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Stephanie BRIAN, Christine Jayat, Aurore Desmis, Jean-Sebastien Garrigue; Pharmaceutical Evaluation Of The Quality And Delivered Dose Of US Latanoprost Generics. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5103.
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Glaucoma is the second most common cause of blindness in the US, and effective intraocular pressure (IOP) lowering therapies are mandatory. Latanoprost eye drops (0.005%), the most widely-used glaucoma medication, has proven effective at managing elevated IOP is now available in generic form. Generics must be identical in strength, quality, shelf-life and efficacy. Since latanoprost is a very sensitive prostaglandin that needs to be stored refrigerated, even slight changes in the packaging and composition might result in drug degradation. The aim of the study was to evaluate the delivery dose of the generics available in the US at purchase, through shelf-life and in-use conditions to address efficacy and safety questions such as the delivered dose which may impact long-term IOP control.
Five generics of latanoprost 0.005% eye drops were bought in the US (Bausch&Lomb, Falcon, Greenstone, Mylan, American Regent) and compared to Xalatan (Pfizer) in terms of physical (pH, osmolality, drop weight) and chemical characterization by HPLC (active ingredient, degradation products and benzalkonium chloride contents). The stability plan was based on notice of products which indicates that products are stable over 8 days at 40°C (shipment condition) then 6 weeks after opening for use(one drop per day) at room temperature up to 25°C. This comparative assessment is planned at purchase and shelf life.
Latanoprost delivery dose varied between 0.93µg to 1.37µg (Xalatan about 1.13 µg). Differences in chemical results and drop weight were noticed between samples from the beginning and magnified after storage 8 days at 40°C. The evaluation of degradation products proved that the quality of the active ingredient is heterogeneous in particularly for 5-trans latanoprost ranging from <0.10% to 2.5% in generics (about 1.6% in Xalatan). For physical characterization, no major differences were noticed to date (from purchase) with pH values about 6.7 and osmolality about 270 mOsm/kg.
In terms of latanoprost delivered dose, the delta at purchase between Xalatan and some generics can be superior to ±10% (up to ±20%). Thus, the right therapeutic dose might not always be delivered with certain generics and patients might be at risk of uncontrolled IOP.
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