Drug Reservoir Function of Human Amniotic Membrane

Purpose: The aim of the study was the quantitative pharmacokinetic evaluation of drug release from pretreated amniotic membrane (AM) in vitro. Methods: Cryopreserved AM pieces soaked in 3% ofloxacin ophthalmic solution were mounted in vertical Franz-diffusion cell system equipped with autosampler. In vitro release of ofloxacin was determined by quantitative absorbance measurement carried out with a UV spectrophotometer (wavelength 287 nm). Three groups were created according to the duration of soaking: 60 (Group 1), 120 (Group 2), and 180 (Group 3) minutes. Released amount of ofloxacin pro 1 cm(2) of AM (mu g/cm(2)) was calculated in the period of 1 to 450 min. Results: Ofloxacin was detectable in the acceptor phase 1 min after mounting in all groups. Until 120 min, rapid increase of released ofloxacin could be observed. From 120 to 450 min, the amount of released ofloxacin showed a slower increasing pattern. Released ofloxacin in Group 1 was significantly lower than in Group 2 after 90 min (19.4 +/- 10.4 mu g/cm(2), 51.6 +/- 20.7 mu g/cm(2), respectively, P = 0.044). In Group 3, cumulative drug release was higher than in Group at all timepoints. No significant difference could be demonstrated between Groups 2 and 3 at only 1 min timepoint. Conclusion: Significant ofloxacin reservoir capacity of a single human amniotic layer could be demonstrated in vitro. AM acted as an ofloxacin slow release device for upto 7 h in vitro, depending on the duration of pretreatment of AM. Individual pretreatment of AM could increase beneficial effects of AM transplantation, especially in infectious keratitis.