BAROS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BAROS (BAROS).
BAROS (burosumab) is a recombinant human monoclonal antibody that binds to and inhibits fibroblast growth factor 23 (FGF23). By neutralizing excess FGF23, it increases renal phosphate reabsorption and enhances production of 1,25-dihydroxyvitamin D, thereby correcting hypophosphatemia and improving bone mineralization.
| Metabolism | Metabolized via general protein catabolism; not metabolized by CYP450 enzymes. |
| Excretion | Renal excretion of unchanged drug accounts for 80-90% of elimination; biliary/fecal excretion accounts for 5-10%. |
| Half-life | Terminal elimination half-life is 12-15 hours in healthy adults; may be prolonged in renal impairment (up to 30 hours in severe cases). |
| Protein binding | 85-90% bound to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg, indicating distribution primarily into extracellular fluid. |
| Bioavailability | Oral: 60-80% (first-pass metabolism reduces bioavailability). |
| Onset of Action | Oral: 1-2 hours; Intravenous: 5-10 minutes. |
| Duration of Action | 12-24 hours depending on dose and renal function; clinical effect correlates with trough concentrations. |
None established.
| Dosage form | GRANULE, EFFERVESCENT |
| Renal impairment | No data available. |
| Liver impairment | No data available. |
| Pediatric use | No data available. |
| Geriatric use | No data available. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BAROS (BAROS).
| Breastfeeding | Excreted in breast milk; M/P ratio = 1.2. Avoid breastfeeding due to potential for infant toxicity. If unavoidable, monitor infant for drowsiness and poor feeding. |
| Teratogenic Risk | BAROS is contraindicated in pregnancy due to teratogenicity. First trimester: high risk of cardiac, CNS, and skeletal defects. Second/third trimesters: risk of fetal growth restriction and oligohydramnios. Animal studies show dose-dependent embryotoxicity. Human data limited but indicates significant risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Concomitant use with oral phosphate and active vitamin D analogs (e.g., calcitriol, phosphate supplements) except during initial titration or adjustment when hypophosphatemia is severe","Severe renal impairment or end-stage renal disease (eGFR <30 mL/min/1.73 m²)","Known hypersensitivity to burosumab or any excipients"]
| Precautions | ["Hyperphosphatemia and risk of nephrocalcinosis/nephrolithiasis: monitor serum phosphorus and renal function","Severe hypersensitivity reactions including anaphylaxis","Potential for injection site reactions","Risk of hyperphosphatemia in patients with severe renal impairment","May increase risk of infections; avoid live vaccines during treatment"] |
| Food/Dietary | High-fat meals (>30% of calories from fat) increase the incidence of gastrointestinal adverse effects such as oily spotting, flatus with discharge, and steatorrhea. Dietary fat intake should be distributed over three main meals. The drug is most effective when combined with a reduced-calorie, low-fat diet. Foods rich in fat-soluble vitamins (A, D, E, K) should be consumed with a multivitamin supplement taken at bedtime to prevent deficiency. |
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| Maternal: Liver function tests, renal function, complete blood count every 2 weeks. Fetal: Ultrasound for growth, amniotic fluid index, and anatomy every 4 weeks starting at 20 weeks gestation. |
| Fertility Effects | Reversible impairment of spermatogenesis and ovulation. In males, decreased sperm count and motility; in females, anovulation and menstrual irregularities. Effects resolve within 3-6 months of discontinuation. |
| Clinical Pearls | BAROS is a brand name for orlistat, a reversible inhibitor of gastric and pancreatic lipases. It reduces dietary fat absorption by approximately 30% at the therapeutic dose of 120 mg three times daily. Monitor for fat-soluble vitamin deficiencies (A, D, E, K) and consider supplementation. Advise patients to take a multivitamin containing these vitamins at bedtime, at least 2 hours after the last dose. BAROS can cause oily spotting, flatus with discharge, fecal urgency, and steatorrhea, especially if dietary fat intake exceeds 30% of total calories. Contraindicated in chronic malabsorption syndrome and cholestasis. Use with caution in patients with a history of hyperoxaluria or calcium oxalate kidney stones. |
| Patient Advice | Take BAROS with each main meal containing fat, up to three times daily. · If you miss a meal or eat a fat-free meal, skip the dose. · Follow a reduced-calorie, low-fat diet (less than 30% of calories from fat) to minimize gastrointestinal side effects. · You may experience oily stools, gas with discharge, or an urgent need to have a bowel movement. These effects are common and often improve with time. · Take a daily multivitamin that contains vitamins A, D, E, and K at bedtime, at least 2 hours after your last dose of BAROS. · BAROS may reduce absorption of some medications; separate administration by at least 2 hours. · If you are taking cyclosporine or levothyroxine, take them at least 3 hours apart from BAROS. · Do not use BAROS if you are pregnant, breastfeeding, or have chronic malabsorption syndrome or gallbladder problems. · Contact your healthcare provider if you develop severe abdominal pain, rectal bleeding, or signs of kidney stones (e.g., pain during urination, back pain). |