Nanomaterials in Chemotherapy
D. Sakthi Kumar, Aswathy Ravindran Girija in Bionanotechnology in Cancer, 2023
Core forming polymer segment provides structural stability as well as a drug loading location in polymer micelles. Several non-covalent interactions, such as hydrophobic, metal complexation, electrostatic interaction, and hydrogen bonding, are responsible for keeping the polymer together in the micellar core as well as for the incorporation of drugs. Common core-forming polymers include polyethers, polyesters, polypeptides, and polycations. For loading anticancer drugs, polyester- based core appeared to be better than those of polyethers. For instance, the loading efficiency of a paclitaxel drug into a micelle containing polyester core was 25% w/w, while those of polyether core loaded a maximum of 1.46% w/w drug [133, 134]. Polypeptides are another core-forming segment, which is biocompatible, and their sidechains can be readily modified. Hence, they are advantageous for designing micelles with appropriate assembly characteristics, efficient drug loading, and drug release [135]. Polycations are mostly used for micelles preparation with negatively charged drugs, especially nucleic acid and protein therapeutic agents, in their core [46, 136]. This category of micelles is known as polyion complex (PIC), in which block copolymers containing neutral and charged polymer segments (block ionomers) assemble in the presence of oppositely charged species via electrostatic interaction [137].
Mass Spectrometric Analysis
Adorjan Aszalos in Modern Analysis of Antibiotics, 2020
A recent study comparing californium-252 PD, FAB, Cl, and desorption Cl methods examined six ionophores, three polyethers and three divalent compounds that bind calcium ions [270]. The spectra of the polyethers are remarkably similar. The positive ion spectra consist mainly of (M + Na)+ and (M + K)+ ions—common for PD and FAB but surprising for ammonia Cl, which would be expected to produce (M + H)+ and (M + NH4)+ ions. These ions reflect the strong affinity of these compounds for alkali ions. The negative ion spectra using FAB and PD show only the (M - H)− ions. The calcium ionophores are cationized by alkali metal ions in PD, but with FAB, Cl, and desorption Cl methods the protonated molecules are the primary ions observed.
Silicones in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
Dimethicone copolyol is typically a copolymer of a polydimethylsiloxane and a polyoxyalkylene ether. Materials in this category containing a significant amount of polyether are soluble and stable in water and lower alcohols. Compounds containing a low polyetherto-silicone ratio are typically not soluble in polar solvents. The nature of the polyether moiety employed (ethylene oxide only, higher glycols, combinations thereof, etc.), the silicone:polyether ratio, and the degree of polymerization will all influence the performance of the end product. Regardless of changes in these parameters, the INCI designation remains the same as long as it is referring to a neat fluid (dilutions are usually provided in cyclomethicone, and the INCI designation will then list both materials).
Extravasation of biodegradable microspheres in the rat brain
Published in Drug Delivery, 2023
Anne-Eva van der Wijk, Theodosia Georgakopoulou, Rob Steendam, Johan Zuidema, Peter L. Hordijk, Erik N.T.P. Bakker, Ed van Bavel
Biodegradable microspheres are widely used as long-acting injectable (LAI) depot formulations to treat chronic diseases. Typically, LAI microspheres are composed of polymers that release their bioactive cargo over a specific time frame, related to polymer swelling, increasing porosity and hydrolytic degradation. They are usually injected subcutaneously or intramuscularly. The released drugs have local or remote targets (Teekamp et al., 2017; Sandker et al., 2018; Nkanga et al., 2020). Physicochemical properties of copolymer blocks can be varied to adjust drug elution profiles and degradation characteristics. Here, we used poly(ether ester urethane) multi-block copolymers (SynBiosys® (InnoCore Pharmaceuticals, Groningen, The Netherlands) composed of various combinations of lactide, glycolide, ε-caprolactone, dioxanone and polyethylene glycol. The composition of these multi-block copolymers can be customized to meet specific needs regarding their physical characteristics, including degradation, hydrophilicity, swelling degree, erosion kinetics and drug release kinetics. Microspheres prepared of poly(ether ester urethane) multi-block copolymers with different composition have been found suitable for the sustained release of small molecules (Zandstra et al., 2015; Sandker et al., 2018), proteins (Hughes et al., 2021; Blanco-Blázquez et al., 2023), growth factors (Blanco-Blázquez et al., 2023) and monoclonal antibodies (Teekamp et al., 2017; Steendam et al., 2022).
Long-acting injectable formulation technologies: challenges and opportunities for the delivery of fragile molecules
Published in Expert Opinion on Drug Delivery, 2022
Andrea Gonella, Sylvestre Grizot, Fang Liu, Adolfo López Noriega, Joël Richard
Locteron™ is a controlled release formulation using microparticles that was designed for the delivery of a recombinant form of interferon-α (interferon-α 2b, produced by Biolex Therapeutic) in combination with oral ribavirin, to HCV patients. The delivery system, PolyActive®, made of poly(ether ester) multiblock copolymers based on poly(ethylene glycol) and poly(butylene terephalate), was produced by a company called OctoPlus N.V [124]. A phase I/II study was started in 2008, comparing safety, tolerability, pharmacokinetics, and viral kinetics of interferon loaded Locteron™ (subcutaneous administration every 2 weeks), with PegIntron®, a commercial formulation (weekly injection) [125]. It was shown that Loctaron™ treatment induced less frequent and severe side effects than PegIntron® and that anti-viral effects were comparable for both treatments [126]. Despite the positive results and the will of testing the formulation in a Phase III study, the project did not move forward, probably due to the approval of a new treatment for HCV [127].
Drug eluting implants in pharmaceutical development and clinical practice
Published in Expert Opinion on Drug Delivery, 2021
Ashley R. Johnson, Seth P. Forster, David White, Graciela Terife, Michael Lowinger, Ryan S. Teller, Stephanie E. Barrett
Commonly used polyols include di-hydroxyl terminated polyesters, poly(ethers), and poly(carbonates) in the molecular weight range of 1000 to 5000 Da. Poly(ester)-based poly(urethanes) often have good mechanical strength and thermal stability. They are, however, susceptible to hydrolysis of the ester linkage, resulting in the production of biodegradable poly(urethanes) with long degradation times. Poly(ether)-based poly(urethanes), on the other hand, have improved hydrolytic stability and exhibit more flexibility, but can be susceptible to oxidative and thermal degradation. For this reason, poly(ether)-based poly(urethanes) are typically stored in the presence of oxidative stabilizers; lubricants and thermal stabilizers are also added to extrudable thermoplastic polyurethanes. Of note, polyethylene oxide based poly(urethanes) are particularly relevant to pharmaceutical applications due their ability to take up water and create pores that enable drug diffusion [64,112].