Long-term Stability and in vitro Release of hPTH(1–34) from a Multi-reservoir Array

Quantification of Anti-Osteoporotic Anabolic Peptide in Stealth Lipid Nanovesicles Through Validated RP-HPLC Method

BACKGROUND

Teriparatide is a recombinant fragment of human parathyroid hormone, a potent osteoanabolic agent used for osteoporosis.

OBJECTIVE

The present study endeavored to develop a simple, rapid, and reliable reverse phase-high performance liquid chromatography (RP-HPLC) method for the determination of teriparatide in pegylated lipid nanovesicles for rapid formulation development/optimization.

METHOD

A rapid RP-HPLC-based analytical method was developed for the quantification of teriparatide in pegylated lipid nanovesicles. The method was optimized on a Waters XBridge C18 (4.6 × 150 mm, 10 μm) column with a mobile phase consisting of 0.1% formic acid in water and acetonitrile both in a linear gradient program. In the method, a short run time of 9 min was achieved at a flow rate of 1.0 mL/min with an injection volume of 50 µL at a detection wavelength of 210 nm. The developed method was validated according to the ICH Q2 (R2) guideline. The method was applied for the quantification of teriparatide in prepared pegylated lipid nanovesicles. Teriparatide encapsulated pegylated lipid nanovesicles were prepared by the ethanol injection method. Further, these vesicles were characterized for % entrapment efficiency (%EE), particle size, zeta potential, and morphology by Cryo-SEM.

RESULTS

The teriparatide was eluting at 4.8 min in the run. Further, for the method validation, the linear relationship between concentration and response was established over the concentration range of 50-250 µg/mL with the R2 > 0.999. The method sensitivity was shown with LOD and LOQ with the value of 100 ng/mL and 500 ng/mL, respectively. The method was found to be accurate and precise with the recovery ranging in 100 ± 2% and RSD <2%, respectively. Minor deliberate changes proved the robustness of the developed method.

CONCLUSIONS

These results indicated that the developed and validated method is accurate, precise, rapid, reliable, and fit for the quantification of teriparatide in different formulations.

HIGHLIGHTS

The RP-HPLC method was developed and validated for the quantification of teriparatide from novel pegylated lipid nanovesicles.

Drug eluting implants in pharmaceutical development and clinical practice

Introduction: Drug eluting implants offer patient convenience and improved compliance through less frequent dosing, eliminating repeated, painful injections and providing localized, site specific delivery with applications in contraception, ophthalmology, and oncology.Areas covered: This review provides an overview of available implant products, design approaches, biodegradable and non-biodegradable polymeric materials, and fabrication techniques with a focus on commercial applications and industrial drug product development. Developing trends in the field, including expanded availability of suitable excipients, development of novel materials, scaled down manufacturing process, and a wider understanding of the implant development process are discussed and point to opportunities for differentiated drug eluting implant products.Expert opinion: In the future, long-acting implants will be important clinical tools for prophylaxis and treatment of global health challenges, especially for infectious diseases, to reduce the cost and difficulty of treating chronic indications, and to prolong local delivery in difficult to administer parts of the body. These products will help improve patient safety, adherence, and comfort.

Recent Advances in Micro-Electro-Mechanical Devices for Controlled Drug Release Applications

In recent years, controlled release of drugs has posed numerous challenges with the aim of optimizing parameters such as the release of the suitable quantity of drugs in the right site at the right time with the least invasiveness and the greatest possible automation. Some of the factors that challenge conventional drug release include long-term treatments, narrow therapeutic windows, complex dosing schedules, combined therapies, individual dosing regimens, and labile active substance administration. In this sense, the emergence of micro-devices that combine mechanical and electrical components, so called micro-electro-mechanical systems (MEMS) can offer solutions to these drawbacks. These devices can be fabricated using biocompatible materials, with great uniformity and reproducibility, similar to integrated circuits. They can be aseptically manufactured and hermetically sealed, while having mobile components that enable physical or analytical functions together with electrical components. In this review we present recent advances in the generation of MEMS drug delivery devices, in which various micro and nanometric structures such as contacts, connections, channels, reservoirs, pumps, valves, needles, and/or membranes can be included in their design and manufacture. Implantable single and multiple reservoir-based and transdermal-based MEMS devices are discussed in terms of fundamental mechanisms, fabrication, performance, and drug release applications.

On-demand antibiotic-eluting microchip for implanted spinal screws

OBJECTIVE

Surgical instrumentation of the spine is susceptible to infection. Intravenous antibiotics is a current mainstay of treating infection; however penetrating the bacterial biofilm and directly targeting the source of the infection is challenging.

METHODS

Using multiple reservoirs of discrete drug doses, microchips represent a new technology capable of on-demand drug release over long periods of time.

RESULTS

A novel solution of integrating vancomycin-eluting microchips into pedicle screws in order directly target and treat spinal infections is proposed.

CONCLUSION

This drug-releasing implant has the potential to provide the particular benefit to high-infection-risk patients in order to avoid reoperation.

Microchips in Medicine: Current and Future Applications

With the objective of improving efficacy and morbidity, device manufacturers incorporate chemicals or drugs into medical implants. Using multiple reservoirs of discrete drug doses, microchips represent a new technology capable of on-demand release of various drugs over long periods of time. Herein, we review drug delivery systems, how microchips work, recent investigations, and future applications in various fields of medicine.

Influence of Parathyroid Hormone-Loaded PLGA Nanoparticles in Porous Scaffolds for Bone Regeneration

Biodegradable poly(lactide-co-glycolide) (PLGA) nanoparticles, containing human parathyroid hormone (PTH (1–34)), prepared by a modified double emulsion-solvent diffusion-evaporation method, were incorporated in porous freeze-dried chitosan-gelatin (CH-G) scaffolds. The PTH-loaded nanoparticles (NPTH) were characterised in terms of morphology, size, protein loading, release kinetics and in vitro assessment of biological activity of released PTH and cytocompatibility studies against clonal human osteoblast (hFOB) cells. Structural integrity of incorporated and released PTH from nanoparticles was found to be intact by using Tris-tricine SDS-PAGE. In vitro PTH release kinetics from PLGA nanoparticles were characterised by a burst release followed by a slow release phase for 3–4 weeks. The released PTH was biologically active as evidenced by the stimulated release of cyclic AMP from hFOB cells as well as increased mineralisation studies. Both in vitro and cell studies demonstrated that the PTH bioactivity was maintained during the fabrication of PLGA nanoparticles and upon release. Finally, a content of 33.3% w/w NPTHs was incorporated in CH-G scaffolds, showing an intermittent release during the first 10 days and, followed by a controlled release over 28 days of observation time. The increased expression of Alkaline Phosphatase levels on hFOB cells further confirmed the activity of intermittently released PTH from scaffolds.

Clinical applications of biomedical microdevices for controlled drug delivery

Miniaturization of devices to micrometer and nanometer scales, combined with the use of biocompatible and functional materials, has created new opportunities for the implementation of drug delivery systems. Advances in biomedical microdevices for controlled drug delivery platforms promise a new generation of capabilities for the treatment of acute conditions and chronic illnesses, which require high adherence to treatment, in which temporal control over the pharmacokinetic profiles is critical. In addition, clinical conditions that require a combination of drugs with specific pharmacodynamic profiles and local delivery will benefit from drug delivery microdevices. This review provides a summary of various clinical applications for state-of-the-art controlled drug delivery microdevices, including cancer, endocrine and ocular disorders, and acute conditions such as hemorrhagic shock. Regulatory considerations for clinical translation of drug delivery microdevices are also discussed. Drug delivery microdevices promise a remarkable gain in clinical outcomes and a substantial social impact. A review of articles covering the field of microdevices for drug delivery was performed between January 1, 1990, and January 1, 2014, using PubMed as a search engine.

Drug-releasing implants: current progress, challenges and perspectives

This review presents the different types and concepts of drug-releasing implants using new nanomaterials and nanotechnology-based devices.

Microelectromechanical systems and nephrology: the next frontier in renal replacement technology

Microelectromechanical systems (MEMS) are playing a prominent role in the development of many new and innovative biomedical devices, but they remain a relatively underused technology in nephrology. The future landscape of clinical medicine and research will only see further expansion of MEMS-based technologies in device designs and applications. This enthusiasm stems from the ability to create small-scale device features with high precision in a cost-effective manner. MEMS also offers the possibility to integrate multiple components into a single device. The adoption of MEMS has the potential to revolutionize how nephrologists manage kidney disease by improving the delivery of renal replacement therapies and enhancing the monitoring of physiologic parameters. To introduce nephrologists to MEMS, this review will first define relevant terms and describe the basic processes used to fabricate devices. Next, a survey of MEMS devices being developed for various biomedical applications will be illustrated with current examples. Finally, MEMS technology specific to nephrology will be highlighted and future applications will be examined. The adoption of MEMS offers novel avenues to improve the care of kidney disease patients and assist nephrologists in clinical practice. This review will serve as an introduction for nephrologists to the exciting world of MEMS.

Reservoir-based drug delivery systems utilizing microtechnology

This review covers reservoir-based drug delivery systems that incorporate microtechnology, with an emphasis on oral, dermal, and implantable systems. Key features of each technology are highlighted such as working principles, fabrication methods, dimensional constraints, and performance criteria. Reservoir-based systems include a subset of microfabricated drug delivery systems and provide unique advantages. Reservoirs, whether external to the body or implanted, provide a well-controlled environment for a drug formulation, allowing increased drug stability and prolonged delivery times. Reservoir systems have the flexibility to accommodate various delivery schemes, including zero order, pulsatile, and on demand dosing, as opposed to a standard sustained release profile. Furthermore, the development of reservoir-based systems for targeted delivery for difficult to treat applications (e.g., ocular) has resulted in potential platforms for patient therapy.

First-in-human testing of a wirelessly controlled drug delivery microchip

The first clinical trial of an implantable microchip-based drug delivery device is discussed. Human parathyroid hormone fragment (1-34) [hPTH(1-34)] was delivered from the device in vivo. hPTH(1-34) is the only approved anabolic osteoporosis treatment, but requires daily injections, making patient compliance an obstacle to effective treatment. Furthermore, a net increase in bone mineral density requires intermittent or pulsatile hPTH(1-34) delivery, a challenge for implantable drug delivery products. The microchip-based devices, containing discrete doses of lyophilized hPTH(1-34), were implanted in eight osteoporotic postmenopausal women for 4 months and wirelessly programmed to release doses from the device once daily for up to 20 days. A computer-based programmer, operating in the Medical Implant Communications Service band, established a bidirectional wireless communication link with the implant to program the dosing schedule and receive implant status confirming proper operation. Each woman subsequently received hPTH(1-34) injections in escalating doses. The pharmacokinetics, safety, tolerability, and bioequivalence of hPTH(1-34) were assessed. Device dosing produced similar pharmacokinetics to multiple injections and had lower coefficients of variation. Bone marker evaluation indicated that daily release from the device increased bone formation. There were no toxic or adverse events due to the device or drug, and patients stated that the implant did not affect quality of life.

Demonstrated solid-state stability of parathyroid hormone PTH(1-34) coated on a novel transdermal microprojection delivery system

PURPOSE

This study assessed conditions necessary for at least a 2-year, ambient temperature storage stability of the peptide parathyroid hormone 1-34, or PTH(1-34), coated on a novel transdermal microprojection delivery system, or ZP-PTH.

METHODS

Liquid coating characterization of high concentration PTH(1-34) formulations (>20% w/w) was assessed by viscosity and contact angle measurements along with RP-HPLC and SEC-HPLC. Solid-state coating morphology of PTH(1-34) on microprojection arrays was determined by SEM, and stability on storage was assessed after dissolution and testing with stability indicating assays. Internal vapor analysis was performed to detect and quantify volatile organics released by patch components into the headspace inside the final package.

RESULTS

Aggregation and oxidation were the primary degradation mechanisms for solid-state PTH(1-34) in this transdermal delivery system. Although these two degradation pathways can be retarded by appropriate stabilizers and use of foil pouch packaging (nitrogen purged and desiccant), the solid-state drug formulation's compatibility with patch components, particularly the plastic retainer ring, surprisingly dictated PTH(1-34) stability. Internal vapor analysis demonstrated that PTH(1-34) was particularly vulnerable to vapors such as moisture, oxygen, and outgassed formaldehyde, and each of these volatiles played a unique and significant role in PTH(1-34)'s degradation mechanism.

CONCLUSIONS

Identifying degradation mechanisms of volatile compounds on solid-state PTH(1-34) peptide stability allowed for the rationale for selection of final formulation, system components and packaging conditions. A >2-yr, ambient temperature storage stability was demonstrated for solid-state drug coated on a novel transdermal microprojection delivery system. This system was successfully tested in a Phase 2 clinical trial for the treatment of post-menopausal women with osteoporosis.