Increase of the pharmacological and pharmacokinetic efficacy of negatively charged polypeptide recombinant hirudin in rats via parenteral route by association with cationic liposomes

Novel drug delivery systems for hirudin-based product development and clinical applications

Hirudin, a natural biological polypeptide macromolecule secreted by the salivary glands of medicinal leech, is a specific thrombin inhibitor with multiple favourable bioactivities, including anti-coagulation, anti-fibrotic, and anti-tumour. Despite several anticoagulants have been widely applied in clinic, hirudin shows advantages in reducing the incidence of bleeding side effects by virtue of its high specificity in binding to thrombin. As a result, hirudin has been tested in clinical practice to prevent and treat several complex diseases. However, the application of this polypeptide macromolecule is compromised by its low bioavailability and bioactivity due to poor serum stability and susceptibility to protease degradation in vivo. To overcome these drawbacks, several studies have proposed novel drug delivery systems (NDDSs) to prevent the degradation and increase the targeting efficiency of hirudin. This systematic review summarises the clinical research on hirudin, including its classification and bioactivities, and highlights the opportunities and challenges in the clinical use of hirudin. The NDDSs designed to enhance the bioavailability and bioactivity of hirudin are discussed to explore its application in the treatment of related diseases. This review may considerably contribute to the advancement of delivery science and technology, particularly in the context of polypeptide-based therapeutics.

Bifunctional Oxaliplatin (IV) Prodrug Based pH-Sensitive PEGylated Liposomes for Synergistic Anticancer Action Against Triple Negative Breast cancer

Triple negative breast cancer (TNBC) exhibits higher susceptibility towards oxaliplatin (OXA) due to a faulty DNA damage repair system. However, the unfavorable physicochemical properties and risk of toxicities limit the clinical utility of OXA. Therefore, to impart kinetic inertness, site-specific delivery, and multidrug action, an octahedral Pt(IV) prodrug was developed by using chlorambucil (CBL) as a choice of ligand. The combination of OXA and CBL exhibited synergistic anti-cancer action in TNBC cell lines. Further, to maximize tumor-specific delivery, intracellular accumulation, and in-vivo performance, the developed prodrug (OXA-CBL) was encapsulated in pH-sensitive PEGylated liposomes into (OXA-CBL/PEG-Liposomes). The fabricated liposomes had smaller particle size < 200 nm and higher drug loading (~ 4.26 ± 0.18%). In-vitro release displayed pH-dependent sustained release for up to 48 h. Cellular internalization revealed maximal uptake via clathrin-mediated endocytosis. The cytotoxicity assay showed reduced IC50 in the 4T1 (~ 1.559-fold) and MDA-MB-231 (~ 1.539-fold) cell lines than free OXA-CBL. In-vivo efficacy in 4T1-induced TNBC model revealed a marked increase in % tumor inhibition rate, while diminished % tumor burden in OXA-CBL/BSA-NPs treated animals. Toxicity assessment displayed no signs of systemic and hemolytic toxicity. Overall, delivery of Pt (IV) prodrug as a pH-sensitive PEGylated liposomes offers a safer and efficient system to manage TNBC.

Biomimetic Platelet Nanomotors for Site-Specific Thrombolysis and Ischemic Injury Alleviation

Due to the mortality associated with thrombosis and its high recurrence rate, there is a need to investigate antithrombotic approaches. Noninvasive site-specific thrombolysis is a current approach being used; however, its usage is characterized by the following limitations: low targeting efficiency, poor ability to penetrate clots, rapid half-life, lack of vascular restoration mechanisms, and risk of thrombus recurrence that is comparable to that of traditional pharmacological thrombolysis agents. Therefore, it is vital to develop an alternative technique that can overcome the aforementioned limitations. To this end, a cotton-ball-shaped platelet (PLT)-mimetic self-assembly framework engineered with a phototherapeutic poly(3,4-ethylenedioxythiophene) (PEDOT) platform has been developed. This platform is capable of delivering a synthetic peptide derived from hirudin P6 (P6) to thrombus lesions, forming P6@PEDOT@PLT nanomotors for noninvasive site-specific thrombolysis, effective anticoagulation, and vascular restoration. Regulated by P-selectin mediation, the P6@PEDOT@PLT nanomotors target the thrombus site and subsequently rupture under near-infrared (NIR) irradiation, achieving desirable sequential drug delivery. Furthermore, the movement ability of the P6@PEDOT@PLT nanomotors under NIR irradiation enables effective penetration deep into thrombus lesions, enhancing bioavailability. Biodistribution analyses have shown that the administered P6@PEDOT@PLT nanomotors exhibit extended circulation time and metabolic capabilities. In addition, the photothermal therapy/photoelectric therapy combination can significantly augment the effectiveness (ca. 72%) of thrombolysis. Consequently, the precisely delivered drug and the resultant phototherapeutic-driven heat-shock protein, immunomodulatory, anti-inflammatory, and inhibitory plasminogen activator inhibitor-1 (PAI-1) activities can restore vessels and effectively prevent rethrombosis. The described biomimetic P6@PEDOT@PLT nanomotors represent a promising option for improving the efficacy of antithrombotic therapy in thrombus-related illnesses.

A novel stearic acid-modified hirudin peptidomimetic with improved pharmacokinetic properties and anticoagulant activity

A novel hirudin isoform 3 mimetic peptide, named peptide S2, has been prepared by introduction of a stearic acid modification. Peptide S2 exhibited superior inhibitory activity to hirulog-1 (Bivariludin) and showed significantly higher anticoagulant potency in vivo. Peptide S2 elevated the thrombin time, prothrombin time and activated partial thromboplastin time of rat and human plasma more efficiently than hirulog-1 and the unmodified form of peptide S2 (peptide 1). Furthermore, peptide S2 inhibited arterial thrombosis and inferior vena cava in rat model 8 h after administration, and was 10-fold more potent than hirulog-1 300 min after administration of 0.1 μmol/kg peptide. The enhanced antithrombotic activity could be attributed to its long half-life (T_1/2 = 212.2 ± 58.4 min), which was 13.1 and 14.7-fold longer than those of hirulog-1 (T_1/2 = 15.1 ± 1.3 min) and peptide 1 (T_1/2 = 13.5 ± 2.6 min), respectively. Further enzymatic degradation and binding assay with human serum albumin (HSA) demonstrated that the longer duration time should be originated from the slowing of trypsin or thrombin–mediated degradation, as well as its binding to HSA. The improved pharmacokinetic properties observed for peptide S2 has made it a promising therapeutic agent for the treatment of thrombi-related diseases.

Recent developments in protein and peptide parenteral delivery approaches

Discovery of insulin in the early 1900s initiated the research and development to improve the means of therapeutic protein delivery in patients. In the past decade, great emphasis has been placed on bringing protein and peptide therapeutics to market. Despite tremendous efforts, parenteral delivery still remains the major mode of administration for protein and peptide therapeutics. Other routes such as oral, nasal, pulmonary and buccal are considered more opportunistic rather than routine application. Improving biological half-life, stability and therapeutic efficacy is central to protein and peptide delivery. Several approaches have been tried in the past to improve protein and peptide in vitro/in vivo stability and performance. Approaches may be broadly categorized as chemical modification and colloidal delivery systems. In this review we have discussed various chemical approaches such as PEGylation, hyperglycosylation, mannosylation, and colloidal carriers including microparticles, nanoparticles, liposomes, carbon nanotubes and micelles for improving protein and peptide delivery. Recent developments on in situ thermosensitive gel-based protein and peptide delivery have also been described. This review summarizes recent developments on some currently existing approaches to improve stability, bioavailability and bioactivity of peptide and protein therapeutics following parenteral administration.

Tumor vasculature targeting following co-delivery of heparin-taurocholate conjugate and suberoylanilide hydroxamic acid using cationic nanolipoplex

The chemical conjugate of low molecular weight heparin with taurocholate (LHT7) was previously designed to offer anticancer activity while minimizing the anticoagulant activity. In the present study, we found that the systemic administration of LHT7 in nanolipoplex could substantially enhance tumor vasculature targeting and anticancer effects. Moreover, we found that co-delivery of LHT7 with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, in nanolipoplex could provide synergistic antitumor effect. LHT7/SAHA nanolipoplex was formulated by encapsulating SAHA inside cationic liposomes, followed by complexation of negatively charged LHT7 onto the cationic surfaces of SAHA-loaded liposomes (SAHA-L). LHT7/SAHA nanolipoplex was positively charged with a mean diameter of 117.6 nm, and stable in serum. The nanolipoplex form of LHT7 could alter its pharmacokinetics and biodistribution. Compared to the free form of LHT7, LHT7 in the nanolipoplex showed 1.9-fold higher mean residence time, and higher tumor vasculature accumulation after its intravenous administration. LHT7/SAHA nanolipoplex showed highest antitumor efficacy in SCC-bearing mice, compared to LHT7, SAHA-L and sequential co-administration of LHT7 and SAHA-L. Consistent with the enhanced antitumor effect, the reduction of abnormal vessels in the tumor site was also the highest in the LHT7/SAHA nanolipoplex-treated group. These results suggested the potential of LHT7/SAHA nanolipoplex for enhanced tumor vasculature targeting, and the importance of nanolipoplex-mediated co-delivery with a histone deacetylase inhibitor for maximal anticancer effect.

Loading 3-deazaneplanocin A into pegylated unilamellar liposomes by forming transient phenylboronic acid-drug complex and its pharmacokinetic features in Sprague-Dawley rats

3-Deazaneplanocin A (DZNep) is an attractive epigenetic anticancer agent through the inhibition of the cellular enhancer of zeste homolog 2 (EZH2) protein. The purpose of this study was to improve the pharmacokinetic characteristics of DZNep in vivo through developing a unilamellar pegylated liposomal formulation encapsulating DZNep (L-DZNep). A remote-loading method in the presence of phenylboronic acid (R-w-PBA) was developed to stably encapsulating DZNep inside liposomes (encapsulation efficiency=50.7% at molar ratio of 1:10 of drug to lipids) through forming a transient PBA-DZNep complex. The pharmacokinetics of L-DZNep was investigated in Sprague-Dawley rats. In comparison with free drug, encapsulation of the DZNep in pegylated liposomes resulted in 99.3% reduction of the plasma clearance, whereas it increased the elimination half-life from 1.1 h to 8.0 h and the area under the plasma concentration curve by 138-fold. These findings demonstrate a novel approach (R-w-PBA method) through the development of L-DZNep, which may be extensively applied for the encapsulation of hydrophilic nucleoside analogs containing vicinal hydroxyl groups and protonable amino in the pegylated liposomes. Additionally, the pegylated liposomes could effectively prolong the retention of DZNep in the systemic circulation and therefore is highly likely to increase the DZNep's tumor localization.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.

Factors affecting drug encapsulation and stability of lipid-polymer hybrid nanoparticles

Lipid-polymer hybrid nanoparticles are polymeric nanoparticles enveloped by lipid layers that combine the highly biocompatible nature of lipids with the structural integrity afforded by polymeric nanoparticles. Recognizing them as attractive drug delivery vehicles, antibiotics are encapsulated in the present work into hybrid nanoparticles intended for lung biofilm infection therapy. Modified emulsification-solvent-evaporation methods using lipid as surfactant are employed to prepare the hybrid nanoparticles. Biodegradable poly (lactic-co-glycolic acid) and phosphatidylcholine are used as the polymer and lipid models, respectively. Three fluoroquinolone antibiotics (i.e. levofloxacin, ciprofloxacin, and ofloxacin), which vary in their ionicity, lipophilicity, and aqueous solubility, are used. The hybrid nanoparticles are examined in terms of their drug encapsulation efficiency, drug loading, stability, and in vitro drug release profile. Compared to polymeric nanoparticles prepared using non-lipid surfactants, hybrid nanoparticles in general are larger and exhibit higher drug loading, except for the ciprofloxacin-encapsulated nanoparticles. Hybrid nanoparticles, however, are unstable in salt solutions, but the stability can be conferred by adding TPGS into the formulation. Drug-lipid ionic interactions and drug lipophilicity play important roles in the hybrid nanoparticle preparation. First, interactions between oppositely charged lipid and antibiotic (i.e. ciprofloxacin) during preparation cause failed nanoparticle formation. Charge reversal of the lipid facilitated by adding counterionic surfactants (e.g. stearylamine) must be performed before drug encapsulation can take place. Second, drug loading and the release profile are strongly influenced by drug lipophilicity, where more lipophilic drug (i.e. levofloxacin) exhibit a higher drug loading and a sustained release profile attributed to the interaction with the lipid coat.

A rapid and simple HPLC method for the determination of curcumin in rat plasma: assay development, validation and application to a pharmacokinetic study of curcumin liposome

This paper describes a sensitive, specific and rapid high-performance liquid chromatography (HPLC) method for the determination of curcumin in rat plasma. After a simple step of protein precipitation in 96-well format using acetonitrile containing the internal standard (IS), emodin, plasma samples were analyzed by reverse-phase HPLC. Curcumin and the IS emodin were separated on a Diamonsil C(18) analytical column (4.6 x 100 mm, 5 microm) using acetonitrile-5% acetic acid (75:25, v/v) as mobile phase at a flow rate of 1.0 mL/min. The method was sensitive with a lower limit of quantitation of 1 ng/mL, with good linearity (r(2) >or= 0.999) over the linear range 1-500 ng/mL. All the validation data, such as accuracy and precision, were within the required limits. A run time of 3.0 min for each sample made high-throughput bioanalysis possible. The assay method was successfully applied to the study of the pharmacokinetics of curcumin liposome in rats.

Comparison of liposome based antigen delivery systems for protection against Leishmania donovani

Liposomes have been widely exploited as antigen delivery systems for a variety of diseases including leishmaniasis. These vesicles can be prepared in various ways which may affect the immunogenicity of the encapsulated antigens. In this study we compared the vaccine potentiality of three cationic formulations with Leishmania donovani promastigote membrane antigens (LAg) and the best vesicle was evaluated for long-term protection against experimental visceral leishmaniasis. We immunized mice with LAg encapsulated in multilamellar vesicles (MLV), dehydration-rehydration vesicles (DRV) and reverse-phase evaporation vesicles (REV) and challenged them with parasites ten days after vaccination. LAg in MLV or DRV induced almost complete protection, while LAg alone or entrapped in REV exhibited partial resistance. Protection observed with antigen incorporated MLV or DRV was predominantly Th1 as evidenced by elicitation of significantly high DTH, IgG2a antibodies and IFN-gamma. MLV encapsulated LAg demonstrated durable cell-mediated immunity and mice challenged ten weeks after vaccination could also resist experimental challenge strongly. Field trials of L. donovani vaccine were unsatisfactory mainly due to lack of an appropriate adjuvant. Cationic MLV when used as adjuvant with protein antigens induced sustained Th1 immunity. Adjuvant potential of cationic MLV can be utilized to design subunit vaccines.