From the Guidelines
The half-life of fentanyl is approximately 2.4 hours in children aged 5 months to 4.5 years, and up to 21 hours in children aged 0.5-14 years with long-term infusions. When considering the half-life of fentanyl, it's essential to take into account the age of the patient and the duration of infusion, as these factors can significantly impact the drug's pharmacokinetics 1. The provided evidence suggests that the half-life of fentanyl can range from 1-15 hours in neonates, and 2.4 hours in children aged 5 months to 4.5 years, with a mean half-life of 21 hours in children aged 0.5-14 years with long-term infusions 1. Some key points to consider when evaluating the half-life of fentanyl include:
- The age of the patient, as neonates and young children may have different pharmacokinetic profiles compared to older children and adults
- The duration of infusion, as long-term infusions can lead to accumulation of the drug in fatty tissues and prolong its effective duration
- The potential for organ dysfunction and hypothermia to affect the metabolism of fentanyl, which can impact its half-life and therapeutic effects
- The importance of monitoring drug levels to ensure that they are within a low to mid therapeutic range prior to neurologic examination to determine brain death, as the elimination half-life does not guarantee therapeutic drug levels for longer-acting medications or medications with active metabolites 1.
From the FDA Drug Label
The mean half-life is approximately 17 hours After system removal, serum fentanyl concentrations decline gradually, falling about 50% in approximately 17 (range 13 to 22) hours. Due to the mean half-life of approximately 17 hours, patients who are thought to have had a serious adverse event, including overdose, will require monitoring and treatment for at least 24 hours
The half-life of fentanyl is approximately 17 hours. This value can range from 13 to 22 hours. 2, 2, 2
From the Research
Half Life of Fentanyl
- The half life of fentanyl is not explicitly stated in the provided studies 3, 4, 5, 6, 7.
- However, the studies discuss the pharmacokinetics and pharmacodynamics of fentanyl, including its absorption, distribution, metabolism, and elimination.
- Transdermal fentanyl patches are designed to deliver a constant rate of fentanyl over a period of 72 hours, with serum concentrations increasing gradually after initial application and levelling off between 12 and 24 hours 3.
- Steady-state plasma fentanyl concentrations can be maintained for as long as the patches are renewed 3.
- The studies focus on the efficacy and safety of transdermal fentanyl patches for chronic pain management, rather than the half life of fentanyl itself 4, 5, 6, 7.
Pharmacokinetics of Fentanyl
- Fentanyl is a synthetic opioid agonist with a high potency and lipid solubility, making it suitable for transdermal delivery 3.
- The formation of a fentanyl depot in the skin tissue allows for gradual increase in serum concentrations after initial application 3.
- Plasma fentanyl levels can be measured to evaluate the efficacy and safety of transdermal fentanyl patches 7.
- The studies discuss the importance of proper dosing and monitoring of fentanyl to minimize adverse effects, such as respiratory depression and constipation 3, 4, 5, 6, 7.