Safety

Rapid Development of Tolerance to Dipyridamole-Associated Headaches

This shows results from a study of healthy volunteers. The occurrence of headaches was not related to plasma concentrations.

Headache was more frequent at the onset of therapy, but rapidly diminished in severity/frequency over time (over 3-5 days).
Rates fell by half on the second day of dosing, and by the 11th day were 3-12%.

"Intensity" in this model was the product of the severity of the headache episodes and their duration (hours). This product was chosen as the outcome variable as it reflects two components of the headaches that are a measure of subjective discomfort.
Any reported event of headache was stratified according to the WHO System Organ Class and rated according to severity (1 = mild, awareness of a sign or symptom that is easily tolerated; 2 = moderate, discomfort enough to cause interference with usual activity; 3 = severe, incapacitating with inability to do work or usual activity).