Overview
This lecture covers fentanyl, including its history, pharmacology, indications, contraindications, dosing, adverse effects, and key nursing considerations for its use in critical care.
History and Background
- Fentanyl was first developed by Jansen in 1959 for anesthesia and pain relief.
- Became widely used as an IV anesthetic in the 1960s.
- Fentanyl citrate (trade name Sublimaze) is the most common IV form.
- Also available as patches and flavored lollipops.
- Fentanyl is a Schedule II controlled opioid, indicating a high potential for abuse and dependence.
Mechanism of Action
- Binds to opioid receptors in the central nervous system, altering pain perception and response.
- Acts mainly on MU receptors (analgesia, respiratory depression, euphoria, sedation) and Kappa receptors (analgesia, sedation).
- Mimics endogenous opioid peptides.
Indications
- Used as adjunct in general and regional anesthesia, sedation, and analgesia.
- Manages acute and chronic pain, including breakthrough cancer pain in opioid-tolerant patients.
- Preferred for critically ill patients due to minimal hypotensive effects and short duration.
Contraindications and Cautions
- Contraindicated in patients with allergy or hypersensitivity to fentanyl.
- Use caution in patients with brain tumors, COPD, decreased respiratory reserve, hepatic/renal disease, bradyarrhythmias, or sleep-related breathing disorders.
Adverse Effects
- CNS: confusion, euphoria, sedation, somnolence, seizures, anxiety, hallucinations, headache.
- Cardiovascular: arrhythmias, chest pain, hypertension, hypotension, bradycardia, DVT, PE.
- ENT: rhinitis, pharyngitis, dry eyes, swelling.
- GI: constipation, abdominal pain, ileus, nausea, vomiting.
- Genitourinary: urine retention.
- Respiratory: apnea, hypoventilation, respiratory depression, dyspnea.
- Skin: diaphoresis, pruritus, erythema (topical).
- Risk of physical dependence.
Dosing and Administration
- IV push: usual dose 25–100 micrograms; supplied as 100 mcg/2mL (50 mcg/mL).
- IV infusion: common concentration 1000 mcg/100mL (10 mcg/mL), typical rates 25–250 mcg/hr.
- PCA (Patient-Controlled Analgesia): provider specifies bolus, continuous dose, demand dose, intervals, PRN doses, and lockout.
- Onset: 1–2 min; Peak: 3–5 min; Duration: 30–60 min (IV).
Pharmacokinetics
- Multiple routes: oral, IM, IV, intranasal, intradermal, transmucosal, epidural, intrathecal.
- Metabolized by liver, excreted mainly by urine.
- Highly lipophilic, accumulates in adipose tissue with prolonged/high doses.
Antidote
- Naloxone (Narcan): 0.4–2 mg IV every 2–3 minutes up to 10 mg maximum; may require continuous infusion.
Nursing Considerations
- Monitor for respiratory depression, especially within the first 24–72 hours of initiation or dose change.
- Use pulse oximetry and preferably end-tidal CO2 for early detection of respiratory depression.
- Withdraw gradually to prevent withdrawal symptoms.
- Monitor circulatory/respiratory status, urinary and bowel function.
- High/prolonged doses can cause constipation; assess need for bowel regimen.
- Keep naloxone available for overdose management.
- May increase amylase and lipase levels; check labs periodically.
Key Terms & Definitions
- Opioid receptor — site in CNS where opioids bind to exert effects.
- MU receptor — opioid receptor subtype causing analgesia, euphoria, respiratory depression.
- PCA (Patient-Controlled Analgesia) — method allowing patients to self-administer preset opioid doses.
- Naloxone (Narcan) — opioid antagonist used to reverse opioid effects.
Action Items / Next Steps
- Monitor vital signs, respiratory and circulatory status closely during fentanyl use.
- Assess and manage bowel and urinary function as needed.
- Ensure naloxone is available and review facility protocols for opioid overdose.