Neomycin/polymyxin B/bacitracin

Neomycin/polymyxin B/bacitracin sold under the brand name Neosporin among others, is an antibiotic cream that contains neomycin, polymyxin B, and bacitracin. It is used to prevent infections.^[1]

Medical uses

Neomycin/polymyxin B/bacitracin ointment is reported to be a safe and effective topical agent for preventing infections in minor skin trauma.^[2]

Neosporin is recommended for burns, scratches, cuts, and minor skin infections.^[3] It is most effective when affected area is cleaned before application of ointment.^[4]

Efficacy

The use of triple-antibiotic ointments, such as neomycin/polymyxin B/bacitracin, decreases infection rates in minor-contaminated wounds.^[5] However, if the wound is sterile, then there are no benefits.^[5][6]

Side effects

Neosporin is for external use only and should not go near mucus membranes such as the eyes or mouth. Neosporin is not recommended for children under the age of two. There are no known side effects when using Neosporin, however users should immediately seek medical attention when experiencing hives, rashes, or itching. Any skin irritations such as pain, burning, or cracked skin that were not present prior to use of ointment must receive immediate care.^[7]

Concern exists that the use of Neosporin contributes to the emergence of antibiotic-resistant bacteria. In the US, the only large market for Neosporin, the ointment may promote the prevalence of MRSA bacteria,^[8] specifically the highly lethal ST8:USA300 strain.^[9] Neosporin has been shown to cause contact dermatitis^[10] in some cases, and may contribute to antibiotic resistance.^[11][12]

Components

The original ointment contains three different antibiotics: bacitracin, neomycin, and polymyxin B, in a relatively low-molecular-weight patented base of cocoa butter, cottonseed oil, sodium pyruvate, tocopheryl acetate, and petroleum jelly.

The generic name for these products, regardless of the base, is "triple antibiotic ointment". In China, this product is called "complex polymyxin B ointment," which is manufactured by Zhejiang Reachall Pharmaceutical. The product was also marketed by the Upjohn Company under the name "Mycitracin", until 1997 when that name was acquired by Johnson & Johnson.^[13]

Some people have allergic reactions to neomycin, so a "double antibiotic ointment" is sold that contains only bacitracin and polymyxin B, such as the cobrand Polysporin.

A "Plus" variant of the ointment exists that adds the analgesic pramoxine, but uses the cheap, simple, long-lasting, but heavier petroleum jelly base common to many over-the-counter topicals. The latest version of this, a high-absorption cream, removes the bacitracin, which is unstable in such a base, but keeps the analgesic.

Active ingredients

The three main active ingredients in Neosporin are neomycin sulfate, polymyxin B sulfate, and bacitracin zinc. One of the main components of Neosporin is Neomycin Sulfate which is a type of antibiotic discovered in 1949 by microbiologist Selman Waksman at Rutgers University.^[14] Neomycin is a type of aminoglycoside antibiotic that fights against Gram positive and gram negative bacteria. Neomycin is often used in order to prevent risk of bacterial infections.^[15] Aminoglycosides such as Neomycin are known for their ability to bind to RNA and to change the proteins being produced by the bacteria with little to no effect on DNA. Neomycin kills bacteria as a result of irregular protein production in the bacterial cell. When the cell can no longer produce the correct proteins, its membrane will be damaged.^[16] Like Neomycin, Polymyxin B is an antibiotic. Polymyxin B alters the bacterial cell wall causing the cellular insides to leak out resulting in cell death. This antibiotic also interferes with the production of tetrahydrofolic acid by altering an enzyme. Without the tetrahydrofolic acid, the bacteria can no longer produce proteins necessary for survival.^[17] Pramoxine is used to temporarily reduce pain from burns, insect bites, and minor cuts. It works like an anesthetic by decreasing the permeability of neuron membranes. This blocks the ability of pain neurons in the area to send signals which results in numbness.^[18]

In some countries bacitracin is replaced with gramicidin.

History

Neosporin is the brand name for a product produced by Johnson & Johnson that contains neomycin sulfate, polymyxin B, and bacitracin. There is no exact date to when the antibacterial ointment was invented, but it was used as early as the 1950s. This antibiotic ointment was patented in the United States on August 27, 1951.^[19]

References

External links

• PubMed Health page
• Treating wounds with neosporin