Chemical Incompatibility - PHARMACEUTICS II (Dispensing Pharmacy) D. Pharm 2nd year PDF Notes

 Chemical incompatibility

q  Chemical Incompatibility may be result of chemical interactions between the ingredients of a prescription; as a result a toxic or inactive product may be formed.

q  It may be often occurs due to

·         Oxidation-reduction,

·         Acid-base hydrolysis or combination reactions,

·         Double decomposition reaction,

·         Complex formation or pH change

q  These reactions may be noticed by

·         Precipitation,

·         Effervescence,

·         Decomposition,

·         Colour change 

·         By explosion.

q  Chemical incompatibility may be intentional or accidental.

1. Precipitate yielding interactions

–      Alkaloidal incompatibilities

–      Soluble salicylates incompatibilities

2. Incompatibility leading to carbon dioxide evolution
3. Herapathite reaction
4. Miscellaneous

Precipitate yielding interactions

q  Generally it is observed that reactions between solutions precede at faster rate produces precipitates which are indiffusible in nature.

q  These precipitates will thick and do not diffuse readily.

q  The reactions between dilute solutions proceed slowly yielding a light diffusible precipitate.

q  The precipitate so formed may be diffusible.

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