Many topical agents are available in wound care (see table).
Some, such as sugar, are primarily used in areas where there is limited access to health care. Some of the actions of honey are similar to sugar, yet honey is available both in pure medical-grade form and impregnated into multiple styles of bandages. Some of these bandages combine multiple agents, such as alginate. Silver-impregnated bandages are available in a variety of styles.
Research on the best available products is pending. Topical antibiotic usage has limited benefit in wound healing.
Maggot therapy is one example of biological therapy. There is limited use in veterinary medicine.
Topical Agents
Topical Agent | Indications and Characteristics |
|---|---|
Granulated sugar |
|
Honey |
|
Silver |
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Antibiotics |
|
Enzymatic agents |
|
Biological (maggot therapy) |
|
Sugar
Sugar has been used as an inexpensive wound dressing for more than three centuries to control odor and infection.
The use of sugar is based on its high osmolality, drawing fluid out of the wound and inhibiting the growth of bacteria. The use of sugar also aids in the debridement of necrotic tissue while preserving viable tissue.
Granulated sugar is placed into the wound cavity in a layer 1 cm thick and covered with a thick dressing to absorb fluid drawn from the wound. The sugar dressing should be changed once daily or whenever strikethrough (when fluid soaks from the wound to the surface of the bandage) is seen. During the bandage change, the wound should be liberally lavaged with warm saline (0.9% NaCl) solution or tap water.
Sugar dressings may be used during the inflammatory phase. Because a large volume of fluid can be removed from the wound, the hemodynamic and hydration status of a patient with a large wound must be monitored to avoid hypovolemia and low colloid osmotic pressure.
Honey
Honey has also been used for wound dressings for centuries.
Some of the beneficial effects of honey are a result of high osmolality, low pH, and hydrogen peroxide activity. However, the major contributor to honey’s antibacterial activity is methylglyoxal. Honey varieties with higher methylglyoxal levels are more bioactive. Leptospermum honey from the manuka bush in New Zealand has the highest methylglyoxal levels and is believed to the most effective for medicinal purposes.
Honey may be placed directly into the wound or soaked into the contact dressing. The use of honey should be limited to the inflammatory phase. Once a granulation bed is present, continued use may desiccate the wound or traumatize the healing tissue during removal.
Whereas topical usage has beneficial antibacterial effects, oral administration has not been shown to have similar benefits.
Silver
Silver has been used as a topical agent in various formulations for several hundred years.
Silver is available in creams (silver sulfadiazine) or embedded within dressings. Silver nanoparticles have antimicrobial benefits and have also been studied for anticancer uses.
Silver is indicated for use in the inflammatory phase in wound healing. While its mechanism is not fully understood, it is bactericidal and may also have benefits in angiogenesis and decreased wound scarring.
Silver can be toxic, and additional research is examining its best uses.
Antibiotics
Like many topical therapies, the use of topical antibiotics can be controversial, and their excessive use may contribute to the global problem of antibiotic resistance.
Zinc-containing antibiotics (eg, bacitracin-zinc) may aid wound healing by the donation of zinc into the wound bed. Zinc has been shown to have both antimicrobial and anti-inflammatory properties.
When infection involves the deeper tissues, systemic antibiotics are indicated, given the limited ability of topical antibiotics to penetrate deeper tissue.
Enzymatic agents
Enzymatic agents (usually in ointment formulation) are proteolytic compounds used to liquefy necrotic tissue. These agents are used in the inflammatory phase of healing. They do not cause the pain that can be associated with surgery, and their application is indicated where surgical debridement may be detrimental to longterm function.
However, in addition to its high expense, enzymatic debridement action can be slow. Enzymatic agents can cause maceration of healthy tissue if left in prolonged contact.
Newer antimicrobial peptides are being developed in a wide variety of topical formulations.
Maggots
Medicinal maggots are used during the inflammatory stage of wound healing to remove necrotic tissue and debris. The common green bottle fly (Lucilia sericata) is used as the source of medical-grade maggots.
The maggots debride necrotic tissue by secreting several proteolytic enzymes to liquefy the debris. Maggots also have a beneficial effect by ingesting bacteria. Finally, some of the secretions may also inhibit biofilm formation.
Maggot therapy may be contraindicated in dry wounds and should not be the primary therapy in a septic patient.
Maggot therapy is not commonly used and may be expensive. In addition to the maggots, a biobag must be used to prevent their movement off the patient.
