SODIUM SULFACETAMIDE
Clinical safety rating: safe
No significant drug interactions For ophthalmic use only can cause local irritation.
Sulfacetamide is a sulfonamide antibiotic that inhibits bacterial dihydropteroate synthase, thereby blocking the synthesis of folic acid and ultimately nucleic acid synthesis, leading to bacteriostatic activity.
| Metabolism | Sulfacetamide is primarily metabolized via acetylation in the liver, yielding N-acetylsulfacetamide, which is the major inactive metabolite. Minor pathways include glucuronidation. |
| Excretion | Renal: 85-100% unchanged drug via glomerular filtration and tubular secretion. Biliary/fecal: <5%. |
| Half-life | 7-12 hours in normal renal function; prolonged to 20-50 hours in renal impairment. |
| Protein binding | 45-55% primarily to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg, indicating distribution into extracellular fluid. |
| Bioavailability | Topical ophthalmic: minimal systemic absorption (<0.5%). Renal excretion of absorbed fraction. |
| Onset of Action | Topical ophthalmic: within 15-30 minutes. No systemic absorption via intact skin. |
| Duration of Action | Topical ophthalmic: 2-4 hours. Repeated applications required for sustained effect. |
| Molecular Weight | 254.24 |
1-2 drops of 10% or 30% solution into conjunctival sac every 2-3 hours during waking hours for 7-10 days.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | Not applicable for ophthalmic use, systemic absorption is minimal. For systemic use: reduce dose or extend interval if CrCl < 50 mL/min. |
| Liver impairment | No adjustment required for ophthalmic use. For systemic use, no specific guidelines; use with caution in severe hepatic impairment. |
| Pediatric use | Children: same as adult dosing, using 10% solution; avoid 30% solution in infants <2 months due to increased risk of kernicterus. |
| Geriatric use | No specific dose adjustment; monitor for local irritation as elderly may have decreased tear production. |
| 1st trimester | Sulfacetamide is generally avoided during the first trimester unless benefit outweighs risk; animal studies show no evidence of harm, but human data are limited. |
| 2nd trimester | Use with caution; sulfonamides have been associated with kernicterus in neonates when given near term, but topical use minimizes systemic absorption. |
| 3rd trimester | Avoid in late pregnancy (especially near term) due to risk of kernicterus in the newborn; alternative agents preferred. |
Clinical note
No significant drug interactions For ophthalmic use only can cause local irritation.
| FDA category | Animal |
| Placental transfer | Sulfacetamide crosses the placenta; systemic levels after topical administration are low, but placental transfer can occur with potential for fetal accumulation, especially in late pregnancy where it may compete with bilirubin for protein binding sites, increasing kernicterus risk. |
■ FDA Black Box Warning
Sulfonamides have been associated with severe adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Fatalities have occurred although rare.
| Common Effects | Stinging |
| Serious Effects |
Hypersensitivity to sulfacetamide or other sulfonamidesHistory of severe sulfonamide allergy (e.g., Stevens-Johnson syndrome)
| Precautions | Hypersensitivity reactions may occur, including Stevens-Johnson syndrome; discontinue at first sign of rash. Use with caution in patients with impaired renal function. Prolonged use may result in overgrowth of nonsusceptible organisms including fungi. For topical ophthalmic use only; not for injection. Inactivate aminobenzoic acid antagonism. |
| Food/Dietary |
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| Breastfeeding | Sulfacetamide is excreted into breast milk in small amounts after topical application; however, systemic absorption is minimal. Caution is advised in nursing mothers with infants who have glucose-6-phosphate dehydrogenase (G6PD) deficiency or hyperbilirubinemia, as sulfonamides may displace bilirubin and increase the risk of kernicterus. Consider alternative therapy in such cases. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. Sulfacetamide crosses the placenta. First trimester: theoretical risk of kernicterus and teratogenicity, but data limited. Second and third trimesters: avoid near term due to risk of kernicterus in newborn; may cause neonatal hyperbilirubinemia if used near delivery. |
| Fetal Monitoring | Monitor maternal renal and hepatic function, CBC with differential, and bilirubin levels in infant if used near term. Assess for signs of hypersensitivity or kernicterus in neonate. |
| Fertility Effects | No known adverse effects on fertility in animal studies; human data insufficient. |
| No known food interactions. Topical use results in negligible systemic absorption, making dietary restrictions unnecessary. |
| Clinical Pearls | Sulfacetamide is a topical sulfonamide antibiotic, effective against Gram-positive and Gram-negative bacteria. It is commonly used for ophthalmic infections like conjunctivitis, blepharitis, and corneal ulcers. Avoid use in patients with known sulfonamide allergy. Do not use for viral or fungal ocular infections. In dermatology, it is used for acne vulgaris and seborrheic dermatitis; combined with sulfur for added keratolytic effect. Monitor for local irritation or hypersensitivity. Prolonged use may lead to overgrowth of non-susceptible organisms including fungi. |
| Patient Advice | Use exactly as prescribed; do not skip doses or discontinue early. · Wash hands before and after application; avoid touching the applicator tip to prevent contamination. · For eye drops: tilt head back, pull lower lid down, apply drop into the pocket, and close eye for 1-2 minutes. · For ointment: apply a small ribbon inside the lower eyelid and blink to spread. · Mild stinging or burning may occur briefly; if severe or persistent, contact doctor. · Do not wear contact lenses during treatment for eye infections. · For acne/skin use: clean skin before application; avoid contact with eyes, mouth, or broken skin. · Report any signs of allergy: rash, itching, swelling, or difficulty breathing. · Complete full course even if symptoms improve; notify doctor if no improvement after a few days. · Store at room temperature; do not freeze; shake eye drops well before use if suspension. · Inform doctor of all medications, especially other topical products, to avoid interactions. · For ophthalmic use: do not share with others; replace bottle after 4 weeks of opening. |