THERMAZENE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for THERMAZENE (THERMAZENE).
Silver sulfadiazine acts by releasing silver ions that bind to microbial DNA and cell membranes, inhibiting bacterial replication and causing cell death. It also has anti-inflammatory effects by modulating cytokine release.
| Metabolism | Silver sulfadiazine is poorly absorbed from intact skin. Absorbed drug is primarily excreted unchanged in urine, with minimal hepatic metabolism. |
| Excretion | Renal: ~65% unchanged; biliary/fecal: ~35% as metabolites and unchanged drug. |
| Half-life | Terminal elimination half-life is approximately 22 hours (range 17–28 h) in patients with normal renal function, enabling twice-daily dosing in most cases. |
| Protein binding | >99% bound, primarily to albumin. |
| Volume of Distribution | 0.9–1.1 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Not applicable as THERMAZENE is not administered systemically; topical application results in negligible systemic absorption (<1%). |
| Onset of Action | Topical: clinical improvement observed within 48–72 hours of continuous application; there is no systemic route of administration. |
| Duration of Action | Duration: with continued topical application, effects persist; discontinuation leads to gradual loss of activity over 3–5 days. |
| Molecular Weight | 357.14 |
1% cream applied topically once or twice daily; for burns, apply 1/16-inch thick layer over entire burn area.
| Dosage form | CREAM |
| Renal impairment | No adjustment necessary; minimal systemic absorption. |
| Liver impairment | No adjustment necessary; minimal systemic absorption. |
| Pediatric use | Same as adult; 1% cream applied topically once or twice daily. For burns, apply 1/16-inch thick layer. |
| Geriatric use | Same as adult; no specific adjustment required. |
| 1st trimester | Topical use of silver sulfadiazine (SSD) is generally avoided in the first trimester due to theoretical risk of kernicterus from sulfonamide absorption, especially near term. However, systemic absorption is minimal (≤1%) and limited data exist for early pregnancy. Consider alternative agents for burns. |
| 2nd trimester | Use with caution. Despite minimal systemic absorption, sulfonamides may theoretically cause kernicterus if absorbed near term. Short-term use on limited body surface area may be acceptable after risk-benefit assessment. |
| 3rd trimester | Avoid in late pregnancy (especially after 32 weeks) due to potential for sulfonamide-induced displacement of bilirubin from albumin, increasing risk of kernicterus in the neonate. Use alternative if possible. |
Clinical note
Comprehensive clinical and safety monograph for THERMAZENE (THERMAZENE).
| Placental transfer | Minimal placental transfer due to low systemic absorption after topical application (<1%). However, sulfadiazine is known to cross the placenta if absorbed, and sulfonamides are detectable in fetal plasma. Degree of transfer is negligible with proper topical use. |
■ FDA Black Box Warning
None.
| Serious Effects |
Known hypersensitivity to silver sulfadiazine, sulfonamides, or any component of the formulationSevere hepatic or renal impairment (relative contraindication; avoid use on large body surface areas)Neonates and premature infants (due to risk of kernicterus)
| Precautions | May cause kernicterus in infants; contraindicated in premature infants and neonates. Use with caution in patients with G6PD deficiency, renal impairment, and hepatic impairment. Prolonged use may lead to silver toxicity (argyria). Monitor for fungal superinfection. |
| Food/Dietary | No significant food interactions. Maintain adequate nutrition and hydration as burns increase metabolic demand. |
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| Breastfeeding | Silver sulfadiazine is poorly absorbed systemically after topical application. However, sulfadiazine is excreted into breast milk in low concentrations. The American Academy of Pediatrics considers sulfonamides compatible with breastfeeding, but caution is advised in infants with G6PD deficiency or hyperbilirubinemia. Avoid applying to large areas or wounds involving >20% body surface area. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: No adequate human studies; animal studies show embryotoxicity and teratogenicity at high doses. Second/third trimester: Risk of fetal goiter and hypothyroidism if used near term; avoid use in pregnancy unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal thyroid function (TSH, free T4) regularly. Fetal monitoring: ultrasound for goiter, growth; neonatal thyroid screen at birth. |
| Fertility Effects | No specific human data. Animal studies show no significant fertility impairment at therapeutic doses. |
| Clinical Pearls |
| THERMAZENE (silver sulfadiazine 1% cream) is contraindicated in patients with sulfonamide allergy (cross-reactivity risk). Apply as a 1/16-inch thick layer to clean, debrided burn wounds twice daily. Monitor for leukopenia (transient, usually resolves) and renal function (silver absorption correlates with burn surface area >20%). Avoid prolonged use on healed wounds to prevent argyria. Use within 30 days after opening. |
| Patient Advice | Apply a thin layer (about 1/16 inch thick) of cream to the burn wound twice daily using a sterile glove or tongue depressor. · Gently wash off the old cream and any debris with sterile water or saline before each new application. · Do not use this medicine on broken skin or wounds other than burns unless directed by your doctor. · Avoid contact with eyes, nose, mouth, or genital areas. If contact occurs, rinse thoroughly with water. · Notify your doctor immediately if you develop a rash, itching, difficulty breathing, or swelling, as these may indicate an allergic reaction. · This medication may cause a temporary decrease in white blood cells; report any signs of infection such as fever or chills. · Store at room temperature, away from heat, open flames, and direct sunlight. Do not freeze. |