Overview of the delivery technologies for inhalation aerosols
Anthony J. Hickey, Heidi M. Mansour in Inhalation Aerosols, 2019
Particle-particle attraction can be broadly classified as either adhesion or cohesion (10). Adhesion usually refers to the attraction of particles of two different chemical composition, while cohesion refers to the attraction of two particles of the same chemical nature. Although these forces are much weaker than covalent bonding, their range extends over greater distances, and thus they are called long-range forces (10). These interparticle interactions are the result of multiple concurrently acting forces, which include molecular interactions, electrostatic interactions, capillary forces, and mechanical interlocking (6,10–12). Uncharged particles can interact with each other through molecular interactions. Even overall neutral particles can possess temporary local concentrations of charge due to instantaneous different electronic configurations. This leads to the formation of permanent or transient dipoles, which can induce complementary dipoles in neighboring particles. Consequently, polarizable neutral charge molecules can attract each other through molecular interactions called London–van der Waals dispersion forces that exerts an influence over a range of approximately 10 nm, rapidly decreasing with increasing distance between the two particles (6,10). In a normal environment with low relative humidity, van der Waals forces are the main contributor to the cohesive/adhesive forces between two particles.
Synthetic Polymers in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
This chapter covers two types of synthetic conditioning polymers, (1) cationic polymers and (2) nonionic polymers. The literature on cationic polymers is extensive. In addition to the polymers addressed in this section, the reader will find references to cationic polymers in the other chapters mentioned above. The prevalence of cationic conditioning polymers is not surprising. It follows from the fact that proteins that comprise the structural elements of hair and skin, that is collagen, keratin, elastin, and so forth, are anionic at the normal physiological pH of the human body (156). Consequently, the attraction of cationic conditioners to these surfaces is greatly enhanced by powerful electrostatic forces. Other types of attractive forces can stimulate polymer adhesion to these surfaces as well, including hydrogen bonding and van der Waals forces. These two forces help explain why many lipophilic and protein-like polymers can also function as conditioning materials. Examples of both are discussed in this section. Synthetic Conditioning PolymersCationic Conditioning Polymers
Gaps and Future Considerations for Development of Transdermal and Topical Delivery Systems
Tapash K. Ghosh in Dermal Drug Delivery, 2020
As previously mentioned, adhesion characteristics are critical for proper product design and therapeutic use. Equally as important, having adequate specifications and acceptance criteria for release and stability is essential. Specification and acceptance criteria, if properly set, powered and justified with scientific data, can detect adhesive property changes that may be due to raw material variation that may not always be evident in raw material acceptance criteria and testing. Additionally, adhesive testing at release and stability allows for monitoring for undesirable trends throughout the life cycle of the product. Adhesion testing can be done by a variety of methods but typically consists of adhesion to steel or other suitable substrate, peel from release liner, probe tack, and shear.
Mucoadhesive drug delivery systems: a promising non-invasive approach to bioavailability enhancement. Part I: biophysical considerations
Published in Expert Opinion on Drug Delivery, 2023
Radha Kulkarni, Suraj Fanse, Diane J. Burgess
Adhesion is defined as a state in which two surfaces are held together by interfacial forces, which may consist of physical and chemical interactions including van der Waals forces, hydrogen bonds, and molecular interlocking. Bioadhesion, a specialized form of adhesion, is the ability of a material (synthetic or biological) to adhere to a biological tissue for an extended period of time by means of interfacial forces [1]. In the context of drug therapy and medicine, not all forms of bioadhesion are found to be desirable. For example, minimal adhesion is desirable to prevent complications such as unwanted thrombus formation and plaque buildup in cardiovascular devices and dental prosthetics, respectively. On the other hand, maximum adhesion and immobility is required for orthopedic implants and drug delivery devices, such as a buccal patch to ensure their safety and efficacy. Mucoadhesion is a subset of bioadhesion, which specifically describes the adhesion of a formulation to the mucus layer that covers certain epithelial tissues [2,3]. This phenomenon has been explored over the past four decades to design specialized mucoadhesive drug delivery systems (MDDS) that increase the contact time of the dosage forms to the tissues.
(PhSe)2 and (pCl-PhSe)2 organochalcogen compounds inhibit Candida albicans adhesion to human endocervical (HeLa) cells and show anti-biofilm activities
Published in Biofouling, 2021
Bruna Marques da Silva, Marília Toledo Braga, Juliene Cristina da Silva Passos, Moisés Lopes Carvalho, Isabela Bueno Rosseti, Laís Mayara Machado de Amorim, João Batista Teixeira da Rocha, Carlos Alberto-Silva, Maricilia Silva Costa
The key steps in the development of fungal biofilm include adhesion, proliferation which includes germ tube formation and hyphal development, maturation and the production of an extracellular matrix, and finally dispersal (Ramage et al. 2009). Attachment of microorganisms to biological tissues is believed to be a significant step in the interaction between pathogen and host, and in vitro and in vivo adhesion experimentations in different models have employed Candida species (Lan et al. 2017). The in vitro adhesion test can be performed with various human epithelial cells, such as the HeLa cell line which originated from a human carcinoma of the cervix. This cell line has been used in several adhesion assays (Segal and Sandovsky-Losica 1995). Based on the current findings, both organochalcogen compounds inhibited C. albicans adhesion to HeLa cells, dependent on the compound concentrations present in the medium. Adhesion is mediated by many different factors such as cell surface hydrophobicity, van der Waals forces and receptor-ligand interactions (Mayer et al. 2013). (PhSe)2 seems to change these factors more efficiently than (pCl-PhSe)2 because the percentage of C. albicans adhered to HeLa cells in presence of (PhSe)2 was significantly greater than for (pCl-PhSe)2.
Metoclopramide loaded buccal films for potential treatment of migraine symptoms: in vitro and in vivo study
Published in Pharmaceutical Development and Technology, 2023
Omar Mady, Sara Hussien, Dalia H. Abdelkader, Enas El-Dahaby
The rabbit intestine mucosal membrane was utilized as a tissue model (Nafee et al. 2003) for determining the bioadhesion strength. The rabbit intestinal membrane was collected, cleaned from debris, stored frozen in phosphate buffer (pH= 6.8), and thawed at room temperature before use. A two-arm balance apparatus used in this study was slightly modified as mentioned in previous studies (Alanazi et al. 2007). The intestinal rabbit was cut longitudinally and placed on the slide exposing the mucosal side to be facing upwards then further cut into square shaped pieces of 4.0 cm2 approximately and fixed on a tissue holder (slide) using cyanoacrylate glue, few drops of phosphate buffer 6.8 PH were placed on the surface of the mucosa. The buccal film (4 cm2) was cut and fixed on another tissue holder (slide), then put on top of the intestinal rabbit membrane fixed on the slide. The two surfaces (mucosal membrane and buccal film) were allowed to be in contact for 2 min to enhance the adhesion. A predetermined weight of polyethylene bag was hung to the hook of the other balance arm. After the preload time, two drops of water/s were placed in the polyethylene bag till the detachment between the two surfaces occurred. The weight of water collected in the bag was recorded and expressed as the weight (g) required for the detachment (bioadhesive strength) (Alanazi et al. 2007). The force of adhesion and bond strength was calculated according to the following equations (Habib et al. 2010):
Related Knowledge Centers
- Bacteria
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- Virus
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