Nail penetration and predicted mycological efficacy of an innovative hydrosoluble ciclopirox nail lacquer vs. a standard amorolfine lacquer in healthy subjects.

BACKGROUND: In a previous study a new hydrosoluble nail lacquer (P-3051) containing 8% ciclopirox (CPX) showed higher nail penetration compared to a water-insoluble 5% amorolfine (MRF) lacquer. To our knowledge, in vivo human data on a similar topic are not available. OBJECTIVES: To compare fingernail penetration of P-3051 with that of MRF reference in humans and to evaluate their predicted efficacy against Trichophyton rubrum and Candida parapsilosis. METHODS: Single centre, randomized, multiple dose, open label, within subjects study. Test and reference were self-applied to all fingernails of either hand for 28 days. At baseline and after 15 and 25 days, the nail free edge was collected for analysis. Efficiency coefficients were calculated for T. rubrum and C. parapsilosis as ratios of nail concentration/minimum inhibitory concentration. The coefficients were classified as very high, high or poor. RESULTS: Nail concentrations after 15 days were 2.82 ± 0.58 µg/mg for CPX and 0.64 ± 0.11 µg/mg for MRF. At day 25 there was a non-significant decline (1.85 ± 0.31 µg/mg, P = 0.077) for CPX and a highly significant (0.13 ± 0.03 µg/mg, P = 0.0002) 80% decline for MRF. Efficiency coefficients were very high/high in all subjects treated with P-3051 against both T. rubrum and C. parapsilosis; they were significantly lower for MRF reference against both pathogens at both observation points. CONCLUSIONS: P-3051 exhibited better penetration and higher predicted efficacy after in vivo multiple application to human fingernails when compared to MRF reference. These in vivo data are in good agreement with our previous in vitro study.

Antihistaminic and antiallergic properties of dextro-mequitamium iodide in upper and lower guinea pig airways: comparison with azelastine.

1. The ability of dextro-mequitamium iodide (d-Meq) to antagonize bronchomotor and inflammatory effects mediated by histamine and antigen challenge in the upper or lower guinea pig airways or both and its potential activity against the recruitment and activation of eosinophils in the bronchial wall have been evaluated in comparison with azelastine. 2. In receptor-binding studies, d-Meq displayed a nanomolar affinity for H1 and muscarinic receptors, and it was endowed with potent bronchodilating properties in the nanomolar range toward tonic contractions induced by histamine and carbachol. 3. d-Meq (100-1,000 nmol/guinea pig) and azelastine (100-5,000 nmol/guinea pig) administered by aerosol significantly inhibited histamine- and antigen-induced increases in insufflation pressure in sensitized animals. 4. d-Meq (1,000-6,000 nmol/kg i.v.) dose dependently inhibited the histamine- or antigen-induced increase in vascular permeability in the upper airways. 5. d-Meq was more effective against histamine than antigen challenge, and its potency was similar or greater than that of azelastine. 6. Aerosolized d-Meq (1,000 nmol/animal) reduced antigen-induced eosinophil accumulation in the bronchoalveolar lavage (BAL) fluid from sensitized guinea pigs. 7. Eosinophils recovered from the BAL fluid of antigen-challenged animals showed an increased chemotaxis in response to LTB4 or platelet-activating factor. Both d-Meq and azelastine (300 nmol/animal) reduced this increase without affecting direct chemotaxis induced by leukotriene B4 (LTB4). 8. These findings provide evidence that local administration of d-Meq might be useful in the treatment of allergic disorders, such as rhinitis and asthma.

1,2-disubstituted cyclohexane derived tripeptide aldehydes as novel selective thrombin inhibitors.

A series of tripeptide arginine aldehydes was synthesized by replacement of proline with 1,2-disubstituted cyclohexane derivatives in the sequence of D-MePhe-Pro-Arg-H. Based on molecular modeling, further modification of the D-MePhe residue resulted in a potent and selective thrombin inhibitor.

Alteration of cytochrome P-450 isozymes by captopril and idrapril in hepatic and renal microsomes of normotensive and spontaneously hypertensive rats.

To examine the effects of angiotensin-converting enzyme (ACE)inhibitors such as captopril and idrapril on the P-450 system, these compounds were administered 100 mg/kg i.p. for 4 days to spontaneously hypertensive (SHRs) and normotensive Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats; thereafter, the principal hepatic and renal microsomal monooxygenase activities were determined. In all the rat strains used, both captopril and idrapril decreased only the P-450 2C11, (as determined by immunoblotting) and its linked activities such as 16alpha-, 2alpha- and 17-testosterone hydroxylases. These changes were accompanied by a significant decrease of blood testosterone levels both in normotensive and, more markedly, in hypertensive rats and by a reduction of systolic blood pressure, but only in SHRs. Only in SHRs as well, the renal immunodetectable P-450 4A content and the P-450 4A-dependent activities, such as the (omega)-lauric acid hydroxylase, diminished after captopril or idrapril treatment. These data suggest that the decrease of increased blood pressure in hypertensive SHRs by the ACE inhibitors may be linked to the downregulation of the circulating testosterone level, the renal P-450 4A expression, and the related formation of the potent vasoconstrictor (omega)-hydroxy arachidonic acid.

Human umbilical vein smooth muscle cells as a model to study thrombin generation and function: effect of thrombin inhibitors.

The aim of the present work was to study how human umbilical vein smooth muscle cells (HUVSMC) can initiate the coagulation process and to investigate the responses of these cells to thrombin. Exposure of HUVSMC to recalcified human plasma led to a time-dependent production of thrombin, measured both as amidolytic activity and as release of fibrinopeptide A. Thrombin activity was dose-dependently reduced by an anti-human tissue factor antibody (76 +/- 3% at 10 micrograms/ml) and by inhibitors like heparin, rec-hirudin, hirulog 1, Napap and hirunorm, a novel hirudin-like thrombin inhibitor (IC50 = 2 +/- 0.4, 8 +/- 1, 130 +/- 22, 199 +/- 29 and 68 +/- 8 nM, respectively). The release of fibrinopeptide A was similarly prevented (IC50 = 14 +/- 1, 132 +/- 25 and 50 +/- 8 nM for rec-hirudin, Napap and hirunorm, respectively). Exogenously added thrombin increased thymidine incorporation into HUVSMC to 240 +/- 30% of basal (EC50 = 0.49 +/- 0.09 nM) and thrombin inhibitors blocked this effect (IC50 = 10 +/- 3, 37 +/- 17, 343 +/- 165 and 1402 +/- 758 nM for rec-hirudin, hirunorm, Napap and hirulog-1, respectively). Also recalcified human plasma was mitogenic for HUVSMC and its effect was mainly due to endogenously generated thrombin, as shown by the use of thrombin inhibitors. In conclusion, HUVSMC are capable of initiating the extrinsic coagulation cascade, leading to the formation of thrombin which promotes clotting and stimulates DNA synthesis. Thrombin inhibitors prevent both coagulative and cellular effects of thrombin.

Experimental pharmacology of hirunorm: a novel synthetic peptide thrombin inhibitor.

Enhanced thrombin activity has been associated with coronary thrombosis and with acute and long-term complications following coronary balloon angioplasty. Blocking thrombin activity with specific inhibitors is proposed as a promising antithrombotic therapy. We describe the anticoagulant and antithrombotic properties of hirunorm, a novel synthetic 26-aminoacid peptide thrombin inhibitor, in comparison with r-hirudin and hirulog-1. Hirunorm was equipotent to hirulog-1 and 1/30 as potent as r-hirudin in blocking alpha-thrombin amidolytic activity (IC50 = 10 +/- 2, 15 +/- 1 and 0.3 +/- 0.1 nM, respectively), but it did not affect trypsin, plasmin and t-PA activities at 10 microM. All the compounds inhibited clot-bound thrombin to clots prepared by thrombin hydrolysis of purified fibrinogen in buffer. Hirunorm and hirulog-1 showed similar species-dependent potency in doubling basal in vitro clotting times of human, rat and rabbit plasma (EC200 varied 70 to 200 nM for TT, 0.7 to 16 microM for aPTT and 0.8 to 17 microM for PT), while r-hirudin was always at least three times more active. When assayed by HPLC or by bioassay of the intact peptide, hirunorm was stable against alpha-thrombin and plasma hydrolases, but it was catabolized by rat liver and kidney enzymes. Venous thrombosis was produced in anaesthetized rats by vena cava ligation following a procoagulant serum injection. Intravenous and subcutaneous hirunorm inhibited venous thrombosis at doses (< or = 0.3 mg/kg) two-three times higher than those of r-hirudin. Hirulog-1 was as active as hirunorm only after i.v. infusion. Arterial thrombosis was obtained in the anaesthetized rat by chemical (FeCl2) stimulation of a common carotid and i.v. infused hirunorm (1-3 mg/kg/30 min) inhibited it dose-dependently; r-hirudin was partly active only at 3 mg/kg, but hirulog-1 was inactive at either dose. Full antithrombotic doses of hirunorm did not affect the bleeding time as measured from punctured mesenteric vessels, in anaesthetized rats. In conclusion, hirunorm is a potent peptide thrombin inhibitor endowed with antithrombotic activity in models of venous and arterial thrombosis.

Reductive metabolism and its role in the disposition of the hydroxamic angiotensin-converting enzyme inhibitor idrapril calcium in rat.

1. The metabolism of 14C-idrapril calcium, the prototype of a new class of angiotensin-converting enzyme inhibitors, was studied in rat after a single intravenous administration. Plasma, urine, faeces, and bile were assayed for total and hplc-fractionated radioactivity. 2. Only one major metabolite (M1, 2-sarcosinamide-cis-1,2-cyclohexanedicarboxylamide) was observed, along with idrapril, in plasma. Three metabolites (M1, M2, cis-1,2-cyclohexanedicarboxylic acid, and M3, a glucuronate derivative of M1) were present in 0-8-h urine, unchanged idrapril being the most abundant product. In bile, two metabolites (M1, M3), but not the parent compound, were found. 3. In conclusion intravenous idrapril undergoes hepatic reduction to M1 and hydrolysis to M2. M1 can be glucuronated to M3 and both are partially excreted in the bile and further processed in the gut to reabsorbable radioactive species.

Role of calcium in angiotensin II-induced prostaglandin release and DNA synthesis in rat vascular smooth muscle cells.

Cellular calcium modulates enzyme activity, cell proliferation, and differentiation. In vascular smooth muscle cells (VSMC), calcium may contribute to increased vascular contractility and structural alterations in both hypertension and atherosclerosis. We investigated the role of calcium in angiotensin II (AII)-induced prostaglandin release and DNA synthesis in VSMC. Prostaglandin levels were determined by radioimmunoassay, and DNA synthesis was determined by the incorporation of [3H]thymidine. AII dose-dependently stimulated the release of prostaglandin E2 and prostaglandin I2, and this effect was synergistically enhanced by the Ca2+ ionophore A23187. Conversely, the AII response was inhibited by EGTA, a chelator of Ca2+ ions and by verapamil and nifedipine, two Ca2+ channel blockers or by incubation of the cells without exogenous Ca2+. TMB-8, an inhibitor of calcium mobilization, also strongly reduced angiotensin response. Similar results were obtained for angiotensin III (AIII) and vasopressin, two other agonists of prostaglandin production. AII- or serum-stimulated DNA synthesis was almost abolished by EGTA, whereas TMB-8, verapamil, and nifedipine had little or no effect. The production of prostaglandins triggered by angiotensins and vasopressin in VSMC is dependent on both intracellular and extracellular calcium, with calcium entering through L-type Ca2+ channels. Extracellular calcium is important for AII and serum mitogenic activity, but L-type Ca2+ channels do not appear to be implicated.

N-3-substituted pyrimidinones as potent, orally active, AT1 selective angiotensin II receptor antagonists.

A novel series of nonpeptide angiotensin II (A II) antagonists containing a pyrimidinone ring which carries a C-linked biphenyltetrazole moiety and a carboxyheteroaryl group on the 3-position have been prepared. Their affinity for the AT1 receptor was determined in a binding assay on rat adrenal cortical membranes. The in vivo antihypertensive properties were tested by evaluating the inhibition of the pressor response to A II followed by iv and id administration. Extensive molecular modeling studies, including comparison of molecular electrostatic potential distributions, conformational analysis, and overlays on a computational pharmacophore model of A II, were used to evaluate structural parameters of the new compounds, in comparison to other known A II antagonists (e.g., DUP-753 and SK&F 108566). According to the modeling studies, the introduction of a (carboxyheteroaryl)methyl moiety at the 3-position of the pyrimidinone ring led to derivatives with increased potency. Methyl 2-[[4-butyl-2-methyl-6-oxo-5-[[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl ]- 4-yl]methyl]-1-(6H)-pyrimidinyl]methyl]-3-thiophenecarboxylate (3k, LR-B/081), one of the most potent compounds in the series (Ki = 1.4 nM), exhibited a marked antihypertensive activity on oral administration to conscious renal hypertensive rats, with long duration of action. It was selected for clinical evaluation in the treatment of hypertension in man.

Effects of idrapril calcium on tissue angiotensin-converting enzyme in rats.

Tissue angiotensin-converting enzyme (ACE) inhibition was measured in rats after single intravenous (i.v.) and oral (p.o.) doses of idrapril calcium, and the correlation between peak inhibition and tissue concentration of the drug was investigated. Five minutes after idrapril calcium (3 mg/kg i.v. as free acid), ACE in the examined tissues (serum, lungs, kidneys, heart, aorta, adrenals, testes, and brain) showed > 50% inhibition, always associated with measurable amounts of idrapril. After 90 min, ACE activity was still inhibited only in serum, lungs, kidneys, and aorta, recovering to basal values by 8 h in all samples but serum. Oral idrapril calcium (30 mg/kg) produced > 50% peak ACE inhibition in serum, lungs, and kidneys, in which measurable levels of the drug were detected, and in the aorta, where idrapril was not detected. Other tissues showed neither marked inhibition nor measurable drug levels. Kinetics of ACE inhibition in affected tissue mirrored those observed after intravenous administration. Idrapril, despite its hydrophilic nature, is able to reach extravascular tissues and to inhibit local ACE. However, in no tissue did the effect on ACE last longer than in serum and the hypothesis of a peculiar role of tissue RAS in determining the hypotensive activity of idrapril calcium is not supported in rats.

4-Diazinyl- and 4-pyridinylimidazoles: potent angiotensin II antagonists. A study of their activity and computational characterization.

A series of N-[biphenylyl(tetrazolyl)methyl]-2-butylimidazoles containing variously substituted diazine or pyridine moieties either as their free bases or N-oxide derivatives attached to the 4-position of the imidazole ring was synthesized and tested for interaction with the AT1 receptors of rat adrenal cortex membranes (receptor binding assay). Some compounds were then chosen for further evaluation in vivo in the A II-induced pressor response in conscious normotensive rats. The most potent in the AT1 binding assay were found to be compounds in which the diazine or pyridine ring nitrogen is adjacent to the point of attachment between the two heteroaromatic rings such as 2-butyl-4-(3,6-dimethylpyrazin-2-yl)-1-[[2'-(1H-tetrazol-5-y l)-biphenyl-4- yl]methyl]-1H-imidazole (3b) or 2-butyl-4-[5-(methoxycarbonyl)pyrid-2-yl]-1-[[2'-(1H-tetrazol++ +-5- yl)biphenyl-4-yl]methyl]-1H-imidazole (6c). The binding affinities and oral activities of the pyridine N-oxide imidazoles in which a stabilizing group ortho to the pyridine ring nitrogen is present were markedly improved as in 2-butyl-4-[(3-methoxycarbonyl)-6-methyl-N-oxopyridin-2-yl]-1-[[2'- (1H- tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-imidazole 31b. Molecular modeling studies were carried out to determine the molecular electrostatic potential values of related model systems and to correlate their receptor interaction energies with the observed activities of our compounds.

Molecular pharmacology of LR-B/081, a new non-peptide angiotensin AT1 receptor antagonist.

This report describes the molecular pharmacological properties of LR-B/081 (methyl 2-[[4-butyl-2-methyl-6-oxo-5-[[2'-(1H-tetrazol-5- yl) [1,1'-biphenyl]-4-yl]methyl]-1 (6H)-pyrimidinyl]methyl]- 3-thiophenecarboxilate), a novel non-peptide angiotensin II receptor antagonist. This compound potently displaced [3H]angiotensin II from angiotensin AT1 (Ki = 1.4 nM, rat adrenal cortex), but not from angiotensin AT2 (Ki > 1 microM, bovine cerebellar cortex) receptors and did not show affinity for other receptor systems (Ki > 10 microM). In saturation studies, LR-B/081 both increased KD and decreased Bmax values in a dose-dependent fashion. The rate of dissociation of [3H]angiotenin II from angiotensin AT1 receptors was not affected by the presence of 1 microM LR-B/081 and the association rate of [3H]angiotensin II was not decreased by the presence of 1 or 30 nM LR-B/081, indicating that the Bmax reduction was not due to an allosteric interaction or to a delay in reaching the steady-state conditions. These data underline the complexity of the antagonistic nature of LR-B/081, presenting features of both competitive and noncompetitive antagonism.

Angiotensin II-induced responses in vascular smooth muscle cells: inhibition by non-peptide receptor antagonists.

The present study investigates the effect of angiotensin II and LR-B/081 (-methyl 2-[[4-butyl-2-methyl-6-oxo-5-[[2'-(1H-tetra-zol-5-yl) [1,1'-biphenyl]-4-yl] methyl]-1(6H)-pyrimidinyl] methyl]-3-thiophenecarboxylate), a novel non-peptide angiotensin II receptor antagonist, on both early and late responses in rat vascular smooth muscle cells. Angiotensin II induced a rapid and transient elevation of inositol trisphosphate intracellular levels, triggered the release of both prostaglandin E2 and prostaglandin I2 (EC50 = 21 +/- 3 and 16 +/- 2 nM, respectively), and, in long-term studies, increased leucine and thymidine incorporation. All angiotensin II effects were antagonized by LR-B/081 and losartan, the reference non-peptide angiotensin AT1-selective receptor antagonist, whereas they were unaffected by PD123177 (1-(4-amino-3-methylphenyl)methyl-5-diphenylacetyl-4,5,6,7-tetr ahy dro-1H- imidazo[4,5-c]pyridine carboxylic acid), a non-peptide angiotensin AT2-selective receptor antagonist. LR-B/081 displayed a much higher potency than losartan in inhibiting angiotensin II-induced prostaglandin E2 (IC50 = 0.15 +/- 0.02 and 39 +/- 9 nM, respectively) and prostaglandin I2 release (IC50 = 0.18 +/- 0.04 and 134 +/- 40 nM, respectively) and was also more potent in blocking the increase in protein synthesis (IC50 = 242 +/- 119 nM and 1221 +/- 687 nM, respectively). Moreover, LR-B/081 and losartan blocked the response to angiotensin III but failed to inhibit the prostaglandin release stimulated by vasopressin or the mitogenic effect of serum. LR-B/081 and losartan were devoid of intrinsic properties in the experimental conditions employed.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacology of LR-B/057, a novel orally active AT1 receptor antagonist.

We studied the pharmacologic properties of LR-B/057, a novel nonpeptide angiotensin II (AII) receptor antagonist. The compound potently displaced [3H]AII from AT1 but not from AT2 receptors in rat adrenal cortex (Ki 3 nM), but did not modify the dissociation rate of the radioligand from the receptors. Both its affinity and the nature of its interaction with AT1 receptors (saturation studies) were markedly affected by the presence of bovine serum albumin (BSA) in the binding assay. In rabbit aorta, LR-B/057 caused nonparallel shifts to the right of the dose-response curve to AII and decreased the maximal response (pKB 9.6). Oral (p.o.) administration of LR-B/057 to conscious rats dose-dependently antagonized the pressor response to AII. LR-B/057 administered either intravenously (i.v.) or p.o. to conscious renal hypertensive rats produced a powerful dose-dependent antihypertensive effect. These results show that LR-B/057 is a potent and selective antagonist at AT1 receptors and has p.o. bioavailability.

Pharmacology of LR-B/081, a new highly potent, selective and orally active, nonpeptide angiotensin II AT1 receptor antagonist.

1. The pharmacological profile of LR-B/081, (methyl 2-[[4-butyl-2-methyl- 6-oxo-5-[[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-1(6H)- pyrimidinyl]methyl]-3-thiophenecarboxylate), a novel antagonist at the angiotensin II (AII) AT1-receptor, was studied in vitro and in vivo. 2. In rabbit aortic strips incubated with LR-B/081 (1-1,000 nM), the concentration-response curve to AII was displaced to the right in a nonparallel fashion and the maximal contraction was progressively reduced, indicating that the compound is an insurmountable antagonist in this preparation (apparent pKB = 9.50 +/- 0.23). However, the interaction of LR-B/081 with AII receptors was found to be reversible, since the maximal response to AII was restored by coincubation with losartan, a surmountable AII AT1-antagonist. Contractions elicited by KCl or phenylephrine were not affected by 10 microM LR-B/081. 3. In rat isolated perfused kidney, LR-B/081 and losartan antagonized the AII-induced vasoconstriction [IC50 (95% confidence limits) = 17(13-24) and 39(32-54) nM, respectively]. The LR-B/081 antagonism was incompletely reversed by excess AII, while losartan was fully displaced. The IC50 values of LR-B/081 and losartan obtained against vasoconstriction induced by endothelin-1 and noradrenaline were two orders of magnitude higher. 4. In pithed rats, the intravenous administration of LR-B/081 (0.2-2 mumol kg-1) dose-dependently shifted to the right in a nonparallel fashion the dose-pressor response curve to AII. The maximal pressor response to AII was reduced by LR-B/081 in a dose-dependent fashion. The coadministration of losartan induced a progressive recovery of the maximal pressor response to All, indicating that in vivo the interaction of LR-B/081 with All receptors is reversible. LR-B/081 at 6 micromol kg-1, i.v. also did not affect the vasopressor response induced by noradrenaline in the pithed rat.5. In conscious normotensive rats, single oral administration of LR-B/081 at 6 micromol kg-1 markedly inhibited the All-induced pressor response; the inhibition lasted more than 24 h.6. In conscious renal hypertensive rats, intravenous LR-B/081 appeared as potent as losartan (ED40mmHg(95% confidence limits) = 0.50(0.36-0.70) and 0.86(0.57-1.3) micromol kg-1, respectively). A single intravenous(2 micromol kg-1) or oral (6 micromol kg-1) administration of LR-B/081 induced a marked fall in blood pressure which lasted for at least 12 h.7. In conscious spontaneously hypertensive rats, LR-B/081 at 20 micromol kg-1 , p.o., induced a marked and sustained fall in blood pressure. The duration of the antihypertensive effect was longer than 12 h.Heart rate was not modified by LR-B/081 treatment. Repeated oral administration of 17 micromol kg-1LR-B/081 for 16 days did not result in the development of tolerance.8 These results demonstrate that LR-B/081 is a potent, selective and orally active antagonist of All at the AT1-receptor subtype, which markedly lowers the blood-pressure in conscious renal and spontaneously hypertensive rats.

Pharmacokinetics and biochemical efficacy of idrapril calcium, a novel ACE inhibitor, after multiple oral administration in humans.

The pharmacokinetic profile and biochemical efficacy of idrapril calcium, a novel angiotensin converting enzyme (ACE) inhibitor, were evaluated in healthy volunteers after multiple dosing for 5 days at the doses of 100, 200 and 400 mg twice daily. The study was conducted as a double-blind, cross-over comparison of idrapril calcium against placebo. Plasma concentrations of idrapril were determined by an indirect enzymatic method. Urinary concentrations were measured by reverse phase high performance liquid chromatography (h.p.l.c.). Plasma samples were also analysed for ACE activity. The pharmacokinetics of idrapril calcium did not change significantly between day 1 and day 5. The values of Cmax and AUC were dose-related over the range of doses tested; tmax was 3-4 h and apparent elimination half-life was 1.4-1.6 h. Plasma ACE activity was maximally inhibited (94-96%) at all dose levels and remained more than 80% depressed from 2 to at least 6 h after idrapril calcium. Although the maximum effect was not dose-related, the duration of inhibition showed some dose-dependency, ACE activity returning to 56, 45 and 29% of the basal value 12 h after the 100, 200 and 400 mg doses, respectively. There were no clinically significant adverse events experienced by the volunteers. No dose-related effects on blood pressure or heart rate were observed. There were no changes in clinical pathology tests, urine analyses or electrocardiograms after dosing with idrapril calcium. Idrapril calcium, the prototype of a new class of ACE inhibitors, appears to be well-tolerated.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelins induce prostacyclin release in both vascular and non-vascular tissue.

The effects of an i.v. administration of endothelin-1, -2 and -3 (0.25-3 nmol kg-1) or their corresponding proendothelins (1-20 nmol kg-1) on blood pressure and 6 keto-prostaglandin F1 alpha (6 keto-PGF1 alpha) release in the anaesthetized ganglion-blocked rat were evaluated. The same peptides were tested for their ability to release 6 keto-PGF1 alpha from the rat vas deferens in vitro. Endothelins and proendothelins showed a transient hypotensive effect followed by a potent, long lasting vasopressor response. Blood pressure increase induced by endothelins was found to be dose-dependently correlated with 6 keto-PGF1 alpha plasma level increases. On the other hand proendothelins produced similar pressor responses, but their effect on 6 keto-PGF1 alpha plasma levels was much less intense at equipressor doses. The effects of endothelins on arterial pressure and 6 keto-PGF1 alpha release were phosphoramidon-insensitive, while the activities of proendothelins were reduced by phosphoramidon (10 mg kg-1 i.v.). Both endothelins (5-15 nmol/l) and proendothelins (100-300 nmol/l) were able to increase to a similar extent 6 keto-PGF1 alpha levels in the rat vas deferens incubation buffer. The releasing activity of endothelins was not modified by the pretreatment with phosphoramidon (50 mumol/l). This pretreatment strongly inhibited proendothelin-1 and -2 effects, but not that of proendothelin-3.

High-performance liquid chromatographic method with electrochemical detection for the determination of idrapril, a novel angiotensin-converting enzyme inhibitor, in biological matrices.

A reversed-phase high-performance liquid chromatographic method for the determination of idrapril in human and rat plasma and urine and in rat tissue homogenates is described. The method is based on the electrochemical detection of idrapril without prior derivatization. Sample preparation simply consists in deproteinization with acetonitrile for plasma and tissue homogenates and in passage through a Sep-Pak C18 cartridge for urine. The limit of quantification is 12.5 ng/ml for plasma, 125 ng/g for tissues and 2.5 micrograms/ml for urine. The method is suitable for monitoring idrapril plasma pharmacokinetics in humans and its tissue distribution and urinary excretion in rats.

Selectivity of LG50643 for postjunctional muscarinic-receptor subtype in the guinea-pig trachea.

The effects of (+/-)-LG50643, a new N-quaternary tropinic ester of phenylcyclohexene carboxylic acid, endowed with a potent antimuscarinic activity, have been investigated on muscarinic receptor-mediated responses of the guinea-pig trachea to electrical field stimulation. An isolated preparation which allows the simultaneous measurement of tritiated acetylcholine release (prejunctional effect) and smooth muscle contraction (postjunctional effect) was used. The guinea-pig epithelium-deprived trachea was stimulated with 500 pulses (20 Hz, 1 ms, 9 V for 5 s, 30 s apart) in the presence of indomethacin (1 microM). Three successive pre- and postjunctional responses were observed. The potencies (-logEC50) of (+/-)-LG50643 for pre- and postjunctional muscarinic receptors were determined and compared with those of selective muscarinic antagonists. In addition, the affinity values of (+/-)-LG50643 for muscarinic-receptor subtypes were determined in radioligand binding experiments in cerebral cortex, heart and salivary glands of rat as target tissues for M1, M2 and M3 receptors, respectively. The results obtained in both functional and binding assays indicate (+/-)-LG50643 is a potent and selective antagonist for the M3-receptor subtype.

Angiotensins induce the release of prostacyclin from rabbit vas deferens: evidence for receptor heterogeneity.

Angiotensin II and angiotensin III stimulated prostacyclin release in a time- and dose-dependent manner in both the prostatic and the non-prostatic part of the rabbit vas deferens. Also, angiotensin I enhanced the production of prostacyclin and its effect was blocked by captopril. Losartan, a type 1 (angiotensin AT1)-selective receptor antagonist, prevented the angiotensin II-induced prostacyclin release. The agonist peptide, p-aminophenylalanine angiotensin II, and the type 2 (angiotensin AT2)-selective receptor antagonist, PD123319, were found active only in the prostatic portion, suggesting heterogeneity of the receptor population. In conclusion, an angiotensin AT1 receptor mostly mediates the angiotensin-induced release of prostacyclin in the rabbit vas deferens.