of cerebral blood vessels and serves to counteract the sedative effect of butalbital. Butalbital has a half-life of about 35 hours. Acetaminophen has a half-life of about 1.25 to 3 hours, but may be increased by liver damage and after an overdose. Caffeine has a half-life of about 2.5 to 4.5 hours. References External links Wikipedia medicine articles ready to translate Analgesics Combination drugs