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Vitreoretinal Surgery in Rare Conditions
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
Drug delivery devices could be biodegradable or non-biodegradable, matrix or reservoir type, implantable or injectable type, and macro-implants or micro-implants. Non-biodegradable implants can provide more controlled and sustained drug release than the biodegradable implants but may be costlier to manufacture and may need removal in the event of a serious adverse event. Reservoir-type implants release the drug slowly [hence are used to treat chronic conditions], while matrix-type implants release the drug rapidly [hence are used to treat acute conditions]. Injectable implants may be delivered as an outpatient procedure, while implantable devices may need short-term admission as their placement into the vitreous cavity is more complex. Nonbiodegradable implants include Vitrasert, Retisert, and Iluvien; Posurdex is the only commercially available biodegradable implant for managing retinal disorders.
Antiviral Drugs as Tools for Nanomedicine
Published in Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji, Viral and Antiviral Nanomaterials, 2022
Significant progress has been made in the field of cancer therapies, but the mortality rate remains high. This strongly demands further research. As mentioned earlier, current cancer therapies, such as surgery on many occasions, are unable to completely remove all cancer cells in the human body; chemotherapy and radiotherapy show severe toxic side effects on normal cells. Recently, there has been significant progress in the application of nanotechnology in diagnosis and therapeutics (Niemeyer and Mirkin 2004; McNeil 2011; Baetke et al. 2015; El-Sayed and Kamel 2020). The field wherein nanomaterials are used in diagnostic or therapeutic applications is known as nanomedicine (Brewer et al. 2007; Kim et al. 2010). Different kinds of nanoparticles, such as polymeric (Amreddy et al. 2017; Afsharzadeh et al. 2018), carbon nanotubes (Li and Al-Jamal 2021; Riley and Narayan 2021), liposomes (Lawrie et al. 2013; Edwards et al. 2015), metallic (Ma et al. 2019; Peng and Liang 2019; Kim et al. 2021), ceramic (Huang et al. 2011; Thomas et al. 2015), semiconductor (Zhu et al. 2017) etc. Many of them have proved their potential inefficient diagnostic and/or therapeutic tools for cancer. The need for the development of novel drug-delivery systems resulted in several innovative delivery systems using the nanotechnology approach. In the present chapter, emphasis is given to nano-delivery approaches for antiviral agents in cancer therapy.
Emerging Technologies for Particle Engineering
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Particle engineering has become a hot topic in the field of modified-release delivery systems during the past decades. It includes a bridge linking drugs and drug delivery systems and has a wide range of pharmaceutical applications. One of the major challenges in drug delivery is to get the drug at the place it is needed in the body thereby avoiding potential side effects to non-diseased organs. This is especially challenging in cancer treatment where the tumor may be localized as distinct metastases in various organs. In the case of nanospheres, where the drug is uniformly distributed, drug release occurs by diffusion or erosion of the matrix. If the nanoparticle is coated by polymer, the release is then controlled by diffusion of the drug from the polymeric membrane. Membrane coating acts as a drug release barrier; therefore, drug solubility and diffusion in or across the polymer membrane becomes a determining factor in drug release. Furthermore, the release rate also can be affected by ionic interactions between the drug and auxiliary ingredients. For drug delivery, not only engineered particles may be used as a carrier, but also the drug itself may be formulated at a nanoscale, and then function as its own “carrier” [27–30]. The composition of the engineered nanoparticles may vary. Source materials may be of biological origin like phospholipids, lipids, lactic acid, dextran, chitosan, or have more “chemical” characteristics like various polymers, carbon, silica, and metals. Table 7.2 summarizes some of the drug delivery formulations with nanotechnology.
Pullulan based derivatives: synthesis, enhanced physicochemical properties, and applications
Published in Drug Delivery, 2022
Surendra Agrawal, Divya Budhwani, Pravina Gurjar, Darshan Telange, Vijay Lambole
Drug delivery is a method of delivering pharmaceutical compounds into the body to achieve a therapeutic effect (Tiwari et al., 2012). Since the exploration of diseases developed and biopharmaceutical achieved progress rapidly, conventional drug delivery systems cannot satisfy the demand anymore. Thus, the required novel drug delivery systems are liposomes, niosomes, proliposomes, microspheres, gels, prodrugs etc. Various types of material have been studied as carriers to explore their potential application in the formulation of novel drug delivery systems. Polysaccharides are one of the types among them, considering their biocompatibility and safety. Pullulan, an exopolysaccharide acts as a carrier due to its physicochemical properties. Modifying it further adds more properties, including stimuli-responsive ability, enhancing therapeutic efficiency, diagnosis, and releasing the combination therapy (Tong et al., 2020). For drug delivery, it can be modified via periodate oxidation, succinylation, cholesterol modification, sulfation, formation of cationic pullulan, incorporation of PEG, and carboxymethylation as listed in Table 2.
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].
Biomedical application of chondroitin sulfate with nanoparticles in drug delivery systems: systematic review
Published in Journal of Drug Targeting, 2021
Abebe Feyissa Amhare, Jian Lei, Huan Deng, Yizhen Lv, Jing Han, Lei Zhang
Biomedical engineering has many contributions to our understanding of barriers to targeted drug delivery. It also has a contribution to the development of new modes of drug delivery [1]. A targeted drug delivery system can help us to transport medicine to an exact location in the body [2]. These targeted drug delivery systems can reduce side effects such as cytotoxicity and the chance of occurring of drug resistance. Drug administration without carriers has induced toxicity to normal tissues and organs. Due to these problems, efforts have been made to overcome these problems by formulating drugs that can be delivered at the target site selectively [3,4]. Nowadays, researchers are using biotechnology such as nanotechnology to improve medications that can target diseases more effectively and precisely.