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A. Jimenez, V. González, G. Panizo, T. Martínez; SYL040012 A New siRNA-Based Treatment for Glaucoma: Pharmacokinetics and Mechanism of Action. Invest. Ophthalmol. Vis. Sci. 2010;51(13):176.
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Sylentis is developing a new product for the treatment of ocular hypertension and glaucoma. SYL040012 is a small interfering RNA (siRNA) currently in Phase I clinical trials. In these experiments, plasma pharmacokinetics and ocular fluid distribution of SYL040012 in a New Zealand white rabbit model were determined. The mechanism of action of SYL040012 was demonstrated by measurement of in vitro and in vivo gene silencing.
SYL040012 is a siRNA targeting β2- adrenergic receptor (ADRB2) and is administered as eyedrops. At different time points after administration, levels of SYL040012 were determined in plasma and ocular fluids. SYL040012 determination was carried out by a novel MS-HPLC method developed in house, with an LOOQ > 90 ng/mL.Measurement of in vitro and in vivo gene downregulation of ADRB2 was carried out by Real time PCR (RT-PCR) using Stepone plus detection system (Applied Biosystems). All RT-PCR amplifications were performed in triplicate, always including reverse transcription controls and no template controls. Results were correlated with efficacy results from SYL040012 application in a New Zealand white rabbit model of ocular hypertension induced by water loading (administration of 60 mL/Kg by oral gavage).
This is the first time that pharmacokinetic results of SYL040012, a siRNA administered in eye drops, are reported. Levels of SYL040012 in plasma were below LOOQ, this result is explained by the short half-life of SYL040012 in this medium (below 5 min). SYL040012 was determined in aqueous humour at different times after administration. Results were correlated with topically administered doses. ADRB2 gene downregulation showed a good dose-response relationship. The inhibitory concentration 50 (IC50) value was calculated to be 9.2 nM by in vitro experiments. In vivo gene downregulation was observed in cornea and ciliary body from animals treated with SYL040012.
These results showed that levels of SYL040012, a siRNA, can be measured by MS-HPLC methods. Pharmacokinetic results proved that plasma levels were below LOOQ and ocular fluid levels correlated well with administered doses. In vivo and in vitro downregulation of ADRB2 verified that the mechanism of action of SYL040012 was mediated by RNA interference.
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