Aspirin and probenecid pretreatment influences the potency of thiopentone and the onset of action of midazolam.

The effects of pretreatment with aspirin and probenecid, two drugs which are highly bound to albumin, on an induction dose of thiopentone and time to onset of action of a fixed dose of midazolam were investigated. Both drugs significantly potentiate thiopentone and shorten the induction time with midazolam. The importance of individual variations in plasma proteins in influencing the action of highly bound drugs is stressed.