Variation in Number of Doses, Bottle Volume, and Calculated Yearly Cost of Generic and Branded Latanoprost for Glaucoma.

PURPOSE

To evaluate discrepancies in doses per bottle, bottle fill volume, and cost among branded and generic formulations of latanoprost.

DESIGN

Comparative economic analysis.

METHODS

This study was conducted at the Ruiz Department of Ophthalmology and Visual Science at The University of Texas Health Science Center at Houston (UTHealth). Four regionally available latanoprost formulations were measured. Number of drops per bottle and actual bottle fill volume were measured for a calculated sample size (10 bottles). Annual cost (using average wholesale price), days use per bottle, drops per milliliter, and number of bottles used per year were calculated. Data were summarized using mean and standard deviation; 1-way analysis of variance and post hoc Tukey's studentized range test were used for comparing means among manufacturers.

RESULTS

Pfizer's branded lantanoprost, Xalatan (New York, New York, USA), had the largest fill volume (P < .001). Pfizer had the highest yearly cost at $1198 (P < .001), whereas Akorn (Lake Forest, Illinois, USA) and Bausch & Lomb (Rochester, New York, USA) had the lowest ($184 and $201, respectively). Pfizer and Bausch & Lomb had the most drops per bottle (87.3 and 88.7, respectively), which was statistically more (P < .001) than either Akorn or Sandoz (Princeton, New Jersey, USA) (77.6 and 76.6, respectively), but there was no statistical difference among the standard deviation of drops per bottle (Levene 0.14).

CONCLUSIONS

Annual cost and number of doses per bottle, factors important to patients, vary significantly depending on the manufacturer of latanoprost. Practitioners can better advise patients by being aware of these differences.