IONSYS
Clinical safety rating
cautionComprehensive clinical and safety monograph for IONSYS (IONSYS).
IONSYS is an iontophoretic delivery system for fentanyl, a mu-opioid receptor agonist. Fentanyl binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception and emotional response.
| Metabolism | Fentanyl is primarily metabolized in the liver via CYP3A4 isoenzyme to norfentanyl (inactive) and other metabolites. |
| Excretion | Renal: approximately 90% as fentanyl metabolites (mainly norfentanyl) and less than 10% as unchanged drug; fecal: less than 10%. |
| Half-life | Terminal elimination half-life: 16.3 ± 9.1 hours for fentanyl released from IONSYS; accounts for prolonged release from depot and is longer than intravenous fentanyl (3-12 hours). |
| Protein binding | Approximately 80-85% bound to plasma proteins, mainly alpha-1-acid glycoprotein and albumin. |
| Volume of Distribution | Volume of distribution at steady state: 4.0 ± 1.2 L/kg; large Vd indicates extensive tissue distribution (including fat and muscle). |
| Bioavailability | Bioavailability of fentanyl from IONSYS via iontophoresis: approximately 100% relative to intravenous fentanyl (systemic absorption is complete). |
| Onset of Action | Onset of analgesia: approximately 10-15 minutes after actuation of the iontophoretic system; peak effect at 30-60 minutes. |
| Duration of Action | Duration of analgesia per dose: approximately 1 hour; system delivers 40 mcg fentanyl per actuation over 10 minutes, with clinical effect lasting 1-2 hours; redosing at 10-minute intervals as needed. |
| Molecular Weight | 336.47 Da |
Apply one 40 mcg fentanyl iontophoretic transdermal system to skin on upper arm or chest; delivers 40 mcg per dose on-demand for up to 24 hours or 80 doses, whichever is shorter. Maximum 2 doses per hour, 6 doses per application. Patient must be opioid-tolerant.
| Dosage form | SYSTEM |
| Renal impairment | No specific dose adjustment; however, fentanyl pharmacokinetics may be altered in severe renal impairment (CrCl <30 mL/min). Use with caution and monitor for adverse effects. |
| Liver impairment | No specific dose adjustment; consider slower elimination in Child-Pugh C; start with lowest effective dose and monitor closely for respiratory depression. |
| Pediatric use | Not approved for use in patients under 18 years of age. |
| Geriatric use | Initiate at lowest effective dose; elderly patients may have reduced clearance and increased sensitivity to fentanyl. Monitor for respiratory depression and avoid use in opioid-naive patients. |
| 1st trimester | Fentanyl is classified as Category C. Limited human data available; animal studies have not demonstrated teratogenicity at clinical doses, though opioid exposure in early pregnancy may be associated with an increased risk of spontaneous abortion. |
| 2nd trimester | Fentanyl readily crosses the placental barrier. Prolonged use during the second trimester may increase the risk of neonatal opioid withdrawal syndrome and potential intrauterine growth restriction. |
| 3rd trimester | Use during late pregnancy or labor may cause neonatal respiratory depression. Chronic use leads to neonatal opioid withdrawal syndrome, characterized by irritability, hyperactivity, abnormal sleep patterns, and gastrointestinal dysfunction. |
Clinical note
Comprehensive clinical and safety monograph for IONSYS (IONSYS).
| Placental transfer | Readily crosses the placenta via passive diffusion; the fetal to maternal serum concentration ratio is estimated between 0.4 and 1.0. |
| Breastfeeding | Fentanyl is excreted in human milk. Although the amount transferred via the iontophoretic system is relatively low, it can cause sedation, poor feeding, and respiratory depression in the nursing infant. Monitoring of the infant for central nervous system depression is mandatory if the mother receives treatment. |
| Lactation Rating | L3 |
| Teratogenic Risk | Pregnancy Category C. First trimester: No adequate studies; animal studies show no teratogenicity but embryotoxicity at high doses. Second and third trimesters: Prolonged use may cause neonatal opioid withdrawal syndrome; avoid regular use due to risk of respiratory depression in neonate. |
| Fetal Monitoring | Monitor for opioid-related adverse effects: respiratory rate, sedation level, oxygen saturation; fetal heart rate monitoring during prolonged use; neonatal monitoring for withdrawal symptoms if used near term. |
| Fertility Effects | No adequate studies; opioids may cause hormonal changes that impair fertility in both sexes; reversible upon discontinuation. |
■ FDA Black Box Warning
IONSYS is indicated for use only in adult patients who are already receiving opioid therapy and have demonstrated opioid tolerance. Because of the risk of respiratory depression, IONSYS should be used only in patients who are in a monitored hospital setting and who have continuous monitoring of respiratory status. Accidental exposure to the gel adhesive containing fentanyl may result in fatal respiratory depression. IONSYS should not be used in opioid-naive patients.
| Serious Effects |
Known hypersensitivity to fentanyl, cetylpyridinium chloride, or any components of the systemSignificant respiratory depressionAcute or severe bronchial asthma in unmonitored settings or in the absence of resuscitative equipmentKnown or suspected gastrointestinal obstruction, including paralytic ileusUse in opioid-naive patients due to the risk of fatal respiratory depressionUse in patients under 18 years of ageUse in out-of-hospital settings
| Precautions | Respiratory depression (especially in opioid-naive patients), Accidental exposure (can cause fatal respiratory depression), Application site reactions (e.g., erythema, itching), Risk of opioid addiction, abuse, and misuse, Risk of serotonin syndrome with concurrent serotonergic drugs, Risk of adrenal insufficiency with prolonged use, Risk of severe hypotension in patients with compromised blood pressure |
| Food/Dietary | No specific food restrictions. Avoid alcohol and grapefruit juice as they may enhance CNS depression or alter fentanyl metabolism. |
| Clinical Pearls | IONSYS (fentanyl iontophoretic transdermal system) provides on-demand analgesia via patient-controlled iontophoresis. Each activation delivers 40 mcg fentanyl, max 6 doses/hour. Use only in opioid-tolerant patients; contraindicated in acute postoperative pain requiring bolus doses. Risk of respiratory depression, especially with concurrent CNS depressants. Monitor for skin irritation at application site; rotate sites every 24 hours. Do not use with other fentanyl products. |
| Patient Advice | Press the button only when you need pain relief; system locks out to prevent overdosing. · Do not apply heat, hot packs, or water to the patch area. · Remove the patch before MRI, diathermy, or defibrillation; the device contains metal. · Report slow or shallow breathing, lightheadedness, or severe sedation immediately. · Keep out of reach of children and dispose of used patches at a take-back location. |
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