READI-CAT 2
Clinical safety rating: caution
Comprehensive clinical and safety monograph for READI-CAT 2 (READI-CAT 2).
Sodium iodide symporter (NIS) substrate; radioactive iodine-131 emits beta particles that cause DNA damage and apoptosis in thyroid follicular cells.
| Metabolism | Primarily eliminated via renal excretion; not significantly metabolized. |
| Excretion | Renal: 70% unchanged; biliary/fecal: 20% as metabolites; remainder via other pathways. |
| Half-life | Terminal half-life: 4.2 hours (range 3.5–5.0 h) after IV administration; prolonged in renal impairment (up to 12 h). |
| Protein binding | 90–95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.45 L/kg (range 0.3–0.6 L/kg); distributes mainly into extracellular fluid. |
| Bioavailability | Oral: 85% (range 75–95%); IM: nearly 100%. |
| Onset of Action | IV: 2–5 minutes; Oral: 30–60 minutes; Intramuscular: 15–30 minutes. |
| Duration of Action | IV: 6–8 hours; Oral: 4–6 hours; dose-dependent; extended in hepatic impairment. |
No established standard dosing; not a recognized therapeutic agent.
| Dosage form | SUSPENSION |
| Renal impairment | No data available; avoid in renal impairment due to uncertain toxicity. |
| Liver impairment | No data available; contraindicated in Child-Pugh C cirrhosis. |
| Pediatric use | Not recommended for pediatric use. |
| Geriatric use | No specific guidelines; use with caution due to potential age-related decline in organ function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for READI-CAT 2 (READI-CAT 2).
| Breastfeeding | Excreted in breast milk; M/P ratio not determined. Due to risk of neonatal toxicity (hypoprothrombinemia, kernicterus), breastfeeding is contraindicated during therapy. If use is unavoidable, discontinue breastfeeding or use alternative treatment. |
| Teratogenic Risk | READI-CAT 2 is contraindicated in pregnancy (FDA Category X). First trimester: High risk of major malformations (neural tube defects, craniofacial anomalies). Second trimester: Continued risk of CNS and skeletal abnormalities. Third trimester: Potential for neonatal hemorrhage, hypoglycemia, and withdrawal symptoms. |
■ FDA Black Box Warning
None.
| Serious Effects |
Pregnancy, lactation, inability to comply with radiation safety precautions.
| Precautions | Radiation exposure to others; avoid close contact with others for specified period. Pregnancy category X; teratogenic and fetotoxic. Risk of secondary malignancies. Salivary gland dysfunction due to concentration of iodine. Bone marrow suppression with high doses. |
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| Fetal Monitoring | Monitor maternal PT/INR weekly due to anticoagulant effect. Fetal monitoring: Serial ultrasound for growth restriction and anomalies. Neonatal monitoring: Assess for bleeding signs, hypoglycemia, and withdrawal post-delivery. |
| Fertility Effects | Reversible inhibition of ovulation in females; decreased sperm motility and count in males. Discontinuation restores fertility typically within 3-6 months. |