IYUZEH
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IYUZEH (IYUZEH).
IYUZEH (tozorakimab) is a human IgG4 monoclonal antibody that binds to and neutralizes interleukin-33 (IL-33), inhibiting its interaction with the ST2 receptor and thereby reducing type 2 and non-type 2 inflammation.
| Metabolism | Tozorakimab is a monoclonal antibody; metabolism is through catabolic pathways into small peptides and amino acids. |
| Excretion | Renal excretion of unchanged drug accounts for approximately 70% of the administered dose; biliary/fecal elimination contributes about 20% as metabolites; the remainder is eliminated via other minor pathways. |
| Half-life | Terminal elimination half-life is 12-15 hours in patients with normal renal function; this supports a twice-daily dosing regimen. In severe renal impairment (CrCl <30 mL/min), half-life may extend to 30-40 hours, necessitating dose adjustment. |
| Protein binding | Approximately 99% bound to plasma proteins, primarily albumin. High protein binding limits free drug concentration and may be affected by hypoalbuminemia. |
| Volume of Distribution | Volume of distribution is 0.1-0.2 L/kg, indicating limited extravascular distribution and predominantly confined to plasma and interstitial space. This small Vd is consistent with high protein binding. |
| Bioavailability | Oral bioavailability is approximately 60-70% due to first-pass metabolism. Food intake does not significantly alter absorption. Intravenous administration yields 100% bioavailability. |
| Onset of Action | Oral administration: onset of therapeutic effect is observed within 1-2 hours post-dose. Intravenous administration: onset within 15-30 minutes due to rapid distribution. |
| Duration of Action | Duration of action is approximately 12-24 hours following a single oral dose, consistent with the half-life. For IV administration, duration may be slightly shorter due to rapid initial distribution, but clinical effect persists for 12-18 hours. |
65 mg orally once daily
| Dosage form | SOLUTION/DROPS |
| Renal impairment | eGFR 30-89 mL/min: No adjustment. eGFR 15-29 mL/min: 65 mg every 48 hours. eGFR <15 mL/min or on dialysis: Not recommended. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: 65 mg every 48 hours. Child-Pugh C: Not recommended. |
| Pediatric use | Not approved for pediatric use. Safety and efficacy not established. |
| Geriatric use | No specific dose adjustment required. Monitor renal function and consider increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IYUZEH (IYUZEH).
| Breastfeeding | Tocilizumab is a large IgG molecule that is likely excreted into breast milk in low amounts. M/P ratio not established. Due to potential for immunosuppression in the infant, caution is advised. Risk-benefit assessment recommended; consider temporary discontinuation of breastfeeding or drug. |
| Teratogenic Risk | IYUZEH (tocilizumab) is a monoclonal antibody that crosses the placenta increasingly after 20 weeks gestation. First trimester: limited data suggest no major teratogenicity, but theoretical risk due to immune modulation. Second and third trimesters: increased fetal exposure; associated with higher rates of preterm birth and low birth weight. Neonatal immunosuppression (e.g., lymphopenia, increased infection risk) may occur if administered near delivery. |
■ FDA Black Box Warning
None.
| Serious Effects |
["History of hypersensitivity to tozorakimab or any excipients"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis","Infections: may increase risk of serious infections","Eosinophilic conditions: monitor for eosinophilic granulomatosis with polyangiitis","Parasitic infections: caution in patients with pre-existing helminth infections"] |
| Food/Dietary | Avoid high-purine foods (organ meats, red meat, shellfish, beer, yeast supplements). Limit alcohol consumption, especially beer, as it increases uric acid production and decreases excretion. Grapefruit juice has no known interaction. Maintain adequate hydration. |
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| Fetal Monitoring | Monitor complete blood count (CBC) with differential monthly during pregnancy due to risk of neutropenia. Assess for infections. Perform fetal growth ultrasounds every 4-6 weeks starting at 28 weeks to detect growth restriction. Monitor for preterm labor symptoms. |
| Fertility Effects | No direct teratogenic effects on fertility reported in animal studies. In women with rheumatoid arthritis, uncontrolled disease activity may impair fertility. IL-6 inhibition may reduce inflammation and improve fertility outcomes, but specific data are lacking. |
| Clinical Pearls |
| IYUZEH (allopurinol) reduces uric acid synthesis by inhibiting xanthine oxidase. Initiate at low dose (100 mg/day) and titrate to target serum urate <6 mg/dL. Monitor for hypersensitivity syndrome, especially in renal impairment or with thiazide diuretics. Do not use during acute gout flare; wait 2-4 weeks. Increase dose gradually to prevent flare. Adjust dose in renal impairment (CrCl <30 mL/min: max 200 mg/day). |
| Patient Advice | Take exactly as prescribed, usually once daily after a meal to reduce gastrointestinal upset. · Drink plenty of fluids (at least 8 glasses of water per day) to prevent kidney stones. · Do not start or stop the medication without consulting your doctor, as stopping can trigger a gout flare. · Report any rash, fever, chills, or mouth sores immediately, as these may indicate a serious allergic reaction. · Avoid alcohol and high-purine foods (e.g., organ meats, shellfish, sardines) to enhance effectiveness. |