Effect of temperature on chlorproguanil and proguanil hydrochloride solutions: a chemical stability study.
Chlorproguanil and proguanil hydrochloride solutions in 0.5 M hydrochloric acid, water and 1 M ammonium hydroxide were subjected to different temperatures (22-80 degrees C) for 68 h. The decomposition rate constants for chlorproguanil ranged from 1.60 to 47.6 x 10(3) h-1 in acid, 3.5 to 18 x 10(3) h-1 in water and 3.87 to 32.5 x 10(3) h-1 in base, between 50 degrees C and 80 degrees C. The activation energy Ea was 96.5, 52.12 and 62.1 kJ mol-1 in acid, water and base respectively. The proguanil decomposition rate constant ranged from 1.72 to 18.5 x 10(3) h-1 in acid, 1.58 to 9.67 x 10(3) h-1 in water and 2.34 to 15.77 x 10(3) h-1 in base, between 50 degrees C and 80 degrees C, with Ea values of 54.7, 73.3 and 62.5 kJ mol-1. Three unidentified degradation products were separated in the acid solution for each of the compounds. Chlorproguanil and proguanil are stable (t1/2 values over 30 days and up to 287 days respectively) in acid, water and base at temperatures below 22 degrees C.
Kolawole
J A
JA
Faculty of Pharmaceutical Sciences, University of Jos, Nigeria.
Mustapha
A
A
Abdul-Aguye
I
I
Ochekpe
N
N
D064753:Ammonium Hydroxide; D000962:Antimalarials / Q000737:chemistry*; D004355:Drug Stability; D006207:Half-Life; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D002727:Proguanil / Q000031:analogs & derivatives* / Q000737:chemistry; D012996:Solutions; D013696:Temperature
D000962:Antimalarials; D006878:Hydroxides; D012996:Solutions; D064753:Ammonium Hydroxide; C007030:chlorproguanil; D006851:Hydrochloric Acid; D002727:Proguanil