Preservative content in generic and brand name glaucoma eye drops

CORRESPONDENCE Preservative content in generic and brand name glaucoma eye drops Canadian generic drops are required to contain the exact concentration of drug found in brand products, but excipients1 (nonmedicinal contents) such as preservatives can vary by up to 10%.2 We are not aware of any studies that compare the preservative concentration in brand products versus Canadian-made generics. The preservative concentration of 31 generic glaucoma eye drops were reviewed and compared with their respective brands between June and December 2014. We also measured the benzalkonium chloride (BKC) concentration in Xalatan® 0.005% w/v (Pfizer, Kirkland, Que.) and 4 latanoprost generics. We determined that most generics have the same preservative as the brand products. Apo-Brimonidine P 0.15% w/v, (Apotex Inc, Toronto, Ont.), was noted to differ from brand Alphagan P 0.15% w/v, (Allergan, Markham, Ont.). The concentration of the preservative in the brand product Purite® (a trademark of Allergan Inc, Irvine, CA, USA) is 0.005% versus 0.008% weight/ volume sodium chlorite (as 25% solution stabilized) in the generic; Purite is composed of 99.5% sodium chlorite. This is slightly different but unlikely to be significant. Brand Travatan Z® 0.004%, (Alcon Canada Inc, Mississauga, Ont.), and its generic Sandoz-Travoprost (Sandoz Canada Incorporated, Boucherville, Que.) are preserved with sofZia® (a trademark of Novartis AG, Switzerland) as both manufacturers are Novartis companies. However, the generics Apo-Travoprost Z (Apotex Inc) and Teva-Travoprost Z (Teva Canada Limited, Toronto, Ont.) are claimed to be preserved with a preservative cocktail similar to the patented sofZia preservative system. Therefore, we are not certain if the preservatives in the generics for Apotex and Teva are exactly the same as the brand products. We used high-performance liquid chromatography3 to measure the concentration of BKC, claimed to be 0.02%, in the brand product Xalatan and 4 of its generics:

Apo-Latanoprost (Apotex Inc), GD-Latanoprost (GenMed, Pfizer Canada Inc, Kirkland, Que.), Sandoz Latanoprost (Sandoz Canada Inc, Boucherville, Que.), and ActLatanoprost (Actavis Pharma Company, Mississauga, Ont.) and found that BKC varied by not 410% from the brand that had a BKC concentration of 191 ⫾ 5.6 μg/ mL (  0.019% w/v). Each sample was evaluated twice. In conclusion, Canadian generic Latanoprost glaucoma drops do not vary more than 10% from the brand with respect to BKC preservative concentration. It is likely that most of the other generics have concentrations of preservatives similar to their brand products.

Disclosure: The authors have no proprietary or commercial interest in any materials discussed in this article.

Numan A.E. Hallaji, * Praveen P.N. Rao, † Graham E. Trope *

Western Hospital, Toronto, Ont; †Pharmaceutical Sciences, School of Pharmacy, Health Sciences Campus, Waterloo, Ont.

*Toronto

Correspondence to: Numan A.E. Hallaji, MBChB: [email protected]

REFERENCES 1. Canada Gazette. Regulations amending the Food and Drug Regulations (743: Non-Medicinal Ingredients). 2010;144. Available from: www.gazette.gc.ca/rp-pr/p2/2010/2010-05-26/html/sor-dors105-eng. html. Accessed April 5, 2016. 2. Minister of Public Works and Government Services Canada. Guidance for industry: pharmaceutical quality of aqueous solutions. Ottawa: Health Canada; 2005. Available from: http://publications. gc.ca/collections/Collection/H42-2-98-2005E.pdf. Accessed March 29, 2016. 3. Analysis of benzalkonium chloride on the Acclaim surfactant column by high-performance liquid chromatography. Thermo Scientific (formerly Dionex), Sunnyvale, California. Application Note 237. Can J Ophthalmol 2016;]:]]]–]]] 0008-4182/16/$-see front matter & 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcjo.2016.05.014

CAN J OPHTHALMOL — VOL. ], NO. ], ] 2016

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