Effect of chemical structure of various penicillins on the stability of beta-lactam group in their molecules. VI. Effects of relative humidity and heat on the stability of amoxicillin trihydrate and amoxicillin sodium in the solid phase
Płotkowiak, Z.; Nogowska, M.
Acta Poloniae Pharmaceutica 46(3): 258-265
1989
ISSN/ISBN: 0001-6837 PMID: 2618770 Document Number: 4034
Dependence of stability of Amoxycillin trihydrate (AMOXY. 3H2O) and Amoxycillin-Natrium (AMOXY-Na) upon relative humidity (RH) and temperature was investigated using the iodometric method for the determination of Amoxycillin. The first order rate constants and activation parameters have been determined at controlled moisture conditions. The straightline relationship lg k = f(RH) at T = const. has been stated, which however is fulfilled by AMOXY-Na only at RH greater than or equal to 50%. The calculated factors of the equation lg k = a + b.1/T + c.RH proved to enable estimation of the stability of the studied antibiotics at any climate conditions. The performed kinetic studies have shown that AMOXY-Na undergoes degradation about 1.5 x 10(3) times faster than AMOXY.3H2O, at RH greater than or equal to 50%.
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