La conjunctivitis is a very common condition, both in adults and children, and can have a wide variety of aetiologies, infectious and non-infectious. In most cases of infectious conjunctivitis, the origin is viral, but a bacterial aetiology is also possible, usually recognisable by the presence of purulent discharge.
In these cases, effective treatment requires both the elimination of the inflammation of the ocular surface and the eradication of the responsible bacterial strain. For this reason, although conjunctivitis is often self-limiting in nature, patients are usually prescribed a broad-spectrum topical antibiotic. Moreover, since conjunctivitis in the active phase is best controlled with preparations containing steroids, combinations of steroids and topical antibiotics are often used.
The combination of steroid and antibiotic treatment is also necessary because microbiological evaluation is not routinely performed in the case of conjunctivitis.
The administration of these combinations also has numerous advantages, which include:
- better compliance;
- lower costs;
- the reduction of the potential wash-out effect.
How to choose a steroid/antibiotic combination
The choice between the different available fixed steroid/antibiotic combinations depends on the pattern of bacterial resistance to the antibiotic included in the formulation. One of the available fixed steroid/antibiotic combinations contains dexamethasone and netilmicin (specifically, 0.1% dexamethasone and 0.3% netilmicin), and is appropriate for all ocular inflammatory conditions for which a corticosteroid is indicated and where a superficial bacterial ocular infection or risk of bacterial ocular infection is present.
Dexamethasone is one of the most widely used corticosteroids in ophthalmology and has proven highly effective in the treatment of ocular inflammation. The antibiotic component of this combination, netilmycin, is a third-generation aminoglycoside characterised by:
- a broad spectrum of activity, including methicillin-resistant strains;
- a low level of conjunctival and corneal toxicity;
- a high rate of efficacy in the treatment of bacterial conjunctivitis.
Moreover, this combination has also been shown to be safe and effective in controlling ocular inflammation after cataract surgery.
Efficacy of the combination netilmycin/dexamethasone in the treatment of bacterial conjunctivitis
The combination netilmycin/dexamethasone in the treatment of external ocular inflammation requiring antibiotic treatment has proven effective in reducing the signs and symptoms of conjunctival inflammation and conjunctival discharge.
The extent of the reduction in conjunctival hyperemia obtained after treatment is in fact 70%, with no rebound effect at the end of therapy. Furthermore, the response rate (i.e. the percentage of patients showing a clinically significant improvement) is approximately 90%.
These results also proved to be equivalent to those of the dexamethasone/tobramycin combination. In fact, one studio A multicentre double-blind equivalence study, conducted on approximately 140 patients, compared the efficacy of the dexamethasone/netilmycin combination with that of the dexamethasone/tobramycin combination in the treatment of external ocular inflammation requiring antibiotic treatment.
The results of the study showed that the two fixed steroid/antibiotic combinations were equivalent in reducing signs and symptoms.
The data also confirm that bacterial pathogens are isolated from a low percentage of patients with clinical signs of conjunctivitis (one third in the study), but that this result does not affect the clinical efficacy of a steroid/antibiotic combination. However, a high eradication rate was observed in the case of infection in all patients, confirming the efficacy of aminoglycosides in the treatment of infections of the anterior segment of the eye.
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