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The Igaki–Tamai stent: The legacy of the work of Hideo Tamai
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
Soji Nishio, Kunihiko Kosuga, Eisho Kyo, Takafumi Tsuji, Masaharu Okada, Shinsaku Takeda, Yasutaka Inuzuka, Tatsuhiko Hata, Yuzo Takeuchi, Junya Seki, Shigeru Ikeguchi
In the 1990s, the biocompatibility of polymers for BRSs, including poly-l-lactic acid (PLLA), was controversial. Zidar et al. [2] reported minimal inflammatory reaction and minimal neointimal hyperplasia with the use of PLLA stents in canine femoral arteries. On the other hand, Van der Giessen et al. [3] observed a marked inflammatory response after implantation of each of five different bioresorbable polymer stents (polyglycolic acid [PGA]/polylactic acid, polycaprolactone, polyhydroxybutyrate valerate, polyorthoester, and polyethyleneoxide/polybutylene terephthalate), in a porcine coronary artery model. Finally, in 1999, the issue of the biocompatibility of polymers was resolved by the development of the Igaki–Tamai stent (Kyoto Medical Planning Co, Ltd, Kyoto, Japan) (Figure 6.14.1) [4]. This was the first-in-human fully BRSs constructed of PLLA. Its development was the successful outcome of a continuous process of trial and error.
Nanomedicines for Ocular NSAIDs: State-of-the-Art Update of the Safety on Drug Delivery
Published in Lajos P. Balogh, Nano-Enabled Medical Applications, 2020
Joana R. Campos, Joana Araújo, Elisabet Gonzalez-Mira, Maria A. Egea, Elena Sanchez-Lopez, Marta Espina, Selma B. Souto, Maria L. Garcia, Eliana B. Souto
A large variety of active substances have been included in microspheres (i.e. anti-proliferatives, anti-inflammatories, immunosuppressants, antibiotics, and even biotechnological therapeutic agents for intraocular administration. Microparticulate systems have been prepared from biodegradable polymers like gelatin, albumin, polyorthoesters, polyanhydrides, and polyesters. The PLA and poly(glycolic) acid (PGA) polymers and their co-polymers PLGA are the most used. For ocular application, and especially for the treatment of diseases affecting the back of the eye, these erodible polymers have been employed to prepare different devices (implants, scleral plugs, pellets, discs, films, rods, nanoparticles, and microparticles) [204]. Park et al. also utilised PEG as additive with poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with brimonidine. The mucoadhesive microparticles increased drug bioavailability of the hypotensive agent compared to the marketed brimonidine formulation [205]. Moritera et al. showed the administration of adryamicin-loaded microspheres in an animal model of proliferative vitreoretinopathy. The retinal detachment was decreased from 50% to 10% in the rabbits after the intravitreal injection and a significant decrease in the retinal toxicity was produced, when comparing a single injection of microspheres with the administration of the same amount of drug in solution [206, 207]. Veloso et al. evaluated the anti-viral effect of ganciclovir-loaded microspheres in infected rabbits’ eyes. In treated eyes, vitritis, retinitis, and optic neuritis decreased in contrast to control eyes. No adverse tissue reaction was clinically or histopathologically observed in the injected eyes [208]. Conti et al. developed PLA and PLGA microparticles loaded with acyclovir. After 14 days, the active substance was detected in the vitreous of rabbits receiving D, L-PLA microparticles [209]. Duvvuri et al. dispersed ganciclovir-loaded microspheres in a thermogellin PLGAPEG-PLGA solution that was then injected in rabbit eyes. Drug levels in the vitreous were significantly higher and maintained for a prolonged time in comparison with a drug solution [210].
Extended release formulations using silk proteins for controlled delivery of therapeutics
Published in Expert Opinion on Drug Delivery, 2019
Burcin Yavuz, Laura Chambre, David L Kaplan
The controlled delivery of therapeutics aims to extend the duration between doses and maintain constant therapeutic levels in plasma, tumors or local injection sites. Such systems also offer additional benefits, including reduced side effects, improved patient compliance for frequent or difficult applications and reduced cost of treatment with well-designed controlled delivery systems[1]. The biomaterials utilized for controlled delivery need to be cost-effective, non-toxic and relatively simple to process with mild techniques in order to meet biocompatibility and regulatory demands. Organic solvents should be minimized, and release profiles should be adjustable in order to achieve clinically relevant therapeutic levels of the delivered therapeutics. Various polymers have been investigated for controlled therapeutic delivery; Including synthetic macromolecules like polyesters, polyorthoesters, polyphosphoesters, and polyanhydrides [2]. Available controlled release formulations currently on the market are mostly based on Food and Drug Administration (FDA) approved synthetic polymers such as polylactide-co-glycolide acid (PLGA) and polycaprolactone (PCL), while FDA approved natural polymers like albumin, alginate, gelatin, collagen, and silk fibroin are being investigated as alternatives, in part to avoid undesirable degradation products and formulation challenges associated with polyesters such as activity loss of peptide-protein structures [3–5].
Single administration vaccines: delivery challenges, in vivo performance, and translational considerations
Published in Expert Review of Vaccines, 2023
Kyprianos Michaelides, Maruthi Prasanna, Raj Badhan, Afzal-Ur-Rahman Mohammed, Adam Walters, M. Keith Howard, Pawan Dulal, Ali Al-Khattawi
A range of controlled release technologies have been investigated, consisting mainly of natural/synthetic polymers and lipid carriers. However, only a limited number of these polymers or carriers are included in United States Food and Drug Administration (FDA) generally recognized as safe list. Natural materials such as chitosan and alginates have been used by some groups, particularly because they are cheaper and more readily available than synthetic polymers. Evidence of sustained release from chitosan microspheres for 6 months was reported for in vitro and in vivo studies with tetanus toxoid vaccine [16]. However, the batch-to-batch variability of these natural polymers and the difficulty in tuning their release mechanism limits their potential as commercial SAV technologies [17]. On the other hand, synthetic biodegradable materials such as polycaprolactone (PCL) and polyorthoesters can be tuned to optimize release kinetics. PCL is a biodegradable polyester frequently used in medical devices for tissue engineering such as sutures [18]. Bansal et al. explored PCL in SAV technology for a tetanus vaccine due to its slow-release properties and ability to produce degradation products that are less acidic in comparison to other biodegradable polymers. Both in vivo and in vitro studies provided promising results by showing sustained release over 30 days and improving both immune response and survival rates in mice models [19]. Tomar et al. achieved in vitro release of Hepatitis B surface antigen (HBsAg) for a period of 6 months and elicited an immune response comparable to the conventional HBsAg aluminum vaccine in vivo [20]. However, PCL use in vaccine delivery is limited to a handful of studies and its use has been surpassed by PLGA.
Recent advances on biodegradable polymeric carrier-based mucosal immunization: an overview
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Lovedeep Kaur, Ankush Sharma, Awesh Kumar Yadav, Neeraj Mishra
Furthermore, patent depicted the utilization of polymeric microparticles including biodegradable polymers with the goal of immunization. It is revealed in this innovation that polymer microparticles involving a biodegradable polymer, for example, poly(alpha-hydroxy corrosive), polyhydroxy butyric corrosive, polycaprolactone, polyorthoester, polyanhydride and polycyanoacrylate are pharmaceutically appropriate excipient with the goal of immunization and can be utilized reasonably for such reason [63].