Uveitis associated with topical beta-blockers

OBJECTIVE

To assess the incidence of uveitis associated with topical beta-blockers.

DESIGN

Retrospective cohort study.

SETTING

A computerized database of a health maintenance organization was used to identify patients who were prescribed metipranolol or other beta-blockers.

PATIENTS

Two groups: 1928 patients using 0.3% metipranolol and 3903 patients using other beta-blockers.

MAIN OUTCOME MEASURE

Cases of uveitis were identified by noting a prescription of a topical corticosteroid and then conducting a chart review.

RESULTS

No cases of uveitis were identified among the 5831 patients. The upper limits of the 95% confidence intervals for the incidence of uveitis in cohorts of this size are 1.87 cases per 1000 person-years of exposure for metipranolol and 1.38 for other beta-blockers.

CONCLUSION

Drug-induced uveitis from metipranolol or other beta-blocker administration is a rare event, even if a causal relationship exists.

A comparison of two regimens for the treatment of Mycobacterium avium complex bacteremia in AIDS: rifabutin, ethambutol, and clarithromycin versus rifampin, ethambutol, clofazimine, and ciprofloxacin. Canadian HIV Trials Network Protocol 010 Study Group

BACKGROUND

Bacteremia with the Mycobacterium avium complex is common in patients with the acquired immunodeficiency syndrome (AIDS), but the most effective treatment for this infection remains unclear.

METHODS

We randomly assigned 229 patients with AIDS and M. avium complex bacteremia to receive either rifampin (600 mg daily), ethambutol (approximately 15 mg per kilogram of body weight daily), clofazimine (100 mg daily), and ciprofloxacin (750 mg twice daily) (the four-drug group) or rifabutin (600 mg daily), ethambutol (as above), and clarithromycin (1000 mg twice daily) (the three-drug group). In the three-drug group the dose of rifabutin was reduced by half after 125 patients were randomized, because 24 of 63 patients had uveitis.

RESULTS

Among 187 patients who could be evaluated, blood cultures became negative more often in the three-drug group than in the four-drug group (69 percent vs. 29 percent, P<0.001). Among patients treated for at least four weeks, the bacteremia resolved more frequently in the three-drug group (78 percent vs. 40 percent, P<0.001). In the three-drug group, bacteremia resolved more often with the 600-mg dose of rifabutin than with the 300-mg dose (P=0.025), but the latter regimen was more effective than the four-drug regimen (P<0.05). The median survival was 8.6 months in the three-drug group and 5.2 months in the four-drug group (P = 0.001). The median Karnofsky performance score was higher in the three-drug group than in the four-drug group from week 2 to week 16 (P<0.05). Mild uveitis developed in 3 of the 53 patients receiving the 300-mg dose of rifabutin, an incidence about one quarter that observed with the 600-mg dose (P<0.001).

CONCLUSIONS

In patients with AIDS and M. avium complex bacteremia, treatment with the three-drug regimen of rifabutin, ethambutol, and clarithromycin leads to resolution of the bacteremia more frequently and more rapidly than treatment with rifampin, ethambutol, clofazimine, and ciprofloxacin, and survival rates are better.

Effects of different antioxidants on lens-induced uveitis

For evaluation of the effects of different free-radical scavengers on biochemical changes in lens-induced uveitis (LIU), ten male Wistar rats were sensitized for 8 weeks using bovine lens protein and Freund's adjuvant. The uveitis was induced by disruption of the lens capsule. One group of animals received superoxide dismutase and catalase (SOD/CAT); a second group of animals was treated with vitamin E. Lipid peroxides (LPO) of the retinal tissue and aqueous humor served as parameter of oxidative tissue damage. Glutathione (GSH/GSSG) of the aqueous humor was evaluated as a parameter of the tissue's redox state. For evaluation of the inflammatory response, myeloperoxidase activity (MPO) was determined in the iris/ciliary-body complex. SOD/CAT produced no improvement in the significantly (P < 0.05) elevated MPO and LPO values recorded for untreated control animals. Following vitamin E treatment the GSH/GSSG and LPO values in aqueous humor were markedly improved as compared with controls. Retinal LPO values were significantly (P < 0.05) reduced as compared with controls. No change in MPO levels was observed. The results demonstrate that enzymes such as SOD and CAT do not influence tissue damage at a significant level, whereas radical chain breakers such as vitamin E can do so. However, the inflammatory response itself is not reduced. To achieve global results, drugs are necessary that act on both free radicals produced by noninflammatory pathways and those originating from inflammation.

Intraocular production of a cytokine (CINC) responsible for neutrophil infiltration in endotoxin induced uveitis

AIMS/BACKGROUND

The subcutaneous injection of bacterial endotoxin in Lewis rats produces an acute intraocular inflammation evolving over a 24 hour period. This endotoxin induced uveitis (EIU) is characterised by a biphasic protein exudation and a cellular infiltrate composed of macrophages and polymorphonuclear neutrophils (PMNs). This model was used to study the mechanism of cellular infiltration in ocular inflammation.

METHODS

EIU was induced by a subcutaneous injection of lipopolysaccharide (LPS) (S typhimurium) at 350 micrograms/kg. The levels of cytokine induced neutrophil chemoattractant (CINC) were measured every 2 hours in the serum and in the aqueous humour by ELISA. The intraocular inflammation was quantified by protein measurement and leucocyte counting.

RESULTS

The kinetics of CINC production in the systemic circulation showed a rapid rise, peaking 2 hours after LPS injection, followed by a progressive decline over the next 8 hours. In the eye, the CINC levels increased above the serum levels 10 hours after EIU induction corresponding to the time of cellular infiltration. When leucocyte entry in the eye was inhibited by 56% and 64% with an antiadhesion molecule antibody, there was only a slight reduction in the aqueous humour CINC levels of 9% and 16%, respectively, indicating that CINC was produced by ocular tissue cells. The specific effect of CINC in the eye was confirmed when a direct intraocular injection of 250 ng of purified CINC was followed by significant PMN infiltration, in the absence of protein exudation.

CONCLUSION

The data indicate that the production of the CINC chemotactic factor by ocular tissue participates in the inflammatory reaction in EIU.

Uveitis during treatment of disseminated Mycobacterium avium-intracellulare complex infection with the combination of rifabutin, clarithromycin and ethambutol

Three patients with a cellular immunodeficiency were treated with rifabutin, clarithromycin and ethambutol for a disseminated infection with Mycobacterium avium-intracellulare complex (MAC). The patients developed uveitis, sometimes in combination with a transient rash, arthralgia, arthritis, jaundice and pseudojaundice. It seems likely that these reactions were caused by rifabutin, alone or together with other drugs such as clarithromycin. These adverse reactions probably depend on the dose, metabolism and excretion of the drug. Inhibition of cytochrome P450 seems to be an important mechanism.

Expression of inducible nitric oxide synthase in the eye from endotoxin-induced uveitis rats

PURPOSE

Inducible nitric oxide (NO) synthase (iNOS) has been implicated in the pathogenesis of endotoxin-induced uveitis (EIU). This study was undertaken to localize the cells, in the eye, which express iNOS during EIU in the rat.

METHODS

EIU was induced in Lewis rats by a single foot pad injection of 150 micrograms lipopolysaccharide (LPS) from Salmonella typhimurium. At different time intervals after LPS injection, the authors evaluated ocular inflammation (slit lamp observation), iNOS localization by in situ hybridization, and comparison of OX-42- and ED1-positive cell appearance and of glial response by specific immunohistochemistry.

RESULTS

iNOS mRNA was not detected in the iris-ciliary body nor in the retina of control rats. It was detected strongly in the epithelial cells of the iris-ciliary body at 6 hours and also in stromal cells of the ciliary processes at 16 hours after LPS injection. In the neuroretina, iNOS mRNA was observed in the inner layers 16 hours after LPS injection. iNOS-positive cells were also present on the vitreous at this time. At 6 and approximately 16 hours after LPS injection, immunohistochemistry experiments revealed a large number of OX-42- and ED1-positive cells (microglia, macrophages, or polymorphonuclear leukocytes) colocalized in part with some iNOS-positive cells in the ciliary body and in the retina. Furthermore, expression of iNOS in Müller cells cannot be excluded.

CONCLUSIONS

These observations confirm that subcutaneous injection of endotoxin dramatically induces NOS mRNA expression in the eye, and they demonstrate that epithelial cells of the iris-ciliary body and cells infiltrating the anterior segment of the eye and the retina are the major source of NO. These results support the hypothesis that both inflammatory and resident ocular cells are involved in iNOS expression during EIU.

Macrophage subpopulations and RPE elimination in the pathogenesis of experimental autoimmune pigment epithelial protein-induced uveitis (EAPU)

Experimental autoimmune pigment epithelial protein-induced uveitis (EAPU) is a new type of disease that destroys the retinal pigment epithelium (RPE), and exhibits a hitherto unknown form of progressive chorioretinal dystrophy in which neuroretinal inflammatory foci are absent. The present study was aimed at studying the expression of adhesion molecules, and the kinetics of the appearance of the main types of macrophages and other intraocular immunocompetent cell populations in the various stages of this disease. EAPU was evoked in Lewis rats by immunization with the membrane protein from bovine RPE cells containing PEP-65 as main constituent. In the uvea, increased expression of intercellular adhesion molecule-1, of class II major histocompatibility complex antigen, and of ED2 macrophage reactivity were observed closely before the onset of EAPU. Expression of these reactivities was also slightly elevated by injections of the applied adjuvants alone. The onset of EAPU was mainly characterized by initial uveal infiltrations of ED1+ macrophages and a minor population of CD4 T cells, and an increase in ED3, ED7 and perivascular ED2 reactive macrophages. This was followed by the development of focal accumulations of ED1+ cells at both sides of the Bruch's membrane-RPE layer (Dálen-Fuchs nodules) which was permeated and disintegrated at these sites. The outer choroidal layer, the anterior iridal surface, and the base of the ciliary body more frequently contained active inflammatory cells than the other uveal areas. Lymphoid cells were found scattered through the uvea, aqueous and vitreous. The sites of increased activity of ED2+ and ED3+ cells in the uvea were rather similar to those of ED1 macrophages in the various stages of EAPU. Starting from multiple foci, the process of the formation of plaque-shaped cell accumulations in severe EAPU progressed along the RPE and exhibited a chronic character. The results of this study show that ED1+, ED2+, ED3+ and ED7+ subpopulations of macrophages are actively involved in an immunopathological process in which the RPE is the target. The thickening of the plaque-shaped cell accumulations stops if the integrity of all RPE cells at that site has been affected. We postulate that this is the result of antigen elimination while additional influence of the abrogation of RPE cytokine production is presumed.

Rifabutin prophylaxis for Mycobacterium avium complex infection in patients with AIDS

Rifabutin, a macrophage-penetrating lipophilic rifamycin, has a long half-life and activity in vitro against Mycobacterium avium complex (MAC). Preliminary studies of patients with AIDS and those with AIDS-related complex defined dose-limiting toxic effects (arthralgia/arthritis and uveitis) and suggested that rifabutin alone might reduce the incidence of MAC infections. Two double-blind, randomized, placebo-controlled trials involving 1,100 subjects confirmed the safety and efficacy of low doses of rifabutin; this therapy halved the rate of MAC bacteremia and significantly reduced symptoms associated with disseminated MAC infections. Subsequent experience with rifabutin as prophylaxis for and treatment of MAC infections has generally supported its safety profile. Emergence of drug-resistant MAC causing infection in patients receiving rifabutin therapy has not been reported. Interactions with azoles and macrolides increase blood levels of rifabutin and have led to the development of uveitis in certain patients. Studies of the cost-effectiveness of rifabutin prophylaxis for MAC infection suggest that it is comparable with other preventive interventions employed in clinical practice.

Additive effect of nitric oxide and prostaglandin-E2 synthesis inhibitors in endotoxin-induced uveitis in the rabbit

The involvement of nitric oxide (NO) and prostaglandin E2 (PGE2) was investigated in a model of intraocular inflammation induced by intravitreal injection of endotoxin (lipopolysaccharide, LPS, 10 ng) in rabbits. The severity of uveitis, the myeloperoxidase (MPO) activity in iris-ciliary body, and the protein concentration in aqueous humor were determined. Nitric oxide synthase (NOS) and cyclooxygenase (COX) activities were assessed respectively by nitrite and PGE2 levels in aqueous humor. Treatment with inhibitors of NOS (NG-nitro-L-arginine methyl ester, L-NAME, 50 mg/kp i.p.) or COX (diclofenac, 30 micrograms, topically), alone or in combination, were compared to a saline-treated group. Diclofenac or L-NAME alone reduced or delayed the intensity of uveitis, and partially decreased the protein concentration in aqueous humor; diclofenac, but not L-NAME, partially reduced the polymorphonuclear leukocyte infiltration in the iris ciliary body as indicated by the MPO activity. Treatment with both inhibitors in combination diminished the clinical uveitis, the disruption of the blood-aqueous barrier and the MPO activity in the iris-ciliary body. We conclude that NO and PGE2 have additive effects in endotoxin-induced uveitis in rabbits, and that the inhibition of both pathways would improve the therapeutical management of uveitis.

Mycobacterium avium complex infection, rifabutin, and uveitis--is there a connection?

Rifabutin, an antimycobacterial agent, has been recommended by the U.S. Public Health Service as prophylaxis against infection due to Mycobacterium avium complex (MAC) in patients with AIDS. When rifabutin is administered as prophylaxis, uveitis has been reported only rarely. However, uveitis has been reported in two studies in which rifabutin was administered at higher doses in combination with an azole, a macrolide, or both for treatment of disseminated MAC infection. The uveitis that has been reported has been predominantly anterior and mild-to-moderate in nature, although severe hypopyon uveitis has occasionally been reported. No etiologic infectious agent has been isolated from any of these patients, and treatment with topical steroids and cycloplegics usually leads to rapid resolution of the uveitis. It is necessary to discontinue prophylaxis or therapy with rifabutin only in cases of uveitis that are refractory to treatment or when the uveitis recurs. Immunologic factors, rather than direct drug toxicity, appear to be the most likely explanation for the occurrence of uveitis in patients receiving rifabutin; however, further study is required to elucidate the mechanisms involved.

[A study on changes of levels of products of lipid peroxidation in retina of rat with experimental autoimmune uveoretinitis]

OBJECTIVE

To understand the mechanisms of the retinal tissue destruction of rat with experimental autommune uveoretinitis (EAU) induced by rabbit retinal soluble antigen.

METHOD

The levels of the following products of lipid peroxidation were determined at different times, conjugated dienes, malondialdehyde, fluorochrome lipid and lipid hydrogen peroxide.

RESULTS

In the process of EAU, the levels of products of lipid peroxidation in the retina were increased gradually in various degrees.

CONCLUSION

It is suggested that the damage from lipid peroxidation mediated by free radicals of the retina be one of the factors which induces the retinal destruction in EAU.

Intraocular penetration of periocular ketorolac and efficacy in experimental uveitis

PURPOSE

To determine in rabbits whether periocular injection of ketorolac tromethamine effectively delivers the drug to the eye and, if so, whether this is efficacious in the treatment of experimental uveitis.

METHODS

Ketorolac was administered by anterior subconjunctival injection, posterior periocular injection, intramuscular injection, or topical eye drops. The aqueous and vitreous were assayed for ketorolac. Anterior subconjunctival and topical ketorolac were compared to control as well as topical and anterior subconjunctival steroid treatments in uveitis induced by the intravitreal injection of tumor necrosis factor.

RESULTS

Anterior subconjunctival injection led to high, though short-lived, levels of drug in the aqueous and vitreous. Posterior periocular injection led to much lower levels. Topical dosing led to relatively low aqueous and undetectable vitreous levels. No ocular levels were detected after intramuscular dosing. All tested antiinflammatory treatments were similarly effective in controlling uveitis.

CONCLUSIONS

Anterior subconjunctival injection of ketorolac produced high intraocular concentrations of drug and was beneficial in controlling the inflammation in this animal model of uveitis.

[Study on the effect and mechanism of qinggan xiehuo decoction in treatment of endotoxin-induced uveitis in rabbits]

The therapeutic efficacy of Qinggan Xiehuo Decoction (QGXHD) on rabbit model of uveitis (1) The symptoms of Liver-Fire such as conjunctival congestion, thirsty dark urine, oliguria, irritability and rapid pulse were markedly relieved (P < 0.05-0.01); (2) The ophthalmic signs, iris hyperemia and aqueous humor turbidity observed through slit-lamp were improved significantly (P < 0.01); (3) The inflammatory infiltration, the protein content and leukocyte count in the aqueous humor decreased markedly (P < 0.01); (4) The concentration of inflammatory mediators in blood and aqueous humor were reduced. (5) Pathological examination showed that the QGXHD could protect the capillary, blood-aqueous barrier and alleviated the uveal damage caused by endotoxin.

Macrophages in the retina of normal Lewis rats and their dynamics after injection of lipopolysaccharide

PURPOSE

To investigate the density, distribution, and morphology of macrophages (bone marrow-derived microglia) and major histocompatibility complex (MHC) class II-positive cells in the retina of Lewis rats and the dynamics of these cells after systemic lipopolysaccharide (LPS) injection.

METHODS

Immunohistochemistry was carried out using monoclonal antibodies specific to monocytes and macrophages (ED1, ED2) and MHC class II-positive cells (OX-6) on whole-mounts of the retina obtained from Lewis rats before and at different time points after footpad injection of 200 micrograms of LPS.

RESULTS

The inner layers of the normal retina contained a network of macrophages, whereby ED1 and ED2 staining revealed similar results. Macrophages were either dendritiform or pleiomorphic in morphology, with the former predominant. The density of positive cells was higher at the peripheral part and the periequatorial part (271 +/- 10 cells/mm2 and 267 +/- 9 cells/mm2, respectively) than at the posterior part (196 +/- 11 cells/mm2; P < 0.0001 in both cases). Lipopolysaccharide injection induced an early adherence of monocytes to retinal blood vessels, followed by a massive influx of the macrophages into the retina. The ED1-ED2 positive cells showed a variety of morphologic appearances: large round cells, pleiomorphic cells, and dendritiform cells. Pleiomorphic cells were striking at 48 hours, whereas dendritiform cells were predominant in the whole retina at 72 hours and thereafter. On day 14, the dendritiform cell numbers returned to approximately preinjection levels. Major histocompatibility class II-positive cells could not be found in the normal retina, nor after LPS injection.

CONCLUSIONS

The network of MHC class II-negative microglia in the retina were studied. These cells may play an important role in immunoregulation and stability of the immunologic microenvironment within the retina. Systemic LPS injection was followed by a massive influx of macrophages into the retina. The absence of MHC class II-positive cells in the retina after LPS challenge may be an important protective mechanism against possible autoimmune damage.

Intravitreal transforming growth factor-beta 2 decreases cellular infiltration in endotoxin-induced ocular inflammation in rabbits

Transforming growth factor-beta (TGF-beta), a multifunctional cytokine which has been identified in normal and inflamed ocular fluids, may play a role in the evolution of inflammatory ocular lesions. In this study we utilized a rabbit model of LPS-induced uveitis to determine if exogenous TGF-beta 2 could alter its course. Recombinant TGF-beta 2 (1-2000 ng), LPS (10 or 20 ng), or TGF-beta 2 (100 ng) plus LPS (10 ng) were injected intravitreally in one eye of a New Zealand white rabbit and the contralateral eye served as a paired control which received an equal volume of vehicle. The uveitic response was assessed by biomicroscopic examination of the anterior uvea and analysis of protein and cells in the aqueous humor. Ocular tissues were processed for histologic, immunohistochemical and in situ hybridization analyses. Rabbits injected with doses of TGF-beta 2 > or = 500 ng developed a mild uveitic response, compared to LPS alone, accompanied by expression of IL-1 beta mRNA and protein in the anterior uvea. Interestingly, rabbits coinjected with LPS (10 ng) and a nonuveitic dose (100 ng) of TGF-beta 2 exhibited a similar increase in ocular vascular permeability, but a decrease in inflammatory cell infiltration into the anterior uvea and aqueous humor (1185 +/- 117 versus 2465 +/- 176; p < 0.05). No evidence of inflammation was observed in eyes injected with 100 ng TGF-beta 2 alone. Similar to other models of inflammation, TGF-beta may interrupt the cascade of events leading to ocular inflammation, thereby suggesting therapeutic potential.

Evidence of cross-link formation of vitreous collagen during experimental ocular inflammation

PURPOSE

To determine the mechanisms of vitreous changes during ocular inflammation.

METHODS

We investigated vitreous changes, with special emphasis on collagen, in an experimental model of ocular inflammation induced by intravitreal injection of endotoxin (Escherichia coli) in rabbits.

RESULTS

Inflammation caused gel contraction and loss of elasticity, accompanied by release of a water-like liquid from the gel, and increases in the amount of insoluble material and high-molecular-weight components of vitreous collagen, presumably due to extensive cross-links of the collagen molecules. Those changes were partially inhibited by intravitreal injection of superoxide dismutase.

CONCLUSIONS

The cross-links of vitreous collagen may promote vitreous gel contraction and release of a water-like liquid from the gel. Superoxide anion may play a role in this process.

Systemic anti-tumor necrosis factor antibody treatment exacerbates endotoxin-induced uveitis in the rat

Tumor necrosis factor is released in the circulation and aqueous humor during endotoxin-induced uveitis, and induces acute uveitis when injected intraocularly in rats. To elucidate the role of tumor necrosis factor in the development of endotoxin-induced uveitis we analysed the effect of neutralizing anti-tumor necrosis factor antibodies and of pentoxifylline, a drug that inhibits tumor necrosis factor synthesis. Lewis rats were treated with: (a) a single intracardial injection of polyclonal rabbit anti-murine tumor necrosis factor antiserum prior to foot pad injection of 200 micrograms lipopolysaccharide; (b) an intraperitoneal injection of 10 mg pentoxifylline 1 hr before, at the time of, and 3 hr after foot pad injection of lipopolysaccharide; or (c) an intravitreal injection of 20 to 500 micrograms pentoxifylline together with 1 microgram lipopolysaccharide. The ocular inflammation was examined by slit-lamp and evaluated for the presence of hyperemia, flare, miosis, infiltrating cells or hypopyon. Levels of tumor necrosis factor in serum and aqueous samples were determined using a bioassay. Systemic treatment with either anti-tumor necrosis factor antibodies or pentoxifylline resulted in a significant inhibition, 90 and 70% respectively, of serum tumor necrosis factor activity at 3 to 4 hr after lipopolysaccharide injection. Systemic pentoxifylline treatment had no influence on the severity of uveitis. Anti-tumor necrosis factor antibody treatment, in contrast, caused an exacerbation of endotoxin-induced uveitis at t = 20 hr; mean uveitis score 3.9 vs. 1.4 in controls; P < 0.01. Intraocular administration of pentoxifylline together with lipopolysaccharide also had an aggravating effect on uveitis, that was associated with increased levels of intraocular tumor necrosis factor. The results show that inhibition of serum tumor necrosis factor activity does not block the development of endotoxin-induced uveitis. In fact, anti-tumor necrosis factor antibody treatment exacerbates the intraocular inflammation. These findings suggest that tumor necrosis factor may have other than proinflammatory properties in this uveitis model.

Rifabutin-associated uveitis

OBJECTIVE

To review rifabutin-associated uveitis and discuss the mechanism and potential role of drug interactions with clarithromycin and fluconazole in contributing to this adverse event.

DATA SOURCES

A MEDLINE search (1991 through September 1994) of English-language literature using the main MeSH headings "rifabutin" and "uveitis" and the subheadings "adverse effects" and "chemically induced." Relevant articles also were selected from references of identified articles. Abstracts from recent medical conferences of infectious diseases, pharmacology, and HIV were screened for additional data.

STUDY SELECTION AND DATA EXTRACTION

All articles and abstracts reporting uveitis potentially related to rifabutin were considered for inclusion. Fifty-four cases were identified. Pertinent information from the case reports, as judged by the authors, was selected and synthesized for discussion.

DATA SYNTHESIS

Rifabutin is being prescribed increasingly for the treatment and prophylaxis of Mycobacterium avium complex (MAC) infection in the HIV-infected population. Uveitis was initially thought to be a rare, dose-limited complication of rifabutin therapy. In an early dose-ranging tolerance study, uveitis was associated with daily doses of 1200 mg or more. Because this toxicity appeared to be dose-related, lower dosages (300-600 mg/d) of rifabutin were selected for study in subsequent clinical trials. More recent reports noting the association of uveitis with these lower dosages of rifabutin have raised concerns about the prevalence of this adverse event. In the 54 identified cases, patients presented with symptoms of unilateral or bilateral uveitis from 2 weeks to more than 7 months following initiation of rifabutin therapy. In all reported cases, patients were receiving concurrent therapy with clarithromycin and/or fluconazole, both of which have inhibitory effects on rifabutin metabolism. In most cases, uveitis resolved within 1-2 months following discontinuation of rifabutin with or without administration of topical corticosteroids.

CONCLUSIONS

Rifabutin is prescribed frequently for the prophylaxis and treatment of MAC infection, especially in patients with HIV. Uveitis is a rare, dose-related toxicity of this therapy. The risk of rifabutin-associated uveitis may be increased in patients receiving concurrent therapy with clarithromycin or fluconazole because of drug interactions. Patients receiving therapy with combinations of any of these agents should be warned about signs and symptoms of uveitis and be monitored closely for the development of rifabutin toxicity. If uveitis develops, rifabutin therapy should be discontinued promptly.

Suramin treatment suppresses induction of experimental autoimmune uveoretinitis (EAU) in rodents

The experimental drug suramin has been shown to possess several immunosuppressive properties. In this study we investigated the effect of suramin on the development of experimental autoimmune uveoretinitis (EAU) in mice and in rats. EAU was induced either by active immunization with a uveitogenic protein or peptide, or by the adoptive transfer of a uveitogenic T cell line. The development of EAU was assessed by clinical evaluation as well as by histopathology. Immunological responses were measured by delayed type hypersensitivity (DTH), lymphocyte proliferation, and serum antibody levels to the immunizing antigen. Suramin treatment was most effective in suppressing EAU when started concurrently with immunization (afferent). Treatment was less effective in suppressing disease when first administered 7 days after immunization or when given to animals that received an adoptive transfer of uveitogenic T cells (efferent). The effect of suramin on DTH and lymphocyte proliferation roughly paralleled its effect on EAU. Aferent treatment of mice with suramin completely suppressed anti-IRBP antibody titers. Interestingly, animals receiving efferent treatment had unreduced IgM levels but little or no IgG, suggesting prevention of the IgM-to-IgG switch. Depressed in vitro lymphocyte proliferative responses in animals treated with suramin during the afferent stage suggested that the suppressive effect on disease was due at least in part to an inhibition of antigen priming. Our results suggest that suramin merits further investigation as a potential treatment for some types of uveitis.

Paget's disease: ocular complications of disodium pamidronate treatment

Three cases of uveitis associated with disodium pamidronate have been notified to the Committee for Safety of Medicines. Two new cases of bilateral anterior uveitis and episcleritis after administration of intravenous disodium pamidronate are described.