Influence of Microenvironment pH,Humidity, and Temperature on the Stability of Polymorphic and Amorphous Forms of Clopidogrel Bisulfate |
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Authors: | Dhara K Raijada Saranjit Singh Arvind K Bansal |
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Institution: | (1) Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160 062 Mohali, Punjab, India;(2) Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160 062 Mohali, Punjab, India; |
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Abstract: | The effect of microenvironment pH, humidity, and temperature was evaluated on the stability of polymorphic and amorphous forms
of clopidogrel bisulfate, when present alone or in combinations. Oxalic acid and sodium carbonate were used as solid stressors
to create acidic and alkaline pH, respectively. The samples without and with stressors were subjected for 3 months to (1)
0% RH, 25% RH, 75% RH, and 85% RH at 40°C and also to (2) 60°C, 80°C, and 100°C at 0% RH. In case of solid samples without
stressors, the mixture of polymorphic and amorphous forms showed more degradation than the individual forms above critical
relative humidity (85% RH). Similar higher degradation was observed between 75% RH and 85% RH in case of acid-stressed samples.
In alkaline microenvironment, all the samples showed identical decomposition attributed to conversion of bisulfate salt to
free base. Thermal studies indicated that polymorphic forms of clopidogrel bisulfate and also its glassy amorphous form were
highly resistant to temperature, whereas the rubbery state of the drug degraded significantly at temperatures of ≥80°C. |
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