Retinal and systemic pharmacokinetics of the anti-inflammatory drug cloricromene following oral administration in the rat and rabbit.

PURPOSE: The aim of this study was to evaluate the retina and plasma distribution of cloricromene, a coumarin derivative, and its active metabolite (MET) after an oral administration in rabbits and rats. METHODS: A single dose of cloricromene was orally administered to rabbits (10 or 100 mg/kg) and to rats (100 mg/kg). Retina and plasma samples were collected at 15, 30, 60, and 90 min following administration. Drug concentrations in the retina and plasma were measured by high-performance liquid chromatography. RESULTS: As anticipated, only the active metabolite was found in all samples. The retina and plasma showed the same T(max); peak levels of the drug were achieved at 15 min in rats and at 30 min in rabbits. In rabbits, MET exposure was approximately dose-proportional in both retina and plasma between the 10- and 100-mg/kg dose. Substantial retinal exposure was observed in both the rat and rabbit, at exposures approximately nine- to sixteenfold lower in the retina than in plasma. CONCLUSIONS: The results showed that the active metabolite of cloricromene reached the retina after a single oral dose with exposures proportional to those in plasma. These data, along with the previously published potency data for cloricromene, suggest that cloricromene could be potentially useful in ischemic-retinal diseases where amelioration of blood flow and inflammation is desirable.

Preparation and characterization of eudragit retard nanosuspensions for the ocular delivery of cloricromene.

The purpose of this study was to improve the stability of cloricromene (AD6) in ophthalmic formulations and its drug availability at the ocular level. To this end, AD6-loaded polymeric nanoparticle suspensions were made using inert polymer resins (Eudragit RS100 and RL100). We modified the quasi-emulsion solvent diffusion technique by varying some formulation parameters (the drug-to-polymer ratio, the total drug and polymer amount, and the stirring speed). The chemical stability of AD6 in the nanosuspensions was assessed by preparing some formulations using (unbuffered) isotonic saline or a pH 7 phosphate buffer solution as the dispersing medium. The formulations were stored at 4 degrees C, and the rate of degradation of AD6 was followed by high performance liquid chromatography (HPLC). The obtained nanosuspensions showed mean sizes and a positive surface charge (zeta-potential) that make them suitable for an ophthalmic application; these properties were maintained upon storage at 4 degrees C for several months. In vitro dissolution tests confirmed a modified release of the drug from the polymer matrixes. Nanosuspensions prepared with saline solution and no or lower amounts of surfactant (Tween 80) showed an enhanced stability of the ester drug for several months, with respect to an AD6 aqueous solution. Based on the technological results, AD6-loaded Eudragit Retard nanoparticle suspensions appear to offer promise as a means to improving the shelf life and bioavailability of this drug after ophthalmic application.

Eudragit RL100 nanoparticle system for the ophthalmic delivery of cloricromene.

A Eudragit RL100 polymer nanoparticle system loaded with cloricromene was prepared and characterized on the basis of physicochemical properties, stability and drug release features. To investigate the ocular bioavailability of cloricromene after inclusion in the polymer matrix, the new nanoparticle system was topically administered in the rabbit eye and compared with an aqueous solution of the same drug. The nanoparticle system showed interesting size distribution and surface charge values, suitable for ophthalmic application. The results indicated that the dispersion of cloricromene within Eudragit RL100 polymer nanoparticles increased its ocular bioavailability and enhanced the biopharmaceutical profile. The new cloricromene-loaded nanoparticle system described here may be useful in clinical practice.

A protective effect of the synthetic coumarine derivative Cloricromene against DNB-colitis in the rat.

Biologic therapies, namely antibodies against tumor necrosis factor-alpha (TNF- alpha) or its receptors, have been recently introduced for the treatment of patients with inflammatory bowel disease (IBD). In the present study the effects of cloricromene, an agent with known antithrombotic actions and with demonstrated anti-TNF- alpha activity were investigated in a rat model of experimental colitis induced with dinitrobenzenesulphonic acid (DNB)/ethanol. We investigated three experimental groups: (i) sham-colitis with vehicle-treatment (controls, n = 6), (ii) colitis with vehicle-treatment (saline, 0.1 ml s.c., daily) (DNB-V, n = 7), (iii) colitis with cloricromene-treatment (10 mg/kg/day s.c.; DNB-C, n = 8). After 7 days, the weight gain, colon wet weight, macroscopic damage score, coagulation parameters, colon mucosal myeloperoxidase activity (MPO), and tissue concentrations of TNF- alpha and of macrophage inhibitory peptide-2 (MIP-2) were assessed. The macroscopic damage scores, colon wet weights, and tissue MIP-2 levels were significantly increased in untreated and in cloricromene-treated rats compared with controls. Cloricromene treatment was associated with a minor body weight loss (p < 0.025) and significantly reduced tissue concentrations of MPO and TNF-alpha (p < 0.02, both). Blood coagulation parameters were not affected by treatment. In the DNB-model treatment with cloricromene effectively reduces tissue levels of TNF- alpha and of myeloperoxidase, whereas MIP-2 concentrations were not influenced. Blood coagulation parameters remained unchanged indicating safety of treatment. Since biological therapies frequently fail to improve disease course of IBD, other therapies with similar targets should be further investigated.

Effects of cloricromene, a coumarin derivative, on endotoxin-induced uveitis in Lewis rats.

PURPOSE: To investigate the effects of cloricromene, a coumarin derivative, in rats subjected to endotoxin-induced uveitis (EIU). METHODS: Endotoxin uveitis was induced in male Lewis rats by a single footpad injection of 200 microg lipopolysaccharide (LPS). Cloricromene was topically applied to the rat eye twice at 1 hour before and 7 hours after injection of LPS. A separate group of animals was treated with vehicle. Rats were killed 16 hours after injection and the eyes enucleated for histologic examination and immunohistochemical analysis. The effect of treatment was also evaluated by slit lamp examination, by the number of intraocular inflammatory cells on histologic sections, and by measuring the protein and TNFalpha levels in the aqueous humor. Nitrite and nitrate production was also measured in the aqueous humor. RESULTS: The histopathology of the iris-ciliary body included inflammatory cell infiltration and nuclear modification of vessel endothelial cells. Cloricromene treatment reduced the inflammatory cell infiltration and improved histologic status of the ocular tissue. Immunohistochemical analysis for P-selectin, intracellular adhesion molecule (ICAM)-1, nitrotyrosine, and poly(ADP-ribose) synthetase (PARS) revealed a positive staining in inflammatory cell infiltration from LPS-treated rats. The degree of staining for P-selectin, ICAM-1, nitrotyrosine, and PARS was markedly reduced in tissue sections obtained from LPS-recipient rats that had received cloricromene. Cloricromene strongly inhibited cell infiltration, protein exudation, TNFalpha production, and nitrite-nitrate formation. CONCLUSIONS: This study provides the first evidence that cloricromene, a coumarin derivative, attenuates the degree of inflammation and tissue damage associated with EIU in rats.

Intradermal injection vs. oral treatment of tinnitus.

Local pharmacological intradermal infiltration is a therapy being used more and more thanks to the positive results achieved, particularly for all those therapies acting on the microcirculation. In trying to better the results obtained with medical therapy for tinnitus sufferers, to assess the effect of a vasoactive drug, the method of administration by the intradermal route, which allows a strengthening of the pharmacological effect, has been added. The present study comprised 120 tinnitus sufferers who underwent intradermal auricle infiltration with a vasoactive drug. The control group includes 115 tinnitus sufferers who underwent systemic vasoactive therapy with the same drug. Forty-five days after beginning intradermal treatment the symptom improved and continued to do so following further infiltrations which patients underwent every 15 days. In the control group we noticed a moderate improvement 45 days after the beginning of oral therapy; thereafter the results reached a plateau by the 60th day. Intradermal vasoactive therapy for idiopathic tinnitus seems to be a new success, which will be an interesting progression in the therapy of this kind of symptom.

Cloricromene reduces myocardial infarct size in rabbits when administered during the early reperfusion period.

Cloricromene is a coumarin derivative without anticoagulant activities that has recently been found to decrease myocardial infarct size after an ischemic-reperfusion injury. This study seeks to determine when the cardioprotective action of cloricromene is exerted in an in vivo rabbit model of ischemic-reperfusion injury. Forty-nine rabbits subjected to 30 min of coronary occlusion and 120 min of reperfusion were randomized into five groups: VEH (n = 11) received saline vehicle; IR (n = 9) received an infusion of cloricromene starting at the onset of ischemia at 8 micrograms.kg-1.min-1; R(-5)(n = 9) and R(+30)(n = 9) received an infusion of cloricromene at 8 micrograms.kg-1.min-1 starting 5 min before reperfusion and 30 min after reperfusion, respectively; and RB(-5)(n = 11) received 300 micrograms/kg bolus of cloricromene 5 min before reperfusion followed by an infusion of 8 micrograms.kg-1.min-1. All infusions were continued until the end of the reperfusion period. Myocardial infarct size was significantly reduced in groups IR, R(-5), and RB(-5). We conclude that cloricromene's effective time of action occurs prior to the first 30 min of the reperfusion period.

Effects of cloricromene on the levels of endothelin and on the microcirculatory function in peripheral atherosclerotic arteriopathies.

The effects of cloricromene on plasma endothelin-1 (ET-1) levels and on microcirculatory function in 9 patients with peripheral atherosclerotic arteriopathy (PAA) and in healthy control subjects were studied. ET-1 levels and microcirculatory function were evaluated both under basal conditions and 30, 60, and 90 min after acute administration of cloricromene (30 mg i.v.). PAA patients had significantly increased levels of ET-1 and impaired vascular parameters (studied by means of Winsor's Index, Gosling's Index, postischemic perfusion index and recovery time) when compared to control subjects. The acute administration of cloricromene (30 mg i.v.) did not change plasma ET-1 both in control subjects and in patients with PAA. In contrast, cloricromene produced a significant improvement in the postischemic perfusion index and in recovery time in arteriopathic patients. Control subjects and patients with PAA also underwent a cold pressor test (CPT) under basal conditions and (72 h later) 30 min after an acute intravenous administration of cloricromene (30 mg i.v.). CPT caused a higher increase in ET-1 in the patients with PAA compared to the control group, and a reduction in the vascular flow at the femoral level, while the pretreatment with cloricromene prevented both the increase in the levels of ET-1 and the reduction of the femoral vascular flow observed after the cold stimulus in patients with PAA. Our data show that cloricromene, besides ameliorating the microcirculatory function, is able to interfere with dynamic mechanisms, such as those induced by the CPT, capable of stimulating the release of ET-1 at the vascular level.

Intravenous carbochromen: a potent and effective drug for estimation of coronary dilatory capacity.

Systemic and coronary haemodynamic effects of carbochromen (0.125 mg kg-1 min-1 for 40 min i.v.) and dipyridamole (0.05 mg kg-1 min-1 for 10 min i.v.) were investigated in 18 patients without detectable heart disease. Both drugs induced a comparable increase in coronary blood flow (carbochromen: from 82 +/- 23 to 337 +/- 68 ml.100 g-1.min-1; dipyridamole: from 78 +/- 9 to 301 +/- 61 ml.100 g-1.min-1). This resulted in a minimal coronary resistance of 0.23 +/- 0.04 mmHg.ml-1.100 g.min for dipyridamole and of 0.24 +/- 0.04 mmHg.ml-1.100 g.min for carbochromen. In response to dipyridamole (n = 12) heart rate increased from 73 to 94 beats min-1 (P less than 0.005) and mean aortic pressure fell from 89 to 78 mmHg (P less than 0.001). After administration of carbochromen (n = 6) no significant systemic effects occurred. Dipyridamole induced a significant increase in myocardial oxygen consumption by 46% (P less than 0.001); after application of carbochromen myocardial oxygen consumption remained unchanged. From these data it can be concluded that for the evaluation of coronary dilatory capacity carbochromen may be more suitable than dipyridamole because (1) maximal coronary vasodilation is induced without changes in myocardial oxygen consumption and (2) no systemic effects occur.

Contrasting effects of pharmacologic vasodilation on true collateral and overlap perfusion in ischemic myocardium.

The effects of chromonar (3.5 and 7.0 mg/kg i.v.), a selective coronary vasodilator, on true collateral blood flow and overlap flow (noncollateral perfusion due to overlapping end arteries of adjacent coronary vessels) were measured independently in anesthetized dogs following acute coronary occlusion. Collateral flow in the ischemic zone was significantly (P less than 0.05) reduced by chromonar in a dose-related manner while transmural overlap flow was increased. True collateral flow was distributed primarily to the subepicardium and chromonar produced a significant reduction in both subepicardial and subendocardial perfusion. Overlap perfusion was distributed equally across the left ventricular wall and chromonar increased perfusion to both subepicardium and subendocardium. The results indicate that there are two independent sources of perfusion of ischemic myocardium and that pharmacologic vasodilation with chromonar produces opposite effects on each: a steal of true collateral blood flow and an increase in overlap perfusion.

[The effect of carbocromen on cardiac cyclic adenosine-monophosphate]. / Wirkung von Carbocromen auf cyclisches Adenosinmonophosphat im Herzen

The coronary-active drug 3-2-diethylaminoethyl)-4-methyl-7-(carbethoxy-methoxy)-2-oxo-1,2-chromene-hydrochloride (carbocromen, Intensain) is known to be an inhibitor of phosphodiesterase (PDE). After intravenous as well as after intraduodenal application of therapeutic doses carbocromen increases in vivo the cAMP-contents of the hearts of rats (by up to 30%) and dogs (up to 50%). This effect is dose related. Correlations between the pharmacokinetic properties and metabolic actions of carbocromen and its influence on the adenylcyclase system are discussed.

[Studies on inhibition of platelet aggregation by carbocromen (author's transl)]. / Untersuchungen zur Hemmung der Thrombozytenaggregation durch Carbocromen

3-(2-Diethylaminoethyl)4-methyl-7-(carbethoxy-methoxy)-2-oxo-1,2-chromene-hydrochloride (carbocromen; Intensaïn) shows dose dependent platelet aggregation inhibitory activity in vitro according to the methods of Born (following ADP, epinephrine and collagen) and of Breddin (platelet agglutination test--PAT--, adhesively). The effect was found to be more pronounced than that of acetylsalicylic acid. Furthermore, in vivo carbocromen inhibited the increased spontaneous platelet aggregation in man.

The effect of carbocromene on strophanthin-induced ventricular tachycardia in dogs.

The antiarrhythmic effect of carbocromene (Intensain) was studied in 17 anaesthetized dogs. Ventricular tachycardia was induced by infusion of K-strophanthin (mean dose: 154 mug/kg i.v.). In 25 out of 26 experiments carbocromene (4 mg/kg i.v.) was effective. Ventricular tachycardia was converted to sinus rhythm in 16 experiments, to atrial tachycardia in 6 experiments and to junctional tachycardia in 3 experiments. The favourable effect started 8 to 50 seconds after the injection with lower doses of carbocromene (3 and 2 mg/kg i.v.) in time intervals of 5 minutes resulted in similar positive effects leading after 2 or 3 injections finally to a second phase of drug effect where ventricular tachycardia was strongly modified for about 30 minutes. The results favour the therapeutic use of this drug in patients with arrhythmia especially with arrhythmias caused by digitalis.