Dipyridamole is an interferon inducer.

2,6-Bis(diethanolamino)-4,8-dipiperidinopyrimido-[5,4-d]-pyrimidine (dipyridamole) induced interferon production in vitro in explanted mouse peritoneal leukocytes and to a lower degree in non-lymphoidal cell cultures of mouse (L cells primary embryo fibroblasts) and human (diploid embryo lung fibroblasts) origin. Dipyridamole induced interferon also in mice after intravenous administration. Peak interferon levels in the blood (128 IU/ml) were attained at 49 hr after injection of 0.1 mg dipyridamole per kg body weight and at 24 and 12 hr after injection of 0.6-1.8 and 16.7 mg/kg respectively. By its pH stability, thermostability and antigenic properties the interferon induced in mice, mouse peritoneal leukocytes and L cells corresponded to IFN-alpha and IFN-beta. This interferon-inducing capacity of dipyridamole may account for its broad-spectrum antiviral effect.