Background The formulation of eye drops needs to prevent any microbial contamination of the eye. For this purpose, pharmaceutical manufacturer can use: the addition of a preservative, the use of a specific packaging including a sterilising filter or a single dose packaging.

Purpose The purpose of the study is to check if the contents of eye drops indicated for the treatment of allergic conjunctivitis can be irritating for the eye.

Material and methods For this purpose, based on Vidal^® 2013, we searched for eye drops used in allergic conjunctivitis and we analysed their excipient formulas searching for those known irritating to the eye.

Results The 21 analysed formulas revealed that the benzalkonium chloride is the only preservative used in this context. Although it is classified as an excipient known to be irritating to the eye, it is still used in 11 cases and cited as an excipient with known effect in only 1 case, while for the rest it is cited as an antimicrobial preservative. The single-dose packaging is used in 7 cases while the packaging including a sterilising filter is used in only 3 cases.

Conclusion Treating allergic conjunctivitis by a potentially irritating drug can be problematic when induced irritation takes over the symptoms of the allergy. This can lead to extend the treatment beyond the expected duration and also create doubts about the efficiency of the drug. It seems wise to choose a drug that does not contain benzalkonium chloride when it comes to treat an allergic conjunctivitis. However, if this is not possible, the ophthalmologist must be aware of this risk when it comes to the clinical evaluation of the patient.

Reference

1. Vidal^® expert database 2013

ReferenceNo conflict of interest.