Acute Lung Injury In Children Due To Chemical And Physical Agents
Lourdes R. Laraya-Cuasay, Walter T. Hughes in Interstitial Lung Diseases in Children, 2019
Other products of combustion, especially from plastics and other synthetic materials used in furniture and buildings, may be toxic when inhaled.151 Burning polyvinylchloride gives off hydrochloric acid157 which may produce alveolitis, bronchiolitis, and pulmonary edema.151 Burning polyurethane foam decomposes to several toxic substances according to the temperature of combustion, including isocyanates, hydrogen cyanate, ammonia, carbon monoxide, acrylonitriles, and hydrogen cyanide.178 Cyanide (and its metabolite, thiocyanate) were found to be elevated in casualties overcome by smoke inhalation in Glasgow.192 Cyanide is produced by burning silk, wool, and plastics.151 Two of the six children with severe smoke inhalation injury described from Liverpool appeared to suffer from cyanide poisoning, although this was not documented by laboratory investigations.178 Oxides of sulfur and nitrogen are irritating and combine with water to produce corrosive acids and alkalis.157 Nitrogen oxide has been reported to be responsible for the development of bronchiolitis obliterans.151 Aldehydes (irritants that also denature protein) are produced by burning cotton, wood, and furniture.151, 157 Smoke from burning wood is very irritating.171
Nonclinical Safety Evaluation of Medical Devices
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
Regarding polymers, the host cell and tissue response (Section 9.5) and the specific chemistry of the polymer can be manipulated to result in resorption or to protect against degradation. Polymers may be biodegradable or stable and the chemistry and response evaluation of each are different. For instance, sutures made of polyesters are designed to resorb. Polyethylene and polypropylene may resorb, particularly if damaged by free radicals, and may be designed with a coating to protect against oxidation. Polyethylene terephthalate (Dacron®) is not designed to resorb and is often used for vascular grafts. The specific chemistry of polyurethane dictates whether it will resorb (Anderson et al. 2008; Thevenot et al. 2008). New generation polyurethanes incorporate antioxidants and anti-adhesion short chain molecules (surface-modifying end groups) to reduce unwanted degradation that may lead to environmental stress cracking of partially degraded and, therefore, brittle device substances. The addition of polycarbonate and polyelastomer segments has improved flexibility and continued stability of some of these polymer materials.
Deaths Due to Asphyxiant Gases
Sudhir K. Gupta in Forensic Pathology of Asphyxial Deaths, 2022
Accidental incidences occur occasionally, e.g., after fumigation, eating bitter almonds, apricot, peach, plum, pear and apple, may occasionally lead to fatalities. Fires involving polyurethane furniture (plastics), silk or woolen articles, can release cyanide and this may result in accidental deaths of people exposed to it. Due to its peculiar bitter almond smell and taste, it is rarely used as homicide. Cyanide along with carbon monoxide are used in gas chamber for capital punishment is considered to be the most dangerous, most complicated and most expensive method of administering the death penalty. Cyanide can be used in Chemical Warfare and Terrorism Agent, as it causes major morbidity and mortality to human to a great extent.34
A review on the treatment of intimal hyperplasia with perivascular medical devices: role of mechanical factors and drug release kinetics
Published in Expert Review of Medical Devices, 2023
Ankur J. Raval, Jigisha K. Parikh, Meghal A. Desai
Nondegradable polymers are used to fabricate various dosage forms such as transdermal patches, coating for permanent implants, and implant devices [95]. Some polymers used for such applications include polyurethanes, silicon, polymethyl methacrylate, polyethylene vinyl acetate, and fluoropolymers. Solute diffusion primarily governs the drug release from the polymer network from these nondegradable polymeric systems. Controlled release systems can be prepared into ‘matrix’ and ‘reservoir’ kind of devices. Matrix-type devices are fabricated by blending drug and compatible polymers in a specific ratio. Generally, devices with this design elute drug under the influence of Fickian diffusion only where concentration gradient plays a dominant role along with diffusion distance, network pathways, and degree of swelling for the polymeric system. Conversely, the reservoir-type devices have a rate-limiting barrier coating over the drug-containing core. The drug release rate is mainly insensitive to concentration gradient and remains relatively constant for reservoir-type systems; however, it is influenced by the outer membrane thickness and its drug permeability.
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].
Dural sealants for the management of cerebrospinal fluid leakage after intradural surgery: current status and future perspectives
Published in Expert Review of Medical Devices, 2019
Ahmet Kinaci, Tristan P.C. Van Doormaal
Polyurethanes are synthetic polymers in which the mechanical properties, biocompatibility, and biodegradability are determined by its composition. Polyurethanes are formed via a reaction between a diisocyanate and a diol. Isocyanates adhesives adhere covalently to the underlying tissue in the presence of water through the formation of urea bond with amines available in the underlying tissue [8]. The major disadvantage of the commonly used polyurethanes is that they are toxic and not readily biodegradable. However, the use of aliphatic isocyanates instead of aromatic isocyanates eliminates toxicity. By incorporating hydrolytically degradable esters bonds by using monomers such as lactic acid or caprolactone enables the development of biodegradable polyurethanes [22,23].
Related Knowledge Centers
- Functional Group
- Isocyanate
- Organic Chemistry
- Polyethylene
- Polymer
- Polyol
- Polystyrene
- Carbamate
- Foam
- Spandex