MAFENIDE ACETATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MAFENIDE ACETATE (MAFENIDE ACETATE).
Mafenide acetate is a sulfonamide antibiotic that inhibits bacterial folic acid synthesis by competitively antagonizing para-aminobenzoic acid (PABA), thereby preventing bacterial growth. It has broad-spectrum activity against gram-negative and gram-positive organisms, including Pseudomonas aeruginosa.
| Metabolism | Mafenide acetate is rapidly metabolized to its active metabolite, p-carboxybenzenesulfonamide, via hydrolysis. The metabolite is excreted renally. |
| Excretion | Renal: approximately 80% excreted unchanged in urine; the remainder is metabolized to p-carboxybenzene sulfonamide (p-CBS) which is also renally excreted. |
| Half-life | Approximately 45 minutes (range 30-60 minutes) for the parent compound; the metabolite p-CBS has a longer half-life of about 4 hours. |
| Protein binding | Less than 10% bound to plasma proteins. |
| Volume of Distribution | 0.3-0.7 L/kg, indicating distribution into total body water and interstitial spaces. |
| Bioavailability | Topical: not applicable; systemic absorption occurs through burn eschar, but bioavailability is variable (estimated 10-30% depending on burn depth and surface area). |
| Onset of Action | Topical application: within hours, antimicrobial effect begins as the drug penetrates burn eschar. |
| Duration of Action | Topical: bacteriostatic effect persists as long as the drug is present; requires twice-daily application due to rapid metabolism and short half-life. |
| Molecular Weight | 186.2 Da (as mafenide base; acetate salt: 246.2 Da) |
Apply topically as a thin layer to affected areas once or twice daily. The dosage form is an 11.1% cream or solution. The cream is applied using a sterile gloved hand; the solution is applied with a sterile spray or brush.
| Dosage form | FOR SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment as systemic absorption is minimal. However, caution in severe renal impairment due to potential acetate accumulation; monitor serum electrolytes. |
| Liver impairment | No dose adjustment required for hepatic impairment. Systemic absorption is minimal; however, monitor for metabolic acidosis in severe hepatic impairment. |
| Pediatric use | Apply topically to affected areas once or twice daily. Use weight-based calculations only if large surface area is involved; generally, apply thin layer covering affected area. Monitor for metabolic acidosis in extensive burns. |
| Geriatric use | No specific dose adjustment required. Use with caution in elderly due to potential for decreased renal function; monitor electrolytes and acid-base balance. |
| 1st trimester | Avoid. Mafenide acetate is a sulfonamide; use in first trimester may be associated with congenital malformations, though definitive human data are lacking. The potential for kernicterus in the newborn if used near term also applies. |
| 2nd trimester | Avoid unless benefit outweighs risk. Sulfonamides may cause kernicterus in the newborn if administered near delivery due to displacement of bilirubin from albumin. |
| 3rd trimester | Avoid, especially during the last few weeks of pregnancy. Risk of kernicterus in the neonate increases; consider alternative agents. |
Clinical note
Comprehensive clinical and safety monograph for MAFENIDE ACETATE (MAFENIDE ACETATE).
| Placental transfer | Placental transfer occurs; sulfonamides cross the placenta readily and achieve fetal concentrations similar to maternal levels. Mafenide acetate is a sulfonamide derivative and expected to cross the placenta. |
| Breastfeeding |
■ FDA Black Box Warning
Mafenide acetate has been associated with metabolic acidosis due to its carbonic anhydrase inhibitory effect, which can lead to hyperchloremic metabolic acidosis. This is particularly significant in patients with renal impairment or those with extensive burns.
| Serious Effects |
Hypersensitivity to mafenide or other sulfonamidesSulfonamide sensitivityUse on large areas of denuded skin (e.g., >20% total body surface area) due to risk of metabolic acidosisKnown G6PD deficiency (relative, but considered absolute by some due to hemolytic risk)
| Precautions | May cause metabolic acidosis; monitor arterial blood gases and serum bicarbonate levels, particularly in patients with renal impairment or extensive burns, Superinfection with nonsusceptible organisms, including fungi, may occur, Application may cause pain, burning, or discomfort; consider analgesic use, Can cause delayed eschar separation and increased rate of graft loss, Use with caution in patients with sulfonamide allergy, Renal function should be monitored |
| Food/Dietary | No known food interactions. |
Loading safety data…
| Mafenide acetate is a sulfonamide that is excreted into breast milk in small amounts. Although it is considered compatible with breastfeeding by many authorities (e.g., AAP), caution is warranted due to the theoretical risk of kernicterus in jaundiced or G6PD-deficient infants. Monitor infant for diarrhea, rash, and hemolysis. The American Academy of Pediatrics considers sulfonamides as usually compatible with breastfeeding but advises caution in infants with hyperbilirubinemia or G6PD deficiency. |
| Lactation Rating | L2 (Safer) – limited data; compatible with monitoring. |
| Teratogenic Risk | Mafenide acetate is a sulfonamide derivative. In the first trimester, sulfonamides are generally avoided due to potential teratogenic risk (e.g., neural tube defects, cardiovascular malformations) based on animal studies. In the second and third trimesters, sulfonamides may increase the risk of kernicterus in the newborn due to bilirubin displacement from albumin; therefore, mafenide acetate should not be used near term. However, topical application results in minimal systemic absorption, reducing fetal exposure. |
| Fetal Monitoring | Monitor maternal renal function, acid-base balance, and for signs of hypersensitivity reactions (rash, fever). Monitor fetal growth and development with standard prenatal care. No specific fetal monitoring required beyond routine; consider periodic ultrasound if prolonged use. In neonates exposed near term, monitor serum bilirubin levels. |
| Fertility Effects | No specific adverse effects on fertility reported in humans. Animal studies have not shown impairment of fertility at clinically relevant doses. |
| Clinical Pearls | Apply with sterile glove; discontinue if hyperchloremic metabolic acidosis occurs; not for use on face or near eyes. |
| Patient Advice | Apply a thin layer to clean wound using a sterile glove or tongue depressor. · Avoid contact with eyes, mouth, or nose. · Report any burning, rash, or difficulty breathing immediately. · Keep wound covered with dressing as directed. · Do not use on large areas or for longer than prescribed. |