Fostamatinib
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Dosing in kidney impairment
This label has no separate kidney-impairment dosing section. Check warnings and clinical pharmacology in the full label.
Drug interactions
Check fostamatinib against a medication listLabel text (4 paragraphs)
Strong CYP3A4 Inhibitors: Concomitant use with a strong CYP3A4 inhibitor increases exposure to R406 (the major active metabolite).( 7 ) Strong CYP3A4 Inducers: Concomitant use is not recommended. ( 7 )
7.1 Effect of Other Drugs on TAVALISSE Strong CYP3A4 Inhibitors Concomitant use with strong CYP3A4 inhibitors increases exposure to R406 (the major active metabolite), which may increase the risk of adverse reactions. Monitor for toxicities of TAVALISSE that may require dose reduction (see Table 1 ) when given concurrently with a strong CYP3A4 inhibitor [see Dosage and Administration (2.4) and Clinical Pharmacology (12.3) ] . Strong CYP3A4 Inducers Concomitant use with a strong CYP3A4 inducer reduces exposure to R406. Concomitant use of TAVALISSE with strong CYP3A4 inducers is not recommended [see Clinical Pharmacology (12.3) ] .
7.2 Effect of TAVALISSE on Other Drugs CYP3A4 Substrates Concomitant use of TAVALISSE may increase concentrations of some CYP3A4 substrate drugs. Monitor for toxicities of CYP3A4 substrate drug that may require dosage reduction when given concurrently with TAVALISSE [see Clinical Pharmacology (12.3) ] . BCRP Substrates Concomitant use of TAVALISSE may increase concentrations of BCRP substrate drugs (e.g., rosuvastatin). Monitor for toxicities of BCRP substrate drug that may require dosage reduction when given concurrently with TAVALISSE [see Clinical Pharmacology (12.3) ] .
P-Glycoprotein (P-gp) Substrates Concomitant use of TAVALISSE may increase concentrations of P-gp substrates (e.g., digoxin). Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with TAVALISSE [see Clinical Pharmacology (12.3) ] .
Contraindications
None. None. ( 4 )
Safety data
Reported adverse events (FAERS)
Liver injury (LiverTox)
E*Likelihood score E*: Suspected but unproven cause of idiosyncratic clinically apparent liver injury.
Fostamatinib is an orally available small molecule inhibitor of spleen tyrosine kinase that is used to treat chronic immune thrombocytopenia. Fostamatinib is associated with transient and usually mild elevations in serum aminotransferase levels during therapy but has yet to be linked to instances of clinically apparent acute liver injury.
ABCDEA: well known cause; E: unlikely cause. [HD]: high doses only.
Pregnancy and lactation
Pregnancy
8.1 Pregnancy Risk Summary Based on findings from animal studies and the mechanism of action, TAVALISSE can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1) ]. There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of fostamatinib to pregnant rats and rabbits during organogenesis caused adverse developmental outcomes that were directly attributed to exposure in utero to the major fostamatinib metabolite (R406) at maternal exposures (AUC) as low as 0.3 and 10 times the exposure in patients at the maximum recommended human dose (MRHD), respectively (see Data ).
Advise pregnant women of the potential risk to a fetus. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. An estimated background risk of major birth defects and miscarriage for the chronic ITP population is 8% and 4-11%, respectively.
Data Animal Data In a fertility and early embryonic development study in female rats, fostamatinib was administered orally for 15 days before mating to Day 7 of pregnancy, which caused a slight decrease in pregnancy rates and an increase in post-implantation loss were seen at maternal doses approximately 4.2 times the dose in patients at the MRHD. In embryo-fetal development studies, pregnant animals were orally administered fostamatinib during the period of organogenesis at doses up to 25 and 50 mg/kg/day in rats and rabbits, respectively.
The adverse developmental outcomes included an increase in embryo-fetal mortality (post-implantation loss), alterations to growth (lower fetal weights), and structural abnormalities (variations and malformations). These effects occurred at maternal exposures (AUCs) of 3,763 ng.h/mL in rats and 111,105 ng.h/mL in rabbits that were approximately 0.3 and 10 times the human exposure at the MRHD in rats and rabbits, respectively. In a peri and postnatal development study in rats, fostamatinib was orally administered at doses of 2.5, 12.5, and 25 mg/kg/day from gestation day 7 until lactation day 20.
The dose of 25 mg/kg/day was associated with maternal toxicity, including decreased body weights, body weight gains, and food consumption. At doses as low as 12.5 mg/kg/day fostamatinib caused increases in newborn mortality (neonatal mortality), alterations in growth and/or development (lower neonatal weights into…
Breastfeeding (LactMed)
No information is available on the clinical use of fostamatinib during breastfeeding. Because the active metabolite of fostamatinib (R406) is 98.3% bound to plasma proteins, the amount in milk is likely to be low. However, the active metabolites has a half-life of 15 hours, and might accumulate in the infant. The manufacturer recommends that breastfeeding be discontinued during fostamatinib therapy and for at least 1 month after the final dose.
Supply and cost
Drug shortage status
Recalls (last 24 months)
Therapeutic equivalence (Orange Book)
Price ladder
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