Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OXYCET vs ILOPERIDONE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, though it can interact with other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Acetaminophen is believed to produce analgesia through central action, possibly mediated through inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways, though the exact mechanism is not fully understood.
Iloperidone is an atypical antipsychotic with high affinity for serotonin 5-HT2A and dopamine D2 receptors; also moderate affinity for D3, D4, 5-HT6, 5-HT7, and α1-adrenergic receptors; low affinity for H1, 5-HT1A, and α2-adrenergic receptors; no affinity for M1 muscarinic receptors.
Management of moderate to moderately severe pain where an opioid analgesic is appropriate,Off-label use: Relief of pain in various conditions including postoperative pain, traumatic pain, and chronic pain
Acute treatment of schizophrenia in adults
1 tablet (325 mg acetaminophen and 5 mg oxycodone) orally every 4 to 6 hours as needed for pain; maximum 12 tablets per day.
1-2 mg orally twice daily; target dose 6-12 mg/day; maximum 12 mg/day
The terminal elimination half-life of oxycodone is approximately 3.5-4 hours for immediate-release formulations. For controlled-release formulations, the half-life is similar due to absorption-limited elimination, but the duration of action is extended due to the formulation. In elderly patients or those with hepatic impairment, half-life may be increased up to 2-fold.
Terminal elimination half-life 18 hours in extensive CYP2D6 metabolizers, 33 hours in poor metabolizers; clinical context: steady-state reached in ~5-7 days.
Oxycodone is extensively metabolized in the liver via cytochrome P450 3A4 (CYP3A4) and CYP2D6 to noroxycodone, oxymorphone, and noroxymorphone. Acetaminophen is primarily metabolized in the liver via conjugation (glucuronidation and sulfation) and, to a lesser extent, via CYP2E1 to a toxic metabolite (NAPQI) which is normally detoxified by glutathione.
Primarily metabolized by CYP3A4 and CYP2D6 to two major metabolites (P88 and P95); also a minor substrate of CYP1A2, CYP2C8, CYP2C9, CYP2C19, and CYP2E1.
Oxycodone is primarily metabolized in the liver via CYP3A4 to noroxycodone and via CYP2D6 to oxymorphone. Renal excretion accounts for approximately 87% of the administered dose, with 8.1% as unchanged oxycodone, 22.8% as noroxycodone, 9.1% as noroxymorphone, 3.2% as oxymorphone, and others. Fecal excretion is about 10%.
Primarily hepatic metabolism via CYP3A4 and CYP2D6; approximately 7% excreted unchanged in urine and 18% in feces; total renal elimination of metabolites ~25%, fecal ~60%.
Approximately 45% bound to plasma proteins, primarily albumin.
~95% bound to serum proteins, primarily albumin and alpha-1-acid glycoprotein.
Volume of distribution is 2.6-3.6 L/kg. This indicates extensive tissue distribution, with oxycodone widely distributed throughout body fluids and tissues, including the brain.
Vd/F ~20 L/kg (oral); large distribution indicates extensive tissue binding.
Oral immediate-release: 60-87% due to first-pass metabolism. Extended-release: approximately the same as immediate-release when adjusted for dose. Intravenous: 100%. Rectal: similar to oral (60-87%).
Oral bioavailability is approximately 96% relative to oral solution; food does not significantly affect absorption.
For Cr Cl 30-50 m L/min: administer every 6 hours; Cr Cl 10-29 m L/min: administer every 8 hours; Cr Cl < 10 m L/min: not recommended due to risk of oxycodone accumulation.
GFR 30-59 m L/min: reduce dose by 50%; GFR 15-29 m L/min: reduce by 75%; GFR <15 m L/min: not recommended
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% or extend dosing interval; Child-Pugh C: contraindicated or use with extreme caution, maximum 50% of normal dose.
Child-Pugh class B: reduce dose by 50%; Child-Pugh class C: contraindicated
Not recommended for children under 18 years due to risk of respiratory depression; for older adolescents (≥18 years), adult dosing may be considered.
Not established; safety and efficacy not evaluated in patients <18 years
Initiate at lowest effective dose, typically one-half of adult dose (one tablet every 6 hours) and titrate slowly; caution due to increased sensitivity and risk of falls and respiratory depression.
Initiate at 1 mg twice daily; increase slowly; monitor for orthostatic hypotension and anticholinergic effects
Addiction, Abuse, and Misuse: Oxycodone exposes users to risks of addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient's risk before prescribing, and monitor regularly for development of these behaviors or conditions. Life-Threatening Respiratory Depression: Serious, life-threatening, or fatal respiratory depression may occur. Monitor closely, especially upon initiation or following a dose increase. Accidental Ingestion: Accidental ingestion of even one dose of oxycodone, especially by children, can result in a fatal overdose of oxycodone. Neonatal Opioid Withdrawal Syndrome: Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated. Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants: Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants may result in profound sedation, respiratory depression, coma, and death. Reserve for use in patients for whom alternative treatment options are inadequate. Hepatotoxicity: Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses exceeding 4000 mg per day, and often involve more than one acetaminophen-containing product.
Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Iloperidone is not approved for the treatment of patients with dementia-related psychosis.
Risk of addiction, abuse, and misuse,Life-threatening respiratory depression,Accidental ingestion (especially in children),Neonatal opioid withdrawal syndrome,Risks from concomitant use with benzodiazepines or other CNS depressants,Hepatotoxicity from acetaminophen,Severe hypotension,Gastrointestinal effects (e.g., constipation, ileus),Seizures in patients with seizure disorders,Serotonin syndrome with concomitant serotonergic drugs,Adrenal insufficiency,Use in patients with head injury or increased intracranial pressure,Use in patients with acute abdominal conditions
Increased mortality in elderly patients with dementia-related psychosis,QT interval prolongation (particularly with concomitant use of drugs that prolong QT or in patients with risk factors),Neuroleptic malignant syndrome (NMS),Tardive dyskinesia,Metabolic changes (hyperglycemia, dyslipidemia, weight gain),Orthostatic hypotension (particularly during initial dose titration),Seizures,Leukopenia, neutropenia, and agranulocytosis,Body temperature regulation impairment,Dysphagia,Cognitive and motor impairment
Hypersensitivity to oxycodone or acetaminophen,Significant respiratory depression,Acute or severe bronchial asthma in an unmonitored setting or in absence of resuscitative equipment,Paralytic ileus,Severe hepatic impairment (for acetaminophen component),Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy
Known hypersensitivity to iloperidone or any component of the formulation
Avoid alcohol. Grapefruit juice may increase oxycodone levels (monitor for opioid effects); high-fat meals may delay absorption but not total exposure. No other significant dietary restrictions.
Grapefruit juice may inhibit CYP3A4 metabolism, increasing iloperidone concentrations; avoid concurrent use. High-fat meals may slightly reduce absorption; take consistency.
Oxycodone/paracetamol (OXYCET). Oxycodone: FDA Category B (but Category D if prolonged use or near term). First trimester: Increased risk of neural tube defects, congenital heart defects; limited data, but avoid if possible. Second and third trimesters: Prolonged use may cause fetal dependence, withdrawal syndrome; near term, neonatal respiratory depression. Paracetamol: Category B; appears safe in standard doses but overdose causes fetal hepatotoxicity.
First trimester: Limited human data; animal studies show increased fetal resorption and developmental delays at doses similar to human exposure. Second and third trimesters: May cause extrapyramidal symptoms and/or withdrawal symptoms in neonates (e.g., agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, feeding disorder).
Oxycodone is excreted into breast milk; relative infant dose approximately 1.6-3.5% of maternal weight-adjusted dose. M/P ratio not firmly established. Use caution; monitor infant for sedation, respiratory depression, poor feeding. Paracetamol is safe; excreted in low levels. If prolonged maternal oxycodone use, risk of neonatal withdrawal.
Iloperidone is excreted into human milk. M/P ratio: unknown. Use caution; consider benefits of breastfeeding vs. risk of infant exposure. Monitor infant for sedation, poor feeding, extrapyramidal symptoms.
Oxycodone distribution volume increases in pregnancy; clearance may increase, potentially requiring higher doses to achieve analgesic efficacy, but no standard adjustment. Avoid chronic use; use lowest effective dose shortest duration. Paracetamol dose 650-1000 mg every 4-6 hours; max 4000 mg/day; no pregnancy-specific dose adjustment unless hepatic impairment.
No specific dose adjustment guidelines exist for pregnancy. Due to increased plasma volume and renal clearance during pregnancy, consider therapeutic drug monitoring to maintain efficacy. Lower doses may be needed if adverse effects occur; use lowest effective dose.
Oxycet is a combination of oxycodone and acetaminophen. Maximum acetaminophen daily dose is 4 g; in chronic alcohol use or hepatic impairment, limit to 2 g. Use with caution in elderly, respiratory compromise, or history of substance abuse. Constipation prophylaxis (e.g., stool softener) is recommended. Avoid concurrent use with other CNS depressants. Monitor for signs of tolerance, dependence, and misuse.
Iloperidone is an atypical antipsychotic with a low propensity for extrapyramidal symptoms but significant QTc prolongation risk; obtain baseline ECG and monitor electrolytes. Titrate slowly to mitigate orthostatic hypotension due to alpha-1 blockade. Dosing adjustments required in CYP2D6 poor metabolizers (reduce dose by 50%). Avoid concomitant use with QT-prolonging drugs or CYP3A4/2D6 inhibitors/inducers.
Take this medication exactly as prescribed. Do not increase dose or frequency without consulting your doctor.,Do not combine with other products containing acetaminophen (e.g., Tylenol) to avoid exceeding 4000 mg per day.,Avoid alcohol while taking this medication; it increases the risk of liver damage and sedation.,This drug can cause drowsiness or dizziness; do not drive or operate heavy machinery until you know how it affects you.,Constipation is common; increase fluid and fiber intake, and consider using a stool softener as recommended.,Do not stop taking suddenly; your doctor will guide you on tapering to prevent withdrawal symptoms.,Store securely out of reach of others; unused medication should be disposed of properly.
Do not drive or operate machinery until you know how iloperidone affects you, as it may cause dizziness, drowsiness, or blurred vision.,Rise slowly from sitting or lying positions to prevent falls due to low blood pressure.,Report any fast, pounding, or irregular heartbeat, especially with lightheadedness or fainting.,Avoid alcohol and grapefruit juice as they may increase side effects or drug levels.,If you experience muscle stiffness, fever, confusion, or sweating, seek emergency help immediately, as these may be signs of neuroleptic malignant syndrome.
No interactions on record
"Iloperidone, an atypical antipsychotic, prolongs the QT interval by blocking cardiac potassium channels (hERG), while Methsuximide, a succinimide anticonvulsant, may also prolong the QT interval via similar mechanisms. Co-administration can lead to additive QT prolongation, increasing the risk of torsade de pointes and other ventricular arrhythmias. This is particularly dangerous in patients with electrolyte imbalances, bradycardia, or pre-existing cardiac disease."
"The interaction between iloperidone and aprepitant results from iloperidone's moderate inhibition of CYP3A4, the primary enzyme responsible for aprepitant metabolism. This inhibition can lead to increased aprepitant plasma concentrations, potentially enhancing its antiemetic effects and risk of adverse events such as hiccups, constipation, and headache. Clinical significance is greater during the 3-day aprepitant regimen for chemotherapy-induced nausea and vomiting, as elevated levels may prolong its therapeutic and side effect profile."
"Concomitant administration of propoxycaine, an ester-type local anesthetic, and iloperidone, an atypical antipsychotic, may increase the risk of QT interval prolongation and torsade de pointes due to additive effects on cardiac repolarization. Propoxycaine can also elevate catecholamine levels, potentially enhancing iloperidone's effects on blood pressure and heart rate. These interactions could manifest as palpitations, syncope, or life-threatening arrhythmias."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OXYCET vs ILOPERIDONE, answered by our medical review team.
OXYCET is a Opioid Analgesic Combination that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, though it can interact with other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Acetaminophen is believed to produce analgesia through central action, possibly mediated through inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways, though the exact mechanism is not fully understood.. ILOPERIDONE is a Atypical Antipsychotic that works by Iloperidone is an atypical antipsychotic with high affinity for serotonin 5-HT2A and dopamine D2 receptors; also moderate affinity for D3, D4, 5-HT6, 5-HT7, and α1-adrenergic receptors; low affinity for H1, 5-HT1A, and α2-adrenergic receptors; no affinity for M1 muscarinic receptors.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OXYCET and ILOPERIDONE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of OXYCET is: 1 tablet (325 mg acetaminophen and 5 mg oxycodone) orally every 4 to 6 hours as needed for pain; maximum 12 tablets per day.. The standard adult dose of ILOPERIDONE is: 1-2 mg orally twice daily; target dose 6-12 mg/day; maximum 12 mg/day. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between OXYCET and ILOPERIDONE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. OXYCET is classified as Category C. Oxycodone/paracetamol (OXYCET). Oxycodone: FDA Category B (but Category D if prolonged use or near term). First trimester: Increased risk of neural tube defects, congenital heart d. ILOPERIDONE is classified as Category A/B. First trimester: Limited human data; animal studies show increased fetal resorption and developmental delays at doses similar to human exposure. Second and third trimesters: May ca. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.