Mechanistic explanation of the (up to) 3 release phases of PLGA microparticles: Monolithic dispersions studied at lower temperatures

Long-Acting Strategies for Antibody Drugs: Structural Modification, Controlling Release, and Changing the Administration Route

Because of their high specificity, high affinity, and targeting, antibody drugs have been widely used in the treatment of many diseases and have become the most favored new drugs for research in the world. However, some antibody drugs (such as small-molecule antibody fragments) have a short half-life and need to be administered frequently, and are often associated with injection-site reactions and local toxicities during use. Increasing attention has been paid to the development of antibody drugs that are long-acting and have fewer side effects. This paper reviews existing strategies to achieve long-acting antibody drugs, including modification of the drug structure, the application of drug delivery systems, and changing their administration route. Among these, microspheres have been studied extensively regarding their excellent tolerance at the injection site, controllable loading and release of drugs, and good material safety. Subcutaneous injection is favored by most patients because it can be quickly self-administered. Subcutaneous injection of microspheres is expected to become the focus of developing long-lasting antibody drug strategies in the near future.

Drug release from PLGA microparticles can be slowed down by a surrounding hydrogel

This study aimed to evaluate and better understand the potential impact that a layer of surrounding hydrogel (mimicking living tissue) can have on the drug release from PLGA microparticles. Ibuprofen-loaded microparticles were prepared with an emulsion solvent extraction/evaporation method. The drug loading was about 48%. The surface of the microparticles appeared initially smooth and non-porous. In contrast, the internal microstructure of the particles exhibited a continuous network of tiny pores. Ibuprofen release from single microparticles was measured into agarose gels and well-agitated phosphate buffer pH 7.4. Optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction, and X-ray μCT imaging were used to characterize the microparticles before and after exposure to the release media. Importantly, ibuprofen release was much slower in the presence of a surrounding agarose gel, e.g., the complete release took two weeks vs. a few days in well agitated phosphate buffer. This can probably be attributed to the fact that the hydrogel sterically hinders substantial system swelling and, thus, slows down the related increase in drug mobility. In addition, in this particular case, the convective flow in agitated bulk fluid likely damages the thin PLGA layer at the microparticles' surface, giving the outer aqueous phase more rapid access to the inner continuous pore network: Upon contact with water, the drug dissolves and rapidly diffuses out through a continuous network of water-filled channels. Without direct surface access, most of the drug "has to wait" for the onset of substantial system swelling to be released.

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.

The Management of Parkinson's Disease: An Overview of the Current Advancements in Drug Delivery Systems

Parkinson's disease (PD) has significantly affected a large proportion of the elderly population worldwide. According to the World Health Organization, approximately 8.5 million people worldwide are living with PD. In the United States, an estimated one million people are living with PD, with approximately 60,000 new cases diagnosed every year. Conventional therapies available for Parkinson's disease are associated with limitations such as the wearing-off effect, on-off period, episodes of motor freezing, and dyskinesia. In this review, a comprehensive overview of the latest advances in DDSs used to reduce the limitations of current therapies will be presented, and both their promising features and drawbacks will be discussed. We are also particularly interested in the technical properties, mechanism, and release patterns of incorporated drugs, as well as nanoscale delivery strategies to overcome the blood-brain barrier.

Machine learning models to accelerate the design of polymeric long-acting injectables

Long-acting injectables are considered one of the most promising therapeutic strategies for the treatment of chronic diseases as they can afford improved therapeutic efficacy, safety, and patient compliance. The use of polymer materials in such a drug formulation strategy can offer unparalleled diversity owing to the ability to synthesize materials with a wide range of properties. However, the interplay between multiple parameters, including the physicochemical properties of the drug and polymer, make it very difficult to intuitively predict the performance of these systems. This necessitates the development and characterization of a wide array of formulation candidates through extensive and time-consuming in vitro experimentation. Machine learning is enabling leap-step advances in a number of fields including drug discovery and materials science. The current study takes a critical step towards data-driven drug formulation development with an emphasis on long-acting injectables. Here we show that machine learning algorithms can be used to predict experimental drug release from these advanced drug delivery systems. We also demonstrate that these trained models can be used to guide the design of new long acting injectables. The implementation of the described data-driven approach has the potential to reduce the time and cost associated with drug formulation 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.

Goserelin/PLGA solid dispersion used to prepare long-acting microspheres with reduced initial release and reduced fluctuation of drug serum concentration in vivo

To prepare Goserelin (GOS) loaded long-acting microspheres with reduced initial release and prolonged drug release time of GOS, GOS/PLGA solid dispersion (by hot-melt extrusion, HME) was dissolved/dispersed in dichloromethane (DCM) to prepare microspheres by O/W method. From results of molecular dynamics simulation, PLGA and GOS molecules completely and uniformly dissolved and dispersed in DCM, respectively. In F5 microspheres (prepared by HME-O/W method), GOS existed as molecular or amorphous state, but not aggregation. Burst release of F5 microspheres (2.75%) was similar with Zoladex^TM implant (0.39%) and less than F10 microspheres (prepared by S/O/W method, 25.92%). After lag phase, GOS released rapidly from F5 microspheres and the cumulative release on the 45^th days was 95.14%. After injection of F5 microspheres, GOS serum concentration was relative steady at the range of 27.64-175.27 ng/mL for nearly 35 days. AUC_{(0-35 day)} of F5 microspheres was almost 2 times that of F10 microspheres. Pharmacodynamics study also showed potential effect of F5 microspheres on inhibiting the secretion of testosterone in male rats. HME-O/W method is potential to establish long-acting PLGA microspheres (loading water-soluble drug) , exhibiting stable drug serum concentration in vivo, and without large concentration fluctuation or serious pain/side effects.

Preparation and in vivo/in vitro characterization of Ticagrelor PLGA sustained-release microspheres for injection

The objective of this paper was to develop a PLGA carrier Ticagrelor sustained-release microspheres preparation, which was expected to continue to release Ticagrelor for 14 days with a high encapsulation rate. Ticagrelor microspheres were prepared successfully with average diameter of 7.31 µm, drug loading of 12.49 ± 0.32% and EE up to 79.09 ± 1.69%. In the release medium of PH7.4 PBS, the microspheres showed good drug release behavior in vitro. In vivo release results also showed that the sustained-release microspheres could effectively control drug release in vivo and maintain a relatively stable blood drug concentration for about 2 weeks. The results indicate that Ticagrelor sustained-release microspheres can be used for long-term treatment of acute coronary syndrome.

A review of existing strategies for designing long-acting parenteral formulations: Focus on underlying mechanisms, and future perspectives

The need for long-term treatments of chronic diseases has motivated the widespread development of long-acting parenteral formulations (LAPFs) with the aim of improving drug pharmacokinetics and therapeutic efficacy. LAPFs have been proven to extend the half-life of therapeutics, as well as to improve patient adherence; consequently, this enhances the outcome of therapy positively. Over past decades, considerable progress has been made in designing effective LAPFs in both preclinical and clinical settings. Here we review the latest advances of LAPFs in preclinical and clinical stages, focusing on the strategies and underlying mechanisms for achieving long acting. Existing strategies are classified into manipulation of in vivo clearance and manipulation of drug release from delivery systems, respectively. And the current challenges and prospects of each strategy are discussed. In addition, we also briefly discuss the design principles of LAPFs and provide future perspectives of the rational design of more effective LAPFs for their further clinical translation.

Ramulus mori polysaccharide-loaded PLGA nanoparticles and their anti-inflammatory effects in vivo

In this study, ramulus mori polysaccharide (RMP) was encapsulated into Poly (lactic-co-glycolicacid) (PLGA) to form PLGA-RMP (PR). The aim of study is to investigate anti-inflammatory effects of PR. The particle size of PR nanoparticles was approximately 205.6 ± 1.86 nm. PR nanoparticles showed significant therapeutic effects on colitis mice model, evidenced by attenuation of the loss of body weight, reduction of the DAI score, and restoration of the colon length. From the histopathological analysis, alleviation of the histopathological damage, less production of IFN-γ and IL-6, and improvement of IL-10 were observed with the treatment of PR. Meanwhile, the treatment of PR not only promoted the expression of ZO-1 and occludin, but also improved the contents of acetate, propionate, and butyrate in the colitis colon. Furthermore, PR extenuated the reduction of the diversity and richness of gut microbiota induced by DSS, and decreased the ratio of Firmicutes to Bacteroidetes while increasing the proportion of Clostridium XIVa, Mucispirillum, and Paraprevotella in the gut microbiota. What's more, PR nanoparticles attenuated the metabolic disorders in the colitis colon induced by DSS. These results indicated that PR nanoparticles could serve as a potent nanomedicine to treat IBD and be used as potential prebiotics.