Opioid analgesics.

This article discusses recent developments in opioid pharmacology. Selective activity at different opioid receptors promises, but has not yet provided, a strong analgesic without opioid side-effects. The startling pharmacokinetic profile of the new esterase-metabolized intravenous opioid, remifentanil, is reflected in the rapid onset of effect and short, predictable recovery, independent of duration of infusion.