What topical antimicrobial agent can cause metabolic acidosis as a complication of its application?

Metabolic Acidosis as a Complication of Topical Antimicrobial Agents

Sodium mafenide (Sulfamylon) is the topical antimicrobial agent that can cause metabolic acidosis as a complication of its application. 1

Mechanism of Metabolic Acidosis with Sodium Mafenide

Sodium mafenide (mafenide acetate) is a sulfonamide antimicrobial agent used topically for burn wound care. Unlike other topical antimicrobials, mafenide has unique properties that lead to metabolic acidosis:

• Mafenide is rapidly absorbed through burn wounds
• It is a potent carbonic anhydrase inhibitor
• This inhibition prevents the kidney from excreting acid (H+) normally
• The result is systemic metabolic acidosis due to impaired renal acid excretion

Comparison with Other Topical Antimicrobial Agents

Silver Sulfadiazine

• Does not typically cause metabolic acidosis directly
• However, its propylene glycol vehicle has been rarely associated with lactic acidosis in extensive burns (0.09% of cases) 2, 3
• This is a different mechanism than mafenide's direct carbonic anhydrase inhibition

Silver Nitrate

• Not associated with metabolic acidosis
• More commonly associated with electrolyte imbalances (particularly hyponatremia) due to sodium loss

Betadine (Povidone-Iodine)

• Not associated with metabolic acidosis
• Main concerns include thyroid dysfunction with prolonged use

Bacitracin

• Not associated with metabolic acidosis
• Primary concerns include contact dermatitis and allergic reactions

Clinical Implications

When using sodium mafenide:

• Monitor for signs of metabolic acidosis (tachypnea, fatigue, confusion)
• Check electrolytes and arterial blood gases in patients with extensive burns
• Be aware that metabolic acidosis is defined as pH < 7.35 with bicarbonate < 15 mEq/L 1
• Consider alternative topical agents in patients with:
  • Pre-existing acidosis
  • Respiratory compromise (unable to compensate)
  • Renal dysfunction

Management of Mafenide-Induced Acidosis

If metabolic acidosis develops:

1. Discontinue sodium mafenide application
2. Consider switching to alternative antimicrobial (silver sulfadiazine, silver nitrate)
3. Monitor acid-base status
4. Severe cases may require bicarbonate therapy, though evidence for this intervention is limited 4

Prevention

• Use sodium mafenide judiciously, especially in patients with large TBSA burns
• Consider alternating with other topical antimicrobials to reduce systemic absorption
• Monitor high-risk patients closely for early signs of metabolic derangement

Sodium mafenide remains an important option for burn wound care due to its excellent penetration through eschar and broad antimicrobial coverage, but clinicians must be vigilant about its unique potential to cause metabolic acidosis.