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Alan Yee, Chau-Minh Phan, Vivian Chan, Miriam Heynen, Lyndon William Jones; The uptake and release kinetics of myristamidopropyl dimethylamine (MAP-D) from contact lenses using radioactive labelling.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1177.
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© ARVO (1962-2015); The Authors (2016-present)
Biocides are an important disinfecting component commonly found in contact lens (CL) multipurpose solutions (MPS). During the disinfection step, the uptake of biocides into CL materials can significantly reduce the efficacy of the MPS to disinfect the lens. An increased release of biocides from the CL can lead to clinical complications such as discomfort and corneal staining. However, detection methods using chromatography and spectrometry can be time-consuming and have low sensitivity. The purpose of this study was to evaluate the uptake and release of myristamidopropyl dimethylamine (MAP-D; ALDOX®) using a radiolabel method.
Radioactive (14C) MAP-D was purchased from Moravek Inc. (CA, USA). Five soft CL materials (lotrafilcon B, balafilcon A, senofilcon A, etafilcon A, omafilcon A) were tested (N=4). The lenses were incubated in PBS (ISO 18369-3) solution containing 2mL of 14C radioactive MAP-D (5µg/mL) for 8 hours, followed by a release period in PBS for 16 hours. The cycle was continued over a 7-day period with a new replenishing solution for each day. The samples were counted for their radioactive signal (CPM) using the LS6500 Beckman Coulter liquid scintillation beta counter (ON, CA). A standard curve was used to convert CPM to µg of MAP-D.
After 7-days, the silicone hydrogel (SH) lenses, lotrafilcon B (36.21±0.42µg), balafilcon A (36.29±1.15µg) and senofilcon A (35.54±1.37µg) had a significantly greater uptake of MAP-D compared to the conventional hydrogel (CH) lenses, etafilcon A (7.66±1.19µg) and omafilcon A (6.54±0.94µg) (p<0.01). However, the percent of MAP-D released was higher for CH lenses, etafilcon A (80%), omafilcon A (93%) compared to SH lenses, lotrafilcon B (25%), balafilcon A (19%) and senofilcon A (19%) over the 7-days (p<0.01).
Radioactive labelling offers a highly sensitive and accurate way of assessing the uptake and release kinetics of MAP-D to CL materials. Greater uptake of MAP-D occurs to SH materials, and the release of MAP-D is relatively minor. While CH materials take up only low amounts of MAP-D, the majority of it is easily released from these materials.
This is a 2020 ARVO Annual Meeting abstract.
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