Fentanyl Blood Concentration-Analgesic Response Relationship in the Treatment of Postoperative Pain

Transdermal fentanyl compared with parenteral buprenorphine in post-surgical pain in swine: a case study

“…Due to individual variation in response to opioids, in some instances this dose level may provide only basal analgesia. Similar variation in analgesic dose response with equivalent doses of TIS fentanyl has been observed in man (Gourlay et al 1988). Depending on the invasiveness of surgery, severity of pain and morbidity, age, condition, fat content and sex of the pig and other factors, TTS fentanyl in pigs may be useful as basal, pre-emptive analgesia.…”

A comparison of patient-controlled analgesia fentanyl and alfentanil for labour analgesia

“…Using this method, Lehmann and colleagues determined that the MEAC of alfentanil for postoperative analgesia varied greatly with a range of 0.6 to 99.2 ng·ml -1 and a median level of 14.9 ng·ml -1 . 10 The eight patients in our study in whom serum alfentanil concentrations were analyzed at delivery all demonstrated levels well above this value despite the average time from last dose to delivery being 17 ± 14.9 min. The pain stimulus of a labour contraction may well require higher serum concentrations for analgesia than those required for postoperative analgesia after abdominal surgery.…”

“…12 In a study of PCA alfentanil after major abdominal and orthopedic procedures, Lehmann and co-workers determined that alfentanil was 1/15th as potent as fentanyl taking into account both intensity and duration of effect. 10 If this figure is correct, then the alfentanil patients may have been receiving less than equipotent doses.…”

“…In four subjects the maternal fentanyl level was below the minimum effective analgesic concentration (MEAC) of 0.63 ng·ml -1 as determined by Gourlay et al . 10 All patients in the alfentanil group had a maternal serum concentration greater than 14.9 ng·ml -1 , the MEAC of alfentanil. 11 …”

Maternal and fetal effects of intravenous patient-controlled fentanyl analgesia during labour in a thrombocytopenic parturient

“…ml -~) that Lehmann suggested is required for postoperative pain relief, 25 and also above the mean MEC (0.63 ng-ml -l) for postoperative fentanyl analgesia. 26 The duration of action of fentanyl following intravenous bolus injection is short, due to redistribution and extensive tissue uptake. 27 A large cumulative dose (1025 I~g in our patient) may cause prolonged effects due to a large volume of distribution limiting the rate at which elimination can occur.…”