The sustained granulopoietic effect of progenipoietin encapsulated in multivesicular liposomes

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.

New G-CSF agonists for neutropenia therapy

INTRODUCTION

Granulocyte colony-stimulating factor (G-CSF; filgrastim) and its pegylated form (pegfilgrastim) are widely used to treat neutropenia associated with myelosuppressive chemotherapy and bone marrow transplantation, AIDS-associated or drug-induced neutropenia, and neutropenic diseases. G-CSF facilitates restoration of neutrophil counts, decreases incidence of infection/febrile neutropenia and reduces resource utilization. G-CSF is also widely used to mobilize peripheral blood stem cells for hematopoietic transplant.

AREAS COVERED

We review the therapeutic use, cost effectiveness and disease impact of G-CSF for neutropenia, development of G-CSF biosimilars and current next-generation discovery efforts.

EXPERT OPINION

G-CSF has impacted the treatment and survival of patients with congenital neutropenias. For chemotherapy-associated neutropenia, cost effectiveness and impact on survival are still unclear. G-CSFs are expensive and require systemic administration. Market entry of new biosimilars, some with enhanced half-life profiles, will probably reduce cost and increase cost effectiveness. There is no evidence that marketed or late development biosimilars display effectiveness superior to current G-CSFs. Second-generation compounds that mimic the activity of G-CSF at its receptor, induce endogenous ligand(s) or offer adjunct activity have been reported and represent attractive G-CSF alternatives, but are in preclinical stages. A significant therapeutic advance will require reduced depth and duration of neutropenia compared to current G-CSFs.

Multivesicular liposome (MVL) sustained delivery of a novel synthetic cationic GnRH antagonist for prostate cancer treatment

Objectives

Multivesicular liposomes (MVLs) are often used as an appropriate carrier for delivering peptides due to high drug loading, relative stability and extended-release behaviour. However, when cationic amphipathic peptides are involved, some challenges may be encountered, including instability of multiple emulsions due to interaction between peptides and lipid membranes (electrostatic and hydrophobic interaction). LXT-101, a cationic amphipathic peptide, is a novel antagonist of gonadotropin-releasing hormone (GnRH) for prostate cancer treatment. The purpose of the current research was to explore simple methods of determining the interaction between peptide and lipid bilayer and to prepare MVLs of LXT-101 (DepoLXT-101) by the modified DepoFoam technique.

Methods

The anionic surfactants were added in the process of DepoLXT-101 preparation in order to minimize the effect of instability resulting from cationic peptides.

Key findings

DepoLXT-101 was obtained with good efficiency and reproduction. The integrity of encapsulated peptide was maintained as shown by RP-HPLC. DepoLXT-101 particles were characterized by morphology and particle size distribution and in-vitro release was also investigated. The release behaviour in vitro in medium of sodium chloride at 37°C showed that 70–90% of LXT-101 was released slowly from MVLparticles over 11 days. According to the fitting results of Ritgar-Pepps model, the in-vitro release of DepoLXT-101 was mainly governed by Fick's diffusion.

Conclusions

The data obtained from in-vivo study indicated that a sustained anticancer effect can be achieved over a 7-day period with subcutaneous administration of DepoLXT-101 in rats.

An extended-release formulation of desferrioxamine for subcutaneous administration

Desferrioxamine mesylate (DFO) remains the first line iron chelating agent. Since it has a short half-life and poor absorption through the gastrointestinal tract, DFO must be administered parenterally, usually by daily subcutaneous infusion administered over 8-12 h. The objective of this paper was the development of multivesicular liposome (depofoam) for the extended-release of DFO and study of iron excretion efficiency compared to the free form of DFO. Depofoam particles were characterized by their morphology, particle size, capture volume, and in vitro release. Also, in vivo activity of this formulation in iron overload rats was studied. The in vitro studies in 0.9% sodium chloride at 37 degrees C showed that the multivesicular liposomes released DFO slowly over several days without a rapid initial release, and 57% of DFO was released in 9 days. Administration of a single dose of 100 mg/kg of an optimized Depo-DFO formulation in an iron overload rats, as a single bolus subcutaneous injection, led to significant elevation of urinary iron excretion at the first day that were maintained at levels of more than 110 microg/kg for 3 days. Administration of the unencapsulated DFO at the same dose resulted in elevation of urinary iron excretion in the first day (approximately 73% amount of iron excretion by Depo-DFO) followed by a quick decline to base line levels in the second day. The total urinary iron excreted by Depo-DFO is 3-times greater than that elicited by DFO. In conclusion, Depo-DFO appears to have potential usefulness as an extended-release formulation of DFO.

Pharmacology of drugs formulated with DepoFoam: a sustained release drug delivery system for parenteral administration using multivesicular liposome technology

Lamellar liposome technology has been used for several decades to produce sustained-release drug formulations for parenteral administration. Multivesicular liposomes are structurally distinct from lamellar liposomes and consist of an aggregation of hundreds of water-filled polyhedral compartments separated by bi-layered lipid septa. The unique architecture of multivesicular liposomes allows encapsulating drug with greater efficiency, provides robust structural stability and ensures reliable, steady and prolonged drug release. The favourable characteristics of multivesicular liposomes have resulted in many drug formulations exploiting this technology, which is proprietary and referred to as DepoFoam. Currently, two formulations using multivesicular liposome technology are approved by the US FDA for clinical use, and many more formulations are at an experimental developmental stage. The first clinically available formulation contains the antineoplastic agent cytarabine (DepoCyt) for its intrathecal injection in the treatment of malignant lymphomatous meningitis. Intrathecal injection of DepoCyt reliably results in the sustained release of cytarabine and produces cytotoxic concentrations in cerebrospinal fluid (CSF) that are maintained for at least 2 weeks. Early efficacy data suggest that DepoCyt is fairly well tolerated, and its use allows reduced dosing frequency from twice a week to once every other week and may improve the outcome compared with frequent intrathecal injections of unencapsulated cytarabine. The second available formulation contains morphine (DepoDur) for its single epidural injection in the treatment of postoperative pain. While animal studies confirm that epidural injection of DepoDur results in the sustained release of morphine into CSF, the CSF pharmacokinetics have not been determined in humans. Clinical studies suggest that the use of DepoDur decreases the amount of systemically administered analgesics needed for adequate postoperative pain control. It may also provide superior pain control during the first 1-2 postoperative days compared with epidural administration of unencapsulated morphine or intravenous administration of an opioid. However, at this timepoint the overall clinical utility of DepoDur has yet to be defined and some safety concerns remain because of the unknown CSF pharmacokinetics of DepoDur in humans. The versatility of multivesicular liposome technology is reflected by the many agents including small inorganic and organic molecules and macromolecules including proteins that have successfully been encapsulated. Data concerning many experimental formulations containing antineoplastic, antibacterial and antiviral agents underscore the sustained, steady and reliable release of these compounds from multivesicular liposomes after injection by the intrathecal, subcutaneous, intramuscular, intraperitoneal and intraocular routes. Contingent on the specific formulation and manufacturing process, agents were released over a period of hours to weeks as reflected by a 2- to 400-fold increase in elimination half life. Published data further suggest that the encapsulation process preserves bioactivity of agents as delicate as proteins and supports the view that examined multivesicular liposomes were non-toxic at studied doses. The task ahead will be to examine whether the beneficial structural and pharmacokinetic properties of multivesicular liposome formulations will translate into improved clinical outcomes, either because of decreased drug toxicity or increased drug efficacy.

Multivesicular liposome formulations for the sustained delivery of interferon alpha-2b

AIM

To develop and optimize a sustained release multivesicular liposome (MVL) formulation of interferon (IFN) alpha-2b.

METHODS

IFN alpha-2b MVL were prepared using a typical double-emulsion procedure. The sustained release effects of IFN alpha-2b MVL were investigated by monitoring the blood IFN alpha-2b concentration using an enzyme-linked immunosorbent assay test after subcutaneous administration to healthy mice.

RESULTS

IFN alpha-2b was successfully encapsulated in MVL with high efficiency, and the integrity of encapsulated protein was maintained. After subcutaneous injection, the MVL slowly released IFN alpha-2b into systemic circulation in a sustained manner. The estimated serum half-life of IFN alpha-2b was approximately 30 h. In addition, varying the size of the MVL preparations could further modify the in vivo release profile.

CONCLUSION

IFN alpha-2b MVL may be a useful sustained release formulation in the clinical treatment of viral diseases.

Multivesicular liposome formulation for the sustained delivery of breviscapine

Breviscapine, a well-known bioactive flavonoid ingredient extracted from the traditional Chinese medicine, has been extensively used in clinic to treat ischemic cerebrovascular and cardiovascular diseases in China. In order to prolong the duration of the drug in the circulation, reduce the frequency of injection administration and subsequently afford patient compliance, multivesicular liposome (MVL, namely DepoFoam) was utilized as a sustained-delivery system for breviscapine. In vitro release and in vivo pharmacokinetics of MVLs containing breviscapine (bre-MVLs) following intramuscular injection to rats were investigated compared with those of traditional liposomes containing breviscapine (bre-TLs). The drug durations both in vitro and in vivo were significantly prolonged for the bre-MVL, and that the drug release in vitro and the absorption in vivo showed a good linear correlation (R=0.9834), which provided an evidence for the suitability to select human plasma as the medium of drug release from MVLs in vitro. Drug release from bre-MVLs (triolein/tricaprylin, 10/0) in vitro extended a long period of 5-6 days, while the bre-TLs released 80% within only 4h. The mean residence time (MRT) obtained from the pharmacokinetics study of bre-MVL was about 16.6- and 5.04-fold longer than those of breviscapine solution (BS) and bre-TL, respectively. A duration in vivo for a period of 4-5 days was fulfilled for bre-MVL. In conclusion, MVL can be successfully used as a sustained delivery system of breviscapine.

Characteristics of a novel phospholipid-based depot injectable technology for poorly water-soluble drugs

Phospholipid concentrates in a water miscible solvent were explored as injectable formulations for the poorly water-soluble drugs, using the anti-infective PHA 244 as model substance. Formulations containing up to 70% w/v phospholipid could dissolve 15% PHA 244. The formulations showed excellent syringe-ability and no precipitation of the drug after dilution in an excess of water. The local tolerability and pharmacokinetics of the formulations were explored after subcutaneous injection into cattle. A slow release pattern over a 2-week period and excellent local tolerability at the injection site were observed. Considering the low manufacturing costs, related to the production of solutions, this SupraVail MLM (Membrane Lipid Matrix) technology is a cost-effective alternative to more expensive depot technologies for poorly water-soluble drugs with similar release characteristics, like sterile aqueous and oily drug substance suspensions, as cited in the literature.