Stability of stored histamine diphosphate solutions. Clinically useful information

Histamine bronchoprovocation challenge has been shown to be extremely safe and useful as both a clinical diagnostic test and as a research tool in the study of bronchial asthma. Despite its widespread usage, information on the stability of histamine diphosphate (HDP) solutions has been lacking. We therefore studied the stability of HDP solutions as a function of time, concentration, fluorescent light exposure, and sterility. Our results indicated that HDP solutions between 2.76 and 22.10 mg/ml (histamine base, 1 to 8 mg/ml) show no evidence of degradation over a 4-month period when kept at 12 degrees C, unless gas sterilization techniques were used in preparing the solutions bacterial contamination was frequent, and at lower concentrations (i.e., between 0.08 and 0.28 mg/ml) HDP solutions that became contaminated with bacteria showed complete degradation within 9 to 11 wk of their preparation.