Stability, drugs kinetics

The stability of suspensions, emulsions, creams, and ointments is dealt with in other chapters. The unique characteristics of solid-state decomposition processes have been described in reviews by D. C. Monkhouse [79,80] and in the monograph on drug stability by J. T. Carstensen [81]. Baitalow et al. have applied an unconventional approach to the kinetic analysis of solid-state reactions [82], The recently published monograph on solid-state chemistry of drugs also treats this topic in great detail [83],... 

Varea et al. described a study of the stability of procaine hydrochloride in cardioplegie solutions, prepared from Ringer s solution and electrolytes (both un-buffered, or buffered with sodium bicarbonate) [156], The content of the drug was measured by ultraviolet speetrophotometry, and the was found to follow pseudo-first order kinetics. The stability of the drug entity in buffered solutions was estimated to be approximately 5-7 days. 

Guillory, P, and Poust, R. (2002), Chemical kinetics and drug stability, in Banker and Rhodes, Eds., Drugs in the Pharmaceutical Sciences, Vol. 121, Marcel Dekker, New York, pp. 139-166. 

ALTERNATIVE ACCELERATED METHODS FOR STUDYING DRUG STABILITY VARIABLE-PARAMETER KINETICS... 

Carstensen, J. T. (2000), Solution Kinetics Kinetic pH profiles Oxidation in solution Catalysis, Complexation, and Photolysis, in Carstensen, J.T. and Rhodes, C.T., Eds., Drug Stability, Principle and Practice, 3rd ed., Marcel Dekker, New York, Chapters 2-5, pp. 19-143. 

Alibrandi, G., Coppolino, S., D Aliberti, S., Ficarra, R., Micali, N., and Villari, A. (2003), Fast drug stability determination by LC variable-parameter kinetic experiments,/. Pharm. Biomed. Anal., 32,1073-1079. 

Giuseppe Alibrandi, Universita di Messina, Messina, Italy, Alternative Accelerated Methods for Studying Drug Stability Variable-Parameter Kinetics... 

Jn drug stability studies, the rates of hydrolysis of indomethacin (Sigma-Chem.) were considerably slower in Pluronic F 127 (BASF) gels than in buffer alone. The degradation of indomethacin followed 1st order kinetics, with linear plots of the 1st order rate constant vs. pH in both Pluronic and aqueous solutions, allowing prediction of the time required for degradation of indomethacin."... 

In the experimental study and interpretation of hydrolytic reaction rates, many kinetic effects provide opportunities for probing the detailed nature of the reaction or have significant practical consequences on drug stability. The topics of temperature dependence, catalysis and solvent effects, were discussed in the first edition of this encyclopedia. 

Cartensen, J.T. Solution kinetics. In Drug Stability Principles and Practices Marcel Dekker, Inc. New York, 2000 19-56. 

Like varying the solvent, varying the salt form also affects other crystal properties including morphology, polymorphs, crystallization kinetics, formulation, drug stability, etc. Therefore, selection of the salt form always involves other considerations in addition to solubility. 

Notari RE. On the merits of a complete kinetic stability study. Drug Stabil 1996 1 1-2. 

Carstensen JT (2000) Solution kinetics. Drugs Pharm Sci 107 (Drug Stability) pp. 19-55. 

Drug stability is an important consideration in pharmacenti-cal unit operations and prolonged storage. It is possible that one polymorph is unstable/metastable (a kinetic polymorph) compared to another form of the same dmg (the thermodynamic polymorph). For example, differences in the chemical and thermal/photochenfical stability of polymorphs are observed for drugs such as carbamazepine, furosemide, ... 

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