China
Africa
Explore chapters and articles related to this topic
Antigen Delivery Systems Used to Induce Immunomodulation
Published in Thomas F. Kresina, Immune Modulating Agents, 2020
M. Zahirul I. Khan, Ian G. Tucker, Joan P. Opdebeeck
The main stumbling block in utilizing these implants for single-step immunization is their nonbiodegradability; a second visit to health personnel is required to remove the implant in an actual immunization program. This limitation prompted a search for biodegradable polymers to replace ethylene-vinyl acetate copolymer as construction material for implants carrying the antigen. The BSA delivered from a biodegradable polymeric implant made of N-benzyloxycarbonyl-l-tyrosyl-l-tyrosine hexyl ester (CTTH)-iminocarbonate induced significant anti-BSA antibodies for over 56 weeks after a single-dose administration in mice [132,133]. A biologically degraded product of the polymer CTTH was found to act as an adjuvant as potent as FCA and MDP in enhancing the immune response.
Trachyonychia
Published in Nilton Di Chiacchio, Antonella Tosti, Therapies for Nail Disorders, 2020
Jacob Griggs, Brandon Burroway, Antonella Tosti
A number of case reports and case series have reported some success in using petroleum jelly;9 corticosteroids;9,11 tazarotene gel;12 5% 5-fluorouracil cream;13 psoralen plus ultraviolet A (PUVA);14and nail plate dressings of ultra-thin adhesive bandages with lactic acid, silicon dioxide, aluminum acetylacetonate, copolymer of vinyl acetate with acrylic acid, and azelaic acid.15 In addition, one case report described increased success of topical steroid treatment by occluding clobetasol propionate ointment with paper tape, which is suggested to help ensure absorption by the nail matrix, the site of the inflammation in trachyonychia.11
Design, Development, Manufacturing, and Testing of Transdermal Drug Delivery Systems
Published in Tapash K. Ghosh, Dermal Drug Delivery, 2020
Timothy A. Peterson, Steven M. Wick, Chan Ko
The mechanism of drug transport across these membranes can be described as a partitioning process from the upstream side of the membrane, followed by diffusion through the polymer film. Suitable materials for these membranes include: polyethylene, various polyurethanes, polydimethylsiloxane, polypropylene and ethylene-vinyl acetate copolymers. The latter have been used extensively and have proven useful for adjusting the rate of drug delivery through the membrane, since the permeability of many drugs depends on the composition of the copolymer (Higuchi and Hussain 1979, Mutalik and Udupa 2006). For many drugs, an increase in the percentage of vinyl acetate in the copolymer membrane will increase permeability (Peterson et al. 1990), primarily due to more favorable partitioning and the reduced crystallinity of the polymer as the vinyl acetate content rises.
Biodegradable and removable implants for controlled drug delivery and release application
Published in Expert Opinion on Drug Delivery, 2022
Vivek P Chavda, Gargi Jogi, Ana Cláudia Paiva-Santos, Ajeet Kaushik
Traditionally, an implantable drug delivery system is classified into two main types, drug implants and implantable pumps. The former employs the use of biodegradable and non-biodegradable polymers in order to release the drug in a controlled manner. Biodegradable implants offer the most convenient option for drug delivery as the implant needs to be placed in the body only once and it does not need to be removed. The degradation products of the biodegradable implants are assumed to be traces of carbon dioxide, water, and mineral elements [4]. In contrast, non-biodegradable implants require surgical procedure twice, as they need to be inserted and removed (once drug delivery is achieved). A copolymer of ethylene and vinyl acetate, namely ethylene vinyl acetate (EVA), is a type of non-degradable thermoplastic polymer used in drug-eluting implants. Recently, Merck commenced and accomplished clinical trials on islatravir-loaded EVA implants. The results obtained demonstrated sustained release of the drug for up to 1 year [18]. Among the different silicone compounds available, polydimethyl-siloxane (PDMS) is a popular non-biodegradable polymer used in medical devices [6].
Influence of process temperature and residence time on the manufacturing of amorphous solid dispersions in hot melt extrusion
Published in Pharmaceutical Development and Technology, 2022
Tobias Gottschalk, B. Grönniger, E. Ludwig, F. Wolbert, T. Feuerbach, G. Sadowski, M. Thommes
Within this work, two commonly applied model drugs (Leuner and Dressman 2000; Sarode et al. 2013) and two polymers (Dinunzio et al. 2013; Sarode et al. 2013; Auch et al. 2019) were used. Each drug was extruded in formulations with both polymers. Griseofulvin (GRI) (Fagron, Rotterdam, Netherlands) and itraconazole (ITR) (Ria International India, Madurai, India) are anti-fungal drugs with a poor solubility in water (GRI ∼8.9 mg/L (Rahman et al. 2020), ITR ∼1 µg/L (Six et al. 2005)). Those ability of ASD formation was shown by a high amount of research studies (Sarode et al. 2013; Nagy et al. 2015; Parikh et al. 2015; Sóti et al. 2015). Licensed market products of ASDs containing those drugs are available (Newman 2015). The used polymers were polyvinylpyrrolidone vinyl acetate (PVPVA) (Plasdone S-630, Ashland Inc., Columbus, OH) and the graft co-polymer Soluplus (SOL) (BASF, Ludwigshafen, Germany). Those are commonly applied carriers in hot melt extrusion (Alshahrani et al. 2015; Bochmann et al. 2019) and were also already applied in ASDs with the applied drugs (Sarode et al. 2013; Nagy et al. 2015; Parikh et al. 2015; Bhardwaj et al. 2018). They were received as donation from the suppliers.
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
The most commonly used non-degradable thermoplastic in drug eluting implants is ethylene vinyl acetate, which is a transparent copolymer of ethylene and vinyl acetate [100]. It is ubiquitous in consumer products, including hot melt glues, flooring, and sporting equipment, among others. Increases in the amount of vinyl acetate incorporated into the polymer (within the typical range of 1 to 40% vinyl acetate) produce a more polar polymer with lower melting point and less crystallinity [101]. EVA is a flexible thermoplastic polymer amenable for thermal processing. It can be processed at relatively low temperatures compared to other biodurable polymers but exhibits high thermal stability, providing a wide window of operation for extrusion without plasticizers and reducing the risk of degrading thermally labile APIs [100]. Shear thinning behavior aides processing and enables the addition of high amounts of API, up to 75 wt% in some reports [102]. The hydrophobicity of EVA results in minimal water uptake so that drying is not required prior to extrusion, unlike poly(esters) and poly(urethanes) which must be dried to avoid hydrolytic degradation during processing [70,103]. EVA has also been processed via injection molding, solvent casting, and spray coating [100].