Prophylactic Effectiveness of Tobramycin-Dexamethasone Eye Drops Compared with Tobramycin/Vehicle Eye Drops in Controlling Post-Surgical Inflammation in Cataract Patients

Ricardo Notivol; Dina Amin; Anna Whitling; David Wells; Margaret Kennedy; Paul C. Cockrum; The International TobraDex Study Group

Disclosures

Clin Drug Invest. 2004;24(9) 

In This Article

Discussion

This study was performed in European countries and in Brazil, with all sites following the same study procedures. The study was conducted in patients scheduled for cataract extraction by phacoemulsification technique followed by implantation of a posterior chamber intraocular lens. Cataract extraction with a posterior chamber intraocular lens implantation was chosen as a routine ocular surgical procedure model as well as a standard controlled, inflammation model. The known cause and onset of ocular clinical inflammation and the high reproducible response are considered the main advantages of this model. Furthermore, the duration of the study (23 days) was sufficient to evaluate the effect of TobraDex® ophthalmic suspension compared with Tobrex®/vehicle. Tobrex®/vehicle was selected for the treatment of the control group instead of placebo, since it was considered unethical to leave patients assigned to this arm with no antibiotic coverage and to put them at risk of endophthalmitis.[4] For practical logistic reasons, anterior chamber inflammation (the primary efficacy variable) was measured by slit-lamp examination rather than by the laser flare-cell meter.[26,27] Although flare-cell meters have demonstrated high sensitivity for flare measurements, it has been reported that slit-lamp is highly reliable to detect a low number of cells.[28]

The two treatment groups were comparable in age, race, iris colour and baseline scores of primary and secondary efficacy parameters, although the number of females in the Tobrex®/vehicle arm was significantly higher than in the TobraDex® group. This finding did not affect the clinical outcome of the study. Efficacy results were consistent at all sites except one; this site (2193) had the lowest rate (14%) of patients completing all study visits.

The primary objective of the study, i.e. to evaluate the superiority of an antibiotic/corticosteroid combination (TobraDex®) compared with an anti-biotic alone (Tobrex®) was met. Cells and flare together are the most reliable measure of ocular inflammation following cataract surgery. The results confirmed the superiority of TobraDex® over Tobrex®/vehicle, both dosed four times daily for 23 days in the primary parameter (anterior chamber inflammation as aqueous reaction, defined as the sum of cells and flare scores). These positive results for TobraDex® in the primary parameter were complemented with similar favourable results in secondary efficacy parameters including physician's impression of inflammatory response.

The higher incidence of adverse events reported in the Tobrex®/vehicle group may be explained by the lack of anti-inflammatory activity in that group resulting in an increased occurrence of hyperaemia, corneal oedema, increased fibrin and conjunctivitis.

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