A method for producing constant plasma concentrations of drugs. Application to methohexitone.

A delivery system in which a dilute infusion of methohexitone is continuously added to a smaller volume of more concentrated solution has been used to infuse exponentially decreasing drug concentrations at a constant rate of infusion. The constants for calculation of concentrations and infusion rate are described. It was possible to achieve and maintain the target plasma concentration required to produce anaesthesia in conjunction with nitrous oxide in oxygen. Methohexitone is the only available drug suitable for this technique, but it requires frequent opioid supplementation and is not the ideal drug for such a technique.