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 dominate burn care, and the way they differ is the way to remember them. Silver sulfadiazine (Silvadene) is the everyday choice: broad antibacterial (plus some antifungal) coverage, soothing, and painless to apply — but it does not penetrate eschar (the thick dead burn crust). Mafenide (Sulfamylon) is the opposite: it penetrates eschar and cartilage (so it’s used on deep burns and the ears/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’s avoided in sulfa allergy. 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 (painless, no 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 (Bactroban) is the go-to for impetigo and for nasal decolonization of MRSA, working by a unique mechanism (blocking bacterial isoleucyl-tRNA synthetase) that avoids cross-resistance.

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 honey 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 kill the very fibroblasts and new skin cells doing the healing, 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.