China
Africa
Explore chapters and articles related to this topic
Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
In the ion exchange mechanism, an ion in the liquid face (usually an aqueous face) is transferred to a solid face (organic or ceramic material). To maintain the charge balance, a counter ion, for example hydrogen, is released from the solid face. The distribution ratio between liquid and solid face is often a function of pH. Furthermore, complexing agents can be used to modify the distribution ratio.
Pharmaceutical and Methodological Aspects of Microparticles
Published in Neville Willmott, John Daly, Microspheres and Regional Cancer Therapy, 2020
Yan Chen, Mark A. Burton, Bruce N. Gray
The use of postloading of microspherical systems is restricted to charged matrices and ionizable drugs with an opposite charge (being ionizable the problem of low water solubility does not arise). The most common drug incorporated into such systems is doxorubicin, which is positively charged at neutral pH. Goldberg et al.14 used in ion-exchange principles to obtain microspherical systems with high drug loading and versatile release properties. The polymer with suitable ion-exchange properties was polyglutamic acid, which formed a stable polymer drug salt with the basic drug doxorubicin. Based on the same principle, others have used ion-exchange resins to incorporate doxorubicin with loadings of more than 35% (W/W) with polystyrene-based cation exchange resins.47,93 It has further been demonstrated that drug incorporation into ionic resins can be affected by the resin’s counter ion.93
High-Performance Liquid Chromatography
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Joel J. Kirschbaum, Adorjan Aszalos
Cephalexin in 20 µl serum was analyzed using an octadecylsilane column and a mobile phase of 30% aqueous acetonitrile solution containing 0.005 M 2-propanesulfonate (adjusted to pH 3 using acetic acid) flowing at 2 ml/min into a 254 nm detector [202]. Responses were linear between 2 and 30 µg/ml. The effect of various counterions on the chromatography was studied.
Promising strategies for improving oral bioavailability of poor water-soluble drugs
Published in Expert Opinion on Drug Discovery, 2023
Bruna Rocha, Letícia Aparecida de Morais, Mateus Costa Viana, Guilherme Carneiro
As the ionic nature of a drug molecule is one of the barriers to its absorption, forming a neutral complex between an ionic drug and a suitable counterion can enhance absorption in the GIT. In addition, some drugs may also be used as counterions for synergistic effects, more notably lidocaine, procainamide, metoclopramide, atenolol, propranolol, timolol, naproxen, ketoprofen, and diclofenac. Thus, absorption through passive diffusion can be enhanced from the formation of neutral ion pairs and changes in drug polarity by combing with different counterions. Furthermore, this strategy can be combined with others, such as encapsulation in nanostructured systems. One particular type is the ion pair formation with polyelectrolytes, which can be anionic (e.g. alginic acid, hyaluronic acid, and carboxymethylcellulose) or cationic polymers (e.g. chitosan and Eudragit -E, -RS, -RL). Selecting suitable polymers for the complex formation can increase retention time at the absorption site, protect the drug from gastric degradation, increase water solubility, enhance cellular transport, and even provide site-specific drug delivery [34]. The formation of ionic complexes has been associated with increased drug bioavailability (Table 1).
Ion-pair compounds of diacerein for enhancing skin permeability in vitro: the compatibility–permeability relationship of counter ion and diacerein
Published in Drug Delivery, 2022
Yan Liang, Manzhen Duan, Wei Yi, Teng Zhang, Yonggang Wang, Zhiming Wu, Huaibo Tang
The properties of ion pairs are affected not only by the properties of drugs, but also by the properties of counter ions. It is worth exploring how the relationship between counter ion and DCN effect on the skin penetration of DCN ion-pair compounds. It was found by the bind energy curve that DCN had the strongest compatibility with triethanolamine among organic amines with different functional groups and laurylamine (N12) among fatty amines. Laurylamine had stronger compatibility of with DCN than triethanolamine. Among organic amines with different functional groups, DCN-Teta was the most potential candidate. The transdermal permeation rate of DCN-fatty acid compounds would increase slowly with the carbon atoms of counter ion increasing, attain the peak at 12, then decreased gradually. The skin permeation rate of DCN-N12 was higher than that of DCN-Teta. It was amazingly found that the in vitro permeation fluxes of DCN ion-pair compounds would increase with enhancing the compatibility of counter ion and DCN.
Ferroportin-inhibitor salt: patent evaluation WO2018192973
Published in Expert Opinion on Therapeutic Patents, 2021
Snehal Kadam, Megha Khaitan, Paromita Banerjee, Anita Mandhare
To understand the patentability aspect of the invention disclosed in the present PCT application, we closely reviewed the international search report issued by WIPO. Earlier PCT filing by Vifor [33] is cited by the search authority as document of particular relevance wherein several examples of compound–I and a general list of possible acids for pharmaceutically acceptable salts are disclosed as ferroportin inhibitors. The present applicationhowever claims salts having specific ratio of counter ions (Figure 4), and 16 polymorphs of two salts of selected example-127 (instead of free base or mixtures of salts and free bases) with improved pharmacokinetic profile, low toxicity, and good bioavailability and hence the present invention may be considered as novel. Further the advantage of obtaining the new salts in crystallized form improves the physicochemical properties providing long-term stability, easy to formulate into a galenic form and easy to handle and prepare. The salts and solvates, hydrates and polymorphs disclosed herein are also claimed for use in combination therapy with co administration of at least one additional pharmaceutically active compound in the form of oral or parenteral formulation [34].