Comparative Pharmacology
Head-to-head clinical analysis: CYANOKIT versus FUSILEV.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYANOKIT versus FUSILEV.
CYANOKIT vs FUSILEV
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Hydroxocobalamin, a form of vitamin B12, acts as a scavenger of cyanide ions by binding with them to form cyanocobalamin, which is then excreted in urine. It has a higher affinity for cyanide than cytochrome c oxidase, thereby restoring mitochondrial function.
FUSILEV (levoleucovorin) is the pharmacologically active isomer of folinic acid. It bypasses dihydrofolate reductase inhibition by dihydrofolate reductase inhibitors (e.g., methotrexate), providing reduced folate that is used in DNA synthesis and repair. It also enhances the efficacy of fluorouracil by stabilizing the ternary complex of thymidylate synthase, thereby inhibiting DNA synthesis.
5 g intravenous infusion over 15 minutes for adults and pediatric patients weighing >=40 kg. A second dose of 5 g may be administered if needed based on clinical response.
Leucovorin (Fusilev) 200 mg/m2 IV over 2 hours, followed by 5-fluorouracil bolus and infusion, repeated every 2 weeks in combination regimens for advanced colorectal cancer.
None Documented
None Documented
The terminal elimination half-life of hydroxocobalamin is approximately 24-28 hours in healthy adults; in cyanide poisoning, the half-life may be prolonged due to reversible binding to cyanide.
The terminal elimination half-life of the active metabolite, 5-methyltetrahydrofolate (5-MTHF), is approximately 6-8 hours in healthy adults; clinically, this supports twice-daily or daily dosing schedules.
Primarily renal elimination as hydroxocobalamin and cyanocobalamin; >90% of an intravenous dose is excreted in urine within 72 hours, with the remainder eliminated in feces via biliary excretion.
Primarily hepatic metabolism; renal excretion of metabolites accounts for approximately 40-60% of the dose; fecal excretion is negligible.
Category C
Category C
Antidote
Antidote