Injectable long-acting in situ forming systems for Radix Ophiopogonis polysaccharide

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.

Biodegradable Nanoparticles Prepared from Chitosan and Casein for Delivery of Bioactive Polysaccharides

Ophiopogon japonicus polysaccharides (OJPs) have great anti-inflammation and immunomodulatory abilities. However, the low bioavailability of OJPs reduces its applicability in the biomedical and pharmaceutical fields. Chitosan (CS) has excellent mucoadhesive properties and absorption-enhancing ability in oral administration. Casein hydrolysate (CL) has good interfacial diffusivity and emulsifying ability, and can interact with polysaccharides to form complexes combining the individual properties of both. Therefore, chitosan and casein hydrolysate are good candidates for developing nanoformulations for oral delivery. In this study, bioactive polysaccharides (OJPs), CS and CL, were combined to prepare CS/OJPs/CL co-assembled biodegradable nanoparticles. The interactions between polysaccharides (CS and OJPs) and peptide (CL) resulted in the formation of nanoparticles with an average particle size of 198 nm and high OJPs loading efficiency. The colloidal properties of the nanoparticles were pH-dependent, which were changed significantly in simulated digestive fluid at different pH values. OJPs released from the CS/OJPs/CL nanoparticles were greatly affected by pH and enzymatic degradation (trypsin and lysozyme). The nanoparticles were easily internalized by macrophages, thereby enhancing the OJPs’ inhibitory ability against Ni²⁺-induced cytotoxicity and LPS-induced nitric oxide production. This study demonstrates that prepared polysaccharide/protein co-assembled nanoparticles can be potential nanocarriers for the oral delivery of bioactive polysaccharides with anti-inflammatory functions.

In vitro evaluation of poloxamer in situ forming gels for bedaquiline fumarate salt and pharmacokinetics following intramuscular injection in rats

The objective of this study was to evaluate in vitro and in vivo drug release from in situ forming gels prepared with poloxamer 338 (P338) and/or 407 (P407) in N-methyl-2-pyrrolidone (NMP)/water mixtures for the model compound bedaquiline fumarate salt. The impact of total poloxamer concentration (20%-25% (w/w)), P338/P407 ratio (100/0%-0/100% (w/w)) and NMP/water ratio (0/100%-25/75% (v/v)) on gel point temperature (GPT) was investigated via a design of experiments (DoE), showing that GPT decreased mainly with increasing poloxamer concentration and decreasing P338/P407 ratio, while the relation with NMP/water ratio was more complex resulting in a flexion. Based on the DoE, four formulations with 10 mg/g bedaquiline fumarate salt, a fixed NMP/water ratio of 25/75% (v/v) and varying total poloxamer concentration and P338/P407 ratio were selected for evaluation of gel erosion in vitro. The fastest eroding formulation had the lowest total poloxamer concentration (20% (w/w)) and the lowest P338/P407 ratio (20.4/79.6% (w/w)), while the formulation with the highest total poloxamer concentration (23.5% (w/w)) and highest P338/P407 ratio (100/0% (w/w)) showed the lowest gel erosion rate. These fast and slow eroding formulations showed a similar trend for in vitro drug release and in vivo pharmacokinetics after intramuscular (IM) injection in rats. In vivo tmax of the IM administered poloxamer in situ forming gels was about 6 h and a short-term sustained drug release was observed in vivo in rats up to 24 h after dosing, similar to a solution of bedaquiline fumarate salt in polyethylene glycol (PEG400)/water. In conclusion, IM administration of the evaluated poloxamer in situ forming gels may be useful for drugs that require a short-term sustained release, but is not able to extend drug release rates up to weeks or months.

Delivery of radix ophiopogonis polysaccharide via sucrose acetateisobutyrate-based in situ forming systems alone or combined with itsmono-PEGylation

This work aimed to achieve long-lasting delivery of radix ophiopogonis polysaccharide (ROP) by sucrose acetate isobutyrate (SAIB)-based in situ forming systems (ISFSs) alone or combined with mono-PEGylation of ROP. When the ‘90%SAIB/10% solvent’ system was used, the mean residence time (MRT) of ROP was prolonged by 4.3 5 ∼ 7.00 times and the initial release rate was reduced significantly. However, this system was only suitable for days-long sustained release of ROP in short-term therapy. As to the ‘SAIB/additives/solvent’ system containing mono-PEGylated ROP, the results indicated that SAIB/poly(d,l-lactide-co-glycolide) (PLGA)/N-methyl-2-pyrrolidone (NMP) was superior to SAIB/polylactic acid (PLA)/NMP and SAIB/PLA/ethanol in controlled release. Moreover, weeks- to months-long (16–60 d) smooth release of ROP could be achieved by varying the concentration (10–30%) and molecular weight (MW) of PLGA (10–50 kDa) or by employing a moderate MW of PEGylated ROP (∼20 or ∼30 kDa). With further increasing the conjugate MW to ∼40 kDa, the contribution of drug elimination to its plasma retention seemed to surpass that of the SAIB-based system, resulting in that the system no longer had an obvious influence on the in vivo behavior of the conjugate. Besides, the results of host response confirmed that with less solvent being used, the SAIB-based systems showed a higher biocompatibility than the PLGA-based systems, suggesting that they could be freely chosen in the prevention and/or cure of chronic diseases.

Panax ginseng Polysaccharide Protected H9c2 Cardiomyocyte From Hypoxia/Reoxygenation Injury Through Regulating Mitochondrial Metabolism and RISK Pathway

Background and Objective: Ischemic heart disease (IHD) has been the major issue of public health. Panax ginseng (ginseng) has been verified as an effective traditional Chinese medicines and exerted cardioprotective effect. This study aimed to investigate the polysaccharide fraction of ginseng on hypoxia/reoxygenation (H/R) injury in cardiomyocytes and the underlying mechanisms.

Methods: Ginseng was extracted by ethanol and fractionated by high-speed counter current chromatography (HSCCC) and column separation. The cardioprotective effect was evaluated in H9c2 cardiomyocytes underwent H/R treatment. The cell viability, apoptosis and mitochondrial respiration were examined.

Results: An acid polysaccharides fraction of ginseng (AP1) was identified the most effective fraction in protecting cardiomyocytes from H/R injury. AP1 restored the mitochondrial function by maintaining mitochondrial membrane potential (MMP), blocking the release of cytochrome C, and increasing the ATP generation and oxygen consumption rate (OCR) of cardiomyocytes. Meanwhile, AP1 induced the expression of glucocorticoid receptor (GR) and estrogen receptor (ER) which further activated reperfusion injury salvage kinase (RISK) pathway. Finally, AP1 increased nitric oxide (NO) production and regulated endothelial function by increasing endothelial NO synthase (eNOS) expression and decreasing inducible NOS (iNOS) expression in H/R injury.

Conclusion: The results suggested that AP1 exerted a protective effect in myocardial H/R injury mainly through maintaining myocardial mitochondrial function, thereby inhibiting myocardial H/R caused apoptosis and increasing the expressions of GR and ER, which in turn mediated the activation of RISK pathway and eNOS-dependent mechanism to resist the reperfusion injury.

Recent advances in polysaccharides from Ophiopogon japonicus and Liriope spicata var. prolifera

O. japonicus and L. spicata var. prolifera are distinguished as sources of highly promising yin-tonifying medicinals, namely Ophiopogonis Radix and Liriopes Radix. Liriopes Radix is generally medicinally used as a substitute for Ophiopogonis Radix in various prescriptions due to their extremely similar nature. Ophiopogonis Radix and Liriopes Radix are both very rich in bioactive polysaccharides, especially β‑fructans. Over the past twelve years, except for work on physical entrapment and chemical modification of obtained β‑fructans, the vast majority of studies are carried out to investigate the bioactivities of O. japonicus polysaccharides (OJP) and L. spicata var. prolifera polysaccharides (LSP), mainly including anti-diabetes, immunomodulation, anti-inflammation, antioxidation, anti-obesity, cardiovascular protection, etc. In addition, OJP and LSP are considered to have the potential to regulate intestinal flora. The main purpose of this review is to provide systematically reorganized information on structural characteristics and bioactivities of OJP and LSP to support their further therapeutic potentials and sanitarian functions.

A mucoadhesive, thermoreversible in situ nasal gel of geniposide for neurodegenerative diseases

Neurodegenerative diseases are becoming prevalent as the population ages. Geniposide could inhibit oxidative stress, reduce apoptosis, protect neuron, and has been used for therapy of the neurodegenerative diseases. The bioavailability of geniposide by nasal route is greater than that by oral administration. However, mucociliary clearance is a rate-limiting factor for nasal route administration. The objective of this study was to develop and evaluate a mucoadhesive, thermoreversible in situ nasal gel of geniposide. The poloxamers (P407, P188) and the hydroxypropyl methylcellulose were used as thermoreversible and mucoadhesive polymers, respectively. Borneol was used as a permeation enhancer. The hydrogel was prepared with the cold method and optimized by the response surface methodology-central composite design. Gelation temperature, pH, clarity, gel strength, mucoadhesive strength, in vitro and ex vivo release kinetics of formulations were evaluated. The optimized amounts of poloxamer407 (P407), poloxamer188 (P188) and hydroxypropyl methylcellulose were determined to be 19.4-20.5%, 1.1-4.0% and 0.3-0.6% respectively. The second-order polynomial equation in terms of actual factors indicated a satisfactory correlation between the independent variables and the response (R2 = 0.9760). An ANOVA of the empirical second-order polynomial model indicated the model was significant (P<0.01). P407, P188, P407×P188, P4072 and P1882 were significant model terms. The effects of P407 on gelation temperature were greater than those of other independent variables. The pH values of all the formulations were found to be within 6.3-6.5 which was in the nasal physiological pH range 4.5-6.5. The drug content, gel strength, mucoadhesive strength of the optimized formulations were 97-101%, 25-50 sec and 4000-6000 dyn/cm2 respectively. The in vitro release kinetics of cumulative release of geniposide was fitted to the zero-order model. The ex vivo cumulative release kinetics of geniposide was fitted to the Weibull model. This study concludes that the release of geniposide is controlled by gel corrosion, and that the permeation of geniposide is time-dependent. The more residence time, mucoadhesive, thermoreversible in situ nasal gel of geniposide for neurodegenerative diseases is of compliance and potential application.

Drug delivery for bioactive polysaccharides to improve their drug-like properties and curative efficacy

Over several decades, natural polysaccharides (PSs) have been actively exploited for their wide bioactivities. So far, many PS-related reviews have been published; however, none focused on the delivery of bioactive PSs as therapeutic molecules. Herein, we summarized and discussed general pharmacokinetic properties of PSs and drug delivery systems (DDSs) developed for them, together with the challenges and prospects. Overall, most bioactive PSs suffer from undesirable pharmacokinetic attributes, which negatively affect their efficacy and clinical use. Various DDSs therefore have been being utilized to improve the drug-like properties and curative efficacy of bioactive PSs by means of improving oral absorption, controlling the release, enhancing the in vivo retention ability, targeting the delivery, exerting synergistic effects, and so on. Specifically, nano-sized insoluble DDSs were mainly applied to improve the oral absorption and target delivery of PSs, among which liposome was especially suitable for immunoregulatory and/or anti-ischemic PSs due to its synergistic effects in immunoregulation and biomembrane repair. Chemical conjugation of PSs was mainly utilized to improve their oral absorption and/or prolong their blood residence. With formulation flexibility, in situ forming systems alone or in combination with drug conjugation could be used to achieve day(s)- or month(s)-long sustained delivery of PSs per dosing.

Hydrophobic mixed solvent induced PLGA-based in situ forming systems for smooth long-lasting delivery of Radix Ophiopogonis polysaccharide in rats

To obtain a sustained in vivo release of Radix Ophiopogonis polysaccharide, hydrophobic solvent-induced in situ forming systems were investigated, including the factors affecting drug release and anti-myocardial ischemic activity of a formulation.

Solvent exchange-induced in situ forming gel comprising ethyl cellulose-antimicrobial drugs

Solvent-exchanged in situ forming gel is a drug delivery system which is in sol form before administration. When it contacts with the body fluid, then the water miscible organic solvent dissipates and water penetrates into the system, leading the polymer precipitation as in situ gel at the site of injection. The aim of this research was to study the parameters affecting the gel properties, drug release and antimicrobial activities of the in situ forming gels prepared from ethyl cellulose (EC) dissolved in N-methyl pyrrolidone (NMP) to deliver the antimicrobial agents (doxycycline hyclate, metronidazole and benzyl peroxide) for periodontitis treatment. The gel appearance, pH, viscosity, rheology, syringeability, gel formation, rate of water diffusion into the gels, in vitro degradation, drug release behavior and antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans and Porphyrommonas gingivalis were determined. Increasing the amount of EC increased the viscosity of system while still exhibiting Newtonian flow and increased the work of syringeability whereas decreased the releasing of drug. The system transformed into the rigid gel formation after being injected into the simulated gingival crevicular fluid. The developed systems containing 5% w/w antimicrobial agent showed the antimicrobial activities against all test bacteria. Thus the developed solvent exchange-induced in situ forming gels comprising EC-antimicrobial drugs exhibited potential use for periodontitis treatment.

A Uniform Ultra-Small Microsphere/SAIB Hybrid Depot with Low Burst Release for Long-Term Continuous Drug Release

PURPOSE

In the present study, a uniform ultra-small microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot (m-SAIB depot) was designed to provide a long-term sustained release drug delivery system which not only reduced the burst release of an SAIB depot, but also eliminated the lag-time of PLGA microspheres.

METHODS

Risperidone loaded m-SAIB depot (Ris-m-SAIB depot) was characterized by in vitro drug release, pharmacokinetics, in vivo degradation and biocompatibility, in comparison with risperidone loaded SAIB depot (Ris-SAIB depot).

RESULTS

Ris-m-SAIB depot showed a low burst release (0.64%) and a reduced in vitro drug release rate due to the encapsulation of most drug in microspheres. After intramuscular administration, the in vivo burst release of Ris-m-SAIB was significantly decreased, as reflected by the low Cmax/Cs(4-td) (approximately 30-fold reduction), in comparison with Ris-SAIB depot. From 4 to 78 days, Ris-m-SAIB depot showed a higher plasma drug level (1.55 ~ 16.30 ng/ml) with a steadier drug release profile compared with Ris-SAIB depot. Ris-m-SAIB depot degraded gradually with a degradation t1/2 of 54.6 days and exhibited good biocompatibility in vivo.

CONCLUSION

These results demonstrate the potential application of a uniform ultra-small microsphere/SAIB hybrid depot for continuously delivering small drug molecules for long periods of time without burst release.

Injectable long-acting systems for Radix Ophiopogonis polysaccharide based on mono-PEGylation and in situ formation of a PLGA depot

Background

Radix Ophiopogonis polysaccharide (ROP), a highly hydrophilic macromolecule, has a unique anti-ischemic action in the myocardium. One of the main problems with its use is its relatively short half-life in vivo. To solve this problem, injectable long-acting drug delivery systems, which combine mono-PEGylation (PEG, polyethylene glycol) with the in situ formation of poly(_d,l-lactide-co-glycolide) copolymer (PLGA) depots, were tested in this study.

Methods

Through a moderate coupling reaction between 20 kDa amino-terminated methoxy-PEG and excessive ROP with activated hydroxyls, a long-circulating and bioactive mono-PEGylated ROP was prepared and characterized. A reasonable and applicable range of PLGA formulations loaded with the mono-PEGylated ROP were prepared, characterized, and evaluated in vivo.

Results

Relative to ROP, the half-life of which was only 0.5 hours, the conjugate alone, following subcutaneous administration, showed markedly prolonged retention in the systemic circulation, with a mean residence time in vivo of approximately 2.76 days. In combination with in situ-forming PLGA depots, the residence time of the conjugate in vivo was prolonged further. In particular, a long-lasting and steady plasma exposure for nearly a month was achieved by the formulation comprising 40% 30 kDa PLGA in N-methyl-2-pyrrolidone.

Conclusion

Long-lasting and steady drug exposure could be achieved using mono-PEGylation in combination with in situ formation of PLGA depots. Such a combination with ROP would be promising for long-term prophylaxis and/or treatment of myocardial ischemia. For high-dose and highly hydrophilic macromolecular drugs like ROP, more than one preparation technology might be needed to achieve week-long or month-long delivery per dosing.