Plasma concentrations of fentanyl with subcutaneous infusion in palliative care patients

Br J Clin Pharmacol. 1995 Dec;40(6):553-6.


1. Plasma concentrations of fentanyl were measured by g.c. in 20 patients (median age: 75 years and range: 54-86 years; eight females) in palliative care receiving the drug by continuous s.c. infusion (median rate: 1200 micrograms day-1 and range: 100-5000 micrograms day-1). 2. The infusion rate was significantly related to the duration of therapy (Spearman rho = 0.56, P < 0.05). The total steady-state plasma concentrations of fentanyl ranged between 0.1 and 9 ng ml-1, with a median of 1 ng ml-1. The unbound fraction of fentanyl in the plasma ranged from 17.8 to 44.4%, with a median value of 33.6%. Infusion rates and both total and unbound plasma concentrations of fentanyl were correlated (Spearman rho = 0.92, P < 0.05 in each case). Even with standardization for dosage, there was an eightfold variation in total plasma concentrations and 3.5-fold variation in unbound plasma concentrations of fentanyl. 3. There is considerable inter-patient variability in the pharmacokinetics of fentanyl with s.c. infusion in the palliative care setting, which necessitates careful titration of dosage according to individual clinical response.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / blood*
  • Analgesics, Opioid / pharmacokinetics
  • Female
  • Fentanyl / administration & dosage
  • Fentanyl / blood*
  • Fentanyl / pharmacokinetics
  • Humans
  • Injections, Subcutaneous
  • Male
  • Middle Aged
  • Neoplasms / blood*
  • Neoplasms / drug therapy
  • Palliative Care*


  • Analgesics, Opioid
  • Fentanyl