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This article is part of a series on nonprescription drugs.
A half-inch scar on my left knee is a graphic reminder of a painful scrape at age 7. Also painful was the burn of Merthiolate antiseptic, applied as first aid to ward off infection.
Today's approved over-the-counter topical (used on the skin) first-aid antimicrobials are less irritating and more effective than Merthiolate, which contains the mercury drug thimerosal. The Food and Drug Administration has approved seven topical OTC antibiotics (see "OTC Antibiotics") and is evaluating OTC topical antiseptics under a proposed rule. The proposal would ban numerous antiseptics, including mercurials, as ineffective and some, including thimerosal, as also unsafe.
Antibiotics are also available by prescription as injectable and oral medicines and medicines for the eye and ear. They are used to treat infections. While some can kill a limited number of bacteria, other varieties affect many bacteria.
Antiseptics weaken microbes, but don't usually kill them. Health-care antiseptics in soaps and other products help prevent the spread of infection in medical facilities.
OTC first-aid antibiotics and antiseptics are applied to the skin to help prevent infection in minor cuts, scrapes and burns.
"Used topically, OTC antimicrobials inhibit the growth of bacteria, but don't necessarily kill them all," says Audrey Love, a microbiologist with the division of OTC drug evaluation in FDA's Center for Drug Evaluation and Research. "If an injury is extensive," Love says, "it should be taken care of by a doctor. But consumers have to consider for themselves, based on reading the labeling, whether a product is something they should use."
FDA has published rules (monographs) establishing adequate labeling for OTC antimicrobials, and conditions under which products would be generally recognized as safe and effective for use without medical supervision. The final antibiotics rule (1987) and proposed antiseptics rule (1991) specify active ingredients and concentrations, as well as labeling information such as product identification, indications for use, warnings, and directions for use. All drugs must meet the agency's good manufacturing practice requirements for product identity, strength, quality, and purity.
Some Restrictions
OTC first-aid antimicrobials are for use only up to one week. If an injury persists or worsens after this time, the label warns consumers to stop use and consult a doctor.
The products are not for existing infections, animal bites, sunburn, punctures, or eye injuries. Nor should they be used for cuts, scrapes or burns needing medical care, such as:
A panel of experts convened by FDA defined first aid as "a process that includes initial adequate cleansing which may or may not be followed by application of a safe, nonirritating product which does not interfere with normal wound healing and which may reduce the bacterial numbers and help prevent infection." (From 1972 to 1981, at FDA's request, 16 outside panels evaluated marketed OTC drugs. Their charge completed, the panels no longer meet.)
FDA requires that labels for antibiotics advise users to first "clean the affected area." Antiseptics also would be labeled with the advice.
Because topical antimicrobials are not totally effective in killing bacteria, FDA does not allow firms to place the claim "Helps kill bacteria" in the same area as the required information. FDA believes the term "kill" implies the product will eliminate all bacteria and could be misleading if appearing with the required term "infection" (or alternate term "bacterial contamination") in the label's indications section. The claim may be used, though, as additional information elsewhere in the label.
More About Antibiotics
In its final rule, FDA listed these antibiotic active ingredients as safe and effective: bacitracin, bacitracin zinc, chlortetracycline hydrochloride, tetracycline hydrochloride, neomycin sulfate, oxytetracycline hydrochloride, and polymyxin B sulfate--the latter two only for combination products because of their limited effectiveness against certain microorganisms when used alone.
The rule does not allow the previously marketed antibiotic gramicidin, because it has the potential to break down red blood cells when absorbed through fresh wounds. The agency called for a well designed, double-blind study (where neither patient nor doctor knows who gets the drug) to show gramicidin's effects.
The data on which FDA based its approval of the other antibiotics included a well-controlled study of minor skin injuries or insect bites in 59 children. Streptococcal infection developed in 15 of the 32 receiving a topical placebo and in three of the 27 receiving a topical antibiotic. Twelve of the 15 eventually needed oral antibiotics, and one of the three did.
The agency agreed with comments that many such injuries are self-healing, but that some do not heal without treatment and it is impossible to make this distinction at the time of injury.
Also, says FDA's Love, there's always a chance someone can be allergic to a drug, prescription or OTC. "People who tend to be allergic," she says, "should talk to their doctor or pharmacist before trying any OTC medicine for the first time."
About 1 in 20 people is allergic to neomycin, according to an article in the August 1995 Harvard Health Letter. If a reaction such as redness, itching or burning occurs, the article advises, "Stop using the preparation immediately, and consult a physician if symptoms worsen or persist for more than 48 hours."
Hypersensitivity reactions may also occur with bacitracin, according to the Handbook of Nonprescription Drugs (10th edition), published by the American Pharmaceutical Association and The National Professional Society of Pharmacists, Washington, D.C. The handbook also states that tetracycline products may trigger reactions in allergic patients, "some of whom may have severe reactions even if exposure is by topical application only."
With repeated use on large areas, neomycin also fosters development of neomycin-resistant strains of Staphylococci bacteria. Neomycin products that include polymyxin B and bacitracin guard against this.
To prevent neomycin overuse, FDA limits the drug to ointments and creams, the most likely dosage forms for small wounds. Also, all OTC antimicrobials must be labeled for short-term use. The agency believes short-term use of neomycin ointments or creams on small wounds would not risk overuse. To reduce the risk even further, FDA requires labels for ointments and creams to identify a dose as "an amount equal to the surface area of the tip of a finger."
Another issue is the combination of a product with a local "caine" anesthetic, such as benzocaine, as is allowed for bacitracin ointment or a combination ointment of bacitracin, neomycin, or polymyxin B. The review panel was concerned an anesthetic might mask symptoms of infection, delaying treatment by a doctor. But FDA believes the required warnings on the label adequately inform consumers when to consult a doctor.
More About Antiseptics
In its proposed rule, FDA listed these active antiseptic ingredients as tentatively safe and effective: ethyl alcohol (48 to 95 percent), isopropyl alcohol, benzalkonium chloride, benzethonium chloride, camphorated metacresol, camphorated phenol, phenol, hexylresorcinol, hydrogen peroxide solution, iodine tincture, iodine topical solution, povidone-iodine, and methylbenzethonium. Five ingredients listed as tentatively effective only in combination products are ethyl alcohol (26.9 percent), eucalyptol, menthol, methyl salicylate, and thymol.
The proposal would ban numerous mercury ingredients and cloflucarban, fluorosalan and tribromsalan antiseptics as not generally recognized as safe and effective for OTC use.
FDA had requested study data on whether use of topical povidone-iodine affected thyroid function. In submitted data, iodine blood levels did increase after two weeks' use, but returned to normal when use was stopped. There was no effect on thyroid function.
Antiseptics would be labeled similarly to antibiotics, but with some differences.
Labels on camphorated metacresol, camphorated phenol, and phenol, for example, would warn, "Do not bandage."
"The drugs can be hard on the skin," says Debbie Lumpkins, a microbiologist in FDA's division of OTC drug evaluation. She explains that, "when bandaged, the skin gets damp, increasing absorption. Therefore, more drug enters the skin and may cause more damage than if you just left the wound uncovered." Labels for ethyl alcohol (48 to 95 percent) and isopropyl alcohol (50 to 91.3 percent) would warn: "Flammable, keep away from fire or flame."
For liquid antiseptics, labels would direct users to let the product dry before bandaging.
Comments on the proposal were minimal, Lumpkins says, emphasizing that FDA's evaluation of the ingredients is still very much an evolving process.
"Frequently," she says, "we find that one study or one article says one thing, and there's another study or article on the other side. We have to determine the facts. Literature searches that we can now do so easily help, but we won't find everything. We rely on people to bring things to our attention."
Recent publications advise against two currently marketed antiseptics. The National Safety Council's 1996 First Aid Pocket Guide states: "DO NOT use hydrogen peroxide. It does not kill bacteria, and it adversely affects capillary blood flow and wound healing." And the Handbook on Nonprescription Drugs states ethyl alcohol "is not a desirable wound antiseptic because it irritates already damaged tissue. The coagulum [crust] formed may, in fact, protect the bacteria."
The final rule will reflect FDA's evaluation of all the data, Lumpkins says. Thus, antiseptic ingredients proposed as safe and effective could be found unsafe or ineffective, or new ingredients could be added, depending on new information.
Whether using an OTC antibiotic or antiseptic, consumers should realize "there are limits to what the products can do," Lumpkins says. "People should read the label, and use the product appropriately. If they notice a change in their condition, or if there's redness or swelling, they shouldn't continue to try to treat it. They should see a doctor."
Dixie Farley is a staff writer for FDA Consumer.
bacitracin zinc--Bacitracin Zinc
chlortetracycline hydrochloride--Aureomycin
neomycin sulfate--Neomycin, Myciguent Cream
tetracycline hydrochloride--Achromycin
bacitracin-polymyxin B aerosol--none currently marketed
bacitracin-neomycin-polymyxin B--Lanabiotic, Medi-Quik Triple Antibiotic, Clomycin Cream (with lidocaine anesthetic), Mycitracin Plus Pain Reliever (with lidocaine)
bacitracin zinc-neomycin--none currently marketed
bacitracin zinc-polymyxin B ointment, aerosol or powder--Polysporin, Polysporin Powder
bacitracin zinc-neomycin-polymyxin B--Neomixin, Neosporin Original
neomycin-polymyxin B ointment or cream--Neosporin Plus Maximum Strength Cream (with lidocaine)
oxytetracycline-polymyxin B ointment or powder--none currently marketed.
--D.F.