Aim: To determine the aqueous humour concentration of the acid hydrolysis products of bimatoprost and latanoprost after a single topical dose of bimatoprost 0.03% or latanoprost 0.005% in humans.
Methods: Randomised, controlled, double-masked, prospective study. 48 eyes of 48 patients scheduled for routine cataract surgery were randomised in an 8:2:2 ratio to treatment with a single 30 μl drop of bimatoprost 0.03%, latanoprost 0.005% or placebo at 1, 3, 6 or 12 h before the scheduled cataract surgery. Aqueous humour samples were withdrawn at the beginning of the surgical procedure and analysed using high-performance liquid chromatography–tandem mass spectrometry.
Results: Bimatoprost acid (17-phenyl trinor prostaglandin F2α) was detected in aqueous samples at a mean concentration of 5.0 nM at hour 1, 6.7 nM at hour 3 and 1.9 nM at hour 6 after bimatoprost treatment. After latanoprost treatment, the mean concentration of latanoprost acid (13,14-dihydro-17-phenyl trinor prostaglandin F2α) in aqueous samples was 29.1 nM at hour 1, 41.3 nM at hour 3 and 2.5 nM at hour 6. Acid metabolites were below the limit of quantitation in all samples taken 12 h after dosing and in all samples from placebo-treated patients. None of the samples from latanoprost-treated patients contained quantifiable levels of non-metabolised latanoprost. Non-metabolised bimatoprost was detected in aqueous samples at a mean concentration of 6.6 nM at hour 1 and 2.4 nM at hour 3 after bimatoprost treatment.
Conclusions: Low levels of bimatoprost acid were detected in aqueous humour samples from patients with cataract treated with a single dose of bimatoprost. Latanoprost acid concentrations in samples from patients treated with latanoprost were at least sixfold higher. These results suggest that bimatoprost acid in the aqueous humour does not sufficiently account for the ocular hypotensive efficacy of bimatoprost.
- BLQ, below the limit of quantitation
- d4, tetradeuterated
- d5, pentadeuterated
- IOP, intraocular pressure
- HPLC–MS/MS, high-performance liquid chromatography–tandem mass spectrometry
- PGF2α, prostaglandin F2α
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Published Online First 29 November 2006
Funding: This study was supported by unrestricted research grants from Allergan, and the Glaucoma Research and Education Foundation.
Competing interests: LBC has received research support from Allergan, Alcon Laboratories and Pfizer. He serves on the Speaker’s Bureau and Glaucoma Advisory Board for Allergan. DW has received speaker honoraria from Alcon Laboratories and Pfizer. YC has received speaker honoraria from Alcon Laboratories and Pfizer. AA, DFW and LAW are employees of Allergan. JH, CWY, SV and AC report no conflicts of interest.
All authors contributed substantially to the conception and design of this study and had full access to the data. A medical writer, Kate Ivins, PhD, drafted the paper under the direction of the authors and was paid by Allergan. The paper was reviewed and approved by all authors. LBC and LAW act as guarantors and accept full responsibility for the integrity of the work.
All authors included in this paper fulfil the criteria of authorship, and there is no one else who fulfils the criteria but has not been included as an author.