Comparative Evaluation of Physical Properties of 3 Commercially available Generic Brands of Latanoprost with Xalatan

Abstract

 

Purpose:

 

The aim of the study was to compare the eye drop volume dispensed, total number of drops dispensed per vial and physical properties (pH, density and relative viscosity of the drop) of 2.5ml vials of 3 commercially available brands of Latanoprost, with Xalatan.

 

Methods:

 

At the standardized temperature of 25^o C, drop size, pH, relative viscosity and total drops per vial were calculated for the four brands of Latanoprost. Drop size was measured by weighing 10 drops individually from 5 different vials of each brand. An average of the values for each experiment was calculated. pH estimation was done by automated pHmeter and Relative Viscosity was calculated by taking an average of three readings using Oswaldt’s Viscometer. On basis of the above values, estimated absolute drug concentration per drop was derived. ANOVA was used to compare between the parameters of the 3 brands and xalatan.

 

Results:

 

There was a significant difference in the mean drop size and number of drops per bottle of each generic brand as compared to Xalatan (p <0.001) The physical properties and absolute drug concentration also varied significantly between the 3 generic brands as compared to Xalatan (Table)

 

Conclusions:

 

Significant differences were been found between the drop size, number of drops per bottle and physical properties of 3 generic commercially available brands of Latanoprost as compared to Xalatan. This study underscores the unmet need for a better quality control in the production of generic prostaglandin analogues and has implications for the IOP lowering efficacy, adverse effect profile and cost of glaucoma therapy with these drugs.  

 

Keywords: clinical laboratory testing • drug toxicity/drug effects