Physico-chemical properties and local toxic effects of injectables.

In Japan, many cases of muscle contracture as a sequela of injections have been reported. We studied the physico-chemical properties and muscle-damaging potential of many injectables which are commonly used in hospitals. Contrary to our expectations, the pH of the injectables was found to range widely from 1.4 to 12.8, and the osmotic ratio from 0.2 to 36. It was also found that their hemolytic potential was closely related to the severity of the muscle lesions in animal experiments and that there were many injectables with strong muscle-damaging potentials. Therefore, doctors should be informed of the physico-chemical properties and tissue-damaging potential of each injectable; pharmaceutical companies should exert all possible efforts to improve injectables; and doctors should keep the administration of intramuscular injections to a minimum and use them only in cases of actual need.