Fentanyl (fentanyl citrate)
Also sold as: Fentanyl Hameln (IV), Duragesic patch, Durogesic (transdermal)
Pregnancy
Cat C
Lactation
Avoid
Schedule
NDPS
Forms
injection 50mcg/mL (as citrate), 2mL ampoule (hospital use — IV/IM/epidural) +3
Indications
- Intraoperative analgesia and anesthesia adjunct (IV)
- Procedural sedation and analgesia (IV)
- Chronic severe cancer pain (transdermal patch — in opioid-tolerant patients)
- Breakthrough cancer pain (transmucosal/intranasal formulations)
- Palliative care — refractory pain or dyspnea (continuous SC infusion)
- Epidural/spinal analgesia (obstetric and post-operative use)
Adult Dosing
Intraoperative IV analgesia
1–3 mcg/kg IV bolus
Supplement with 25–50 mcg increments as needed
CRITICAL: All fentanyl doses are in MICROGRAMS (mcg), not milligrams (mg). Dose confusion is a leading cause of fatal overdose.
Procedural sedation (IV)
1–2 mcg/kg IV slowly over 2–3 minutes
Titrate to effect; continuous monitoring mandatory
Chronic cancer pain — transdermal patch (opioid-tolerant patients only)
<60 mg oral morphine/day equivalent → 12 mcg/h patch; 60–134 mg/day → 25 mcg/h patch
Change patch every 72 hours; escalate dose every 3 days as needed
Apply to flat, hairless, non-irritated skin (upper chest, back, or upper arm). Rotate sites. Opioid-naive patients must NOT receive patches.
Palliative care — continuous SC infusion
12–25 mcg/h
Continuous infusion; titrate based on breakthrough dose requirements
Pediatric Dosing
Intubation/ventilation must be available for neonates. Transdermal patch only in opioid-tolerant children ≥2yr.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| Mild-to-moderate renal impairment | No dose adjustment required (fentanyl and its metabolite norfentanyl are largely inactive) |
| Severe renal impairment | Use with caution; start at lower doses and titrate slowly. Preferred over morphine — no active renally-cleared metabolites |
| Haemodialysis | Fentanyl is not significantly dialyzed; no supplemental dose needed |
Hepatic Adjustment
Fentanyl is extensively metabolized by CYP3A4 in the liver. Severe hepatic impairment: significantly increased plasma levels due to reduced clearance and increased bioavailability (patches). Reduce dose by 25–50% and titrate slowly. Monitor for prolonged sedation and respiratory depression.
Pregnancy & Lactation
Pregnancy: Category C
Pregnancy Category C, Category D near term. Crosses placenta freely. Neonatal respiratory depression and opioid withdrawal syndrome if used near term or chronically. Short-term IV use during labor (epidural) is widely practiced with monitoring. Avoid transdermal fentanyl in pregnancy (continuous systemic absorption).
Lactation: Avoid
Excreted in breast milk in small amounts. After single-dose parenteral use (e.g., epidural during delivery), breastfeeding after 24 hours is generally considered safe. Avoid transdermal patches and repeated high-dose parenteral use during breastfeeding — cumulative infant exposure may cause sedation.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| CYP3A4 inhibitors (clarithromycin, erythromycin, ritonavir, ketoconazole, itraconazole, fluconazole, grapefruit juice) | CYP3A4 inhibitors dramatically increase fentanyl plasma levels — can double or more the exposure, causing life-threatening respiratory depression. Avoid concurrent use. If unavoidable (e.g., patient on HIV protease inhibitors), reduce fentanyl dose by 25–50% and monitor closely. | Major |
| CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, phenobarbital, St. John's Wort) | Dramatically reduce fentanyl plasma levels (by 50–75%), causing inadequate analgesia. Increase fentanyl dose when inducer is added; reduce when inducer is stopped (risk of overdose on inducer discontinuation). | Major |
| MAO Inhibitors | Serotonin syndrome, hyperpyrexia, and cardiovascular collapse. Contraindicated within 14 days of MAOI use. | Major |
| Benzodiazepines / CNS depressants (midazolam, diazepam, propofol, alcohol) | Profound additive CNS and respiratory depression — FDA black box warning. Classic anesthesia drug interaction: fentanyl + midazolam combination used in procedural sedation requires full monitoring (oxygen, suction, defibrillator, naloxone). | Major |
| Naloxone | Opioid antagonist — reverses fentanyl-induced analgesia, sedation, and respiratory depression. Due to fentanyl longer half-life (IV bolus: 30–60 min; transdermal: 17–27 h), repeated naloxone doses or continuous infusion may be required for reversal of patch overdose. | Major |
| Serotonergic drugs (SSRIs, SNRIs, triptans) | Fentanyl has weak serotonergic activity. Combined with serotonergic drugs, low risk of serotonin syndrome — monitor for signs (agitation, tremor, hyperthermia) especially at high fentanyl doses. | Moderate |
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Side Effects
Common
- Respiratory depression (dose-dependent — the most critical side effect)
- Sedation and cognitive impairment
- Nausea and vomiting (less than morphine)
- Constipation (less than morphine — fewer GI receptors activated with IV dosing)
- Pruritus (especially with epidural/spinal routes)
- Urinary retention
- Bradycardia and hypotension (with rapid IV bolus)
- Muscle rigidity (chest wall and glottic) with rapid high-dose IV — "wooden chest syndrome" — managed with neuromuscular blockade
- Transdermal patch: local skin reactions (erythema, pruritus at application site)
Serious / Discontinue If
- Fatal respiratory depression — highest risk with IV bolus in opioid-naive patients, concurrent CNS depressants, CYP3A4 inhibitors, accidental patch ingestion or misuse. KEEP NALOXONE AVAILABLE AT ALL TIMES.
- Chest wall rigidity (wooden chest syndrome) — rapid high-dose IV fentanyl causes glottic and thoracic muscle rigidity, making manual ventilation difficult; treat with succinylcholine or naloxone.
- Transdermal patch risks: heat-induced dose acceleration (heating pads, hot bath, fever, electric blankets — can cause fatal overdose by dramatically increasing absorption); inadvertent patch ingestion by children (medical emergency); fentanyl patch misuse (gel extraction).
- Physical dependence and opioid withdrawal — taper patches gradually (reduce dose by 50% every 6 days) when discontinuing.
- Hypotension and bradycardia (especially with IV opioid + benzodiazepine combination).
- Opioid-induced hyperalgesia with chronic high-dose use.
Contraindications
- Opioid-naive patients — transdermal patches (patches are for opioid-tolerant patients only; minimum prior opioid equivalent: oral morphine 60mg/day x1 week)
- Acute or post-operative pain — transdermal patches (too slow to onset; unpredictable absorption in perioperative state)
- Acute respiratory depression or severe bronchial asthma in unmonitored settings
- Paralytic ileus
- Concurrent MAOI therapy (within 14 days)
- Known hypersensitivity to fentanyl
- NDPS controlled substance — hospital formulary management and prescription compliance mandatory in India
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Fentanyl Hameln 50mcg/mL injection | Hameln Pharma | Hospital formulary pricing only |
| Durogesic 25mcg/h transdermal patch | Janssen (Johnson & Johnson) | ₹485/patch |
| Duragesic 12mcg/h transdermal patch | Janssen (Johnson & Johnson) | ₹385/patch |
Monitoring Required
- Respiratory rate, oxygen saturation, and level of consciousness — continuous monitoring for IV administration; 4-hourly for first 24 hours of patch initiation
- Pain score (NRS/VAS) — assess at rest and on movement
- Sedation score — excessive sedation is a warning sign preceding respiratory arrest
- Body temperature — fever increases transdermal patch absorption significantly
- Skin inspection at patch site — apply to flat, non-irritated, hairless skin; rotate sites each change
- Signs of opioid overdose — pinpoint pupils, unresponsive, apneic (for patch users: have naloxone at home)
- Breakthrough pain frequency and analgesic requirements (guide patch dose titration)
- Renal function periodically (less concern than morphine, but volume depletion affects clearance)
- CYP3A4 inhibitor/inducer medication review at every visit
- NDPS controlled substance compliance — hospital/pharmacy register, limited quantity prescriptions
Patient Counseling Points
- The fentanyl patch delivers medicine through your skin continuously for 72 hours (3 days). Apply to flat, non-irritated, hairless skin — upper chest, back, or upper arm. Press firmly for 30 seconds.
- CRITICAL: Never use a heating pad, electric blanket, or sit in a hot bath/sauna while wearing this patch — heat dramatically increases the amount of medicine absorbed and can cause a fatal overdose.
- The patch takes 12–24 hours to build up to its full pain-relieving level. Do not remove and replace with a new patch sooner than 72 hours unless directed.
- When changing the patch, fold the old patch in half (sticky sides together) and flush it down the toilet immediately — accidental contact or ingestion by children or pets can be fatal.
- ALERT: If you or someone at home becomes very difficult to wake up, is breathing very slowly, or has blue lips — call emergency services immediately and apply naloxone if available.
- Keep naloxone available at home. Your caregiver should know how to use it.
- Do not cut the patch into pieces — this destroys the rate-limiting membrane and releases all the medicine at once.
- Store unused patches in the original packaging, at room temperature, away from children. Never put a used patch in household waste — always flush or return to pharmacy.
- Tell all doctors, dentists, and emergency providers that you are on a fentanyl patch. Show them where the patch is applied.
- This medicine causes physical dependence — do not stop abruptly. Your doctor will help you reduce the dose gradually when the time comes.
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Clinically reviewed by: Dr. Arun Bhaskar, MD, DM Palliative Medicine, Tata Memorial Hospital Mumbai
Last reviewed: 2026-04-01
References
- Janssen Pharmaceutica. Durogesic (fentanyl transdermal) Prescribing Information. 2023.
- Peng PW, Sandler AN. A Review of the Use of Fentanyl Analgesia in the Management of Acute Pain in Adults. Anesthesiology. 1999.
- Sinatra R. Causes and Consequences of Inadequate Management of Acute Pain. Pain Med. 2010.
- CDSCO. Controlled Drug Narcotic Prescribing — NDPS Act 1985 Compliance. India.