamin E-TPGS, and sodium lauryl sulphate (SLS) and one potential resuspending agent (polyethylene glycol 4000) was used to assess the stability and resuspendability of indomethacin suspensions. The stability and resuspendability was assessed during four weeks of storage at three different temperatures for all stabilizers at five different concentrations. PVP K30, PVP K17 and P338 yielded stable indomethacin suspensions with minor particle growth. Statistical and machine learning modelling identified stabilizer type as a critical factor influencing resuspendability. Increased storage temperature was found to negatively impact resuspendability, particularly in formulations containing polysorbates. Addition of the resuspending agent PEG4000 did not have significant impact on the resuspendability of vitamin E-TPGS and PS20 formulations while it had a negative effect on the resuspendability of formulations with PVP K30 and P338.

An in-situ forming controlled release soft hydrogel-based C5a peptidase drug delivery system to treat psoriasis

The potent pro-inflammatory cytokine, interferon gamma (IFN-γ), is an enticing therapeutic target because of its accelerator role in several acute and chronic inflammatory processes. In this work, poloxamer 407 is developed as an in-situ gelling polymer for a long-acting formulation to deliver a serine protease, C5a peptidase (ScpA) from Streptococcus pyogenes. ScpA is well known for its activity against the complement factor C5a but has also recently been shown to cleave IFN-γ in vitro into inactive fragments. A compact and uniform gel microstructure was obtained by including dextran in the gel formulation. The sol-gel transition at physiologically temperatures occurred above 19 % w/w poloxamer 407 resulting in a release profile of active ScpA for up to 8 days, with no loss in specific enzymatic activity. No cytotoxicity from ScpA before or after release from the hydrogels to a human immortalized keratinocyte cell lines was detected. Using an in vitro psoriatic skin model with IFN- γ inducing the psoriatic state, the constant and prolonged release of ScpA from this simple thermo-responsive hydrogel, administered once, restored health as effectively as two doses of free enzyme over a 5 day period. These promising results confirm the feasibility of developing ScpA as a long-acting therapeutic using a poloxamer based in-situ forming parenteral gel for local delivery.

Recent advances in poly(amino acids), polypeptides, and their derivatives in drug delivery

Poly(amino acids), polypeptides, and their derivatives have demonstrated significant potential as biodegradable biomaterials in the field of drug delivery. As degradable drug carriers, they can effectively load or conjugate drug molecules including small molecule drugs, nucleic acids, peptides, and protein-based drugs, enhancing the stability and targeting of the drugs in vivo. This strategy ultimately facilitates precise drug delivery and controlled release, thereby improving therapeutic efficacy and reducing side effects within the body. This review systematically describes the structural characteristics and preparation methods of poly(amino acids) and polypeptides, summarizes the advantages of poly(amino acids), polypeptides, and their derivatives in drug delivery, and detailedly introduces the latest advancements in this area. The review also discusses current challenges and opportunities associated with poly(amino acids), peptides, and their derivatives, and offers insights into the future directions for these biodegradable materials. This review aims to provide valuable references for scientific research and clinical translation of biodegradable biomaterials based on poly(amino acids) and peptides.

An Evaluation of the Subcutaneous Depot Release of TV-46000, A Novel Long-Acting Injectable (LAI) Formulation of Risperidone, Under Extreme Conditions in Dogs, Minipigs and Humans

BACKGROUND

TV-46000 (Uzedy, Teva), a long-acting subcutaneous antipsychotic, is an injectable formulation of risperidone and is approved by the FDA for the treatment of schizophrenia in adults. Its innovative copolymer-based drug delivery depot technology (licensed from MedinCell, Jacou, France) allows for plasma concentrations of the total active moiety of risperidone (TAM) to reach clinically relevant levels within 6-24 h and the maintenance of these therapeutic levels with monthly and bimonthly dosing regimens.

OBJECTIVE

As part of the development program for TV-46000, the effect of extrinsic factors of manipulation on the site of injection, and on the pharmacokinetic (PK) profile of TAM following TV-46000 administration was evaluated.

METHODS

Studies were conducted assessing the effect of heat and rubbing with male Gottingen minipigs and the effect of rubbing with male beagle dogs. A pilot clinical study in healthy volunteers was performed to evaluate the effect of rubbing.

RESULTS

These investigations showed that heating or rubbing of the TV-46000 sc injection site immediately post-injection had no clinically meaningful impact on safety and no burst or uncontrolled release was evident. Furthermore, no impact of injection site manipulation on TAM exposure was observed after depot formation (≥0.5 h post-injection).

CONCLUSIONS

The observed similarity in findings between the animal and human studies supports the suitability of animal models for evaluation of the effect of extrinsic factors on injection sites and its translatability to clinical settings.

Patient-Centric Long-Acting Injectable and Implantable Platforms─An Industrial Perspective

The increasing focus on patient centricity in the pharmaceutical industry over the past decade and the changing healthcare landscape, driven by factors such as increased access to information, social media, and evolving patient demands, has necessitated a shift toward greater connectivity and understanding of patients' unique treatment needs. One pharmaceutical technology that has supported these efforts is long acting injectables (LAIs), which lower the administration frequency for the patient's provided convenience, better compliance, and hence better therapeutical treatment for the patients. Furthermore, patients with conditions like the human immunodeficiency virus and schizophrenia have positively expressed the desire for less frequent dosing, such as that obtained through LAI formulations. In this work, a comprehensive analysis of marketed LAIs across therapeutic classes and technologies is conducted. The analysis demonstrated an increasing number of new LAIs being brought to the market, recently most as aqueous suspensions and one as a solution, but many other technology platforms were applied as well, in particular, polymeric microspheres and in situ forming gels. The analysis across the technologies provided an insight into to the physicochemical properties the compounds had per technology class as well as knowledge of the excipients typically used within the individual formulation technology. The principle behind the formulation technologies was discussed with respect to the release mechanism, manufacturing approaches, and the possibility of defining predictive in vitro release methods to obtain in vitro in vivo correlations with an industrial angle. The gaps in the field are still numerous, including better systematic formulation and manufacturing investigations to get a better understanding of potential innovations, but also development of new polymers could facilitate the development of additional compounds. The biggest and most important gaps, however, seem to be the development of predictive in vitro dissolution methods utilizing pharmacopoeia described equipment to enable their use for product development and later in the product cycle for quality-based purposes.

Injectable long-acting formulations (ILAFs) and manufacturing techniques

INTRODUCTION

Most therapeutics delivered using short-acting formulations need repeated administration, which can harm patient compliance and raise failure risks related to inconsistent treatment. Injectable long-acting formulations (ILAFs) are controlled/sustained-release formulations fabricated to deliver active pharmaceutical ingredients (APIs) and extend their half-life over days to months. Longer half-lives of ILAFs minimize the necessity for frequent doses, increase patient compliance, and reduce the risk of side effects from intravenous (IV) infusions. Using ILAF technologies, the immediate drug release can also be controlled, thereby minimizing potential adverse effects due to high initial drug blood concentrations.

AREA COVERED

In this review, we have discussed various ILAFs, their physiochemical properties, fabrication technologies, advantages, and practical issues, as well as address some major challenges in their application. Especially, the approved ILAFs are highlighted.

EXPERT OPINION

ILAFs are sustained-release formulations with extended activity, which can improve patient compliance. ILAFs are designed to deliver APIs like proteins and peptides and extend their half-life over days to months. The specific properties of each ILAF preparation, such as extended-release and improved drug targeting capabilities, make them an effective approach for precise and focused therapy. Furthermore, this is especially helpful for biopharmaceuticals with short biological half-lives and low stability since most environmental conditions can protect them from sustained-release delivery methods.

Peptide Acylation in Aliphatic Polyesters: a Review of Mechanisms and Inhibition Strategies

Biodegradable polyesters are widely employed in the development of controlled release systems for peptide drugs. However, one of the challenges in developing a polyester-based delivery system for peptides is the acylation reaction between peptides and polymers. Peptide acylation is an important factor that affects formulation stability and can occur during storage, in vitro release, and after drug administration. This review focuses on the mechanisms and parameters that influence the rate of peptide acylation within polyesters. Furthermore, it discusses reported strategies to minimize the acylation reaction.

Ethoxy acetalated dextran nanoparticles for drug delivery: A comparative study of formulation methods

Dextran-based polymers, such as ethoxy acetalated dextran (Ace-DEX), are increasingly becoming the focus of research as they offer great potential for the development of polymer-based nanoparticles as drug delivery vehicles. Their major advantages are the facile synthesis, straightforward particle preparation and the pH-dependent degradation of the particles that can be fine-tuned by the degree of acetalation of the polymer. In this study we have shown that Ace-DEX can not only compete against the commonly used and FDA-approved polymer poly(lactic-co-glycolic acid) (PLGA), but even has the potential to outperform it in its encapsulation properties, e.g., for the herein used anti-inflammatory leukotriene biosynthesis inhibitor BRP-187. We used three different methods (microfluidics, batch nanoprecipitation and emulsion solvent evaporation) for the preparation of BRP-187-loaded Ace-DEX nanoparticles to investigate the influence of the formulation technique on the physicochemical properties of the particles. Finally, we evaluated which production method offers the greatest potential for achieving the demands for a successful translation from research into pharmaceutical production by fulfilling the basic requirements, such as reaching a high loading capacity of the particles and excellent reproducibility while being simple and affordable.

Developing a robust in vitro release method for a polymeric nanoparticle: Challenges and learnings

Nanomedicines have emerged as a promising approach for targeted therapeutic delivery and specifically as a beneficial alternative to conventional cancer therapies as they can deliver higher concentrations of chemotherapeutic agents at the tumour site compared to healthy tissue, thus providing improved drug efficacy and lower systemic toxicity. Long acting injectables are increasingly becoming the focus of pharmaceutical research, as they can reduce dosing frequency and improve the life quality of patients. Development of an in vitro release (IVR) method for modified release nanomedicines is challenging because of the uniqueness and range of different formulation design approaches, as well as the complex nature of drug release mechanisms which may result in inherent variability. Regulatory guidance on the development of dissolution or release methods for parenteral products is limited relative to oral products. This article details the extensive in vitro release method development work conducted on a polymeric nanoparticle to develop the release media composition and selection of suitable apparatus and sampling technique to separate the released drug from the formulation. The aim was to develop a suitably robust analytical method that generated clinically relevant in vitro release data.

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.

Revisiting the in-vitro and in-vivo considerations for in-silico modelling of complex injectable drug products

Complex injectable drug products (CIDPs) have often been developed to modulate the pharmacokinetics along with efficacy for therapeutic agents used for remediation of chronic disorders. The effective development of CIDPs has exhibited complex kinetics associated with multiphasic drug release from the prepared formulations. Consequently, predictability of pharmacokinetic modelling for such CIDPs has been difficult and there is need for advanced complex computational models for the establishment of accurate prediction models for in-vitro-in-vivo correlation (IVIVC). The computational modelling aims at supplementing the existing knowledge with mathematical equations to develop formulation strategies for generation of predictable and discriminatory IVIVC. Such an approach would help in reduction of the burden of effect of hidden factors on preclinical to clinical translations. Computational tools like physiologically based pharmacokinetics (PBPK) modelling have combined physicochemical and physiological properties along with IVIVC characteristics of clinically used formulations. Such techniques have helped in prediction and understanding of variability in pharmacodynamic parameters of potential generic products to clinically used formulations like Doxil®, Ambisome®, Abraxane® in healthy and diseased population using mathematical equations. The current review highlights the important formulation characteristics, in-vitro, preclinical in-vivo aspects which need to be considered while developing a stimulatory predictive PBPK model in establishment of an IVIVC and in-vitro-in-vivo relationship (IVIVR).

Drug delivery breakthrough technologies - A perspective on clinical and societal impact

The way a drug molecule is administered has always had a profound impact on people requiring medical interventions - from vaccine development to cancer therapeutics. In the Controlled Release Society Fall Symposium 2022, a trans-institutional group of scientists from industry, academia, and non-governmental organizations discussed what a breakthrough in the field of drug delivery constitutes. On the basis of these discussions, we classified drug delivery breakthrough technologies into three categories. In category 1, drug delivery systems enable treatment for new molecular entities per se, for instance by overcoming biological barriers. In category 2, drug delivery systems optimize efficacy and/or safety of an existing drug, for instance by directing distribution to their target tissue, by replacing toxic excipients, or by changing the dosing reqimen. In category 3, drug delivery systems improve global access by fostering use in low-resource settings, for instance by facilitating drug administration outside of a controlled health care institutional setting. We recognize that certain breakthroughs can be classified in more than one category. It was concluded that in order to create a true breakthrough technology, multidisciplinary collaboration is mandated to move from pure technical inventions to true innovations addressing key current and emerging unmet health care needs.

Long-Acting Therapeutic Delivery Systems for the Treatment of Gliomas

Despite the emergence of cutting-edge therapeutic strategies and tremendous progress in research, a complete cure of glioma remains elusive. The heterogenous nature of tumor, immunosuppressive state and presence of blood brain barrier are few of the major obstacles in this regard. Long-acting depot formulations such as injectables and implantables are gaining attention for drug delivery to brain owing to their ease in administration and ability to elute drug locally for extended durations in a controlled manner with minimal toxicity. Hybrid matrices fabricated by incorporating nanoparticulates within such systems help to enhance pharmaceutical advantages. Utilization of long-acting depots as monotherapy or in conjunction with existing strategies rendered significant survival benefits in many preclinical studies and some clinical trials. The discovery of novel targets, immunotherapeutic strategies and alternative drug administration routes are now coupled with several long-acting systems with an ultimate aim to enhance patient survival and prevent glioma recurrences.