SYNRIBO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SYNRIBO (SYNRIBO).
Omacetaxine mepesuccinate inhibits protein synthesis by binding to the ribosomal A-site and preventing aminoacyl-tRNA binding, thereby inhibiting peptide elongation. It also induces apoptosis in leukemic cells.
| Metabolism | Omacetaxine is primarily hydrolyzed by plasma esterases; CYP450 metabolism is minimal. The major metabolite is 4'-DMHHT (4'-demethylhomoharringtonine). |
| Excretion | Primarily fecal (80%) and renal (20%) as unchanged drug, with negligible metabolism. |
| Half-life | Terminal half-life approximately 9.3 ± 7.0 hours; clinical context: once-daily subcutaneous dosing maintains steady-state concentrations. |
| Protein binding | 60–70% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Vd approximately 1.4 L/kg, indicating extensive distribution into tissues. |
| Bioavailability | Subcutaneous: approximately 70% (range 50–80%). |
| Onset of Action | Subcutaneous: clinical effect (reduction of blood counts) observed within 4–6 weeks of initiation. |
| Duration of Action | Duration of pharmacodynamic effect (leukemia cell suppression) extends beyond plasma elimination; dosing continues until progression or unacceptable toxicity. |
1.25 mg/m2 subcutaneously twice daily for 14 consecutive days, followed by 7 days rest (21-day cycle).
| Dosage form | POWDER |
| Renal impairment | No formal dose adjustment recommended; use caution in severe renal impairment (CrCl <30 mL/min) due to limited data. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose to 1.0 mg/m2; Child-Pugh C: reduce dose to 0.8 mg/m2. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been studied. |
| Geriatric use | No specific dose adjustment; monitor for increased toxicity due to age-related renal and hepatic function decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SYNRIBO (SYNRIBO).
| Breastfeeding | It is not known whether omacetaxine is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants, advise women not to breastfeed during treatment with SYNRIBO and for at least 1 week after the last dose. |
| Teratogenic Risk | Pregnancy Category D. Based on its mechanism of action (protein synthesis inhibition) and animal studies, SYNRIBO (omacetaxine mepesuccinate) can cause fetal harm. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, omacetaxine mepesuccinate was embryotoxic and teratogenic in rats and rabbits. Avoid use during pregnancy unless the potential benefit justifies the potential risk to the fetus. Use effective contraception during treatment and for at least 3 months after the last dose. |
■ FDA Black Box Warning
SYNRIBO can cause severe myelosuppression, including fatal or life-threatening neutropenia, thrombocytopenia, and anemia. Monitor blood counts frequently and manage with dose delays/reductions.
| Serious Effects |
["Hypersensitivity to omacetaxine mepesuccinate or any excipients"]
| Precautions | ["Myelosuppression (neutropenia, thrombocytopenia, anemia)","Hemorrhage due to thrombocytopenia","Hyperglycemia","Elevated liver enzymes (AST/ALT)","Embryo-fetal toxicity"] |
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| Fetal Monitoring | Monitor complete blood counts (CBCs) regularly during treatment. Monitor for myelosuppression (neutropenia, thrombocytopenia, anemia). For pregnant patients, perform fetal monitoring with ultrasound and assess for growth restriction. Monitor for signs of infection or bleeding. |
| Fertility Effects | Based on animal studies, omacetaxine mepesuccinate may impair fertility in males and females. In rats, decreased fertility and increased pre- and post-implantation loss were observed. |