Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OXYCONTIN vs TACROLIMUS
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, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with oxycodone. Clinically, dosage is titrated to provide adequate analgesia and may be limited by adverse reactions, including respiratory and CNS depression.
Tacrolimus is a calcineurin inhibitor. It binds to FK506-binding protein 12 (FKBP12), forming a complex that inhibits calcineurin phosphatase activity. This prevents dephosphorylation and nuclear translocation of nuclear factor of activated T-cells (NFAT), thereby inhibiting transcription of interleukin-2 (IL-2) and other cytokines, leading to suppressed T-cell activation and proliferation.
Management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate,Off-label: Treatment of opioid dependence (as part of substitution therapy)
Prophylaxis of organ rejection in patients receiving allogeneic liver, kidney, or heart transplants,Treatment of rejection in liver, kidney, and heart transplants,Off-label: Treatment of moderate to severe atopic dermatitis (topical),Off-label: Graft-versus-host disease (GVHD) prophylaxis and treatment
10 mg orally every 12 hours; titrate based on pain severity and prior opioid exposure.
0.1-0.2 mg/kg/day orally in two divided doses (immediate-release); 0.05-0.15 mg/kg/day orally once daily (extended-release); 0.01-0.05 mg/kg/day continuous IV infusion.
4.5-5.0 hours (immediate-release); controlled-release OXYCONTIN has an apparent half-life of 4.5-8.7 hours. Terminal half-life is ~3.5-4 hours for immediate-release, reflecting context-sensitive elimination.
Terminal elimination half-life is approximately 8.7-21.7 hours in healthy volunteers and 18-41 hours in liver transplant recipients. Prolonged half-life in hepatic impairment requires dose adjustments.
Oxycodone is metabolized primarily via CYP3A4 to noroxycodone (major metabolite) and via CYP2D6 to oxymorphone (minor metabolite). Both metabolites are active, with oxymorphone having higher potency. Oxycodone and its metabolites are conjugated and excreted in urine.
Primarily metabolized by cytochrome P450 3A4 (CYP3A4) and to a lesser extent by CYP3A5 in the liver and intestinal wall. It is a substrate of P-glycoprotein (ABCB1).
Primarily renal (90% as metabolites, 10% unchanged). Also biliary/fecal (10%).
Primarily fecal (approximately 93%), with renal excretion accounting for about 2.4% of the unchanged drug. Biliary excretion is a minor route for metabolites.
38-45%, primarily bound to albumin.
Approximately 99% bound, primarily to albumin and alpha-1-acid glycoprotein.
2.6-3.0 L/kg. Extensive tissue distribution, high Vd indicates penetration into peripheral tissues.
Approximately 0.85-1.5 L/kg, reflecting extensive tissue distribution and binding to lymphocytes.
Oral immediate-release: 60-87% (first-pass metabolism). Oral extended-release (Oxy Contin): 60-87% (similar). Intravenous: 100%.
Oral: about 17-25% (variable due to first-pass metabolism and food effects); topical: minimal systemic absorption (less than 5% in healthy skin).
Cr Cl 30-60 m L/min: reduce dose by 25%; Cr Cl <30 m L/min: reduce dose by 50% and administer every 12 hours; hemodialysis: avoid use.
No standard dose adjustment for renal impairment; monitor renal function closely and reduce dose if nephrotoxicity occurs. For GFR < 30 m L/min, consider dose reduction by 50% and close monitoring.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: reduce dose by 75%; monitor trough levels.
Not approved for pediatric patients <18 years; for children ≥11 years (opioid-tolerant): 0.2 mg/kg orally every 12 hours, titrate; maximum single dose 10 mg.
0.15-0.3 mg/kg/day orally in two divided doses (immediate-release); 0.03-0.1 mg/kg/day continuous IV infusion; titrate to target trough levels.
Initiate at 5 mg orally every 12 hours; titrate cautiously; monitor for respiratory depression and constipation.
Start at lower end of dosing range (0.05-0.1 mg/kg/day orally); monitor renal function and trough levels closely due to age-related decline in renal function.
WARNING: ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; and RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS
Increased susceptibility to infection and the possible development of lymphoma. Only physicians experienced in immunosuppressive therapy and management of transplant patients should prescribe tacrolimus. Patients receiving tacrolimus should be managed in facilities equipped and staffed with adequate laboratory and supportive medical resources.
Addiction, abuse, and misuse: Oxy Contin exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient's risk prior to prescribing, and monitor all patients regularly for the development of these behaviors or conditions.,Life-threatening respiratory depression: Serious, life-threatening, or fatal respiratory depression may occur. Monitor for respiratory depression, especially during initiation of therapy or following a dose increase. Instruct patients to swallow tablets whole; crushing, chewing, or dissolving can cause rapid release and absorption of a potentially fatal dose.,Accidental ingestion: Accidental ingestion of even one dose of Oxy Contin, especially by children, can result in a fatal overdose of oxycodone.,Neonatal opioid withdrawal syndrome: Prolonged use of Oxy Contin during pregnancy can result in withdrawal in the neonate. Neonatal opioid withdrawal syndrome, unlike opioid withdrawal in adults, 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 CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate.
Increased risk of lymphomas and other malignancies, particularly skin cancer,Increased susceptibility to infections, including opportunistic infections and reactivation of latent viruses (e.g., BK virus, CMV, EBV),Nephrotoxicity: acute and chronic renal impairment, monitor renal function closely,Neurotoxicity: tremors, headache, seizures, posterior reversible encephalopathy syndrome (PRES),Hyperkalemia: monitor serum potassium levels,Hypertension: monitor blood pressure and manage accordingly,Post-transplant diabetes mellitus: monitor blood glucose levels,Anaphylactic reactions: risk with intravenous formulation due to castor oil derivative (polyoxyl 60 hydrogenated castor oil) in some formulations,QT prolongation: caution in patients with risk factors or with drugs that prolong QT interval
Significant respiratory depression,Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment,Known or suspected gastrointestinal obstruction, including paralytic ileus,Hypersensitivity (e.g., anaphylaxis) to oxycodone or any other components of the product
Hypersensitivity to tacrolimus or any component of the formulation,Hypersensitivity to hydrogenated castor oil (present in some intravenous formulations)
Avoid alcohol, which can increase oxycodone absorption and central nervous system depression. Grapefruit juice may alter oxycodone metabolism; limit or avoid consumption. No specific food restrictions, but high-fat meals may slow absorption slightly; take with or without food consistently.
Grapefruit and grapefruit juice increase tacrolimus levels by inhibiting CYP3A4 and must be avoided. High-fat meals decrease absorption; consistent timing relative to meals recommended.
FDA Pregnancy Category C prior to 2020; no adequate studies in pregnant women. First trimester: Limited data suggest possible increased risk of neural tube defects (1.8-fold) and oral clefts (1.5-fold) with opioid use, but confounded by underlying conditions. Second and third trimesters: Chronic use may cause fetal opioid dependence and neonatal abstinence syndrome (NAS); maternal withdrawal may precipitate preterm labor. Avoid prolonged use near term due to risk of neonatal respiratory depression.
First trimester: Increased risk of congenital malformations including cardiac anomalies. Second and third trimesters: Risk of fetal growth restriction, preterm delivery, and neonatal hyperkalemia. Tacrolimus crosses the placenta.
Oxycodone is excreted into breast milk; relative infant dose is approximately 2.7–8.8% of maternal weight-adjusted dose. M/P ratio unknown. Monitor infant for sedation, respiratory depression, and poor feeding. American Academy of Pediatrics considers oxycodone compatible with breastfeeding with caution; avoid rapid accumulation in mothers with impaired metabolism (CYP2D6 poor metabolizers).
Tacrolimus is excreted into breast milk. M/P ratio (concentration in milk:plasma) is approximately 0.3-0.9. It is recommended to use with caution; monitor infant for immunosuppression and tacrolimus trough levels.
Pregnancy increases oxycodone clearance by 1.3- to 2.5-fold due to enhanced hepatic metabolism (CYP3A4 and CYP2D6 induction) and increased renal blood flow. Dose adjustments may be necessary to maintain analgesia; clinical monitoring for pain control and withdrawal symptoms is essential. Titrate to effect; avoid abrupt discontinuation. Postpartum clearance returns to baseline over 1-2 weeks.
Increased dose requirements due to increased volume of distribution and clearance. Monitoring tacrolimus trough levels recommended every 1-2 weeks; dose adjustments to maintain therapeutic range (typically 5-15 ng/m L).
Oxy Contin is an extended-release formulation of oxycodone, indicated for around-the-clock pain management. Do not crush, chew, or break tablets, as this can lead to rapid release and fatal overdose. Use with caution in patients with respiratory compromise, head injury, or increased intracranial pressure. Monitor for signs of misuse, abuse, or addiction. Abrupt discontinuation may precipitate withdrawal; taper dose gradually. Constipation is common; consider prophylactic laxatives. Contraindicated in severe asthma, paralytic ileus, or hypersensitivity.
Monitor trough levels 2-3 days after dose changes; target 5-15 ng/m L for most indications. Use with caution in renal impairment due to nephrotoxicity. Strong CYP3A4 interaction potential; avoid grapefruit and adjust azole antifungals. Hypomagnesemia common; supplement as needed.
Take Oxy Contin exactly as prescribed, usually every 12 hours. Do not take more or less than directed.,Swallow the tablet whole with water. Do not crush, chew, or break the tablet, as this can cause a dangerous overdose.,Avoid alcohol and other central nervous system depressants (e.g., benzodiazepines, sedatives) as they increase the risk of severe sedation, respiratory depression, and death.,Do not stop taking Oxy Contin suddenly; ask your doctor how to safely discontinue the medication to avoid withdrawal symptoms.,Common side effects include constipation, nausea, drowsiness, and dizziness. Contact your doctor if you experience severe constipation, difficulty breathing, or signs of allergic reaction.,Store Oxy Contin in a secure place out of sight and reach of children and pets. Dispose of unused medication via a drug take-back program.,Do not drive or operate heavy machinery until you know how Oxy Contin affects you.,Inform all healthcare providers that you are taking Oxy Contin, especially before surgery or emergency treatment.
Take consistently with or without food, but do not switch between.,Avoid grapefruit and grapefruit juice.,Report signs of infection, tremors, or kidney issues (swelling, decreased urine).,Do not take any new medications without consulting your doctor.,Use sun protection due to increased skin cancer risk.,Do not miss doses; if you do, take as soon as remembered unless near next dose.
No interactions on record
"Tacrolimus, a potent CYP3A4 inhibitor, significantly decreases the metabolism of citalopram, a CYP3A4 substrate, leading to elevated citalopram plasma concentrations. This pharmacokinetic interaction increases the risk of dose-dependent adverse effects such as QT prolongation, serotonin syndrome, and central nervous system toxicity. Clinical outcomes may include corrected QT (QTc) interval prolongation, increasing the risk of torsade de pointes, and enhanced serotonergic effects requiring careful monitoring."
"Tacrolimus, a calcineurin inhibitor, primarily induces nephrotoxicity through afferent arteriolar vasoconstriction and direct tubular injury. Etofenamate, a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, reduces prostaglandin synthesis, leading to decreased renal blood flow and glomerular filtration rate. Concomitant use synergistically impairs renal function, increasing the risk of acute kidney injury, hyperkalemia, and hypertension, particularly in patients with preexisting renal impairment or volume depletion."
"Tacrolimus, a calcineurin inhibitor and CYP3A4 substrate, may inhibit the metabolism of isoflurophate, a long-acting cholinesterase inhibitor used in glaucoma. This interaction can lead to increased systemic exposure of isoflurophate, potentially exacerbating cholinergic side effects such as bradycardia, hypersalivation, and bronchospasm. Clinically, patients may experience enhanced toxicity, including prolonged muscle weakness or respiratory depression, especially in those with compromised hepatic function."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OXYCONTIN vs TACROLIMUS, answered by our medical review team.
OXYCONTIN is a Opioid Analgesic that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with oxycodone. Clinically, dosage is titrated to provide adequate analgesia and may be limited by adverse reactions, including respiratory and CNS depression.. TACROLIMUS is a Calcineurin Inhibitor that works by Tacrolimus is a calcineurin inhibitor. It binds to FK506-binding protein 12 (FKBP12), forming a complex that inhibits calcineurin phosphatase activity. This prevents dephosphorylation and nuclear translocation of nuclear factor of activated T-cells (NFAT), thereby inhibiting transcription of interleukin-2 (IL-2) and other cytokines, leading to suppressed T-cell activation and proliferation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OXYCONTIN and TACROLIMUS 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 OXYCONTIN is: 10 mg orally every 12 hours; titrate based on pain severity and prior opioid exposure.. The standard adult dose of TACROLIMUS is: 0.1-0.2 mg/kg/day orally in two divided doses (immediate-release); 0.05-0.15 mg/kg/day orally once daily (extended-release); 0.01-0.05 mg/kg/day continuous IV infusion.. 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 OXYCONTIN and TACROLIMUS 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. OXYCONTIN is classified as Category C. FDA Pregnancy Category C prior to 2020; no adequate studies in pregnant women. First trimester: Limited data suggest possible increased risk of neural tube defects (1.8-fold) and o. TACROLIMUS is classified as Category D/X. First trimester: Increased risk of congenital malformations including cardiac anomalies. Second and third trimesters: Risk of fetal growth restriction, preterm delivery, and neonat. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.