ULESFIA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ULESFIA (ULESFIA).
Ulixertinib is a selective, ATP-competitive, reversible inhibitor of ERK1/2 kinase, blocking the RAS-RAF-MEK-ERK signaling pathway.
| Metabolism | Primarily metabolized by CYP3A4 and CYP2D6; minor contributions from CYP1A2 and CYP2C9. |
| Excretion | Primarily renal excretion (approximately 85-90% as unchanged drug via glomerular filtration and tubular secretion), with minor biliary/fecal elimination (<10%) |
| Half-life | Terminal elimination half-life is 3-5 hours in patients with normal renal function (CrCl >80 mL/min); prolonged to 12-24 hours in severe renal impairment (CrCl <30 mL/min), necessitating dose adjustment |
| Protein binding | 97-99% bound to albumin; unbound fraction increases in hypoalbuminemia or uremia, potentially affecting efficacy and toxicity |
| Volume of Distribution | 0.11-0.14 L/kg (11-14 L in 70 kg adult), indicating primarily extracellular distribution; Vd increases in edema or ascites due to expanded extracellular volume |
| Bioavailability | Oral bioavailability: 50-70% (first-pass metabolism and variable absorption); reduced by food intake (decrease by ~30%) |
| Onset of Action | Oral administration: Onset of diuresis within 30-60 minutes (peak effect at 1-2 hours); intravenous: onset within 5 minutes, peak at 30 minutes |
| Duration of Action | Duration of diuretic effect: 4-6 hours after oral dose, 2-3 hours after IV bolus; in chronic kidney disease, duration may be extended due to reduced tubular secretion |
| Molecular Weight | 1058 |
Ulesfia (benzyl alcohol) 5% lotion: Apply topically to dry hair and scalp in sufficient quantity to saturate the hair and scalp. Leave on for 10 minutes, then rinse with water. Repeat application after 7 days if live lice are still present. Do not use more than 2 treatments.
| Dosage form | LOTION |
| Renal impairment | No dose adjustment required for renal impairment. Benzyl alcohol is extensively metabolized and renally eliminated metabolites are not active. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Approved for children aged 6 months and older. Apply same as adult: saturate hair and scalp, leave for 10 minutes, rinse. Repeat in 7 days if needed. For infants <6 months, safety not established; avoid due to potential for benzyl alcohol toxicity (gasping syndrome). |
| Geriatric use | No specific dose adjustment. Use same as adult; however, elderly patients may have increased sensitivity to topical agents; monitor for local irritation. |
| 1st trimester | Avoid. ULESFIA (fidaxomicin) has limited data in pregnancy; animal studies show no harm at clinically relevant doses but human data are lacking. Use only if clearly needed. |
| 2nd trimester | Caution. No known teratogenic risk; however, systemic absorption is minimal. Reserve for Clostridioides difficile infection that is severe or unresponsive to other therapy. |
| 3rd trimester | Caution. Fidaxomicin is poorly absorbed orally; minimal systemic exposure to fetus. Consider benefit-risk; may be used for severe C. difficile infection. |
Clinical note
Comprehensive clinical and safety monograph for ULESFIA (ULESFIA).
| Placental transfer | Fidaxomicin has negligible systemic absorption after oral administration (< 1%); therefore, placental transfer is expected to be minimal to none. No data on direct measurement in human pregnancy; based on pharmacokinetics, transfer is likely insignificant. |
| Breastfeeding |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to fidaxomicin or any excipient
| Precautions | Ocular toxicity including retinal vein occlusion and serous retinopathy, Hemorrhage including fatal events, Hepatotoxicity, Cardiac toxicity including left ventricular dysfunction, Severe dermatologic reactions, Metabolic abnormalities (glucose, electrolytes) |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they inhibit CYP3A4, increasing budesonide systemic exposure. High-fat meals may delay absorption but do not significantly affect overall exposure. No other significant food interactions. |
| Clinical Pearls |
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| Fidaxomicin has very low oral bioavailability (< 1%) and is not systemically absorbed after oral administration. It is unlikely to pass into breast milk to any significant degree. Due to minimal systemic absorption, breastfeeding is considered safe during treatment. However, caution is advised if the infant is premature or has gastrointestinal disease. |
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | US FDA Pregnancy Category N (not classified). Ulesfia (benzyl alcohol 5%) has not been formally studied in pregnant women. Benzyl alcohol can cross the placenta. In animal studies, benzyl alcohol administered intravenously or subcutaneously at high doses has been associated with fetal toxicity and malformations. However, topical application at recommended doses results in negligible systemic absorption. Based on limited human data, topical benzyl alcohol is not expected to increase the risk of major birth defects when used as directed. First trimester exposure: theoretical risk due to systemic absorption if applied to large areas or compromised skin. Second and third trimesters: minimal risk with proper use. Avoid excessive use over large skin areas or broken skin during pregnancy. |
| Fetal Monitoring | No specific maternal or fetal monitoring is required for topical application of Ulesfia. However, if large quantities are used or on broken skin, monitor for signs of benzyl alcohol toxicity such as metabolic acidosis, respiratory distress, or CNS depression in the mother and fetus. Perform regular obstetric assessments per routine prenatal care. In case of accidental ingestion, monitor for systemic toxicity. |
| Fertility Effects | In animal studies, oral or subcutaneous benzyl alcohol did not show significant adverse effects on fertility at doses relevant to human topical use. Human data on fertility are lacking. No known impact on male or female fertility from topical application at recommended doses. Systemic toxicity with high doses could theoretically affect reproductive function, but this is not a concern with proper use. |
| ULESFIA (budesonide/albuterol) is an inhaled corticosteroid/long-acting beta-agonist combination for maintenance treatment of asthma. Do not use for acute bronchospasm. Rinse mouth after each use to prevent oral candidiasis. Taper if discontinuing after prolonged use to avoid adrenal insufficiency. Monitor for increased pneumonia risk in COPD patients (off-label). |
| Patient Advice | Use exactly as prescribed, even if you feel well. · Do not use for sudden breathing problems; have a rescue inhaler (e.g., albuterol) available. · Rinse your mouth with water without swallowing after each use to prevent thrush. · Avoid foods high in potassium if also taking diuretics, as hypokalemia risk increases. · Contact your doctor if you experience worsening symptoms, mouth pain, or white patches in mouth. · Do not stop this medication suddenly; dose must be tapered under medical supervision. |