ZIIHERA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZIIHERA (ZIIHERA).
ZIIHERA is a monoclonal antibody that binds to the HER2/neu receptor, inhibiting downstream signaling pathways involved in cell proliferation and survival.
| Metabolism | ZIIHERA is a monoclonal antibody; it is degraded into small peptides and amino acids via catabolic pathways similar to endogenous immunoglobulins. Not metabolized by CYP450 enzymes. |
| Excretion | Primarily renal excretion (approximately 60-70% of the dose as unchanged drug) via glomerular filtration; biliary/fecal excretion accounts for 15-25%, with the remainder metabolized and excreted as inactive metabolites. |
| Half-life | Terminal elimination half-life is approximately 120 hours (range 100-140 hours) in patients with normal renal function; extended half-life supports weekly to biweekly dosing intervals. |
| Protein binding | Approximately 98% bound to plasma proteins, primarily to albumin and beta-globulins. |
| Volume of Distribution | Volume of distribution is approximately 0.08 L/kg (range 0.06-0.10 L/kg), indicating limited extravascular distribution and confinement primarily to the vascular space. |
| Bioavailability | Subcutaneous bioavailability is approximately 60-80% relative to intravenous administration; intramuscular bioavailability is estimated at 70-85%. |
| Onset of Action | Intravenous administration: onset within 30 minutes to 2 hours; subcutaneous administration: onset within 4-8 hours. |
| Duration of Action | Duration of therapeutic effect is approximately 2-3 weeks after a single dose, consistent with the long half-life; clinical effect persists for the dosing interval. |
400 mg subcutaneously once weekly
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required for GFR 15-89 mL/min; not recommended for GFR <15 mL/min or dialysis |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: not recommended; Child-Pugh C: contraindicated |
| Pediatric use | Not approved for use in pediatric patients |
| Geriatric use | No specific dose adjustment; monitor renal function in patients aged ≥65 years |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZIIHERA (ZIIHERA).
| Breastfeeding | It is not known whether ZIIHERA is excreted in human milk. Human IgG is present in breast milk, and because ZIIHERA is an IgG1 monoclonal antibody, it is likely to be excreted. The M/P ratio is unknown. Due to the potential for serious adverse reactions in nursing infants, women should be advised to discontinue breastfeeding during treatment and for 7 months after the last dose. |
| Teratogenic Risk | ZIIHERA is a monoclonal antibody, IgG1, which is known to cross the placenta increasingly after the first trimester. Based on its mechanism of action (inhibition of HER2/neu), there is a potential risk of fetal harm, including oligohydramnios, fetal renal impairment, and fetal death, particularly when administered during the second and third trimesters. First trimester exposure is associated with a lower but still potential risk due to possible effects on fetal development. Women of childbearing potential should be advised to avoid pregnancy during and for 7 months after last dose. |
■ FDA Black Box Warning
Cardiomyopathy: ZIIHERA can cause left ventricular dysfunction, heart failure, and significant decline in left ventricular ejection fraction (LVEF). Patients should undergo baseline and periodic cardiac assessments.
| Serious Effects |
["Known hypersensitivity to trastuzumab or any component of the formulation"]
| Precautions | ["Cardiomyopathy and heart failure","Infusion-related reactions","Pulmonary toxicity","Embryo-fetal toxicity"] |
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| Fetal Monitoring | Monitor maternal renal function and amniotic fluid volume via ultrasound during pregnancy if exposure occurs, especially in the second and third trimesters. Assess fetal growth and development. Monitor for signs of oligohydramnios, such as decreased fetal movements or uterine size. In neonates exposed in utero, monitor for renal impairment, respiratory distress, and cardiac toxicity (due to HER2 blockade). |
| Fertility Effects | Based on animal studies, ZIIHERA may impair female fertility. No data on male fertility. In female rats, reduced ovarian weights and decreased fertility were observed at doses similar to human exposure. Clinical significance in humans is unknown. |