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Neomycin/polymyxin/steroid treats infection
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The combination drug neomycin and polymyxin B sulfates and dexamethasone (Maxitrol, Alcon and Dexacidin, Ciba Vision) has been approved since October 1964. It is available in suspension or ointment form and is an inexpensive, broad-spectrum drug that can be used to treat many eye inflammations.
The conditions for which I often prescribe this combination drug are phlyctenular reactions, severe epidemic keratoconjunctivitis, postoperative cataract therapy and acute red eye with anterior chamber reaction from hypoxia with contact lens wear.
Maxitrol or Dexacidin is preserved with 0.004% benzalkonium chloride and uses 0.5% hydroxypropyl methylcellulose as the vehicle. Hydrochloric acid is added to help adjust the pH of the solution. Each milliliter of solution contains dexamethasone 0.1%, neomycin sulfate 3.5 mg/mL and polymyxin B sulfate 10,000 units/mL. The solution is supplied in 5-mL bottles.
Maxitrol and Dexacidin ointment is also available in 3.5-gm ophthalmic tubes. It is preserved with methylparaben 0.05% and propylparaben 0.01%. The vehicle is white petrolatum, and it also contains anhydrous liquid lanolin. It is important to be aware of the lanolin because some patients are allergic to lanolin in cosmetics and lotions.
Effective against bacteria
Neomycin is effective against both gram-positive and gram-negative bacteria. Polymyxin B is active against gram-negative bacteria. Good coverage can be expected against most strains of Staphylococcus aureus, Pseudomonas aeruginosa, Hemophilus influenzae, Neisseria species and Escherichia coli. This combination usually provides inadequate coverage against Serratia marcescens and Streptococcus pneumoniae.
Allergic reactions
We have been trained to be concerned about allergic reaction to neomycin. The dexamethasone suppresses the inflammatory response, and I cannot remember an allergic reaction in the past 15 years of prescribing this drop or ointment.
A greater concern is increased intraocular pressure (IOP) or the possibility of masking a herpes simplex infection. Other issues are fungal infection and bacterial strains resistant to the antibiotics in this drop/ointment. As I have mentioned in other columns, the correct diagnosis is imperative before you begin treatment with a steroid.
Treatment plans
Tips for using Maxitrol and Dexacidin |
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During postoperative cataract therapy, this drop is most often used four times daily for 1 to 2 weeks after cataract surgery. While it is used initially to prevent infection, the steroid also reduces the natural inflammatory response to surgical injury. Dexamethasone helps reduce scarring and the anterior chamber reaction after cataract surgery.
To treat phlyctenular reaction, use the drop four times daily for 5 days in the affected eye and taper to three times daily on day 6, twice daily on day 7 and once daily on day 8. Lid scrubs should also be prescribed twice daily during the treatment period.
To treat epidemic keratoconjunctivitis, prescribe the drop four times daily for 1 week for the affected eye(s). Re-evaluate at 1 week and decide whether the drop should be tapered or continued four times daily. Lubricants, saline rinses and Voltaren (diclofenac sodium, Ciba Vision) are other supportive treatments that may provide comfort for the patient.
Once the risk of secondary bacterial infection has subsided and the initial red eye response has resolved, the Maxitrol/Dexacidin may be discontinued and Flarex (fluorometholone acetate 0.1%, Alcon) or FML (fluorometholone 0.1%, Allergan) begun. The corneal infiltrates will usually reduce in density and size while on the steroid.
When the Flarex or FML is tapered, the infiltrates will often increase in size and density. Sometimes, it is necessary to slowly taper the steroid over a 2- to 6-week period. You should monitor the infiltrates and then adjust the steroid drops accordingly.
This combination drug can be used to treat acute red eye caused by hypoxia or chemical contamination of a contact lens. An acute red eye occurs most often when patients sleep in daily-wear soft lenses. The patient may present with corneal edema, ciliary flush, sometimes infiltrates and, usually, a few cells or mild flare in the anterior chamber. The eye is painful, photophobic and injected.
Prescribe Maxitrol/Dexacidin four times daily for 3 days, homatropine 2% twice daily for 3 days and ibuprofen 400 mg four times daily for 3 days. Check again in 3 days, and taper the medications if the inflammation is subsiding.
Predictable, with few complications
Even though many consider this medication an old drug with few indications, I find that Maxitrol and Dexacidin take care of the above conditions in a predictable manner with few complications.
Our cataract surgeons have tried the newer steroid/antibiotic combinations and also the nonsteroidal anti-inflammatory drugs over the past 5 years. For most patients, they are now back to using Maxitrol/Dexacidin the first week after cataract surgery.
For more than 32 years, the combination of dexamethasone, neomycin and polymyxin B has provided broad coverage for many common eye pathogens and has reduced the inflammation and injuries caused by their toxins.
After surgery, it has been a work horse in preventing infection plus reducing scarring and anterior chamber inflammation. It is readily available and is inexpensive when compared to many of the newer eye medications. It may not be in vogue, but Maxitrol/Dexacidin continues to be a reliable and effective treatment option.