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Bertram M, Allbaugh RA, Mochel JP, Peraza J, Page L, Sebbag L. Influence of Schirmer strip wetness on volume absorbed, volume recovered, and total protein content in canine tears. Vet Ophthalmol 2021; 24:425-428. [PMID: 33720492 DOI: 10.1111/vop.12876] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/31/2021] [Accepted: 02/12/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Determine the protein content and volume of tears sampled by Schirmer strips wetness ranging from 20 to 35 mm. ANIMALS STUDIED Ten healthy beagle dogs. PROCEDURES Each dog underwent 20 tear collections per day (10 sessions in each eye, spaced by ≥1 h) for 4 separate days, providing 200 tear samples for each length of wetness evaluated: 20, 25, 30, and 35 mm. A Schirmer strip was placed in each eye until the selected mm-mark was reached, calculating the volume absorbed (VA) as the difference between the post- and pre-collection weight (assuming 1 mg~1 µL for tear fluid), and the volume recovered (VR) as the amount pipetted from the tube following centrifugation. Total protein content (TPC) was measured with infrared spectroscopy. Outcome measures were compared with the Kruskal-Wallis test. RESULTS Median values for VA (µL), VR (µL) and TPC (mg/mL) were as follows: 20 mm (18, 10, 5.94), 25 mm (22, 12.5, 5.97), 30 mm (25.5, 16, 5.89), and 35 mm (31, 22.5, 7.13). Both VA and VR were significantly greater (p < .001) for Schirmer strips wetness of 35»30»25»20 mm. TPC was significantly greater (p < .001) for 35 > 20-30 mm, but not among other groups (p = 1.000). CONCLUSIONS The study established normative data to consider when canine studies use Schirmer strips to collect tears for bioanalytical purposes (eg, proteomics, pharmacokinetics). Although 35 mm yielded higher VA and VR, the higher TPC could be explained by greater disruption of ocular surface homeostasis. Absorption to 20-30 mm is the suggested length of strip wetness for bioanalytical tear collection in dogs.
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Affiliation(s)
- Morgan Bertram
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Rachel A Allbaugh
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Jonathan P Mochel
- SMART Pharmacology, Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Jacqueline Peraza
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Lauren Page
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Lionel Sebbag
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.,SMART Pharmacology, Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
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Sebbag L, Kirner NS, Wulf LW, Mochel JP. Tear Film Pharmacokinetics and Systemic Absorption Following Topical Administration of 1% Prednisolone Acetate Ophthalmic Suspension in Dogs. Front Vet Sci 2020; 7:571350. [PMID: 33195562 PMCID: PMC7652929 DOI: 10.3389/fvets.2020.571350] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/08/2020] [Indexed: 01/21/2023] Open
Abstract
The study aimed to determine the tear film pharmacokinetics following topical administration of 1% prednisolone acetate—assessing whether two drops would provide a superior kinetic profile compared to one drop—and to determine the fraction of an eye drop that reaches the systemic circulation in dogs. Two separate experiments were conducted in eight healthy Beagle dogs: (i) Instillation of 1 drop (35 μL) or 2 drops (70 μL) of 1% prednisolone acetate ophthalmic suspension in each eye, followed by tear collections with Schirmer strips from 0 to 720 min; (ii) Instillation of 1 or 2 drops of 1% prednisolone acetate in both eyes 4 times daily for 3 days, followed by blood collection 10–15 min after each topical administration on Day 3. Tear and blood samples were analyzed with high performance liquid chromatography to determine the levels of prodrug (prednisolone acetate), active metabolite (prednisolone) and total prednisolone (prednisolonetotal = prodrug + active metabolite). Prednisolone levels represented 10 and 72% of prednisolonetotal concentrations in tears and plasma, respectively, indicating a greater hydrolysis of prodrug in the blood vs. tear compartment. For eyes receiving one or two drops, tear film prednisolonetotal concentrations were high (~3.1 mg/mL) immediately following topical administration but rapidly decreased by ~45% at 1 min and ~95% at 15 min. No differences were noted between 1 vs. 2 drops in tear film prednisolonetotal concentrations (including maximal concentration, Cmax) or residual drug levels in tears at any time point (P ≥ 0.097); however, instillation of 2 drops provided a higher average tear concentration (Cavg) and overall drug exposure to the ocular surface (AUClast) over the 12-h sampling period (P = 0.009). Average plasma prednisolonetotal concentration represented ≤ 2% of the dose applied to the ocular surface, and did not differ significantly for dogs receiving 1 drop (17 ng/mL) or 2 drops (20 ng/mL) 4 times daily for 3 days (P = 0.438). In sum, topical corticotherapy is beneficial for inflammatory conditions of the canine anterior segment given the relatively high concentrations achieved in tears, although caution is warranted to prevent unwanted local or systemic adverse effects.
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Affiliation(s)
- Lionel Sebbag
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Nicolette S Kirner
- Lloyd Veterinary Medical Center, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Larry W Wulf
- PhAST Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Jonathan P Mochel
- Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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Sebbag L, Mochel JP. An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface. Med Res Rev 2020; 40:2566-2604. [PMID: 32735080 DOI: 10.1002/med.21716] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/01/2020] [Accepted: 07/15/2020] [Indexed: 12/15/2022]
Abstract
Preclinical animal studies provide valuable opportunities to better understand human diseases and contribute to major advances in medicine. This review provides a comprehensive overview of ocular parameters in humans and selected animals, with a focus on the ocular surface, detailing species differences in ocular surface anatomy, physiology, tear film dynamics and tear film composition. We describe major pitfalls that tremendously limit the translational potential of traditional laboratory animals (i.e., rabbits, mice, and rats) in ophthalmic research, and highlight the benefits of integrating companion dogs with clinical analogues to human diseases into preclinical pharmacology studies. This One Health approach can help accelerate and improve the framework in which ophthalmic research is translated to the human clinic. Studies can be conducted in canine subjects with naturally occurring or noninvasively induced ocular surface disorders (e.g., dry eye disease, conjunctivitis), reviewed herein, and tear fluid can be easily retrieved from canine eyes for various bioanalytical purposes. In this review, we discuss common tear collection methods, including capillary tubes and Schirmer tear strips, and provide guidelines for tear sampling and extraction to improve the reliability of analyte quantification (drugs, proteins, others).
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Affiliation(s)
- Lionel Sebbag
- Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.,Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Jonathan P Mochel
- Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
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Sigmund AB, Ward DA, Cox SK, Hendrix DVH. Tear film concentrations of topically applied 0.5% oxytetracycline ointment in normal canine eyes. Vet Ophthalmol 2020; 23:707-713. [PMID: 32524758 DOI: 10.1111/vop.12783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/07/2020] [Accepted: 05/10/2020] [Indexed: 01/20/2023]
Abstract
OBJECTIVE To determine the tear film levels of oxytetracycline in normal canine eyes after application of the ophthalmic ointment, Terramycin™ (0.5% oxytetracycline, polymyxin B sulfate), to guide appropriate treatment frequency. ANIMALS STUDIED Ten research beagles. PROCEDURES Ten research beagles with confirmed normal eyes were administered 0.02 mL of Terramycin™ ophthalmic ointment onto the dorsal bulbar conjunctival surface of the right eye. Tear samples were collected via dye-less Schirmer tear strips at 2, 4, 6, 8, and 12 hours post-administration. The sample for each timepoint was collected on a separate day, and concentrations of oxytetracycline were determined using high-performance liquid chromatography (HPLC). RESULTS There was a semi-logarithmic decline in the median tear concentration of oxytetracycline. The median (2.5th and 97.5th percentiles) tear concentrations of oxytetracycline at 2, 4, 6, 8, and 12 hours were 43.5 μg/mL (11.1-302.2 μg/mL), 28.7 μg/mL (8.04-113.7 μg/mL), 16.1 μg/mL (4.96-37.7 μg/mL), 9.2 μg/mL (4.52-28.1 μg/mL), and 6.11 μg/mL (4.36-26.7 μg/mL), respectively. Mean (±SD) drug recovery via HPLC was 88% (±7.5%). CONCLUSIONS Ophthalmic Terramycin™ achieves a substantially higher tear level than the MIC for common bacterial corneal pathogens up to 12 hours post-administration in normal eyes. Anti-collagenolytic tear levels were not achieved at the timepoints evaluated or with the manufacturer-prescribed dosing frequency. HPLC can be used to analyze tear concentrations of ophthalmic ointment formulations.
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Affiliation(s)
- Alex B Sigmund
- Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN
| | - Daniel A Ward
- Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN
| | - Sherry K Cox
- Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN
| | - Diane V H Hendrix
- Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN
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Pereira CS, Zulim LFC, Giuffrida R, Cruz AG, Foglia BT, Benguella H, Batista AS, Andrade SF. Antimicrobial susceptibility and minimal inhibitory concentration of bacteria isolated from the eyes of dogs with keratoconjunctivitis sicca. PESQUISA VETERINÁRIA BRASILEIRA 2019. [DOI: 10.1590/1678-5150-pvb-6200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT: The objective of this study was to evaluate the antimicrobial susceptibility profile of bacteria isolated from the eyes of dogs with keratoconjunctivitis sicca (KCS). We evaluated 65 dogs diagnosed with KCS and 30 healthy dogs (Control Group). Conjunctival swab samples were collected after KCS was diagnosed. Microbiological examinations were performed, including aerobic culture, antimicrobial susceptibility testing and minimum inhibitory concentration (MIC) determination for chloramphenicol, tobramycin, ofloxacin and moxifloxacin. MICs of the fifteen most resistant strains of Staphylococcus pseudintermedius (Staphylococcus intermedius Group, SIG) and the fifteen most resistant strains of gram-negative bacteria were determined. By percentage, the microorganisms exhibited the highest susceptibility to polymyxin B, tobramycin and chloramphenicol and the lowest to tetracycline. Three multi-drug-resistant strains of SIG were detected: one displayed isolated susceptibility to cefazolin, another to vancomycin, and another to polymyxin B and amikacin. The species of bacteria isolated from the eyes of dogs with KCS presented variable susceptibility to the antibiotics tested. We found evidence of the emergence of quinolone-resistant strains of SIG and further evidence of increased ocular prevalence. These findings reinforce the need to identify the bacteria involved and their antimicrobial susceptibility profile, as secondary infections can serve as exacerbating and perpetuating factors in KCS.
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Sebbag L, Yan Y, Smith JS, Allbaugh RA, Wulf LW, Mochel JP. Tear Fluid Pharmacokinetics Following Oral Prednisone Administration in Dogs With and Without Conjunctivitis. J Ocul Pharmacol Ther 2019; 35:341-349. [PMID: 31070497 PMCID: PMC6659750 DOI: 10.1089/jop.2019.0020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose: To describe the pharmacokinetics (PK) of prednisone and prednisolone in tear fluid of dogs receiving oral prednisone at anti-inflammatory to immunosuppressive doses and to assess the impact of induced conjunctivitis on lacrimal drug levels. Methods: Six healthy Beagle dogs were administered 4 courses of prednisone at 0.5, 1.0, 2.0, and 4.0 mg/kg given orally once a day for 5 days. At steady state, topical histamine was applied to induce mild (1 mg/mL) or severe (375 mg/mL) conjunctivitis in 1 eye of each dog and tear samples were collected from both eyes at selected times. Prednisone and prednisolone were quantified in tears by liquid chromatography-mass spectrometry. Results: Lacrimal prednisone and prednisolone concentrations ranged from 2 to 523 ng/mL and 5 to 191 ng/mL, respectively. Drug concentrations were overall greater in dogs receiving higher doses of prednisone, but were not correlated with tear flow rate. Eyes with conjunctivitis often had larger amounts of prednisone and prednisolone in tear fluid compared to control eyes (up to +64%), but differences were not statistically significant. Significantly greater, but clinically insignificant, levels of prednisolone were found in eyes with severe versus mild conjunctivitis for oral prednisone doses ≥1.0 mg/kg. Conclusions: Disruption of the blood-tear barrier with conjunctivitis did not significantly affect drug levels in tears. Based on drug PK in tears, oral prednisone is likely safe for the management of reflex uveitis and ocular surface diseases. However, further prospective trials using systemic corticotherapy in diseased animals are warranted to confirm findings from this preclinical study.
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Affiliation(s)
- Lionel Sebbag
- 1Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa.,2Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Yuqi Yan
- 3Lloyd Veterinary Medical Center, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Joe S Smith
- 2Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa.,4Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Rachel A Allbaugh
- 1Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Larry W Wulf
- 5PhAST Laboratory, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Jonathan P Mochel
- 2Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa
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Varga M. Cardiorespiratory Disease. TEXTBOOK OF RABBIT MEDICINE 2014. [PMCID: PMC7150336 DOI: 10.1016/b978-0-7020-4979-8.00011-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
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Czerwinski SL, Lyon AW, Skorobohach B, Léguillette R. Pharmacokinetic analysis of topical tobramycin in equine tears by automated immunoassay. BMC Vet Res 2012; 8:141. [PMID: 22909398 PMCID: PMC3489562 DOI: 10.1186/1746-6148-8-141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 08/14/2012] [Indexed: 11/24/2022] Open
Abstract
Background Ophthalmic antibiotic therapy in large animals is often used empirically because of the lack of pharmacokinetics studies. The purpose of the study was to determine the pharmacokinetics of topical tobramycin 0.3% ophthalmic solution in the tears of normal horses using an automated immunoassay analysis. Results The mean tobramycin concentrations in the tears at 5, 10, 15, 30 minutes and 1, 2, 4, 6 hours after administration were 759 (±414), 489 (±237), 346 (±227), 147 (±264), 27.6 (±28.4), 14.8 (±66.6), 6.7 (±18.6), and 23.4 (±73.4) mg/L. Mean tobramycin concentration was maintained above the MIC90 for commonly isolated bacteria for 68.5 min. Conclusion A single dose of topical tobramycin resulted in therapeutic concentrations of tobramycin in the tears for 1 h after administration. Therapeutic levels of tobramycin remained in equine tears 6 times longer than was reported in rabbit tears.
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Affiliation(s)
- Sarah L Czerwinski
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
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Thomasy SM, Covert JC, Stanley SD, Maggs DJ. Pharmacokinetics of famciclovir and penciclovir in tears following oral administration of famciclovir to cats: a pilot study. Vet Ophthalmol 2012; 15:299-306. [PMID: 22339892 DOI: 10.1111/j.1463-5224.2011.00984.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To validate a means of collecting tears from cats, develop an assay for quantifying famciclovir and penciclovir in tears, and to assess famciclovir and penciclovir concentrations and pharmacokinetics in the tears of cats being treated orally with famciclovir for suspected herpetic disease. ANIMALS Seven client-owned cats. PROCEDURES Cats were treated orally with a median (range) dose of 40 (39-72) mg of famciclovir/kg three times daily for at least 24 h. At various time points following famciclovir administration, tear samples were collected using Schirmer tear test strips. Tear famciclovir and penciclovir concentrations were measured using liquid chromatography-mass spectrometry, and concentration-time profiles were analyzed noncompartmentally. The relationship between famciclovir dose and tear penciclovir concentration near its maximum was evaluated using least squares linear regression. RESULTS Maximum tear famciclovir concentration of 0.305 μg/mL occurred at 2.64 h; elimination half-life was 2.28 h. Maximum tear penciclovir concentration (0.981 μg/mL) occurred 2.25 h following oral administration of famciclovir; elimination half-life was 2.77 h. A significant positive correlation was noted between famciclovir dose and tear penciclovir concentration at various time points between 0.5 and 3.75 h following drug administration (P = 0.025). Tear penciclovir concentration exceeded the concentration shown to have in vitro efficacy against feline herpesvirus (FHV-1) (0.304 μg/mL) in about half of samples collected. CONCLUSIONS Oral administration of 40 mg of famciclovir/kg to cats resulted in a tear penciclovir concentration-time profile that approximated the plasma penciclovir concentration-time profile and frequently achieved a penciclovir concentration at the ocular surface likely to be effective against FHV-1.
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Affiliation(s)
- Sara M Thomasy
- Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
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Pumphrey SA, Pizzirani S, Pirie CG. 360-degree conjunctival grafting for management of diffuse keratomalacia in a dog. Vet Ophthalmol 2011; 14:209-13. [DOI: 10.1111/j.1463-5224.2010.00864.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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