Incompatibility signifies the problems arising when two or more ingredients prescribed, result into undesirable changes in the appearance, safety or therapeutic purpose of the product.
Interaction of a drug with another drug, or of a drug with additives or adjuvants, dosage errors, omissions etc., also fall under incompatibility.
Incompatibility may occur in compounding and dispensing of prescriptions so also at any stage during formulation, manufacturing, packaging, storage or administration of drugs.
Contrary to expectations, the importance of incompatibility has increased in modern pharmaceutical practice mainly due to the introduction of large number of newer and more complex drugs as well as the indiscriminate use of combination therapy.
In present day dispensing practice since the pharmacist invariably reviews each and every prescription, he should be in a position to detect and overcome the incompatibilities. This calls for the ingenuity of a pharmacist who is knowledgeable in pharmacy, pharmacology and chemistry.
The problem of incompatibility is to be solved mainly through two angles firstly the detection or prediction of possible occurrence, and secondly, the correction which comprises of preventing or minimizing the incompatibility.
Incompatibility may be classified as physical, chemical and therapeutic.