Wound & Burn Agents

A burn destroys the skin’s barrier, so the great danger is wound sepsis — invasive infection of the burn. Two topical antimicrobials are labeled for burn-wound sepsis, and the way they differ is the way to remember them. Silver sulfadiazine (Silvadene) is a commonly used topical burn antibiotic: broad antibacterial (plus some antifungal) coverage, affordable, easy to use, and well tolerated — but it penetrates eschar poorly (the thick dead burn crust) and can slow re-epithelialization — so it is stopped once healing is visible, and with repeated use it forms a pseudoeschar that hides the wound from assessment and is often painful to debride. Mafenide (Sulfamylon) is the opposite: it penetrates eschar and cartilage (so it is used for burns of the ears and nose), but it stings and burns on application.

Each carries a specific safety catch that flows from being a sulfonamide. Silver sulfadiazine can cause a transient leukopenia (monitor the CBC) and, because sulfonamides displace bilirubin, it is contraindicated in near-term pregnancy, premature infants, and newborns under 2 months (kernicterus risk) — and it should be avoided after a severe prior sulfonamide reaction (potential cross-sensitivity). Mafenide inhibits carbonic anhydrase, so it can cause metabolic acidosis — monitor acid-base status and watch for compensatory fast breathing. Two burn drugs, mirror-image trade-offs: silver sulfadiazine (well tolerated, poor eschar penetration, watch the CBC) versus mafenide (painful, penetrates eschar, watch the acid-base balance).

Beyond burns, a handful of agents cover everyday wounds. Triple antibiotic ointment (Neosporin — bacitracin/neomycin/polymyxin B) prevents infection in minor cuts and scrapes, but its neomycin component is one of the most common causes of allergic contact dermatitis — so if a wound gets redder and itchier under Neosporin, suspect allergy, not spreading infection. Mupirocin is the most widely used topical antibiotic for impetigo and for nasal decolonization of MRSA; it blocks bacterial isoleucyl-tRNA synthetase, though resistance is rising with heavy use.

Two specialty agents address healing itself. Collagenase (Santyl) is an enzymatic debrider — it digests the collagen anchoring dead tissue in a wound while sparing healthy tissue, a gentle alternative to sharp debridement (note it’s inactivated by silver, iodine, and acidic soaks, so pair it only with compatible cleansers like saline). Becaplermin (Regranex) is recombinant PDGF that stimulates granulation in diabetic foot ulcers. A historical note worth knowing: becaplermin once carried a boxed warning for increased cancer mortality with heavy use, but the FDA removed that boxed warning in 2018 after further data — though a contraindication for known malignancy at the application site remains.

It’s tempting to think a wound heals because of the drug on it, but the deeper principle is that topical antimicrobials only reduce the bacterial burden — the wound bed does the healing, and only if the conditions are right. That means cleaning and, where needed, debriding the wound first (dead tissue harbors bacteria and blocks healing), maintaining moisture balance (a wound kept moist — not wet, not dry — re-epithelializes faster than one left to scab), and controlling infection and the wound edge. Dressings are matched to the exudate — silver or iodine dressings for bioburden, hydrocolloids for lighter wounds.

One counterintuitive rule ties it together: avoid full-strength cytotoxic antiseptics — undiluted hydrogen peroxide, povidone-iodine, or Dakin’s solution — on clean, granulating tissue. They are toxic to the fibroblasts and keratinocytes doing the healing and can delay it, doing more harm than good on a healthy wound bed (they still have a role, diluted, in clearly infected wounds). So the nurse’s sequence is consistent across every product in this class: assess the wound, clean/debride it, choose the agent that fits, keep it appropriately moist, and protect the healing tissue.