Penetration of ocular compartments by tetracyclines. II. An experimental study with doxycycline

Case Report: Treatment of Severe Neuroretinitis and other Sequelae Associated with Cat Scratch Disease

SIGNIFICANCE

Severe vision loss from Bartonella neuroretinitis can best be treated to improve visual outcomes with a combination of systemic corticosteroids and antibiotics. Topical ketorolac 0.5% and difluprednate 0.05% are presented as a new adjunct therapy to potentially improve visual outcomes.

PURPOSE

This case illustrates severe posterior pole complications that can occur with cat scratch disease disseminated to the eye. Combination therapy with antibiotics and corticosteroids results in better visual outcomes. Topical treatment might further enhance visual outcome by preventing inflammatory damage without significant immunosuppression.

CASE REPORT

A 17-year-old male presented with right eye vision loss. He had been hospitalized two weeks prior for optic neuritis and treated with intravenous methylprednisolone. After 3 days vision had improved from 20/200 to 20/40. After positive serology for Bartonella henselae was obtained, he was released and treated with oral rifampin, doxycycline and prednisone. Sixteen days later he regressed to 20/200 and many more ophthalmic complications were observed. After discontinuation of rifampin, oral prednisone was continued for an additional two weeks and doxycycline was continued for approximately 3 weeks. Topical drops ketorolac 0.5% BID and difluprednate 0.05% QID were used for over 6 weeks before tapering after vision returned to normal.

CONCLUSIONS

Bartonella neuroretinitis associated with preretinal hemorrhage, vitritis and subretinal hemorrhage can be successfully treated with a combination of systemic medications and topical drops. Monotherapy with doxycycline is effective and well tolerated. Rifampin can cause rapid metabolization and reduction in plasma levels of both prednisone and doxycycline and should be avoided with combined therapy. Oral prednisone and topical difluprednate are recommended to quell initial inflammation during the first few weeks. The anti-inflammatory effects of doxycycline and topical ketorolac used for longer duration may be beneficial in preventing tissue damage without systemic immunosuppression and result in better visual outcomes.

Borrelia Ocular Infection: A Case Report and a Systematic Review of Published Cases

INTRODUCTION

Lyme borreliosis can cause many diverse manifestations, also ocular disease where the diagnosis of ocular borreliosis is challenging. The primary aim was to report on the evidence of Borrelia spirochetes in the ocular tissue in presumed ocular borreliosis.

METHODS

A systematic review of pathological eye conditions was performed where Borrelia has been suspected in relevant ocular tissue, together with a case report of diagnosed uveitis with polymerase chain reaction (PCR)-confirmed Borrelia afzelii in the vitreous. The evidence for clinical and laboratory diagnosis was evaluated systematically. As a secondary aim, the treatment of ocular Borrelia infection was also evaluated for confirmed cases.

RESULTS

Thirteen includable studies were found, and after the removal of case duplicates, eleven unique cases were extracted. Apart from the present case report, 4 other cases reported strong evidence for the detection of B. spirochetes in ocular tissue. Four cases presented reasonable evidence for assumed detected Borrelia, while three additional cases showed only weak diagnostic credibility that Borrelia was detected.

CONCLUSION

This systematic review, including all reported cases and our case report, supports evidence of ocular infection of Borrelia species. Furthermore, in case of suspicion of infection and seronegativity, it is justified to look for Borrelia in eye tissue samples. In addition, microscopy without using PCR is not sufficient to confirm the diagnosis of borreliosis on ocular tissue. In the articles studied, there was no unambiguous recommendation of treatment.

Doxycycline Ameliorates the Severity of Experimental Proliferative Vitreoretinopathy in Mice

After successful surgeries for patients with rhegmatogenous retinal detachment, the most common cause of retinal redetachment is proliferative vitreoretinopathy (PVR), which causes severe vision impairment and even blindness worldwide. Until now, the major treatment for PVR is surgical removal of the epiretinal membrane, while effective treatment to prevent PVR is still unavailable. Therefore, we investigated the potential of doxycycline, an antibiotic in the tetracycline class, to treat PVR using a mouse model. We used the human retinal pigment epithelial cell line, ARPE-19, for in vitro and in vivo studies to test doxycycline for PVR treatment. We found that doxycycline suppressed the migration, proliferation, and contraction of ARPE-19 cells with reduced p38 MAPK activation and total MMP activity. Intravitreal doxycycline and topical tetracycline treatment significantly ameliorated the PVR severity induced by ARPE-19 cells in mice. PVR increased the expression of MMP-9 and IL-4 and p38 MAPK phosphorylation and modestly decreased IL-10. These effects were reversed by doxycycline and tetracycline treatment in the mouse retina. These results suggest that doxycycline will be a potential treatment for PVR in the future.

Determination of Pharmacokinetic and Pharmacokinetic-Pharmacodynamic Parameters of Doxycycline against Edwardsiella ictaluri in Yellow Catfish (Pelteobagrus fulvidraco)

This study aimed to examine the pharmacokinetics of doxycycline (DC) in yellow catfish (Pelteobagrus fulvidraco) and to calculate related pharmacokinetic-pharmacodynamic (PK/PD) parameters of DC against Edwardsiella ictaluri. The minimum inhibitory concentration of DC against E. ictaluri was determined to be 500 µg/L. As the increase of oral dose from 10 to 40 mg/kg, the area under the concentration vs. time curve from 0 to 96 h (AUC_0-96) values were considerably increased in gill, kidney, muscle and skin, and plasma, except in liver. C_max values exhibited a similar dose-dependent increase trend in plasma and tissues except in liver, but other PK parameters had no apparent dose-dependence. The PK/PD parameter of the ratio of AUC_0-96 to minimum inhibitory concentration (AUC_0-96h/MIC) was markedly increased in plasma and tissues dose-dependently except in liver, but %T > MIC values were increased only moderately at some dose groups. After receiving the same dose with disparate time intervals from 96 to 12 h, the AUC_0-96h/MIC was distinctly increased in plasma and tissues, but the %T > MIC had a decreasing trend. When administering 20 mg/kg with a time interval of 96 h, the AUC_0-96h/MIC values were consistently >173.03 h and the %T > MIC values were above 99.47% in plasma and all tissues. These results suggest that administration of DC at 20 mg/kg every 96 h is a preferable regimen in yellow catfish.

Stepwise candidate drug screening for myopia control by using zebrafish, mouse, and Golden Syrian Hamster myopia models

Background

We developed a preclinical protocol for the screening of candidate drugs able to control myopia and prevent its progression. The protocol uses zebrafish, C57BL/6 mice, and golden Syrian hamster models of myopia.

Methods

A morpholino (MO) targeting the zebrafish lumican gene (zlum) was injected into single-cell zebrafish embryos, causing excessive expansion of the sclera. A library of 640 compounds with 2 matrix metalloproteinase (MMP) inhibitors (marimastat and batimastat), which have the potential to modulate scleral remodelling, was screened to identify candidates for mitigating scleral diameter expansion in zlum-MO-injected embryos. The myopia-prevention ability of compounds discovered to have superior potency to inhibit scleral expansion was validated over 4 weeks in 4-week-old C57BL/6 mice and 3-week-old golden Syrian hamsters with form-deprivation myopia (FDM). Changes in the refractive error and axial length were investigated. Scleral thickness, morphology of collagen fibrils in the posterior sclera, messenger RNA (mRNA) expressions, and protein levels of transforming growth factor-β2 (TGF-β2), tissue inhibitor of metalloproteinase-2 (TIMP-2), MMP-2, MMP-7, MMP-9, and collagen, type I, alpha 1 (collagen Iα1) were investigated in C57BL/6 mice, and MMP-2, MMP-9, and MMP activity assays were conducted in these mice.

Findings

In the zebrafish experiment, atropine, marimastat, batimastat, doxycycline, and minocycline were the drugs that most effectively reduced expansion of scleral equatorial diameter. After 28-day treatment in diffuser-wearing mice and 21-day treatment in lid-sutured hamsters, myopic shift and axial elongation were significantly mitigated by eye drops containing 1% atropine, 50 µM marimastat, 5 µM batimastat, or 200 µM doxycycline. MMP-2 mRNA expression in mouse sclera was lower after treatment with atropine, marimastat, batimastat, or doxycycline. The protein levels and activity of MMP-2 and MMP-7 were significantly reduced after treatment with atropine, marimastat, batimastat, doxycycline, and minocycline. Furthermore, scleral thickness and collagen fibril diameter were not lower after treatment with atropine, marimastat, batimastat, or doxycycline than those of occluded eyes.

Interpretation

Stepwise drug screening in a range of models from zlum-MO-injected zebrafish to rodent FDM models identified effective compounds for preclinical myopia control or prevention. On the basis of the 640 compounds that were screened, MMP inhibitors may offer alternatives for clinical trials.

Funding

This research was supported by grants from Taiwan's Ministry of Science and Technology and Ministry of Health and Welfare.

Therapeutic measures for sulfur mustard-induced ocular injury

The use of sulfur mustard (SM) in global terrorism is still a relevant threat to both civilian population and military personnel. Casualties exposed to SM may present mild, moderate or severe acute ocular lesions followed by a complete ocular resolution, chronic lesions or re-emerged ocular pathologies after a latent period. Current treatment for SM-induced ocular injury is based mainly on the clinical manifestation at the different stages of the injury and includes pharmaceutical and surgical interventions. These therapeutic measures are beneficial but not sufficient, and the ocular injury remains a continuous challenge for medical professionals. This review focuses on treatment experience carried out in humans and studied in animal models, for both SM-induced ocular acute injury and late pathology. In general, therapeutic measures are based on clinical features of the ocular injury or on the involvement of specific factors during the ocular injury that point out towards potential treatments. Anti-inflammatory treatments and limbal stem cell transplantation techniques were developed based on the clinical manifestation of the ocular injury. Optional therapies for impaired corneal innervation and endothelium are suggested for future research. Additionally, studies on potential treatments with anti-matrix metalloproteinase (MMP), anti-vascular endothelial growth factor (VEGF) and anti-IL-6 agents are discussed. Consequently, future studies may reveal the potential of additional pharmacological and biological treatments or advanced cellular and molecular biology methods to serve as novel therapeutic measures and techniques for this complicated ocular injury.

Pharmacokinetics and tissue distribution of doxycycline after oral administration of single and multiple doses in horses

OBJECTIVE

To determine pharmacokinetics, safety, and penetration into interstitial fluid (ISF), polymorphonuclear leukocytes (PMNLs), and aqueous humor of doxycycline after oral administration of single and multiple doses in horses.

ANIMALS

6 adult horses.

PROCEDURE

The effect of feeding on drug absorption was determined. Plasma samples were obtained after administration of single or multiple doses of doxycycline (20 mg/kg) via nasogastric tube. Additionally, ISF, PMNLs, and aqueous humor samples were obtained after the final administration. Horses were monitored for adverse reactions.

RESULTS

Feeding decreased drug absorption. After multiple doses, mean +/- SD time to maximum concentration was 1.63 +/- 1.36 hours, maximum concentration was 1.74 +/- 0.3 microg/mL, and elimination half-life was 12.07 +/- 3.17 hours. Plasma protein binding was 81.76 +/- 2.43%. The ISF concentrations correlated with the calculated percentage of non-protein-bound drug. Maximum concentration was 17.27 +/- 8.98 times as great in PMNLs, compared with plasma. Drug was detected in aqueous humor at 7.5% to 10% of plasma concentrations. One horse developed signs of acute colitis and required euthanasia.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that doxycycline administered at a dosage of 20 mg/kg, PO, every 24 hours will result in drug concentrations adequate for killing intracellular bacteria and bacteria with minimum inhibitory concentration < or = 0.25 microg/mL. For bacteria with minimum inhibitory concentration of 0.5 to 1.0 microg/mL, a dosage of 20 mg/kg, PO, every 12 hours may be required; extreme caution should be exercised with the higher dosage until more safety data are available.

Ocular penetration of oral doxycycline in the horse

OBJECTIVE

To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation.

RESULTS

Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration.

CONCLUSIONS

Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.

Investigations on the ocular pharmacokinetics of bendazac in rabbits

The ocular pharmacokinetics of bendazac were studied in rabbits, following intravenous administration of bendazac lysine. The compound and its 5-hydroxyderivative were determined in different eye compartments and plasma by radioassay, using [14C]bendazac, and HPLC. The highest concentrations were found in the iris and in descending order in the ciliary body, retina, cornea, tears, aqueous humor, vitreous, and lens. The time course of concentrations in the plasma, aqueous and vitreous humor, ciliary body, and retina showed kinetics described by the exponential equation y = aebx with a half-life of 2.47, 4.56, 3.59, and 3.22 hr, respectively; in the lens the half-life was 17.77 hr.