Intracameral ketorolac concentration at the beginning and end of cataract surgery following preoperative topical ketorolac administration

Douglas A Katsev,1 Cailyn C Katsev,1 Jen Pinnow,2 Catherine M Lockhart3 1Santa Barbara Surgery Center, Santa Barbara, CA, 2Pinnow Consulting, Bellingham, WA, 3Omeros Corporation, seattle, WA, USA Purpose: To evaluate the intracameral concentration of ketorolac tromethamine (ketorolac) at the beginning and end of cataract surgery following preoperative topical administration.Setting: Santa Barbara Surgery Center, Santa Barbara, CA, USA.Design: This was a pre–post, interventional, single-arm study.Patients and methods: Patients undergoing cataract extraction and lens replacement (CELR) were eligible. Written informed consent was obtained from 14 patients who were prescribed topical ophthalmic ketorolac according to the surgeon’s usual practice beginning the day prior to surgery. The surgeon withdrew 100 µL of aqueous humor from the operative eye immediately prior to the initial surgical incision and again just prior to final anterior chamber reinflation and wound closure. Ketorolac concentrations in the intracameral fluid samples were measured.Results: Thirteen of 14 patients used four doses of ketorolac the day prior to surgery as directed, and one patient used three doses. On the day of surgery, all 14 patients administered one drop of topical ketorolac on awakening and one drop after arriving at the surgery center. Preoperative ketorolac concentrations for the 12 patients from whom samples were collected ranged from 4.9 to 369 ng/mL. End-of-procedure sample concentrations ranged from <1.0 (the lower limit of quantification [LLOQ]) to 6.32 ng/mL, with eight of 12 patients having ketorolac levels below the LLOQ. Conclusion: At-home compliance with topical ketorolac was good, with 92.9% of patients using it as directed. Following CELR, levels of ketorolac in the aqueous humor were low, and 66.7% of patients had undetectable levels. Keywords: cataract surgery, NSAIDs, ketorolac, topical administration, intracameral drug concentratio

The methane cycle in ferruginous Lake Matano.

In Lake Matano, Indonesia, the world's largest known ferruginous basin, more than 50% of authigenic organic matter is degraded through methanogenesis, despite high abundances of Fe (hydr)oxides in the lake sediments. Biogenic CH₄ accumulates to high concentrations (up to 1.4 mmol L⁻¹) in the anoxic bottom waters, which contain a total of 7.4 × 10⁵ tons of CH₄. Profiles of dissolved inorganic carbon (ΣCO₂) and carbon isotopes (δ¹³C) show that CH₄ is oxidized in the vicinity of the persistent pycnocline and that some of this CH₄ is likely oxidized anaerobically. The dearth of NO₃⁻ and SO₄²⁻ in Lake Matano waters suggests that anaerobic methane oxidation may be coupled to the reduction of Fe (and/or Mn) (hydr)oxides. Thermodynamic considerations reveal that CH₄ oxidation coupled to Fe(III) or Mn(III/IV) reduction would yield sufficient free energy to support microbial growth at the substrate levels present in Lake Matano. Flux calculations imply that Fe and Mn must be recycled several times directly within the water column to balance the upward flux of CH₄. 16S gene cloning identified methanogens in the anoxic water column, and these methanogens belong to groups capable of both acetoclastic and hydrogenotrophic methanogenesis. We find that methane is important in C cycling, even in this very Fe-rich environment. Such Fe-rich environments are rare on Earth today, but they are analogous to conditions in the ferruginous oceans thought to prevail during much of the Archean Eon. By analogy, methanogens and methanotrophs could have formed an important part of the Archean Ocean ecosystem