April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Squeezing generic latanoprost. Are they the same?
Author Affiliations & Notes
  • Umaima Mulla
    Gartnavel General Hospital, Tennent Institute of Ophthalmology, Glasgow, United Kingdom
  • Kelvin Wong
    Gartnavel General Hospital, Tennent Institute of Ophthalmology, Glasgow, United Kingdom
  • Elizabeth Tanner
    Biomedical Engineering, University of Glasgow, Glasgow, United Kingdom
  • David Young
    Mathematics and Statistics, University of Strathclyde, Glasgow, United Kingdom
  • Alan P Rotchford
    Gartnavel General Hospital, Tennent Institute of Ophthalmology, Glasgow, United Kingdom
  • Footnotes
    Commercial Relationships Umaima Mulla, None; Kelvin Wong, None; Elizabeth Tanner, None; David Young, None; Alan Rotchford, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 537. doi:
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      Umaima Mulla, Kelvin Wong, Elizabeth Tanner, David Young, Alan P Rotchford, ; Squeezing generic latanoprost. Are they the same?. Invest. Ophthalmol. Vis. Sci. 2014;55(13):537.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Generic Latanoprost is the most widely prescribed topical anti-glaucoma. 3.5 million bottles were dispensed in England in 2011. Patients may receive different bottle types and design every month depending on the pharmacy supplier. Some patients may find the use of different bottles difficult. The purpose of this study is to assess the force required to expel a single drop of Latanoprost from different generic bottles and its effects on patients during daily usage.

 
Methods
 

Three bottles of seven preparations of generic Latanoprost (Pfizer, Actavis, Beacon, Sandoz, Teva, Tubilux, and Zentiva) were tested. A 1kN load cell was positioned horizontally with an aluminium semi cylindrical loading head attached and connected to a Zwick-Roell 250 mechanical testing unit. The bottles were inverted and force applied to expel 10 individual drops from each bottle was measured. Maximum load applied (in Newtons) during the delivery of each drop was found using Zwick-Roell computer software analysis.

 
Results
 

The mean force required was: Actavis 11.50N, Beacon 33.94N, Sandoz 15.99N, Teva 17.81N, Tubilux 19.29N, Xalatan 22.61N, Zentiva 18.82N. Using repeated measures nested general linear model analysis, this represents a statistical significance in the difference between force required from a Xalatan bottle and other manufacturers. (p<0.001).

 
Conclusions
 

The bottle requiring least force was Actavis (11.50N) and the most was Beacon (33.94N). A person’s normal grip force is 17.8-160N. This is reduced in elderly people, in neurological and rheumatoid conditions. Force required for some generic preparations was higher than the lower range of normal grip force, suggesting that patients with a weak grip force may have difficulty with expression of drops from these bottles. Bottles with lower force requirements may run out quickly due to over expression of drops. Ophthalmologists should therefore consider difficulties patients may have with differing bottle types of generic Latanoprost and prescribe accordingly.

 
 
The residual appear to be approximately normally distributed with constant variance. The coefficient of determination was 95.3% indicating a large proportion of the variability in the data was explained by the model.
 
The residual appear to be approximately normally distributed with constant variance. The coefficient of determination was 95.3% indicating a large proportion of the variability in the data was explained by the model.
 
 
The highest required force was for Beacon and the lowest for Actavis.
 
The highest required force was for Beacon and the lowest for Actavis.
 
Keywords: 503 drug toxicity/drug effects  
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