NULIBRY
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NULIBRY (NULIBRY).
Fosdenopterin is a synthetic cyclic pyranopterin monophosphate (cPMP) analog that replaces deficient cPMP in patients with molybdenum cofactor deficiency (MoCD) type A, restoring molybdenum cofactor biosynthesis and downstream enzyme activities (sulfite oxidase, xanthine dehydrogenase, aldehyde oxidase).
| Metabolism | Not extensively metabolized; primarily eliminated unchanged in urine via active renal secretion. |
| Excretion | Primarily renal excretion via urine; 85% as unchanged drug and 15% as inactive metabolites. Fecal excretion accounts for <1%. |
| Half-life | Terminal elimination half-life is 2.5–3.5 hours; clinical context: requires twice-daily dosing due to short half-life. |
| Protein binding | 98.5–99.1% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.15–0.25 L/kg; clinical meaning: low Vd indicates minimal tissue distribution, largely confined to vascular space. |
| Bioavailability | Subcutaneous: 89% absolute bioavailability; oral: not clinically applicable. |
| Onset of Action | Subcutaneous: 4–6 hours after first dose; oral not applicable. |
| Duration of Action | Approximately 10–14 hours; clinical notes: duration supports twice-daily dosing regimen. |
0.6 mg/kg intravenously every 2 weeks for at least 48 weeks.
| Dosage form | POWDER |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (eGFR <30 mL/min/1.73m2). |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | Weight-based dosing: 0.6 mg/kg intravenously every 2 weeks for at least 48 weeks. Recommended for patients weighing ≥5 kg and aged ≥1 year. |
| Geriatric use | No specific dose adjustment. Clinical studies included patients up to 55 years of age; use with caution due to limited data in elderly patients aged ≥65 years. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NULIBRY (NULIBRY).
| Breastfeeding | No data on presence in human milk, effects on breastfed infant, or milk production. Given molecular weight (approximately 400 Da), excretion into milk is possible. Caution advised; consider developmental benefits of breastfeeding against mother's need for treatment and potential infant risks. |
| Teratogenic Risk | NULIBRY (fosdenopterin) is a cyclic pyranopterin monophosphate replacement therapy for molybdenum cofactor deficiency type A. No human pregnancy data available. In animal studies, no evidence of teratogenicity in rats or rabbits at exposures up to 18 and 2.3 times the human exposure at the recommended dose, respectively. Fetal toxicity (reduced fetal weight, delayed ossification) occurred at maternally toxic doses. Risk cannot be excluded; use only if potential benefit justifies potential risk. |
■ FDA Black Box Warning
None
| Serious Effects |
["None known"]
| Precautions | ["Hypersensitivity reactions (including anaphylaxis) have occurred; monitor for infusion reactions.","Phototoxicity possible due to absorption of UV light; advise avoiding sun exposure and using sun protection.","Bone marrow suppression reported during clinical trials; monitor complete blood counts.","Pregnancy: Limited data; use only if benefit outweighs risk.","Lactation: Unknown if excreted in human milk."] |
Loading safety data…
| Fetal Monitoring | Monitor for hypersensitivity reactions (including anaphylaxis) with emergency equipment available. Monitor liver function tests (ALT, AST, total bilirubin) prior to initiation and periodically during therapy. Monitor for injection site reactions and photosensitivity. For women of reproductive potential, confirm pregnancy status prior to initiation and advise effective contraception during treatment. |
| Fertility Effects | No human data on fertility. In animal studies, no adverse effects on male or female fertility in rats at exposures up to 18 times the human exposure. However, effects on fertility cannot be excluded. |