Keywords

Because the intravenous anesthetic agents are given essentially as unit doses, drug–drug interactions (DDIs) in this drug class have not generally been determined to involve induction or inhibition of the cytochrome P450 system. Remember that inhibition of P450 enzymes generally happens on the order of days and induction on the order of weeks—this requires sustained dosing of the drug.

Nonetheless, significant and clinically relevant DDIs do occur with these drugs as anyone can attest who has ever looked in dismay at the precipitate that formed in an intravenous line just as induction was taking place.

Another interesting DDI that occurs in this drug class is the interaction between dexmedetomidine and spinal bupivacaine (see Dexy’s Midnight Spinal). The phenomenon of prolongation of the block has been reported, but the mechanism is still not fully elucidated. It is a good illustration, however, of the need to remain vigilant and motivated to educate oneself about attendant DDIs whenever a new anesthetic drug comes on the market. The drug is introduced and then, usually in fairly short order, the case reports start appearing.