DURAGESIC-50
Clinical safety rating
cautionComprehensive clinical and safety monograph for DURAGESIC-50 (DURAGESIC-50).
Fentanyl is a potent synthetic opioid agonist primarily at μ-opioid receptors, with additional weak affinity for κ- and δ-opioid receptors. It increases potassium conductance and decreases calcium influx, leading to hyperpolarization and reduced neurotransmitter release, resulting in analgesia and sedation.
| Metabolism | Primarily metabolized by CYP3A4 to norfentanyl and other inactive metabolites. Minimal metabolism via CYP3A5. Less than 1% excreted unchanged in urine. |
| Excretion | Primarily renal: ~75% as metabolites (mostly norfentanyl, <10% unchanged fentanyl); ~9% biliary/fecal; <10% excreted in urine as unchanged drug. |
| Half-life | Mean terminal elimination half-life 20–27 h (range 13–40 h). Prolonged with hepatic impairment, elderly, or obesity. Clinical context: Requires ~5 days to reach steady state; accumulation risk with continuous use. |
| Protein binding | ~80–85% bound to serum proteins, primarily albumin and alpha-1-acid glycoprotein (AAG). |
| Volume of Distribution | 3–8 L/kg (mean ~4 L/kg). High Vd indicates extensive tissue distribution (e.g., muscle, fat). Clinical meaning: large reservoir; slow redistribution contributes to long half-life. |
| Bioavailability | Transdermal: ~92% relative to IV fentanyl (due to first-pass metabolism avoidance; absolute bioavailability ~45% for gel reservoir, ~40% for matrix patch). Not used orally (poor bioavailability <30%). |
| Onset of Action | Transdermal: 12–24 h for clinical analgesia; significant opioid effect typically by 24 h. Not suitable for acute pain due to slow onset. |
| Duration of Action | 72 h per application. Serum concentrations decline slowly after removal (half-life ~17 h), so analgesic effect persists for 12–24 h post-removal. |
| Molecular Weight | 336.47 |
Apply one 50 mcg/h transdermal system every 72 hours; initiate at 25 mcg/h in opioid-naive patients; titrate based on response and tolerability.
| Dosage form | FILM, EXTENDED RELEASE |
| Renal impairment | GFR 30-59 mL/min: reduce dose by 50% and monitor closely. GFR <30 mL/min: contraindicated due to accumulation of active metabolite. |
| Liver impairment | Child-Pugh Class A: no adjustment needed. Child-Pugh Class B: reduce dose by 50% and monitor. Child-Pugh Class C: avoid use. |
| Pediatric use | Approved for opioid-tolerant children ≥2 years; dose based on morphine equivalent daily dose (MEDD) conversion; apply system every 72 hours; initial dose not to exceed 25 mcg/h. |
| Geriatric use | Start at lowest available dose (25 mcg/h) and titrate slowly; monitor for respiratory depression, sedation, and constipation; consider reduced clearance and increased sensitivity. |
| 1st trimester | Fetal risk not ruled out. Prolonged use may cause neonatal withdrawal syndrome. Avoid unless clearly needed. |
| 2nd trimester | Fetal risk not ruled out. Prolonged use may cause neonatal withdrawal syndrome. Use only if benefit outweighs risk. |
| 3rd trimester | May cause neonatal respiratory depression, withdrawal syndrome. Avoid prolonged use or high doses near term. |
Clinical note
Comprehensive clinical and safety monograph for DURAGESIC-50 (DURAGESIC-50).
| Placental transfer | Fentanyl crosses the placenta rapidly and extensively. Plasma protein binding is about 80-85% in mothers, but free drug crosses readily. Umbilical vein to maternal vein ratio is approximately 0.8-0.9. |
| Breastfeeding | Fentanyl is excreted into breast milk in low concentrations. With maternal use of transdermal fentanyl, the relative infant dose is estimated to be <5% of the weight-adjusted maternal dose. However, risk of sedation and respiratory depression in the infant exists. Use with caution, monitor infant for drowsiness and difficulty feeding. Discontinue breastfeeding if infant shows signs of opioid toxicity. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: No adequate human data; animal studies show increased risk of skeletal variations. Second and third trimesters: Prolonged use may cause neonatal opioid withdrawal syndrome and respiratory depression at birth. Avoid during labor due to risk of neonatal respiratory depression. |
| Fetal Monitoring | Assess fetal heart rate and uterine activity during prolonged use. Monitor for maternal respiratory depression, sedation, and constipation. In neonates, monitor for signs of withdrawal (irritability, hypertonia, poor feeding) for at least 48 hours after delivery if used near term. |
| Fertility Effects | In animal studies, fentanyl at high doses impaired fertility and caused reduced pregnancy rates. Human data limited; may alter menstrual cycle and reduce sperm count via hypothalamic-pituitary-gonadal axis suppression. Effects are typically reversible upon discontinuation. |
■ FDA Black Box Warning
WARNING: RISK OF MEDICATION ERRORS, ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL EXPOSURE; NEONATAL OPIOID WITHDRAWAL SYNDROME; CYTOCHROME P450 3A4 INTERACTION; RISK FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; and RISK OF SERIOUS, LIFE-THREATENING, OR FATAL RESPIRATORY DEPRESSION IN CHILDREN.
| Serious Effects |
Hypersensitivity to fentanyl or any component of the patchAcute or postoperative pain management (patches not indicated due to variable absorption)Concurrent use of MAO inhibitors or within 14 days of discontinuationSevere respiratory depressionParalytic ileusKnown or suspected gastrointestinal obstruction
| Precautions | Risk of respiratory depression, especially in non-opioid-tolerant patients or with dose initiation/titration, Risk of hypotension, bradycardia, and QT prolongation, Risk of serotonin syndrome with serotonergic drugs, Risk of adrenal insufficiency with prolonged use, Risk of severe hypotension in patients with compromised ability to maintain blood pressure, Use caution in patients with head injury, increased intracranial pressure, or impaired consciousness, May obscure the course of acute abdominal conditions, Risk of withdrawal with abrupt discontinuation, Application site reactions, Fever may increase fentanyl absorption through the skin, Not indicated for acute or postoperative pain, Should be used only in opioid-tolerant patients for chronic pain |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they may increase fentanyl levels. No other significant food interactions. |
| Clinical Pearls | Convert oral morphine to transdermal fentanyl using a 100:1 ratio (e.g., oral morphine 100 mg/day = fentanyl 100 mcg/hr patch). Rotate patch sites every 72 hours to avoid skin irritation; apply to non-irradiated, intact skin. Do not cut or damage the patch. Initiate only in opioid-tolerant patients. Titrate no more frequently than every 72 hours. Monitor for respiratory depression, especially in opioid-naive patients, COPD, or sleep apnea. Naloxone may be needed but duration of fentanyl action may exceed naloxone's effect. Heat exposure (e.g., fever, heating pads) increases absorption and risk of toxicity. Remove old patch before applying new one. |
| Patient Advice | Apply patch to flat, non-hairy skin on chest, back, or upper arm; avoid irritated or scarred skin. · Wash hands after applying; do not touch the gel or cut the patch. · Dispose of used patches by folding adhesive sides together and flushing down toilet or placing in child-resistant container. · Avoid heating pads, hot tubs, electric blankets, or sunbathing while wearing patch. · Do not stop or change dose without talking to doctor; withdrawal may occur. · Keep patches out of reach of children and pets; accidental exposure can be fatal. · Common side effects include nausea, constipation, drowsiness, and dizziness. · Seek emergency care if you have trouble breathing, slow heartbeat, or severe drowsiness. · Do not drink alcohol or take other sedatives without doctor approval. · If patch falls off, apply a new one at a different site and note the time to track 72-hour schedule. |
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