Which opioid agonist is metabolized by plasma cholinesterases?

Remifentanil is the opioid agonist metabolized by plasma cholinesterases. This unique feature distinguishes it from other opioids, as remifentanil's metabolism is extremely rapid and occurs through hydrolysis by non-specific plasma esterases rather than through liver enzymes. This results in a shorter duration of action, making it particularly advantageous in settings where quick recovery from analgesia is necessary, such as in surgeries or procedural sedation.

The rapid breakdown of remifentanil allows for tight control of opioid effects and eliminates the accumulation seen with longer-acting opioids. This characteristic is especially useful for patients who require a fast return to baseline function after the discontinuation of the drug.

In contrast, the metabolism of other opioids like sufentanil, alfentanil, and fentanyl primarily involves liver metabolism through cytochrome P450 enzymes, which means their effects last longer and they may require more careful monitoring during and after administration. Thus, remifentanil's distinctive metabolic pathway highlights its utility in clinical situations requiring quick onset and offset of opioid effects.