A Pharmacist's Guide to the Care and Management of Diabetic Foot Ulcers

When an individual is diagnosed with diabetes, the management and prevention of potential complications of this disease can appear to be challenging. One of the major challenges diabetic patients encounter is the possibility of developing foot problems, in particular foot ulcers. The incidence of foot ulcers and the possible complications resulting from them are considered to be the most common cause of hospitalization among the diabetic population.¹

It is estimated that 15% of all diabetic patients will have a foot ulcer in their lifetime, and these ulcers typically occur in patients over the age of 40.² A nonhealing foot ulcer precedes up to 85% of all amputations. Through effective patient education and counseling, however, many of these amputations can be prevented.¹

Contributing Factors to the Development of Diabetic Foot Ulcers

Neuropathy, poor circulation, decreased resistance to infection, and foot injuries or deformities can all be contributing factors.

Neuropathy

Because neuropathy can cause a decrease in an individual's ability to feel sensations, an injury to the foot can go undetected for a period of time. Ulcers frequently result from a preexisting cause, such as a corn or callus that was left untreated. Traumas from cold, heat, shoe pressure, or penetration by a sharp object also are possible causes.³

Poor Circulation

Poor circulation is a complication in many patients with diabetes. Blood supply to the feet may be decreased and healing rates may be compromised, resulting in an increased incidence of developing infections.

Decreased Resistance to Infection

Because diabetes makes individuals more susceptible to infections, injuries to the feet may not heal without the aid of antibiotic therapy.

Foot Injuries or Deformities

Certain foot deformities such as bunions and hammertoes, which can cause excess pressure on areas of the foot, may potentiate the development of foot ulcers.

Symptoms of Foot Ulcers

A foot ulcer is a break in the skin or a deep sore that occurs primarily on the ball of the foot or on the bottom of the big toe. Ulcers that form on the side of the foot usually are the result of improperly fitting shoes. Although, in most cases, ulcers are initially painless, the patient should be examined by a physician to prevent further complications, such as infections, which, if left untreated, can result in amputation.

In 1999, the American Diabetes Association established the following guidelines to aid health care professionals in the general care of diabetic foot ulcers⁴:

• Establish the ulcer's etiology
• Measure its size
• Establish its depth and determine the involvement of deep structures
• Examine it for purulent exudate, necrosis, sinus tracts, and odor
• Assess the surrounding tissue for signs of edema, cellulitis, abscess, and fluctuation
• Exclude systemic infection
• Perform a vascular evaluation

Treatment Options

Various conventional treatment options are available for the care and management of diabetic foot ulcers.

OTC Products

Diabetic patients need to become familiar with daily skin care necessities. Among the OTC products available are Cetaphil and Zim's Crack Cr?me, Diabetic Formula. The latter, specially formulated for diabetic use, soothes, moisturizes, and protects the skin.

Debridement

Debridement is a surgical procedure that involves the removal of necrotic tissue from the affected area, thus decreasing the risk of developing infection and promoting closure of the wound and healing. Saline solutions should be used to irrigate the wound. Various debriding agents?such as collagenase, hypertonic saline gel, papain, or urea?provide some degree of chemical or enzymatic debridement.⁴ They often are used in conjunction with surgical debridement. Wound dressings frequently are used to protect the ulcer from additional injury and to reduce the chance of infections. Debridement is contraindicated in individuals with substantial vascular problems.

Infection Control

If infection is suspected, empiric oral or parenteral antibiotic therapy should be initiated. Because most mild infections are caused by aerobic gram-positive cocci, such as streptococci or Staphy-lococcus aureus, initiating therapy with agents such as cephalexin, amoxicillin/clavulanate, clindamycin, or dicloxacillin usually provides adequate coverage.⁵ Other possible recommended empiric treatment options for more serious infections include ticarcillin/clavulanate, cefoxitin, ampicillin/sulbactam, or a fluoroquinolone plus clindamycin, because these therapies provide coverage against anaerobes and aerobes.⁵ Therapies always can be adjusted in accordance with the results of culture and sensitivity reports.

Off-loading

When an individual constantly bears weight on an ulcer, the healing process may be compromised. Offloading involves the reduction of pressure on the wound through the use of insoles, therapeutic footwear, total contact casts, or devices such as crutches or wheelchairs.

Surgery

Some individuals may require vascular surgery to restore arterial perfusion and to prevent possible amputation. In some cases, despite every attempt to treat an ulcer, amputations must be performed. Between 1993 and 1995, approximately 67,000 amputations were performed.⁴

Agents That Promote Healing

In the last decade, the FDA has approved such agents as recombinant growth factors and bioengineered skin patches to aid in improving the healing of foot ulcers. When these agents have been used with traditional treatments, the chances of healing have increased.

Growth Factors

Becaplermin gel (from Johnson & Johnson) is a recombinant human platelet?derived growth factor. It is currently the only FDA-approved growth factor indicated for the treatment of lower-extremity diabetic ulcers that extend into the subcutaneous tissue or beyond and have an adequate blood supply.⁵ This agent enhances the formation of new granulation tissue and induces fibroblast proliferation and differentiation to promote wound healing.⁶ It typically is applied to the wound daily with a clean cotton swab in a thin, even layer. The wound is then covered with a saline-moistened gauze dressing.

Skin Replacements

In 2001, the FDA approved Dermagraft (from Advanced Tissue Sciences), which is a cryopreserved human fibroblast?derived dermal substitute. It is indicated for use in the treatment of diabetic foot ulcers that extend through the dermis without tendon muscle or bone exposure. It is used in conjunction with standard wound care protocols. When Dermagraft is applied to the ulcer, the mesh material components are gradually absorbed, and the human cells begin to grow and replace the damaged skin. This product should not be used on infected ulcers. It also is suggested that the product not be used on individuals who are allergic to products derived from cows, because there is bovine serum in the packing solution.⁷

In 2000, the FDA approved Graftskin (from Organogenesis Inc) for use in treating diabetic foot ulcers of >3 weeks duration. Graftskin is a bilayered skin substitute. It is indicated for use in conjunction with conventional diabetic foot care. Similar to human skin, Graftskin consists of living skin cells and structural protein. The lower dermal layer combines bovine type 1 collagen and human fibroblasts. The upper epidermal layer is formed by producing epidermal cells. Graftskin should not be used on infected ulcers or in individuals with hypersensitivities to any of the agent's components.⁸ It is important to stress to patients that compliance with the recommended wound care regimen is directly related to treatment outcomes. The management and prevention (Table) of further complications of diabetic foot ulcers involves selecting proper therapeutic measures, such as proper wound care, antibiotic therapy, debridement if necessary, and in some cases revascularization.

Conclusion

Pharmacists can help diabetic patients prevent foot ulcers or decrease the complications of the ailment by educating them about the necessity of maintaining good glycemic control, through diet and exercise; practicing daily foot care routines and inspection; making proper footwear choices; and seeking medical attention immediately, if needed. Most foot ulcerations can heal with early intervention and proper medical treatment. Pharmacists can play a key role in decreasing the incidence of this common complication of diabetes by simply reminding patients of how important it is to use preventive measures.

Ms. Terrie is a clinical pharmacy writer based in Slidell, La.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to: astahl@mwc.com.