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Topical antibiotics and antiseptics
Roger Selvage 6283

Topical antibiotics and antiseptics

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OTCs Today

Mary Warner

Image of tubes of ointments.

A tube of nonprescription antibiotic ointment or bottle of antiseptic is a staple in most medicine cabinets, and for good reason. These products can prevent infection of small cuts, scrapes, or other skin injuries that don’t require medical intervention.

Although nonprescription antibiotics and antiseptics are often thought of as being similar, there are important differences between them. Antiseptics inhibit the growth of bacteria on the skin’s surface, while antibiotics kill bacteria directly. And while antiseptics can target bacteria, viral species, and fungi, antibiotics are only effective against bacteria.

Active ingredients

Nonprescription antibiotics contain one or more of three active ingredients—bacitracin, neomycin, and polymyxin B sulfate—with triple antibiotic ointment being the most commonly available. Each of these medications targets specific bacteria, which gives the triple antibiotic ointment a wide spectrum of activity.

Bacitracin is a mixture of cyclic polypeptides produced by Bacillus licheniformis. It targets gram-positive bacteria, especially those that cause skin infections such as Staphylococcus aureus, Staphylococcus epidermis, and Streptococcus pyogenes. It disrupts cell-wall synthesis by interfering with the lipids that transport the building blocks of the peptidoglycan cell wall.

Neomycin is an aminoglycoside antibiotic that inhibits bacterial protein synthesis of gram-negative bacteria, while polymyxin B sulfate alters bacterial outer membrane permeability resulting in leakage of cellular molecules and inhibition of cellular respiration in gram-negative bacteria.

Antiseptics contain either benzalkonium, iodine admixtures, alcohol, or hydrogen peroxide, all of which affect the cellular envelope of the microorganism or interfere with critical enzyme processes.

How effective are they?

Results of published research on the efficacy of nonprescription topical antibiotics and antiseptics are mixed. A 2011 study published in the Journal of the American Academy of Dermatology compared the wound-healing properties of a topical emollient with that of an antibiotic ointment containing neomycin, bacitracin and polymyxin and an antibiotic ointment containing bacitracin and polymyxin B and found that the nonantibiotic emollient cream was equally as effective as the topical antibiotics in healing wounds and preventing infection.

A 2018 systematic review published in Infection and Drug Resistance analyzed 10 studies comparing topical antibiotics with placebo and four studies that compared antiseptics with antibiotics. The authors found that topical antibiotics were effective in reducing the risk of infections in uncomplicated wounds compared to placebo or antiseptics, but the absolute risk reduction was minimal compared to that with a placebo. In addition, there was no statistically significant absolute reduction when compared to antiseptics.

Availability

Topical antibiotics are available as creams or ointments, while antiseptics are available as liquids and sprays. Ointments are appropriate for minor burns and wounds in which the skin is intact because they maintain a moist healing environment. Creams are most appropriate for cuts and scrapes as they allow some fluid to pass through the film.

To prevent contaminating the medication, the patient should not apply ointments and creams directly from the container onto the burn or wound, but rather apply the product to a clean hand or gauze and then apply it to the site of the injury. Liquid antiseptics should be applied using gauze or a cotton ball, while antiseptic sprays should be held approximately 6 inches from the skin while spraying for 1 to 3 seconds.

What to tell your patients

Ensure that patients understand the difference between a topical antibiotic and an antiseptic to confirm that they are using the appropriate product for their situation. Although topical antibiotics and antiseptics are well tolerated and carry a minimal risk of hypersensitivity, advise patients to contact their health care provider if they experience contact dermatitis.

Finally, because of the increasing importance of antimicrobial stewardship, judicious use of topical antibiotics is prudent, and antiseptics should be considered as a reasonable alternative to topical antibiotics.

For further information, see Chapter 41 in APhA’s Handbook of Nonprescription Drugs, available in the bookstore on pharmacist.com or in PharmacyLibrary. ■

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