Discontinuation of Injectable Bacitracin
For decades, injectable bacitracin was used for its narrow and specific approved indication: the treatment of pneumonia and empyema in infants caused by susceptible staphylococci. However, as the medical field advanced, safer and more effective antibiotics emerged, rendering the injectable form of bacitracin largely obsolete for its intended purpose. Despite this, it continued to be used off-label for other applications, such as intraoperative irrigation for surgical wounds.
In April 2019, an advisory committee to the FDA convened to review the drug's safety and efficacy. The committee voted nearly unanimously that the risks associated with injectable bacitracin far exceeded its clinical benefits.
The primary safety concerns included:
- Nephrotoxicity: Significant kidney toxicity, including tubular and glomerular necrosis, was a serious risk, especially with systemic administration.
- Anaphylactic Reactions: Severe, life-threatening allergic reactions, including anaphylaxis, were also a noted risk.
Based on the advisory committee's findings and its own review, the FDA formally requested the voluntary withdrawal of injectable bacitracin from the market in January 2020. This was followed by official notices of withdrawal of approval for specific drug applications in 2021 and 2022, solidifying its removal for reasons of safety and effectiveness.
The Continued Use of Topical Bacitracin
It is crucial to understand that the discontinuation only affected the injectable form. Topical bacitracin remains a popular and readily available over-the-counter product for preventing minor skin infections. Unlike its systemic counterpart, bacitracin is poorly absorbed through the skin when applied topically, which significantly reduces the risk of systemic side effects like nephrotoxicity.
Common uses for topical bacitracin include:
- Treating minor cuts, scrapes, and burns.
- Used in combination with other antibiotics like neomycin and polymyxin B in multi-ingredient ointments (e.g., Neosporin).
- As a single-ingredient alternative for those with allergies to neomycin.
Understanding the Risks of Topical Bacitracin
While generally safe for topical application, bacitracin is not without risk. Its most common adverse effect is allergic contact dermatitis, a rash that can develop from repeat or prolonged use. In 2003, the American Contact Dermatitis Society even named bacitracin its "Contact Allergen of the Year" due to the high number of reported reactions. In rare instances, systemic absorption through broken or denuded skin can lead to more serious, although still infrequent, anaphylactoid reactions.
Symptoms of an allergic reaction to topical bacitracin include:
- Redness and itching that may mimic worsening infection.
- Hives.
- Swelling of the lips or face.
These reactions are distinctly different from the organ-specific toxicity of the injectable form, but they still warrant careful monitoring. For this reason, healthcare professionals often advise limiting its application to a small amount on the wound itself for only a few days.
Comparison of Bacitracin Formulations and Alternatives
| Feature | Injectable Bacitracin (Discontinued) | Topical Bacitracin (Available OTC) | Neosporin (Contains Bacitracin) | Polysporin (Contains Bacitracin) |
|---|---|---|---|---|
| Availability | Discontinued for safety reasons. | Available over-the-counter. | Available over-the-counter. | Available over-the-counter. |
| Systemic Risk | High risk of nephrotoxicity and anaphylaxis. | Minimal systemic absorption; rare anaphylactoid risk. | Minimal systemic absorption; rare anaphylactoid risk from bacitracin. | Minimal systemic absorption; rare anaphylactoid risk from bacitracin. |
| Allergy Risk | Anaphylactic reactions. | Allergic contact dermatitis is common. | Includes neomycin, a potent sensitizer, in addition to bacitracin. | Allergic contact dermatitis is a possibility. |
| Ingredients | Bacitracin only. | Bacitracin only. | Bacitracin, Neomycin, Polymyxin B. | Bacitracin, Polymyxin B. |
| Purpose | Formerly used for infant pneumonia. | Minor skin infection prevention. | Broad-spectrum infection prevention for minor wounds. | Infection prevention for minor wounds. |
The FDA's Role and Market Evolution
The FDA's decision to remove injectable bacitracin from the market is a clear example of how drug safety standards evolve. The regulatory process, including committee review and post-marketing surveillance, is designed to ensure that the risk-benefit profile of a drug remains favorable. The availability of superior and safer treatments for the same conditions played a critical role in the final determination. This action also serves as a reminder to healthcare professionals and the public that drug safety is an ongoing process, and medications that were once standard of care may become outdated due to emerging evidence. For example, safer alternatives for surgical irrigation are now widely used.
Conclusion
The reason bacitracin was discontinued relates specifically to its injectable form, which posed significant risks to kidney function and triggered severe allergic reactions. The availability of more effective and safer alternatives made the continued use of injectable bacitracin unjustifiable. The topical ointment version, which remains an over-the-counter option for minor skin infections, was not affected by this withdrawal. However, users should be aware of the risk of allergic contact dermatitis associated with topical bacitracin and should discontinue use and consult a doctor if a rash appears. The FDA's action highlights the ongoing importance of monitoring and evaluating medications to ensure patient safety in the face of medical progress.
