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Three-Dimensional Printing: Future of Pharmaceutical Industry
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Manju Bala, Anju Dhiman, Harish Dureja, Munish Garg, Pooja A Chawla, Viney Chawla
Genina et al investigated the fabrication of subcutaneous rods and the intrauterine system of indomethacine loaded in ethylene vinyl acetate by using fused deposition modelling (Genina et al. 2016).
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.
Implantation of a sustained-release ganciclovir implant
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
April Harris, Stephen A Meffert, Mandi D Conway
The sustained-release ganciclovir implant (Vitrasert, Chiron Vision, Irvine, CA) currently available is 10 mm in length and 3.5 mm in height (Fig. 54.1). It consists of a nominally 4.5 mg ganciclovir pellet (which may actually contain between 4.5 and 6.4 mg of the drug) with a polyvinyl alcohol coating over its entire surface. This coating is permeable to ganciclovir. A second layer of ethylene vinyl acetate is partially coated over the surface of the pellet. This layer is impermeable to ganciclovir. The tab that extends from the posterior surface of the implant is an extension of the polyvinyl alcohol membrane and is trimmed at the time of surgery to 3 mm.
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].
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].
An update on the contribution of hot-melt extrusion technology to novel drug delivery in the twenty-first century: part I
Published in Expert Opinion on Drug Delivery, 2019
Venkata Raman Kallakunta, Sandeep Sarabu, Suresh Bandari, Roshan Tiwari, Hemlata Patil, Michael A Repka
Genina et al. [103] utilized ethylene vinyl acetate (EVA) to produce IND-loaded EVA filaments using HME. The drug-loaded EVA filaments were employed in FDM 3D printing to produce custom-made, T-shaped intrauterine devices and subcutaneous rods. Similarly, Fu et al. developed personalized progesterone-loaded vaginal rings using FDM 3D printing. The progesterone-loaded filaments were fed into FDM 3D printers to print vaginal rings in different shapes, namely ‘O’, ‘Y’, or ‘M’. These vaginal rings showed long-term sustained-release of progesterone for more than a week [104]. This HME-based FDM 3D printing was also utilized as a platform for miscellaneous applications, such as the development of polypills (multiple drugs in one dosage form) as bilayer dosage forms [105], duocaplets, multilayer tablets [106], and two compartment capsule dosage forms [107]. This two-compartment capsule form can be used for pulsatile release of one drug or two compartments filled with two different drugs as polypill. The printing of these two compartments can be tailored with different polymer materials for free solubility or gastric resistant.