The correlation between predicted and measured patient specific analgesic concentrations after intravenous titration: a guide for initial maintenance requirements with methadone.
The relationship between the analgesic methadone concentrations measured and those predicted using a pharmacokinetic approach were assessed in 22 patients referred for long-term management of severe pain with intravenous methadone. Five milligrams of methadone were administered IV every 10 minutes until the patient reported a visual analog scale (VAS) pain score of less than or equal to 2. Initial maintenance infusion rates were chosen based on the number of 5 mg doses required to produce satisfactory analgesia. Overall, the methadone concentrations predicted using pharmacokinetic modeling were in excellent agreement with those actually measured. Over 95% of the variance in the data was explained using this model (r2 = 0.9704). Using the rapid titration paradigm described here, one can obtain a reasonable estimate of patient specific analgesic (target) concentration as well as initial infusion requirements for methadone.
Denson
D D
DD
Department of Anesthesia, University of Cincinnati College of Medicine, Ohio.
Concilus
R R
RR
Gregg
R V
RV
Crews
J C
JC
D006801:Humans; D007262:Infusions, Intravenous / Q000379:methods; D008691:Methadone / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D010147:Pain Measurement / Q000187:drug effects*; D013997:Time Factors
D008691:Methadone