Solutions of two compounds, pralidoxime chloride and sodium chloride, were given intramuscularly to normal human subjects. The ensuing increase in creatine phosphokinase (CPK) activity in the blood was directly related to the concentration and osmolarity of the injected solution when the volume was kept constant, and directly related to the volume when the concentration or osmolarity was kept constant. These findings suggest that the diluent may make a significant contribution to the increase in CPK observed after intramuscular administration of drugs.
(JAMA 229:1894-1897, 1974)
Sidell FR, Culver DL, Kaminskis A. Serum Creatine Phosphokinase Activity After Intramuscular InjectionThe Effect of Dose, Concentration, and Volume. JAMA. 1974;229(14):1894–1897. doi:10.1001/jama.1974.03230520036027