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Alexander Pleet, Medi Eslani, Ali R Djalilian, Ahmad Aref; The effects of brimonidine on human Meibomian gland epithelial cells. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4922.
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Topical eye drops remain the cornerstone of treatment for glaucoma. It has been estimated that nearly 60% of medically treated patients with glaucoma report ocular surface disease symptoms, including dry eye. Alphagan-PTM which contains 0.15% brimonidine and 0.005% PuriteTM as a preservative is a common glaucoma medication. Its generic form includes 0.2% brimonidine with 0.005% benzalkonium chloride (BAK) as a preservative. We evaluated the effects of brimonidine eye drops on immortalized human Meibomian gland epithelial cells (MGC) in vitro.
MGCs (kindly provided by David Sullivan) were first expanded in serum-free medium and then differentiated in the presence of 10% serum for 1 week. The cells were exposed to different concentrations of brimonidine and preservatives in cell culture media for 3 days: brimonidine 0.15% (preservative-free), brimonidine 0.02% + 0.0005% BAK (1:10 dilution of the drop form), Alphagan-PTM 0.015% (1:10 dilution of the drop form, containing 0.0005% PuriteTM), and PuriteTM 0.005%. Phosphate Buffered Saline (PBS) was used as a control. Apo-Tox-GloTM and MTT assays were used to assess cytotoxicity and viability. LipidTOXTM staining was used to assess the neutral lipid accumulation inside the MGCs.
The formulation of brimonidine 0.15% (without any preservatives or additives) significantly decreased viability and lipid content of MGCs while significantly increasing cytotoxicity by 2.5 fold compared to control (P < 0.001 for all comparisons). Exposure to PuriteTM 0.005% did not have noticeable effects on viability or cytotoxicity of MGCs (P > 0.1), whereas it significantly reduced their lipid content by 3 fold (P < 0.001). However, final concentration one-tenth of the original Alphagan-PTM or brimonidine eye drop did not alter viability or lipid content of MGCs (P > 0.1).
These studies demonstrate that the chemical form of brimonidine in concentrations used in eye drops is toxic to the MGCs in vitro. PuriteTM in the concentration used in Alphagan-PTM is not toxic to the MGCs, but it does affect their lipid content.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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