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1. The metabolism of delmopinol, an inhibitor of plaque formation and gingivitis. has been studied after mouth rinsing or an oral dose of 14C-delmopinol to healthy male volunteers. The metabolite pattern was studied in urine and plasma samples (unhydrolysed or hydrolysed with conjugate cleaving enzymes) by liquid chromatography (LC) with radio detection. Metabolite identifications were carried out by gas chromatography-electron-impact mass spectrometry (GC-MS) and by liquid chromatography-thermospray mass spectrometry (LC-MS). 2. The metabolic clearance of delmopinol was high, and < 0.2% of the dose was excreted as intact delmopinol in the urine. The main metabolites were, for both administration routes, glucuronide conjugates of delmopinol and of (omega-1-hydroxy) delmopinol. These metabolites were predominant and accounted for nearly the entire urinary radioactivity and most of the plasma radioactivity. After mouth rinsing, parent delmopinol was also one of the main compounds in plasma. 3. Several other products of oxidation of the aliphatic side-chain were present in minor amounts in urine. These metabolites also appeared to be excreted as glucuronic acid conjugates. 4. Glucuronidated (omega-1-hydroxy) delmopinol separated into three peaks by the LC system used. This could be due to different chromatographic properties of conjugate isomers, positional or optical.

The selective serotonin reuptake inhibitors (SSRIs) have obtained global attention but have not demonstrated superior efficacy in major depression compared with older tricyclic antidepressants. From a pharmacological viewpoint the noradrenergic system in the brain appears to have a central role in neurotransmitter organization. The importance of noradrenaline in depression is supported by its association with clinical parameters such as vigilance and drive. Reboxetine is a selective noradrenaline reuptake inhibitor--the first in its class to be marketed. In both preclinical and clinical studies reboxetine has been found to be an effective and safe antidepressant. Furthermore, reboxetine restores a patients' social functioning, producing a better quality of remission than fluoxetine.

Reboxetine is a new antidepressant acting by selective inhibition of noradrenaline reuptake (NARI) at the synaptic cleft. The efficacy of reboxetine is similar to other antidepressants such as tricyclic and Selective Serotonin reuptake inhibitors once (SSRI). A faster onset of action (in a mean of 10 days) is suggested by preliminary studies. Reboxetine seems also to improve social adjustment of the treated depressed patients. Due to its selectivity, reboxetine presents a favourable safety profile. Treatment of depression will certainly benefit from this new compound. However, some issues need to be clarified such as the use of reboxetine in combination with other antidepressants.

In vitro studies were conducted to identify the hepatic cytochrome P-450 (CYP) enzymes responsible for the oxidative metabolism of the individual enantiomers of reboxetine. In human liver microsomes, each reboxetine enantiomer was metabolized to one primary metabolite, O-desethylreboxetine, and three minor metabolites, two arising via oxidation of the ethoxy aromatic ring and a third yet unidentified metabolite. Over a concentration range of 2 to 200 microM, the rate O-desethylreboxetine formation for either enantiomer conformed to monophasic Michaelis-Menten kinetics. Evidence for a principal role of CYP3A in the formation of O-desethylreboxetine for (S, S)-reboxetine and (R,R)-reboxetine was based on the results from the following studies: 1) inhibition of CYP3A activity by ketoconazole markedly decreased the formation of O-desethylreboxetine, whereas inhibitors selective for other CYP enzymes did not inhibit reboxetine metabolism, 2) formation of O-desethylreboxetine correlated (r(2) = 0.99; p <.001) with CYP3A-selective testosterone 6-beta-hydroxylase activity across a population of human livers (n = 14). Consistent with inhibition and correlation data, O-desethylreboxetine formation was only detectable in incubations using microsomes prepared from a Baculovirus-insect cell line expressing CYP3A4. Furthermore, the apparent K(M) for the O-desethylation of reboxetine in cDNA CYP3A4 microsomes was similar to the affinity constants determined in human liver microsomes. In addition, (S,S)-reboxetine and (R,R)-reboxetine were found to be competitive inhibitors of CYP2D6 and CYP3A4 (K(i) = 2.5 and 11 microM, respectively). Based on the results of the study, it is concluded that the metabolism of both reboxetine enantiomers in humans is principally mediated via CYP3A.

A water-soluble phosphoramidate prodrug (L-758,298, compound I) of the potent and selective human Substance P receptor antagonist L-754, 030 (compound II) is under development as an i.v. drug for treatment of emesis, migraine, and chronic pain. Compound I undergoes hydrolysis readily to II under acidic conditions. In the studies reported herein, we investigated the stability of I in blood and hepatic subcellular fractions from rats, dogs, and humans as well as the conversion of I to II in rats and dogs after i.v. dosing. Compound I was converted to II rapidly in rat blood but was stable in dog and human blood. However, the conversion was rapid in liver microsomes prepared from dogs and humans. As expected from the results of in vitro studies, the in vivo conversion of I to II was rapid after i.v. dosing of I to rats and dogs. The relative extent of exposure of II after i.v. dosing of I was estimated by comparing the dose-adjusted area under the plasma concentration versus time curve values of II after i.v. dosing of I with those after i.v. dosing of II. In rats, the extent of exposure was estimated to be approximately 90 and approximately 100% at 1 and 8 mg/kg, respectively; in dogs, that was approximately 59% at 0.5 mg/kg. A nonproportional increase in the area under the concentration versus time curve value of II with dose was observed after i.v. administration of I in dogs from 0.5 to 32 mg/kg, suggesting that the elimination of II might have been saturated at higher doses.

Background: Ketoconazole is a potent inhibitor of the cytochrome P450 3A4 enzyme. Reboxetine, a selective norepinephrine reuptake inhibitor, is metabolized by cytochrome P450 3A4. The potential interaction of reboxetine with this representative from the azole derivative class was examined., Methods: Eleven healthy volunteers received (1) 4 mg reboxetine orally on the second day of a 5-day regimen of 200 mg ketoconazole once daily and (2) 4 mg reboxetine orally in a crossover design. Plasma concentrations of reboxetine enantiomers [R,R(-)-reboxetine and the more active S,S(+)-reboxetine] were measured by high-performance liquid chromatography-tandem mass spectrometry. Effects of ketoconazole on enantiomer pharmacokinetics were assessed by ANOVA., Results: Ketoconazole increased R,R(-)-reboxetine and S,S(+)-reboxetine mean area under the plasma concentration-time curves (AUC) by 58% and 43%, respectively (P < .02). Oral clearance of both enantiomers was consequently decreased 34% and 24%, respectively, by ketoconazole (P < .005). Ketoconazole did not significantly affect maximal plasma concentrations (P > .1). Mean terminal half-life after administration of ketoconazole (21.5 hours and 18.9 hours) was significantly longer than after reboxetine alone (14.8 hours and 14.4 hours; P < or = .005). The AUC ratio for R,R(-)-reboxetine to S,S(+)-reboxetine was reduced by ketoconazole administration (2.76 after ketoconazole versus 2.39; P < .003)., Conclusion: Ketoconazole decreases clearance of both reboxetine enantiomers. Although the adverse effect profile for reboxetine was not altered by ketoconazole, the results of this study suggest that caution should be used and that a reduction in reboxetine dose should be considered when the two are coadministered.

Background: Reboxetine [(R,S)-2[(R,S)-alpha-(2-ethoxyphenoxy)benzyl]morpholine methanesulfonate] is a racemic compound that consists of equal proportions of R,R- and S,S-enantiomers. This study investigated the hemodynamic effects of reboxetine and the R,R-enantiomer compared with placebo in volunteers. The pharmacokinetics of reboxetine and its enantiomers were also investigated in the study., Methods: Nine healthy, male volunteers received single doses of 4 mg reboxetine, 2 mg R,R-enantiomer, and placebo at weekly intervals. Reboxetine and the R,R-enantiomer were well tolerated in all volunteers., Results: The heart rates of patients in the supine and standing positions were increased after reboxetine administration compared with the R,R-enantiomer (P < .05, except supine heart rate at 6 hours) and placebo (P < .05). Supine systolic and diastolic blood pressure was also increased by 3 +/- 4 and 1 +/- 4 mm Hg, respectively, after reboxetine compared with R,R-enantiomer (-2 +/- 4 and -4 +/- 3 mm Hg) and placebo (-4 +/- 4 and -4 +/- 4 mm Hg) administration. The systolic and diastolic blood pressure measurements for subjects while standing did not differ significantly among treatments. There was no significant difference between the maximum plasma concentration, mean time to maximum plasma concentration, plasma half-life, or area under the plasma concentration-time curve (AUC) of the R,R-enantiomer after reboxetine or R,R-enantiomer administration. The ratio of the mean AUC values for the R,R- and S,S-enantiomers was 2.1., Conclusion: These findings suggest that the S,S-enantiomer is responsible for the hemodynamic effects of reboxetine in humans. Increases in supine blood pressure after reboxetine administration may be interpreted as regression to the mean value and not caused by any treatment effect.

We have used an ex vivo binding assay in the mouse to evaluate the brain penetration of cannabinoid receptor ligands. After intraperitoneal or oral administration, the pharmacological activity linked to the compound was assessed by using by [3H]WIN 55212-2 binding on cerebellar membranes. The brain penetration was high for compounds like methanandamide or delta9-tetrahydrocannabinol but poor for synthetic agonists such as (cis)-3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-(trans)-4-(3-hydr oxypropyl)cyclohexanol (CP 55940) or, R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrol[1,2,3-d e]-1,4-benzoxazin-6-yl)(1-napthalenyl)methanone monomethane-sulfonate (WIN 55212-2). After oral administration the duration of action of delta9-tetrahydrocannabinol, methanandamide and WIN 55212-2 is limited and decreased 4 h after administration. The cannabinoid CB1 receptor antagonist: N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1 H-pyrazole-3-carboxamide hydrochloride (SR141716A) exhibited a good brain penetration and a long duration of action.

Reboxetine is a racemic mixture of FCE 22071 and FCE 21684 enantiomers. The pharmacokinetics of the enantiomers of reboxetine were observed to be linear in male healthy subjects (n = 6) after the administration of 1.5, 3, 4.5 mg dose of reboxetine as solutions. Kinetic analysis was based on chiral HPLC assay of the enantiomers in plasma collected up to 72 h after each administration. C(max) and AUC were more than double for FCE 22071 (C(max): 38.3+/-13.5, 76. 6+/-26.3, 99.8+/-24.1 ng/mL and AUC(infinity): 605.8+/-233.2, 1288. 3+/-796.4, 1780.7+/-669.3 ng. h/mL for 1.5, 3, 4.5 mg, respectively) than for FCE 21684 (C(max): 15.2+/-5.3, 34.6+/-14.0, 43.1+/-12.3 ng/mL and AUC(infinity): 247.0+/-103.9, 529.1+/-278.4, 773.0+/-355.3 ng. h/mL), whatever the administered dose. The half-lives of the enantiomers were similar (FCE 22071: 13.1, 11.0, 12.6 h and FCE 21684: 12.8, 11.2, 12.2 h after 1.5, 3, 4.5 mg, respectively) and not substantially affected by the dose level., (Copyright 1999 John Wiley & Sons, Ltd.)

This phase I study was performed to assess the feasibility of combining cisplatin/etoposide (VP-16) with the arotinoid Ro 40-8757 and to determine the dose-limiting toxicity (DLT) of Ro 40-8757 in this combination. Patients with non-small cell lung cancer were eligible. Treatment consisted of Ro 40-8757 p.o. day 1-21, cisplatin 100 mg/m2 i.v. on day 2 and VP-16 100 mg/m2 i.v. on day 2-4, repeated every 3 weeks. Eighteen patients were evaluable for toxicity and response. The doses of Ro 40-8757 ranged from 84 mg/m2 once daily to 42 mg/m2 thrice daily (tid). DLT consisting of delayed nausea/vomiting was reached at 42 mg/m2 tid. Consequently, the maximum tolerated dose was set at one dose level below the DLT, i.e. 28 mg/m2 tid. Skin toxicity occurred but was well manageable. Pharmacological analyses showed a small increase in the volume of distribution of cisplatin and VP-16 between the first and third course. However, no relationship with side effects was found. A response was achieved in 50% of patients. The combination of cisplatin/VP-16 with Ro 40-8757 appears to be feasible at a dose schedule of 28 mg/m2 tid. The response rate was at the upper rate of what can be expected with cisplatin and VP-16.

The absolute configuration of an enantiomer of the title compound, (+/-)-1. fumaric acid salt, was determined by X-ray crystallographic analysis of (+)-1 [salt of (+)-tartaric acid [(+)-2]]. This salt for X-ray crystallographic analysis was prepared by a simple method. The analysis of (+)-1 [salt of (+)-2] showed that this enantiomer has the 5-S and 1-R absolute configuration. The final R and Rw values were 0.0614 and 0.0713, respectively.

The absolute bioavailability of reboxetine enantiomers was assessed in six male and six female volunteers. In a two-way crossover study, subjects received 1.0 mg reboxetine orally and 0.3 mg reboxetine as an intravenous bolus. The R,R(-) and S,S(+) enantiomers in serial plasma and urine samples were determined by a validated LC-MS-MS method. There were no significant differences between treatments for clearance or dose-corrected AUC(0-infinity) values. The absolute bioavailability was 0.919 and 1.02 for R,R(-) reboxetine and S,S(+) reboxetine, respectively. A secondary objective of the study was to assess gender effects on pharmacokinetics of the enantiomers. Significant differences in volume of distribution between genders were observed, but differences in weight-corrected volumes were not significant. Weight-corrected systemic clearance and oral clearance tended to be lower in males, but this difference reached statistical significance only for weight-corrected oral clearance of R,R(-) reboxetine. C(max) after oral administration was 40 and 48% higher in women than men for R,R(-) reboxetine and S,S(+) reboxetine, respectively. These results indicate that reboxetine enantiomers are well absorbed after oral administration and that little first-pass metabolism occurs. There are no clinically significant effects of gender on the pharmacokinetics of reboxetine enantiomers.

The administration of an ultra-short-acting beta-adrenergic antagonist, esmolol, has been introduced as a novel method for beating-heart surgery. In the present study, a new ultra-short-acting beta-blocker, ONO-1101, was administered during cardiopulmonary bypass (CPB) to investigate its effects on cardiac function and hemodynamics. Nine adult mongrel dogs underwent 60 min of CPB during which they were given either ONO-1101 (ONO group; n = 4) or saline (control group; n = 5). In the ONO group, the hearts became flaccid enough for surgery to be performed without cardiac standstill within 10 min after the commencement of ONO-1101 with significant decreases in the heart rate, the preload recruitable stroke work (PRSW), and the slope of the end-systolic left ventricular pressure-volume relationship (Emax). The mean arterial pressure and systemic vascular resistance also decreased, but were maintained above 50 mmHg during CPB without catecholamine. These indices increased to the control group level 20 min after the discontinuation of ONO-1101. The serum concentration of ONO-1101 decreased from the maximum level of 121 +/- 15 microg/ml soon after infusion to 11 +/- 5 microg/ml within 30 min after discontinuation. These data suggest that ONO-1101 may be useful to enable beating-heart surgery to be performed without aortic cross-clamp as an ultra-short-acting beta-adrenergic blocker.

Recent studies have demonstrated that the pharmacological tolerance observed after prolonged exposure to plant or synthetic cannabinoids in adult individuals seems to have a pharmacodynamic rather than pharmacokinetic basis, because down-regulation of cannabinoid receptors was assessed in the brain of cannabinoid-tolerant rats. In the present study, we have examined the time-course of cannabinoid receptor down-regulation by analyzing cannabinoid receptor binding, using autoradiography, and mRNA expression, using in situ hybridization, in several brain structures of male adult rats daily exposed to delta9-tetrahydrocannabinol (delta9-THC) for 1, 3, 7, or 14 days. With only the exception of a few number of areas, most of the brain regions exhibited a progressive decrease in cannabinoid receptor binding. Two facts deserve to be mentioned. First, the pattern of this down-regulation process presented significant regional differences in terms of onset of the decrease and magnitude reached. Second, the loss of cannabinoid receptor binding was usually accompanied by no changes in its mRNA expression. Thus, some structures, such as most of the subfields of the Ammon's horn and the dentate gyrus in the hippocampus, exhibited a rapid (it appeared after the first injection) and marked (it reached approximately 30% of decrease after 14 days) reduction of cannabinoid receptor binding as a consequence of the daily delta9-THC administration. However, no changes occurred in mRNA levels. Decreased binding was also found in most of the basal ganglia, but the onset of this reduction was slow in the lateral caudate-putamen and the substantia nigra (it needed at least three days of daily delta9-THC administration), and, in particular, in the globus pallidus (more than 3 days). The magnitude of the decrease in binding was also more moderate, with maximal reductions always less than 28%. No changes were seen in the entopeduncular nucleus and only a trend in the medial caudate-putamen. However, the decrease in binding in some basal ganglia was, in this case, accompanied by a decrease in mRNA levels in the lateral caudate-putamen, but this appeared after 7 days of daily delta9-THC administration and, hence, after the onset of binding decrease. In the limbic structures, cannabinoid receptor binding decreased in the septum nuclei (it needed at least 3 days of daily delta9-THC administration), tended to diminish in the nucleus accumbens and was unaltered in the basolateral amygdaloid nucleus, with no changes in mRNA levels in these last two regions. Binding also decreased in the superficial and deep layers of the cerebral cortex, but only accompanied by trends in mRNA expression. The decrease in binding was initiated promptly in the deep layer (after the first injection) and it reached more than 30% of reduction after 14 days of daily delta9-THC administration, whereas, in the superficial layer, it needed more than 3 days of daily delta9-THC administration and reached less than 30% of reduction. Finally, no changes in binding and mRNA levels were found in the ventromedial hypothalamic nucleus. In summary, the daily administration of delta9-THC resulted in a progressive decrease in cannabinoid receptor binding in most of the brain areas studied, and it was a fact that always occurred before the changes in mRNA expression in those areas where these existed. The onset of the decrease in binding exhibited regional differences with areas, such as most of the hippocampal structures and the deep layer of the cerebral cortex, where the decrease occurred after the first administration. Other structures, however, needed at least 3 days or more to initiate receptor binding decrease. Two structures, the entopeduncular nucleus and the ventromedial hypothalamic nucleus, were unresponsive to chronic delta9-THC administration, whereas others, the medial caudate-putamen and the basolateral amygdaloid nucleus, only exhibited trends.

1. The absorption and excretion of delmopinol, an inhibitor of plaque formation and gingivitis, were studied in healthy male volunteers. Each subject received a single dose of a 10-ml aqueous solution of 14C-delmopinol at 2 mg/ml as a 1-min mouth rinse (the intended route of administration; n=6) or as an oral dose (n=6). 2. After mouth rinsing, 72% of the dose was expectorated. The retained portion of the dose was rapidly absorbed and eliminated. Of the dose, 25% was recovered in the urine. Renal excretion was predominant also after oral administration with 92% of the dose excreted in the urine. The total recovery of 14C-activity after 6 days was 99% (rinsing) and 95% (oral) with the bulk, 20% (rinsing) and 80% (oral), of the dose excreted already within 8 h. 3. Peak plasma levels of 14C-labelled compounds were attained at 1.5 h after rinsing and 0.5 h after oral administration; total concentrations were approximately 200 and 3000nmol/l, respectively. For parent delmopinol, peak plasma levels of 49 nmol/l (rinsing) and 8 nmol/l (oral) occurred after 1.5 and 1.3 h, respectively. After rinsing, the concentration of delmopinol declined with a half-life of 2.4 h. The plasma level of 14C-labelled compounds declined multiphasically. In the terminal elimination phase (after 72 h) remaining radioactivity, < 2% of dose (rinse) and < 5% of dose (oral), decreased with a half-life of approximately 130 and 160 h, respectively. 4. Results indicate a very low bioavailability (1-3%) due to extensive first-pass metabolism of delmopinol after oral administration. A high plasma clearance (> 60 l/h) and a large volume of distribution (> 200 l) were also indicated. 5. The results of rapid and almost complete recovery in the urine support that delmopinol can safely be used in the treatment of patients with plaque or gingivitis.

Cytochrome P450 3A4 (CYP3A4), the major phase I drug metabolizing enzyme in humans, and the MDR1 gene product P-glycoprotein (P-gp) are present at high concentrations in villus tip enterocytes of the small intestine and share a significant overlap in substrate specificity. A large body of research both in vitro and in vivo has established metabolism by intestinal CYP3A4 as a major determinant of the systemic bioavailability of orally administered drugs. More recently it has been recognized that drug extrusion by intestinal P-gp can both reduce drug absorption and modulate the effects of inhibitors and inducers of CYP3A-mediated metabolism. There is relatively little data regarding the effects of CYP3A and P-gp on peptide drugs; however, studies with the cyclic peptide immunosuppresant cyclosporine as well as peptidomimetics such as the HIV-protease inhibitor saquinavir (Invirase) and a new cysteine protease inhibitor K02 (Morpholine-Urea-Phe-Hphe-Vinyl sulfone; Axys Pharmaceuticals) provide some insight into the impact of these systems on the oral absorption of peptides.

Restenosis is the reobstruction of an artery following interventional procedures such as balloon angioplasty or stenting. Local pharmacotherapeutic approaches using controlled release systems are under investigation to inhibit the regional pathophysiologic process of restenosis. We have been investigating biodegradable nanoparticles (100 +/- 39 nm in diameter, mean +/- sd) for the local intra-arterial drug delivery. The purpose of this study was to investigate nanoparticle surface modifications (see Table 1) to enhance their arterial uptake. The PLGA (polylactic polyglycolic acid copolymer) nanoparticles were formulated by an oil-in-water emulsion solvent evaporation technique using a 2-aminochromone (U-86983, Upjohn and Pharmacia) (U-86) as a model antiproliferative agent. The various formulations of nanoparticles were evaluated for the arterial wall uptake by using an ex-vivo dog femoral artery model. The selected formulations were then tested in vivo in acute dog femoral artery and pig coronary artery models. The nanoparticles surface modified with a cationic compound, didodecyldimethylammonium bromide (DMAB), demonstrated 7-10-fold greater arterial U-86 levels compared to the unmodified nanoparticles in different ex-vivo and in-vivo studies. The mean U-86 levels were 10.7 +/- 1.7 microg/10 mg (dog) and 6.6 +/- 0.6 microg/10 mg (pig) in the artery segments ( approximately 2 cm) which were infused with the nanoparticles. The pig coronary studies further demonstrated that the infusion of nanoparticles with higher U-86 loading reduced the arterial U-86 levels, whereas increasing the nanoparticle concentration in the infusion solutions increased the arterial U-86 levels. The biodistribution studies in pigs following coronary arterial administration of nanoparticles demonstrated disposition of U-86 in the myocardium and distally in the liver and the lung. The mechanism of enhanced arterial uptake of the DMAB surface modified nanoparticles seems to be due to the alteration in the nanoparticle surface charge. The unmodified nanoparticles had a zeta potential of -27.8 +/- 0.5 mV (mean +/- sem, n = 5), whereas the DMAB modified nanoparticles demonstrated a zeta potential of +22.1 +/- 3.2 mV (mean +/- sem, n = 5). The adsorption of DMAB to the nanoparticle surface followed the Freundlich isotherm with binding capacity k = 28.1 microg/mg and affinity constant p = 2. 33. In conclusion, surface modified nanoparticles have potential applications for intra-arterial drug delivery to localize therapeutic agents in the arterial wall to inhibit restenosis.

In vitro preformulation testing has shown that the solubility and dissolution rate of the model drug compound ucb 11056 are highly pH dependent. Considering this, different sustained-release (SR) oral dosage forms of ucb 11056 were developed aiming to obtain the most constant and complete release of the drug during transit in the gastrointestinal (GI) tract. Classical approaches based on the use of SR formulations such as hydrophilic matrix tablets or pellets coated with one film-forming polymer (Eudragit NE30D or L30D-55) did not fulfill all expectations on the basis of their in vitro evaluation, i.e., the drug release and pattern remained highly dependent on the pH of the dissolution medium. Therefore, taking advantage of the flexibility of release adjustment obtainable from coating of pellets with different kinds of pH-sensitive film layers, a quite satisfactory pH independence of the release characteristics was obtained using formulation blends of neutral and anionic acrylic polymers. For the selected SR pellets batch 15 coated with NE30D/L30D-55 (7:3), the tridimensional topographic representation of the drug release versus time and pH showed that, notwithstanding the pH-dependent aqueous solubility of the drug, the release profiles were relatively homogeneous for any pH value ranging between 1 and 7.

Sustained-release (SR) dosage forms consisting of pellets coated with different pH-sensitive film layers, previously optimized in vitro with regard to pH independence of their drug release characteristics, were evaluated in vivo after single administration to Beagle dogs. In vivo performances were compared to those of a nonoptimized SR matrix tablet and a reference instant release (IR) capsule, in terms of the observed plasma pharmacokinetic profiles for the parent drug (ucb 11056) and its primary metabolite (ucb 26201), the bioavailability results, and the drug tolerance data. All SR dosage forms were seen to be effective in prolonging the relatively short biological half-life of the compound and in reducing the incidence of concentration-related side-effects, e.g., emesis, and of behavioral symptoms, e.g., restlessness, discomfort, and indisposition. The film-coated SR pellets offer a number of advantages over the monolithic SR matrix system in terms of a drug delivery pattern less dependent on pH changes in the gastrointestinal (GI) tract, a higher flexibility for adjusting and controlling the pharmacokinetic profiles, and a consequently more efficient approach for keeping all concentration-related side-effects under control.

Steady-state concentrations of S12024, a novel compound for treatment of Alzheimer's disease, were studied to determine the pharmacokinetic parameters of S12024 in Phase IIa patients and to assess the effect of patient characteristics on those pharmacokinetics. A prospective sparse sampling strategy was used to obtain oral repeated data (n = 285) from 89 patients, which were analyzed using a one-compartment model and the NONMEM computer program. The model suggested that apparent clearance of S12024 was influenced by the study and by patient age. In the Spanish study, apparent clearance was increased by 68% and 26% for doses of 100 mg and 300 mg, respectively, and patient age decreased oral clearance by approximately 10% per decade in the patient age range (50 to 90 years). Data from only a few patients in the Spanish study were probably responsible for the observed study influence on apparent clearance of S12024, and no measured covariates could explain this effect. The model provided an excellent characterization of the observed data and it predicted correctly the plasma concentrations from an earlier Phase I trial and a subsequent Phase IIb study. The present model, built from Phase IIa data, provides a basis for examining the influence of patient covariates and the magnitude of their effects on the pharmacokinetics of S12024. The study effect is probably an artefact that will disappear by further expanding of the population model in the future.

CAM 5500 and CAM 5187 are new nonpeptide tachykinin NK3 receptor antagonists with different lipophilicity and solubility. We have developed and validated two separate, simple HPLC methods for quantitation of these two compounds in plasma to support oral pharmacokinetic/bioavailability studies in rats. The two compounds in plasma were extracted on cyano SPE cartridges with different washing schemes to optimize extraction efficiency and chromatographic specificity. The analytes and internal standard in the resulting extracts were chromatographed on a C18 HPLC column, using mobile phases containing different phosphate buffer strengths and acetonitrile concentrations. Both compounds were detected using UV, Peak area ratios were proportional over the concentration range of 50-3000 ng ml-1 for CAM 5500, and 100-1500 ng ml-1 for CAM 5187. Stability profiles of both drugs and internal standard in rat plasma at 37 degrees C and in injection solvent at ambient temperature were good. Assay precision, based on quality controls, was < 5.6% and 13.4% (%RSD) for CAM 5500 and CAM 5187, respectively. Similarly, assay accuracy for both compounds was within +/- 7.1% and +/- 6.0% (%RE), respectively. The HPLC methods were successfully applied to assay samples from two oral bioavailability studies. Oral bioavailability studies were conducted for each compound in rats receiving a PO dose of 20 mg kg-1 or an i.v. dose of 5 mg kg-1. Despite their difference in lipophilicity and solubility, the absolute oral bioavailability of CAM 5500 (5.3 +/- 4.8%) is similar to that of CAM 5187 (8.8% +/-3.2%).

The synthesis of a series of 2,4-disubstituted morpholines is described and their affinities at human dopamine receptors reported. The orally bioavailable 7-azaindole compound 11 has nanomolar affinity at the hD4 receptor with > 1000-fold selectivity over the hD2 receptor.

Indeloxazine hydrochloride (IDX), a cerebral activator, has a bitter astringent taste. To prepare powders of IDX without this bitter taste, microparticles (median diameter, 130 microns) of IDX were coated with a mixture comprising hydrogenated oil and surfactants in a fluidized bed using the side-spray method. Drug release from the resulting coated particles was significantly delayed. Dissolution rate was remarkably enhanced, however, by heat-treating the coated particles at a temperature above the melting point of the surfactant in the coated layer. The results of differential scanning calorimetry measurements show that part of the surfactant in the coated layer exists separately. Further, surface changes in the coated layer before and after heat treatment showed that this enhancement of dissolution rate was due to rediffusion of the surfactant in the coated layer followed by melting of the surfactant. This effect allows the design of powders of IDX which release the drug quickly and with bioequivalence to the commercial IDX 20 mg tablets while sufficiently suppressing the bitter taste.

(R)-3-(1-[2-(4-benzoyl-2-(3,4-difluorophenyl)-morpholin-2-yl)- ethyl]-4-phenylpiperidin-4-yl)-1-dimethylurea (SR 144190) is a new non-peptide antagonist of tachykinin NK2 receptors. SR 144190 potently and selectively inhibited neurokinin A binding to NK2 receptors from various species, including humans. In in vitro functional assays, it was a potent, selective and competitive antagonist of NK2 receptors with apparent affinities (pA2 values) between 9.08 and 10.10. In vivo, SR 144190 blocked [Nle10]neurokinin A-(4-10)-induced bronchoconstriction in guinea pigs (ID50 = 21 micrograms kg-1 i.v. and 250 micrograms kg-1 i.d.) and [beta Ala8]neurokinin A-(4-10)-induced urinary bladder contraction in rats (ID50 = 11 micrograms kg-1 i.v. and 190 micrograms kg-1 i.d.). It prevented citric acid-induced cough and airway hyperresponsiveness to acetylcholine in guinea pigs (1 mg kg-1 i.p.) as well as castor oil-induced diarrhoea in rats (0.01-10 micrograms kg-1 s.c. or p.o). Finally, it blocked the turning behaviour induced by intrastriatal injections of [Nle10]neurokinin A-(4-10) in mice (ID50 = 3 micrograms kg-1 i.v. and 16 micrograms kg-1 p.o.).

The pharmacokinetics and metabolism of reboxetine, a selective noradrenaline reuptake inhibitor, in humans and animal models are reviewed here. Reboxetine has potent antidepressant activity, low affinity for alpha-adrenergic and muscarinic receptors and low toxicity in animals. It is a mixture of (R,R) and (S,S) enantiomer, the latter being more potent but no qualitative differences in pharmacodynamic properties are observed between the two. Humans rapidly absorb reboxetine (tmax about 2 h) with a terminal half-life of elimination (t1/2) of 13 h, allowing twice-daily administration. Animal models also rapidly absorb reboxetine (tmax 0.5-2 h) but t1/2 was 1-2 h. Food does not affect bioavailability. There were no major inter-species differences in the metabolic profile of reboxetine. Elimination is principally renal in humans and monkeys. Reboxetine has linear pharmacokinetics in young, healthy males for single doses of 1-5 mg and in elderly, female depressed patients (up to 4 mg b.i.d.). Multiple dosing, gender or liver insufficiency had no significant effects on the pharmacokinetics. Elderly (particularly frail elderly) patients and patients with severe renal impairment may need dose reduction. Reboxetine shows no clinically relevant interaction with lorazepam and has no inhibitory effects on the major enzymes involved in drug metabolism. It may be possible to use reboxetine in combination with monoamine oxidase inhibitors as it has no inhibitory effect on this enzyme; in addition, it may protect patients against tyramine-induced reactions. In conclusion, reboxetine seems to be an antidepressant with negligible interference with the pharmacokinetics of other drugs thus fewer drug-drug interactions are expected.

We conducted a randomized study with four parallel groups to investigate the effect of single and multiple doses of activated charcoal on the absorption and elimination of pholcodine administered in a cough syrup. The first group received 100 mg of pholcodine on an empty stomach with water only (control); the second group took 25 g of activated charcoal immediately after pholcodine; the third group received 25 g of activated charcoal 2 h and the fourth group 5 h after ingestion of the 100-mg dose of pholcodine. In addition, the fourth group received multiple doses (10 g each) of charcoal every 12 h for 84 h. Blood samples were collected for 96 h and urine for 72 h. Pholcodine concentrations were measured by high-performance liquid chromatography. A significant reduction in absorption was found when charcoal was administered immediately after pholcodine; the AUC0-96h was reduced by 91% (p < 0.0005), the Cmax by 77% (p < 0.0005), and the amount of pholcodine excreted into urine by 85% (p < 0.0005). When charcoal was administered 2 h after pholcodine, the AUC0-96h was reduced by 26% (p = 0.002), the Cmax by 23% (p = NS), and the urinary excretion by 28% (p = 0.004). When administered 5 h after pholcodine, charcoal produced only a 17% reduction in the AUC0-96h (p = 0.06), but reduced the further absorption of pholcodine still present in the gastrointestinal tract at the time of charcoal administration, as measured by AUC5-96h (p = 0.006). Repeated administration of charcoal failed to accelerate the elimination of pholcodine. We conclude that activated charcoal is effective in preventing the absorption of pholcodine, and its administration can be beneficial even several hours after pholcodine ingestion.

UR-9746 and UR-9751 are novel azole derivatives each containing a morpholine ring. They were examined for both in vitro and in vivo activities against Coccidioides immitis. In vitro, UR-9746 and UR-9751 were active, with MICs of 25 and 3.1 micrograms/ml, respectively, against C. immitis Silveira; minimum fungicidal concentrations were > 100 micrograms/ml, the highest concentration tested, for both compounds. Antifungal activity in serum showed the desirable characteristic of remaining severalfold above the MIC at all times. Against systemic murine coccidioidomycosis, UR-9746 and UR-9751 prolonged survival at dosages of > or = 10 mg/kg/day and showed increased reduction of infectious burden in the spleens, livers, and lungs of treated mice with escalating dosage. Both compounds lacked observable toxicity and on a milligram-per-kilogram of body weight basis were > or = 10-fold superior to fluconazole in prolonging survival and clearing infection with C. immitis.

Reboxetine, (RS)-2-[(RS)-alpha-(2-ethoxyphenoxy)benzyl]morpholine methanesulphonate, is a racemic compound and consists of a mixture of the (R,R)- and (S,S)-enantiomers. The pharmacokinetics of reboxetine enantiomers were determined in a crossover study in three male beagle dogs. Each animal received the following oral treatments, separated by 1-week washout period: 10 mg/kg reboxetine, 5 mg/kg (R,R)- and 5 mg/kg (S,S)-. Plasma and urinary levels of the reboxetine enantiomers were monitored up to 48 h post-dosing using an enantiospecific HPLC method with fluorimetric detection (LOQ: 1.1 ng/ml in plasma and 5 ng/ml in urine for each enantiomer). After reboxetine administration mean tmax was about 1 h for both enantiomers. Cmax and AUC were about 1.5 times higher for the (R,R)- than for the (S,S)-enantiomer, mean values +/- SD being 704 +/- 330 and 427 +/- 175 ng/ml for Cmax and 2,876 +/- 1,354 and 1,998 +/- 848 ng.h/ml for AUC, respectively. No differences between the (R,R)- and (S,S)-enantiomers were observed in t1/2 (3.9 h). Total recovery of the two enantiomers in urine was similar, the Ae (0-48 h) being 1.3 +/- 0.7 and 1.1 +/- 0.7% of the enantiomer dose for the (R,R)- and the (S,S)-enantiomers, respectively. No marked differences in the main plasma pharmacokinetic parameters were found for either enantiomer on administration of the single enantiomers or reboxetine. No chiral inversion was observed after administration of the separate enantiomers, as already observed in humans.

The pharmacokinetics of reboxetine have been investigated in 12 healthy male volunteers after a single 2 mg dose of reboxetine and at steady state, following the last administration of a multiple-dose regimen (2mg twice a day for 5 1/2 d). Reboxetine was analysed in plasma and urine samples collected up to 72 h post-dosing using an HPLC method with UV detection. The urinary excretion rate of 6-beta-hydroxycortisol, used as a marker for cytochrome P450IIIA activity, was also tested, and any possible alteration was correlated to reboxetine plasma levels. The dosing regimen was well tolerated by all subjects. Reboxetine pharmacokinetic parameters, calculated after the single dose using non-compartmental analysis, were in good agreement with those obtained in previous studies. Following the multiple-dosing regimen, no significant deviations from expectation based on linear superposition was observed. The accumulation ratio, based on repeated-dose/single-dose ratios of Cmax, AUC(0-12 h), and C(12 h) was approximately two. A slight rise was recorded for the average excretion rate of 6-beta-hydroxycortisol over 48 h by the end of treatment; however, the difference was not statistically significant and the mean excretion rates were within the normal reference range. Thus a significant induction of P450IIIA was not indicated.

A sensitive and specific high-performance liquid chromatographic method was developed and validated for the determination of the third-generation retinoid (arotinoid) mofarotene (Ro 40-8757) in human, rat and dog plasma, using direct injection of deproteinated plasma samples, automated column switching (on-line solid-phase extraction) and ultraviolet detection. Plasma (0.5 ml) was deproteinated by adding ethanol (1 ml) containing the internal standard Ro 42-8659 (200 ng/ml). After centrifugation, 0.9 ml of the supernatant were directly injected onto a precolumn packed with C18 Corasil 37-50 microns. Polar plasma components were washed out from the precolumn using 1% ammonium acetate-acetic acid-acetonitrile (900:9:100, v/v/v). After valve switching, the pre-concentrated compounds were transferred to the analytical column (C18) in the backflush mode, separated by gradient elution and detected at 300 nm. The retention times (total run times) were approximately 15 and 20 min for the internal standard and mofarotene, respectively. The method was linear in the range 10-1000 ng/ml with a limit of quantification of 10 ng/ml. The mean recoveries were 80.4%, 81.7% and 77.8% (range 10-1000 ng/ml) and the inter-assay precision was 2.7% (range 20-1000 ng/ml), 1.5% and 2.0% (both range 100-1000 ng/ml) for human, rat and dog plasma, respectively. Mofarotene was found to be stable in human, rat and dog plasma stored at -20 degrees C for 3 months and 22 degrees C for 24 h. The method was successfully applied to clinical, pharmacokinetic and toxicokinetic studies.

This study describes the binding characteristics of cannabinoid binding sites expressed in rat cerebellar membranes using the tritiated derivative of SR141716A, the newly described cannabinoid receptor antagonist. A single population of high-affinity binding sites (K(D) = 0.59 +/- 0.08 nM; Bmax = 3.86 +/- 0.42 pmol mg-1 of protein) was demonstrated. Kinetic, competition and saturation experiments give similar results in terms of SR141716A affinity. delta 9-tetrahydrocannabinol and the 11-hydroxy derivative competitively inhibited the specific binding of [3H]SR141716A (Ki = 47 +/- 9 and 32 +/- 4 nM, respectively). The cannabinoid agonist WIN55212-2 has a 25-fold lower affinity for [3H]SR141716A than for [3H]WIN55212-2, showing that the two ligands do not recognize the cannabinoid binding site in the same fashion.

The metabolism of montirelin hydrate (CAS 90243-66-6, NS-3) was studied in rats after intravenous administration of 14C-labeled or unlabeled NS-3. 1. Four radioactive metabolites (M-1 to M-4) were found in the urine after administration of 14C-NS-3. M-3 (major metabolite) and M-2 showed the same Rf values as (-)-N-[[(3R,6R)-6-methyl-5-oxo-3-thiomorpholinyl]carbonyl]-L-histi dyl-L- proline (CNK-6004) and (+)-N-[[(3R,6R)-6-methyl-5-oxo-3- thiomorpholinyl]carbonyl]-L-histidine (CNK-6001), respectively. 2. M-3 and M-2 were purified from the urine after administration of unlabeled NS-3, and their chemical structures were identified by mass spectrometry, 1H-nuclear magnetic resonance spectroscopy, thin-layer chromatography and high performance liquid chromatography. Consequently, M-3 was identified as CNK-6004 formed by deamidation at a prolinamide moiety of NS-3, and M-2 as CNK-6001 formed by deprolination of CNK-6004.

Pharmacokinetics of 14C-labeled montirelin hydrate (CAS 90243-66-6, NS-3) in rats was studied after single or repeated intravenous administration. 1. Radioactivity concentrations in tissues after single administration to male and female rats were highest in the kidney followed (in this order) by plasma, liver, blood, pancreas, uterus (female rats), lung and skin and low in various brain sites 5 min after administration. The concentrations in most tissues were practically parallel to those in plasma over the 24-h period after administration. After decreasing rapidly the concentrations rose slightly for 10 h and then decreased gradually. 2. Five min after single administration to male rats, the concentration of the main metabolite CNK-6004 (deamidated product) was lower in the plasma, but higher in the liver and kidney than the NS-3 concentration. From 0.5 to 2 h after administration, the concentration of CNK-6004 was higher than that of NS-3 in the plasma, liver and kidney, accounting for 33-64% of the radioactivity concentration. 3. After administration to rats on the 18th day of pregnancy, the radioactivity concentrations in the fetal whole body and fetal tissues peaked later than those in the maternal plasma, tissues and placenta. The maximum concentration in the fetal tissues was 2% or less of that in the maternal plasma. 4. After administration to lactating rats, the radioactivity concentration in milk reached the maximum 10 h after administration, and decreased gradually in parallel with the concentration in the plasma 24 to 168 h after administration. 5. During repeated once daily administration for 10 days, the radioactivity concentration in the plasma 24 h after each administration reached practically steady state level after the 7th administration and decreased with a half-life of 38.1 h after the last administration. 6. The radioactivity concentrations in most tissues after the last administration were not significantly different from those after a single administration. Decreased elimination of the radioactivity was observed in the white fat and skin, in which radioactivity levels were higher than those in the other tissues a long time after the last dose. 7. Excretion of the radioactivity in the urine and feces during repeated administration was constant after the 2nd administration. The excretion by 168 h after the last administration was 66.9 and 14.3% of the cumulative dose in the urine and feces, respectively (total: 81.2%). 8. The composition of metabolites in the plasma, liver, kidney and urine after the last administration did not differ markedly from that after a single administration. Once daily repeated administration for 7 days had no effect on the liver drug metabolizing enzyme activities.

The arotinoid mofarotene is a novel potent anticancer compound. The metabolic profiles obtained from rat, dog, and human plasma showed a good correlation with the corresponding in vitro profiles observed with liver microsomes and hepatocytes. Interspecies differences in its metabolism were investigated using microsomes prepared from the livers of the mouse, rat, dog, cynomolgus monkey, and humans. These in vitro experiments showed that, both qualitatively and quantitatively, the metabolic profiles obtained with cynomolgus monkey liver samples were similar to those observed with human liver material. However, rat and dog were also confirmed to be suitable species for assessing the safety of mofarotene, and were used in toxicology. The involvement of cytochrome P450 (CYP) in the metabolism of mofarotene was examined with human liver microsomes. CYP3A4 plays a major role in the metabolism, and CYP1A2 might be responsible for a minor pathway. Finally, the potential induction by mofarotene of four major CYP isoenzymes was investigated in rats. These experiments showed that CYP1A1 was clearly induced, whereas a slight induction of CYP3A and CYP2B was observed. Repeated administration of mofarotene had no effect on CYP2E1. These studies with liver microsomes and hepatocytes aided the selection of appropriate species for toxicology, and have provided information that will help to predict potential drug-drug interactions in clinical trials.

The pharmacokinetics of reboxetine, a new antidepressant agent, were found to be close to linear in a crossover study comparing administration of single 2, 3, 4, and 5 mg capsule doses in 15 healthy male volunteers, and in the same study the capsules were bioequivalent to the proposed therapeutic tablet formulation (4 mg). Kinetic analysis was based on HPLC assay of reboxetine in plasma and urine collected up to 72 h after each administration. Plasma levels indicated a rapid absorption (tmax approximately equal to 2 h) and an elimination half-life of about 13 h. Clearance and volume of distribution were modest (ratios to bioavailability: CL/F approximately equal to 29 mL min-1; Vz/F approximately equal to 32 L); urinary excretion was approximately 9% of dose, corresponding to a renal clearance of only 3 mL min-1 (a value consistent with the rate of glomerular filtration of unbound drug). In vitro, binding to plasma proteins, estimated from radioactivity levels following dialysis of 14C-labelled reboxetine, appeared to be dominated by alpha 1-acid glycoprotein without marked saturation up to plasma concentrations of over 500 ng mL-1 (2.8-3.1% unbound with human plasma from three additional volunteers; 1.8-2.0% for 2 gL-1 orosomucoid alpha 1-acid glycoprotein, and 46.4-47.4% for 40 g L-1 albumin), whilst the mean Cmax in the current study was much lower (164 ng mL-1 after a 5mg dose).

The successful introduction of angiotensin converting enzyme (ACE) inhibitors in the treatment of patients with essential hypertension or heart failure has increased interest in the (patho)physiological role of the renin-angiotensin system (RAS). ACE is not only involved in the formation of angiotensin II from angiotensin I, but also inactivates vasoactive substances such as bradykinin and substance P. Accumulation of these substances during treatment with ACE inhibitors may contribute to both their therapeutic action and certain adverse effects associated with their use, such as cough and angioneurotic oedema. Renin inhibitors offer an alternative approach to inhibit the RAS. The major advantage of these, still experimental, drugs is their high specificity for the RAS since angiotensinogen is the only known substrate of renin. The currently available renin inhibitors are pseudopeptides that are rapidly taken up by the liver and excreted in the bile. Consequently, these drugs are subjected to a considerable first pass effect which limits their oral bioavailability. Additionally, plasma elimination half-life times are short and the duration of action is limited. Despite these shortcomings, single oral or intravenous administration results in a 80 to 90% inhibition of plasma renin activity and a slight reduction in blood pressure in patients with hypertension. The extent of blood pressure reduction is dependent on the patient's salt balance. After 1 week of oral treatment with the renin inhibitor remikiren, the antihypertensive effect was reduced in salt-repleted hypertensive patients. Subsequent intravenous administration of the drug did not further affect blood pressure, indicating that it was not the first pass effect that was limiting the efficacy of remikiren.(ABSTRACT TRUNCATED AT 250 WORDS)

The single-dose and steady-state pharmacokinetics of teniloxazine, an investigational drug with antidepressant and anti-anoxic properties, were compared in 12 healthy volunteers and 12 cirrhotic patients, following oral administration of 80 mg teniloxazine maleate every 12 h for 7 days. In healthy volunteers, an increase in oral clearance, CLo (from a mean (s.d.) value of 14.6 (3.9) to 18.0 (6.6) ml min-1 kg-1; mean % ratio between the two values (95% CI), 123 (94-151)) and a significant shortening of t 1/2 (from 6.2 (2.7) to 4.8 (1.4) h; mean % ratio (95% CI), 78 (58-98)) were observed upon repeated administration, suggesting autoinduction of teniloxazine metabolism. In cirrhotic patients, the pharmacokinetic parameters of teniloxazine remained essentially invariant with time. Compared with normal subjects, CLo was about halved in cirrhotic patients, whereas t 1/2 was more than doubled. As a consequence of these modifications, the multiple-dose regimen resulted in a two-fold mean drug accumulation in cirrhotic patients, compared with virtually no accumulation in healthy volunteers. Although no adverse events were noted in either study group, it is suggested that maintenance doses for patients with liver dysfunction should initially be at the lower end of the therapeutic range.

Reperfusion of ischemic myocardium may aggravate the ischemic state of injury and thus augment infarct size (reperfusion injury). The aim of this study was to reduce infarct size by an intervention at the time of reperfusion that acts only on a reperfusion-specific pathomechanism. It was investigated whether SIN-1C, a metabolite of molsidomine, can protect against reperfusion injury in canine hearts in vivo. Ten anesthetized open chest dogs underwent 1 h of left anterior descendent artery (LAD) occlusion and were randomly assigned to receive either intracoronary SIN-1C or vehicle infusion as a placebo during the first hour of reperfusion. The infusion was adjusted to LAD flow to achieve a regional blood concentration of 5 x 10(-3) M. Infarct size was assessed by triphenyltetrazolium staining after 6 h of reperfusion. Left ventricular pressure (LVP) was similar in both groups (SIN-1C: 101 +/- 6, placebo: 89 +/- 6 mm Hg, mean +/- SEM, n = 5) at the beginning of the experiment and did not change significantly thereafter from baseline values in both groups. During SIN-1C infusion, the LAD flow was increased (SIN-1C: 195 +/- 38, control: 86 +/- 17 ml/min/100 g at 30 min of reperfusion, p < 0.05), while systemic hemodynamics remained unaltered. A reduction in infarct size (percent of area at risk) was seen in the SIN-1C group (11.4 +/- 2.8%) compared with the placebo group (24.4 +/- 3.9%, p < 0.05). Infusion of papaverin (5 x 10(-5) M) following an identical protocol caused a similar vasodilation as SIN-IC, but did not reduce infarct size in five additional dox experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

L-689,502, N-[2(R)-hydroxy-1(S)-indanyl]-5(S)-(1,1-dimethylethoxy- carbonyl-amino)-4(S)-hydroxy-6-phenyl-2(R)-(4-[2(R)-(4-morpholinyl) ethoxy]phenyl)methylhexamide, is a potent and specific inhibitor of human immunodeficiency virus-type 1 (HIV-1) protease in vitro. Metabolism of this compound in rat liver slices produced four major and several minor metabolites. The major metabolites were identified as morpholin-2-one, 3'(S)-hydroxyindan and 4'-hydroxyindan analogs, and a 4-O-glucuronic acid conjugate of the parent compound. The metabolites were characterized by Heteronuclear Multiple Quantum Coherence and Nuclear Overhauser Effect techniques in NMR spectroscopy, by MS, and/or comparison with authentic standards. Two of the minor metabolites were similarly characterized as a 2(R)-[4-(2-carboxymethoxy)phenyl]methyl analog and a product with a degraded morpholino ring. The hydroxyindan metabolites were lower in activity than L-689,502, whereas the morpholin-2-one and carboxymethoxyphenyl analogs were approximately 6- and 11-fold more potent as inhibitors of HIV-1 protease, respectively.

The pharmacokinetics of mofarotene were investigated in mice, rats and dogs following single intravenous and oral administrations. Healthy volunteers were also given a single oral dose of 300 mg mofarotene. The data indicate a similar disposition for mofarotene in all species studied: low clearance consistent with a high bioavailability following oral dosing, and large volume of distribution indicating an extensive tissue uptake. Also in vitro in liver microsomes, the values for intrinsic clearance were in all species within a 2-fold range. The dog, however, tended to exhibit, both in vitro and in vivo, the lowest clearance. Although (due to the lack of protein binding data) a direct prediction of the in vivo clearance from in vitro data was not possible, the experiments with liver microsomes did provide a clear insight into the rate of elimination of mofarotene in vivo in the different species studied including man.

Amorolfine is a structurally unique, topically active antifungal agent, which possesses both fungistatic and fungicidal activity in vitro. Its spectrum of in vitro activity includes dermatophyte, dimorphic, some dematiaceous and filamentous fungi, and some yeasts. In clinical trials, application of amorolfine 5% nail lacquer once or twice weekly for up to 6 months produced mycological and clinical cure in approximately 40 to 55% of patients with mild onychomycosis 3 months after cessation of therapy. Overall cure and improvement was observed in approximately 85 to 90% of patients with superficial dermatomycoses following treatment with amorolfine 0.25% cream for up to 6 weeks. However, few controlled, comparative trials are available for these different mycoses, and only small numbers of patients have been evaluated to date. Both preparations appear to be well tolerated; only minor localised adverse events have been reported in clinical trials. At present, the major potential indication for topical amorolfine appears to be onychomycosis. Within this clinical setting, amorolfine should be reserved for patients with mild infection without nail matrix involvement. Systemic therapy, however, remains essential for patients with severe intractable onychomycosis involving the nail bed. Evidence to date does not clarify whether the use of adjuvant topical amorolfine reduces the need for systemic therapy in patients with severely infected nails, or whether amorolfine is beneficial in individuals unresponsive to other treatment options.

Allometric scaling (a technique which uses data obtained in laboratory animals to predict human pharmacokinetics) works well for drugs that are cleared intact, but is less successful with extensively metabolised compounds. This paper describes a new method to improve the accuracy of such projections, by integrating metabolic data obtained in vitro (e.g. with liver microsomes or hepatocytes) into these calculations. The approach was used prospectively, to predict the clearance of mofarotene (Ro 40-8757) in humans from in vivo kinetic data obtained in mouse, rat and dog. This compound was selected to illustrate this approach because it is exclusively eliminated through metabolism. Without the metabolic correction or using empirical correcting factors, the values predicted for man were 2.7 and 0.6 ml/min/kg. This fell outside the range subsequently obtained in healthy volunteers dosed orally with 300 mg of mofarotene (7.5 +/- 4.0 ml/min/kg, n = 12). However, inclusion of the microsomal or hepatocyte data gave values of 5.1 and 4.2 ml/min/kg, respectively, illustrating that the integration of in vitro metabolic data improves the accuracy of kinetic extrapolations. In contrast to the existing empirical techniques, this approach offers a rational basis to predict clearance of metabolized compounds in human.

Reboxetine, (RS)-2-[(RS)-alpha-(2-ethoxyphenoxy)benzyl]morpholine methanesulphonate, is a racemic compound and consists of a mixture of the (R,R)- and (S,S)-enantiomers. In this study, brain and plasma levels of both enantiomers were determined in mice and rats after oral administration of reboxetine at doses (1.1 mg/kg, mouse; 20 mg/kg, rat) twice the respective ED50 values in the antireserpine test. Plasma and brain concentrations of each enantiomer were measured up to 6 h postdosing using an HPLC method with fluorimetric detection after derivatization with a chiral agent (FLEC). In mice and rats, brain and plasma levels of the (R,R)-enantiomer were always higher than those of the (S,S)-enantiomer. After normalization for dose, the mean AUC0-tz values of both the (R,R)- and (S,S)-enantiomers in mouse brain were about 23 and 32 times higher than in rat brain, respectively. In plasma, the corrected mean AUC0-tz values were about 5 (R,R) and 10 (S,S) times higher in mice than in rats. These results provide evidence for the higher bioavailability and/or lower clearance of both enantiomers in mice than in rats, and for a higher penetration of both enantiomers into mouse brain compared to rat brain.

There has been great interest in the use of drugs attempting to modify the properties of malignant cells without necessarily destroying them. The family of compounds known as the retinoids have shown particular promise in this area. Current interest is directed towards established retinoids such as ATRA and 13-CRA. Newer synthetic retinoids such as fenretinide, the arotinoid Ro 40-8757, and 9-cis retinoic acid have been entering clinical trials. Ro 40-8757 is a particularly interesting new arotinoid with properties quite distinct from the other retinoids. It has different binding proteins and appears to regulate different genes than the classical retinoids such as ATRA or 13-CRA. Furthermore, it appears active against a different spectrum of malignancies. It also appears to have a relatively favourable side-effect profile. In addition to its anti-proliferative effects, this arotinoid may play a role in protection of bone marrow function after use of cytotoxic drugs. Development of Ro 40-8757 was halted before the compound had entered phase II testing due to lack of resources. Future developmental programmes for retinoids should move rapidly to explore the potential of interesting combinations identified in preclinical models. Retinoids should be considered primarily as drugs which modulate and enhance the effects of other active anticancer agents. Their development should not be prevented because they are unlikely to be active as single agents against common solid tumours.

The transport characteristics of the renin inhibitor ((3S,4S)-4-[N-morpholinoacetyl-(1-naphthyl)-L-alanyl-N-methyl-(4-t hiazolyl)-L- alanyl]amino-3-hydroxy-5-cyclohexyl-1-(4-pyridyl)-1-pentanone; CH3-18) in rat small intestinal brush-border membrane vesicles (BBMV) were examined by a rapid filtration technique. The uptake of CH3-18 was markedly stimulated by an inwardly directed H+ gradient (pH 7.5 inside, pH 5.5 outside) and showed an uphill transport. It was competitively inhibited by tripeptides and tetrapeptides, but not by amino acids or dipeptides. A countertransport effect on the uptake of CH3-18 was observed in the vesicle preloaded with a tripeptide. Effects of the fragments of several renin inhibitors were evaluated by their inhibitory and countertransport effects on the uptake of CH3-18. The morpholino group at the N-terminal was found to be important for the uptake of CH3-18.

The aim of this study was the discovery of nonpeptide renin inhibitors with much improved oral absorption, bioavailability, and efficacy, for use as antihypertensive agents. Our prior efforts led to the identification of A-74273 [1,R = 3-(4-morpholino)propyl], with a bioavailability of 26 +/- 10% [10 mg/kg intraduodenally (id), dog]. In vivo metabolism studies of A-74273 showed that the morpholino moiety underwent metabolic degradation. Computer modeling of A-74273 bound to renin indicated that the C-terminus was involved in a hydrogen-bonding network. New C-terminal groups were examined in two series of nonpeptides for effects on renin binding potency, lipophilicity (log P), and aqueous solubility. Those groups which possessed multiple hydrogen-bonding ability (3,5-diaminotriazole, cyanoguanidines, morpholino) provided particularly potent renin binding. Intraduodenal bioavailabilities of selected compounds, evaluated in rats, ferrets, and dogs, were higher for inhibitors with moderate solubility as well as moderate lipophilicity, in general. Although the absolute values varied substantially among species, the relative ordering of the inhibitors in terms of absorption and bioavailability was reasonably consistent. Such well absorbed inhibitors (e.g. 41, 44, and 51) were demonstrated as highly efficacious hypotensive agents in the salt-depleted dog. We report here the discovery of a series of efficacious nonpeptide renin inhibitors based on the 3-azaglutaramide P2-P4 replacement, the best of which showed id bioavailabilities > 50% in dog.