Pharmaceuticals charged

Paraxanthine—see Xanthine, 1,7-dimethyl-Parent name nomenclature, 1, 35 Parham cycloalkylation in chroman synthesis, 3, 783 Paromomycins as pharmaceuticals, 1, 154 Partial charge transfer from donor to acceptor stacks, 1, 350 Pasteurellosis... 

This chapter considers ionizable drug-Uke molecules and the effect of such ionization on pharmaceutic properties. Most medicinal substances are ionizable [1]. The biological medium into which these substances distribute embraces a range of pH values. The ionization constant, pK, can teU the pharmaceutical scientist to what degree the molecule is charged in solution at a particular pH. This is important to know, since the charge state of the molecule strongly influences its other physicochemical properties. 

The pH-partition hypothesis, now widely accepted in pharmaceutical research, suggests that membrane permeability will be highest at the pH where the molecule is least charged however, this is also the pH where the molecule is least soluble. (In Brodie s work, the compounds tested have relatively high water solu-... 

The determination of the zeta potential of particles in a disperse system provides useful information concerning the sign and magnitude of the charge and its effect on the stability of the system (see Sec. II.B) [56, 206 208], It can be of value in the development of pharmaceutical suspensions, particularly if the... 

The book is organized into eight chapters. Chapter 1 describes the physicochemical needs of pharmaceutical research and development. Chapter 2 defines the flux model, based on Fick s laws of diffusion, in terms of solubility, permeability, and charge state (pH), and lays the foundation for the rest of the book. Chapter 3 covers the topic of ionization constants—how to measure pKa values accurately and quickly, and which methods to use. Bjerrum analysis is revealed as the secret weapon behind the most effective approaches. Chapter 4 discusses experimental... 

Zeevi, A., Klang, S., Alard, V., Brossard, F. and Benita, S. (1994) The design and characterization of a positively charged submicron emulsion containing a sunscreen agent. International Journal of Pharmaceutics, 108 (1), 57-58. 

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