New ideas about the solubility of drugs.
Methods are described for detecting precipitation of ionisable drugs under conditions of changing pH, estimating kinetic solubility from the onset of precipitation, and measuring solubility by chasing equilibrium. Definitions are presented for kinetic, equilibrium, and intrinsic solubility of ionisable drugs, supersaturation and subsaturation, and for chasers and non-chasers, which are two classes of ionisable drug with significantly different solubility properties. The use of Bjerrum Curves and Neutral-Species Concentration Profiles to depict solubility properties are described and illustrated with case studies showing super-dissolving behaviour, conversion between crystalline forms and enhancement of solubility through supersaturation, and the use of additives and simulated gastrointestinal fluids.
Box
Karl
K
Sirius Analytical Ltd., Riverside, Forest Row Business Park, Forest Row, East Sussex, RH18 5DW, UK.
Comer
John E
JE
Gravestock
Tom
T
Stuart
Martin
M
D000465:Algorithms; D001702:Biopharmaceutics / Q000145:classification; D002626:Chemistry, Pharmaceutical / Q000295:instrumentation / Q000379:methods*; D003196:Computer Graphics; D003198:Computer Simulation; D004176:Dipyridamole / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012995:Solubility; D013656:Taurocholic Acid / Q000737:chemistry
D004364:Pharmaceutical Preparations; D013656:Taurocholic Acid; D004176:Dipyridamole