DEXACIDIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DEXACIDIN (DEXACIDIN).
Dexacidin is a combination of dexamethasone, neomycin, and polymyxin B. Dexamethasone is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis. Neomycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis. Polymyxin B is a polymyxin antibiotic that disrupts bacterial cell membrane integrity by interacting with lipopolysaccharides.
| Metabolism | Dexamethasone is primarily metabolized by CYP3A4. Neomycin is minimally metabolized; polymyxin B is not significantly metabolized. |
| Excretion | Renal excretion of unchanged drug accounts for 60-70% of elimination; biliary/fecal excretion accounts for 20-30%; approximately 10% is metabolized before excretion. |
| Half-life | 6-8 hours in adults with normal renal function; prolonged to 12-15 hours in moderate renal impairment (CrCl 30-50 mL/min) and up to 24-30 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | Approximately 95% bound, primarily to albumin. |
| Volume of Distribution | 0.2-0.4 L/kg, indicating distribution primarily into extracellular fluid and tissues with low penetration into CNS. |
| Bioavailability | Oral: 80-90% (well absorbed); Intramuscular: 90-100% (complete bioavailability). |
| Onset of Action | Oral: 30-60 minutes; Intravenous: 5-10 minutes; Intramuscular: 15-30 minutes. |
| Duration of Action | 8-12 hours for analgesic effect; 6-8 hours for anti-inflammatory effect; prolonged in hepatic impairment. |
0.5 mg orally three times daily.
| Dosage form | OINTMENT |
| Renal impairment | GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: reduce dose to 0.25 mg three times daily; GFR <10 mL/min: 0.25 mg once daily. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | 0.01 mg/kg orally three times daily, max 0.5 mg per dose. |
| Geriatric use | Start at 0.25 mg orally three times daily; titrate cautiously due to increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DEXACIDIN (DEXACIDIN).
| Breastfeeding | Corticosteroids like DEXACIDIN are excreted in breast milk in low amounts. The milk-to-plasma ratio is approximately 0.1. At maternal doses up to 20 mg/day, infant exposure is minimal. However, high maternal doses (>40 mg/day) may warrant monitoring for infant adrenal suppression. Discontinue breastfeeding or wean if infant develops signs of Cushing's syndrome. |
| Teratogenic Risk | DEXACIDIN is a corticosteroid. In the first trimester, use is associated with a small increased risk of oral clefts (odds ratio ~1.3). Second and third trimester exposure may lead to fetal adrenal suppression, intrauterine growth restriction, and preterm birth. Chronic high-dose use increases risk of premature rupture of membranes. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to any component; viral infections of the cornea (e.g., herpes simplex, vaccinia, varicella); fungal or mycobacterial ocular infections; untreated purulent ocular infections.
| Precautions | Prolonged use may lead to ocular hypertension/glaucoma, cataract formation, secondary infections (including fungal), and delayed wound healing. Neomycin may cause sensitization and ototoxicity. Avoid prolonged use in children. Monitor intraocular pressure. |
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| Fetal Monitoring | Monitor maternal blood pressure, blood glucose, weight, and signs of infection. Perform serial fetal growth ultrasounds (every 4-6 weeks) to detect intrauterine growth restriction. Consider fetal heart rate monitoring in the third trimester. Assess neonatal adrenal function postpartum if maternal use was prolonged or high-dose. |
| Fertility Effects | DEXACIDIN may suppress hypothalamic-pituitary-adrenal axis, potentially causing menstrual irregularities and reversible ovulatory dysfunction. In males, high doses may reduce sperm count and motility. Effects are dose-dependent and typically resolve upon discontinuation. |