In vitro and in vivo evaluation of dihydropyrimidinone C-5 amides as potent and selective alpha(1A) receptor antagonists for the treatment of benign prostatic hyperplasia.

alpha(1) Adrenergic receptors mediate both vascular and lower urinary tract tone, and alpha(1) receptor antagonists such as terazosin (1b) are used to treat both hypertension and benign prostatic hyperplasia (BPH). Recently, three different subtypes of this receptor have been identified, with the alpha(1A) receptor being most prevalent in lower urinary tract tissue. This paper explores 4-aryldihydropyrimidinones attached to an aminopropyl-4-arylpiperidine via a C-5 amide as selective alpha(1A) receptor subtype antagonists. In receptor binding assays, these types of compounds generally display K(i) values for the alpha(1a) receptor subtype <1 nM while being greater than 100-fold selective versus the alpha(1b) and alpha(1d) receptor subtypes. Many of these compounds were also evaluated in vivo and found to be more potent than terazosin in both a rat model of prostate tone and a dog model of intra-urethral pressure without significantly affecting blood pressure. While many of the compounds tested displayed poor pharmacokinetics, compound 48 was found to have adequate bioavailability (>20%) and half-life (>6 h) in both rats and dogs. Due to its selectivity for the alpha(1a) over the alpha(1b) and alpha(1d) receptors as well as its favorable pharmacokinetic profile, 48 has the potential to relieve the symptoms of BPH without eliciting effects on the cardiovascular system.

Design and biological activity of (S)-4-(5-([1-(3-chlorobenzyl)-2-oxopyrrolidin-3-ylamino]methyl)imidazol-1-ylmethyl)benzonitrile, a 3-aminopyrrolidinone farnesyltransferase inhibitor with excellent cell potency.

The synthesis, structure-activity relationships, and biological properties of a novel series of imidazole-containing inhibitors of farnesyltransferase are described. Starting from a 3-aminopyrrolidinone core, a systematic series of modifications provided 5h, a non-thiol, non-peptide farnesyltransferase inhibitor with excellent bioavailability in dogs. Compound 5h was found to have an unusually favorable ratio of cell potency to intrinsic potency, compared with other known FTIs. It exhibited excellent potency against a range of tumor cell lines in vitro and showed full efficacy in the K-rasB transgenic mouse model.

Effect of carbamate thioester derivatives of methyl- and 2-chloroethyl isocyanate on glutathione levels and glutathione reductase activity in isolated rat hepatocytes.

The present study examined the effects of S-(N-methylcarbamoyl)glutathione (SMG), S-(N-methylcarbamoyl)-L-cysteine (L-SMC) and some analogs of these S-linked conjugates of methyl isocyanate (MIC) on the activity of glutathione reductase (GR) in freshly isolated rat hepatocytes and on the levels of reduced and oxidized glutathione (GSH and GSSG) in exposed cells. Both SMG and its monoethyl ester (0.5 mM) were found to inhibit GR weakly, although L-SMC proved to be an effective inhibitor of the enzyme (60 +/- 4% activity remaining after a 4-hr incubation at 0.5 mM). The cysteine adduct (SCC) of 2-chloroethyl isocyanate (CEIC) was a strong inhibitor of GR (27 +/- 1% activity remaining after a 1-hr incubation at 0.1 mM) and was essentially equipotent with the antitumor agent N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU). L-SMC depleted intracellular GSH in a time- and concentration-dependent manner up to 2 hr of incubation, beyond which time GSH levels began to recover. Exposure of cells to the enantiomeric conjugate, D-SMC, led to a similar concentration- and time-dependent inhibition of GR and fall in intracellular GSH, but in this case the depletion of GSH was extensive and was sustained throughout the 5-hr incubation period. Only a small amount (less than 10%) of the GSH that was lost from cells exposed to SMC was recovered in the medium, indicating that SMC did not cause efflux of GSH (most of the free cysteine released during breakdown of SMC was recovered in the medium). Experiments with hepatocytes exposed for 5 hr to SCC (0.1 mM) demonstrated that GSSG levels were elevated by 32 +/- 5% relative to controls. Collectively, these results indicate that carbamate thioester conjugates of MIC and CEIC inhibit GR, probably via release of the free isocyanate at the cell surface, which then penetrates the hepatocyte. The inhibitory effects of the isocyanates on GR, coupled with their propensity to react spontaneously with GSH, combine to deplete significantly intracellular stores of GSH.

Olanzapine: interaction study with imipramine.

Olanzapine is an "atypical" antipsychotic agent with a high affinity for serotonin 5HT2A/C, 5HT3, 5HT6, and dopamine D1, D2, D3, D4 receptors. Depressed patients with psychotic disorders frequently require treatment with concomitant antipsychotic and antidepressant medications. Imipramine pharmacokinetics serve as a marker for hepatic CYP2D6, CYP1A2, CYP3A activity. An open-label, three-way randomized crossover study was done to determine the safety, pharmacokinetics, and potential for a drug interaction between olanzapine (5 mg) and imipramine (75 mg). Each drug was administered alone and in combination. Nine healthy men, ages 32 to 54 years, enrolled in the study. Psychomotor performance capacities, plasma olanzapine, imipramine, desipramine concentrations, and clinical laboratory tests were measured. Pharmacokinetic variables, vital signs, subjective tests for liveliness, and psychomotor outcomes were analyzed using a two-way ANOVA. Olanzapine was safe. Sedation, postural hypotension, and minor vital sign alterations occurred during all treatments. On the liveliness questionnaire, patients generally reported poorer (less lively) scores with olanzapine alone or coadministered with imipramine versus baseline scores. These effects disappeared within 24 hours after administration. Olanzapine alone and in combination decreased motor-speed tasks (finger tapping and visual-arm random reach) compared with baseline or imipramine treatment. Peak 6-hour changes were statistically significant but clinical importance was only marginal. Olanzapine concentrations were < 19% greater than with imipramine. But olanzapine did not affect the kinetics of imipramine or desipramine and, therefore, did not show a metabolic drug interaction involving CYP2D6.

Lack of effect of olanzapine on the pharmacokinetics of a single aminophylline dose in healthy men.

STUDY OBJECTIVE: To test whether olanzapine, an atypical antipsychotic, is an inhibitor of cytochrome P450 (CYP) 1A2 activity, we conducted a drug interaction study with theophylline, a known CYP1A2 substrate. DESIGN: Two-way, randomized, crossover study. SETTING: Clinical research laboratory. SUBJECTS: Nineteen healthy males (16 smokers, 3 nonsmokers). INTERVENTIONS: Because the a priori expectation was no effect of olanzapine on theophylline pharmacokinetics, a parallel study using cimetidine was included as a positive control. In group 1, 12 healthy subjects received a 30-minute intravenous infusion of aminophylline 350 mg after 9 consecutive days of either olanzapine or placebo. In group 2, seven healthy subjects received a similar aminophylline infusion after 9 consecutive days of either cimetidine or placebo. MEASUREMENTS AND MAIN RESULTS: Concentrations of theophylline and its metabolites in serum and urine were measured for 24 and 72 hours, respectively. Plasma concentrations of olanzapine and its metabolites were measured for 24 hours after the next to last dose and 168 hours after the last olanzapine dose. Olanzapine did not affect theophylline pharmacokinetics. However, cimetidine significantly decreased theophylline clearance and the corresponding formation of its metabolites. Urinary excretion of theophylline and its metabolites was unaffected by olanzapine but was reduced significantly by cimetidine. Steady-state concentrations of olanzapine (15.3 ng/ml), 10-N-glucuronide (4.9 ng/ml), and 4'-N-desmethyl olanzapine (2.5 ng/ml) were observed after olanzapine 10 mg once/day and were unaffected by coadministration of theophylline. CONCLUSION: As predicted by in vitro studies, steady-state concentrations of olanzapine and its metabolites did not affect theophylline pharmacokinetics and should not affect the pharmacokinetics of other agents metabolized by the CYP1A2 isozyme.

Metabolic activation of unsaturated derivatives of valproic acid. Identification of novel glutathione adducts formed through coenzyme A-dependent and -independent processes.

The ability of 2-n-propyl-4-pentenoic acid (delta 4-VPA) and 2-n-propyl-2(E)-pentenoic acid ([E]-delta 2-VPA), two unsaturated metabolites of valproic acid (VPA), to form reactive intermediates, deplete hepatic glutathione (GSH) and cause accumulation of liver triglycerides was investigated in the rat. With the aid of ionspray liquid chromatography-tandem mass spectrometry (LC-MS/MS), three GSH adducts were detected in the bile of delta 4-VPA-treated animals and were identified as 4-hydroxy-5-glutathion-S-yl-VPA-gamma-lactone, 5-glutathion-S-yl-(E)-delta 3-VPA and 3-oxo-5-glutathion-S-yl-VPA. A fourth conjugate was identified tentatively as 4-glutathion-S-yl-5-hydroxy-VPA. Quantitative analysis of the corresponding N-acetyl-cysteine (NAC) conjugates in urine indicated that metabolism of delta 4-VPA via the GSH-dependent pathways accounted for approximately 20% of an acute dose (100 mg kg-1 i.p.). In contrast, when rats were given an equivalent dose of (E)-delta 2-VPA, only one GSH adduct (5-glutathion-S-yl-(E)-delta 3-VPA) was detected at low concentrations in bile. In vitro experiments with rat liver mitochondria demonstrated that delta 4-VPA undergoes coenzyme A- and ATP-dependent metabolic activation in this organelle via the beta-oxidation pathway to intermediates which bind covalently to proteins. When liver homogenates and hepatic mitochondria from rats injected with delta 4-VPA, (E)-delta 2-VPA or VPA were analyzed for GSH content, it was found that only delta 4-VPA depleted GSH pools significantly. Treatment of rats with delta 4-VPA and (to a lesser extent) VPA led to an accumulation of liver triglycerides, whereas (E)-delta 2-VPA had no measurable effect. It is concluded that delta 4-VPA undergoes metabolic activation by both microsomal cytochrome P-450-dependent and mitochondrial coenzyme A-dependent processes, and that the resulting electrophilic intermediates, which are trapped in part by GSH, may mediate the hepatotoxic effects of this compound. In contrast, (E)-delta 2-VPA is not transformed to any appreciable extent to reactive metabolites, which thus accounts for the apparent lack of hepatotoxicity of this positional isomer in the rat.

Stereoselective synthesis of the diunsaturated metabolites of valproic acid.

Two diene metabolites of valproic acid (VPA), (E)-2-n-propyl-2,4-pentadienoic acid and (E)-2-(1'-propenyl)-(E)-2-pentenoic acid, were stereoselectively synthesized. Mesylate elimination in the final step to produce the unsaturation at position 2 was stereospecific for the (E)-configuration in the case of 2. Gas chromatography-mass spectroscopy and NMR were used to confirm the configuration of each diene including the minor isomers, (Z)-2-n-propyl-2,4-pentadienoic acid and (Z)-2-(1'-propenyl)-(E)-2-pentenoic acid. Analysis of the dienes, as PFB derivatives by negative chemical ionization GC-MS from a serum extract of a patient on VPA therapy, revealed the presence of four peaks that in order of elution correspond to 9, 18, 1, and 2.

In vivo formation of the thiol conjugates of reactive metabolites of 4-ene VPA and its analog 4-pentenoic acid.

The terminal olefin metabolite of valproic acid (VPA), 4-ene VPA, is an analog of the experimental hepatotoxin 4-pentenoic acid and is believed to play a role in the hepatotoxicity of VPA. The formation of glutathione and N-acetylcysteine conjugates of the putative electrophilic metabolites of 4-ene VPA and 4-pentenoic acid was studied in vivo in the rat. Animals were treated intraperitoneally with the sodium salts of VPA, 4-ene VPA, (E)-2,4-diene VPA, 4-pentenoic or (E)-2,4-pentadienoic acids, and methylated bile and urine extracts were analyzed by LC/MS/MS and GC/MS techniques. The alpha,beta-unsaturated reactive metabolite of 4-pentenoic acid, 3-oxo-4-pentenoic acid, was isolated and identified as its thiol conjugates. In contrast, 3-oxo-4-ene VPA or its thiol conjugates could not be demonstrated as metabolites even though synthetic standards were available to facilitate their detection. Isolation of the thiol conjugates of 3-oxo-4-pentenoic acid provides the first direct spectroscopic evidence for the in vivo formation of the metabolite of 4-pentenoic acid considered responsible for the irreversible inhibition of fatty acid metabolism. The biliary and urinary metabolite profiles of 4-ene VPA and 4-pentenoic acid revealed basic differences between the in vivo metabolism of these two unsaturated carboxylic acids.

Identification and characterization of the glutathione and N-acetylcysteine conjugates of (E)-2-propyl-2,4-pentadienoic acid, a toxic metabolite of valproic acid, in rats and humans.

The severe hepatotoxicity of valproic acid (VPA) is believed to be mediated through reactive metabolites. The formation of glutathione (GSH) and N-acetylcysteine (NAC) adducts of reactive intermediates derived from VPA and two of its metabolites, 2-propyl-4-pentenoic acid (4-ene-) and 2-propyl-2,4-pentadienoic acid [(E)-2,4-diene VPA], was investigated in the rat. Rats were dosed ip with 100 mg/kg of VPA, 4-ene-, or 2,4-diene-VPA, and methylated bile and urine extracts were analyzed by LC/MS/MS and GC/MS, respectively. The GSH conjugate of (E)-2,4-diene VPA was detected in the bile of rats treated with 4-ene- and (E)-2,4-diene VPA. The NAC conjugate was a major urinary metabolite of rats given (E)-2,4-diene VPA and was a prominent urinary metabolite of those animals given 4-ene VPA. The NAC conjugate was also found to be a metabolite of VPA in patients. Both the GSH and NAC adducts were chemically synthesized and their structures established to be 5-(glutathion-S-yl)3-ene VPA and 5-(N-acetylcystein-S-yl)3-ene VPA by NMR and mass spectrometry. In contrast to the very slow reaction of the free acid of (E)-2,4-diene VPA with GSH, the methyl ester reacted rapidly with GSH to yield the adduct. In vivo it appears the diene forms an intermediate with enhanced electrophilic reactivity to GSH as indicated by the facile reaction of the diene with GSH in vivo [about 40% of the (E)-2,4-diene VPA administered to rats was excreted as the NAC conjugate in 24 hr]. The characterization of the GSH and NAC (in humans and rats) conjugates of (E)-2,4-diene VPA suggests that VPA is metabolized to a chemically reactive intermediate that may contribute to the hepatotoxicity of the drug.

Cytochrome P-450-mediated dehydrogenation of 2-n-propyl-2(E)-pentenoic acid, a pharmacologically-active metabolite of valproic acid, in rat liver microsomal preparations.

The pharmacologically active metabolite of valproic acid (VPA), (E)-delta 2-VPA, is being investigated for therapeutic use as a potentially nonteratogenic antiepileptic drug. Although its anticonvulsant properties have been studied extensively, there is little information on the metabolic fate of (E)-delta 2-VPA in mammalian systems. In this in vitro study, we investigated the biotransformation of (E)-delta 2-VPA in rat liver microsomal preparations. Acidified microsomal incubation products were extracted with ethyl acetate, converted to trimethylsilyl or pentafluorobenzyl derivatives, and analyzed by GC/MS. From the resulting electron impact and negative ion chemical ionization spectra, an oxygenated species and a diene compound were found to be the major microsomal metabolites of (E)-delta 2-VPA. These metabolites, whose formation was shown to be cytochrome P-450-dependent, were identified as 4-OH-(E)-delta 2-VPA and (E)-delta 2,4-VPA by comparing their GC/MS properties with those of synthetic reference materials. Quantification of the metabolites by selected ion monitoring GC/electron impact-MS showed that formation of the diene paralleled that of the allylic alcohol as a function of time, when the ratio of the diene to the allylic alcohol remained constant at 0.45 +/- 0.045 during the 60-min incubation. This value for partition ratio indicates that the formation of the diene was a relatively favored metabolic pathway compared with the cytochrome P-450-catalyzed dehydrogenation of VPA to give delta 4-VPA.(ABSTRACT TRUNCATED AT 250 WORDS)

Olanzapine 10-N-glucuronide. A tertiary N-glucuronide unique to humans.

In humans, a major metabolite of the atypical antipsychotic olanzapine in the plasma and in the urine was found to be an N-glucuronide. Unexpectedly, the glucuronic acid moiety was linked through a nitrogen of the benzodiazepine nucleus of olanzapine by way of a secondary amine linkage, rather than through a nitrogen on the piperazine substituent of the nucleus, to give a quaternary ammonium glucuronide. Derivatization with phenylisothiocyanate to yield a thiourea adduct indicated that conjugation occurred via a secondary amine. Subsequently, mass spectrometry and nuclear magnetic resonance studies with the isolated metabolite and later with the synthesized metabolite indicated that the glucuronide was linked at the 10- position of olanzapine. This phase 2 metabolite was only detected in the plasma and urine of human subjects and not in mice, rats, or monkeys; a trace of this metabolite was detected in dog urine. The N-10 glucuronide was resistant to enzymatic and base hydrolysis but was cleaved under acidic conditions. Formation of an N-glucuronide metabolite directly with the benzodiazepine nucleus has not previously been reported.

Metabolic profiling of valproic acid in patients using negative-ion chemical ionization gas chromatography-mass spectrometry.

A negative-ion chemical ionization gas chromatographic-mass spectrometric method for the determination of valproic acid (VPA) and fourteen of its metabolites in a single chromatographic run is reported. The assay features the use of four internal standards and is applicable to the analysis of small serum and urine volumes. A combination of pentafluorobenzyl and trimethylsilyl derivatization resulted in the [M - 181]- ion as the base peak for all the metabolites measured. When these ions were monitored sensitivities in the low picogram levels were achieved. The VPA metabolite profile was determined in pediatric patients on VPA monotherapy and on combined VPA therapy with either carbamazepine or clobazam. The recently characterized diene metabolite, (E,E)-2,3'-diene-VPA, was found to be a major serum metabolite of VPA. In the patient groups taking VPA in combination with carbamazepine, the induction of omega and omega-1 pathways of VPA metabolism was apparent, while the levels of the beta-oxidation products were significantly decreased.

Negative ion chemical ionization gas chromatography/mass spectrometry of valproic acid metabolites.

A negative ion chemical ionization (NICI) gas chromatographic/mass spectrometric method is described for the identification of 15 valproic acid (VPA) metabolites as their pentafluorobenzyl derivatives. Samples analyzed were serum, urine and saliva taken from a volunteer on VPA at steady state and also given selected doses of (2H6)VPA. Metabolite peaks were identified by comparison to synthetic standards. All the metabolites, like the parent drug, produced abundant [M - 181]- ions, except 3-keto VPA, which gave an [M - 181 - CO2]- ion. Using the NICI method, two new VPA metabolites were identified. One of these metabolites was characterized as 4'-keto-2-ene VPA by synthesis, while the second one appeared to be a positional isomer of 4'-keto-2-ene VPA. The sensitivity of the method was also sufficient to detect metabolites of VPA in saliva. The ratio of the levels of (Z)-2-ene VPA to (E)-2-ene VPA was much greater in saliva than in serum, suggesting stereoselective plasma protein binding or transport of these two metabolites. The lower limit of detection for the quantification of VPA in serum or saliva was 2 ng ml-1.

Glutathione and N-acetylcysteine conjugates of 2-chloroethyl isocyanate. Identification as metabolites of N,N'-bis(2-chloroethyl)-N-nitrosourea in the rat and inhibitory properties toward glutathione reductase in vitro.

The antitumor agent N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU) is known to be unstable in aqueous solution, and to degrade spontaneously to reactive alkylating and carbamoylating intermediates. Whereas the alkylating component is believed to be responsible for the antitumor effects of this drug, it has been speculated that the carbamoylating species 2-chloroethyl isocyanate (CEIC) may mediate some of the serious adverse effects of BCNU therapy. In order to determine whether CEIC is released from BCNU in vivo, rats were administered an ip injection of the drug and a targeted search was made by ionspray LC-MS/MS techniques for the glutathione (GSH) conjugate of CEIC in bile and for the corresponding N-acetylcysteine (NAC) adduct in urine. Both of these S-linked conjugates were identified on the basis of their HPLC and MS/MS characteristics, which were identical to those of the respective reference compounds prepared by synthesis. Quantitative studies indicated that, following an ip dose of BCNU (24 mg kg-1), excretion of the GSH conjugate in bile over 4 h accounted for 3.90 +/- 0.64% of the administered dose, while excretion of the mercapturic acid derivative in urine over 24 h accounted for a further 18.1 +/- 3.3% (n = 4). Experiments conducted in vitro demonstrated that the S-linked conjugates of CEIC were of limited stability under simulated physiological conditions, decomposing to generate free GSH and NAC. In addition, both adducts inhibited rat liver glutathione reductase in vitro, when they were essentially equipotent to BCNU.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation of the naturally occurring isothiocyanate sulforaphane in the rat: identification of phase I metabolites and glutathione conjugates.

Sulforaphane (SFN) is a naturally occurring isothiocyanate present in cruciferous vegetables, such as broccoli, that has been identified as a potent inducer of glutathione S-transferase activities in laboratory animals. The present studies were carried out to elucidate the metabolic fate of SFN in the rat. Particular emphasis was placed on glutathione (GSH)-dependent pathways because conjugation with GSH is a major route by which many isothiocyanates are eliminated in mammals. Male Sprague-Dawley rats were administered a single dose of SFN (50 mg kg-1 ip), and bile and urine were collected over ascorbic acid. Analysis of biological fluids was carried out by ionspray LC-MS/MS using the neutral loss (129 Da) and precursor ion (m/z 164) scan modes to detect GSH and N-acetylcysteine (NAC) conjugates, respectively. In bile, five thiol conjugates (designated M1-M5) were detected. Metabolites M2 and M4 were identified as the GSH conjugates of SFN and erucin (ERN, the sulfide analog of SFN), respectively, by comparing their LC-MS/MS properties with those of standards obtained by synthesis. M1 was characterized as the GSH conjugate of a desaturated metabolite of SFN (tentatively assigned the structure of delta 1-SFN), suggesting that the parent compound also undergoes oxidative metabolism. Metabolites M3 and M5 were identified as the NAC conjugates of SFN and ERN, respectively, and together with the NAC conjugate of delta 1-SFN, these species also were detected in urine. Quantitative determination of the former two mercapturates in urine indicated that approximately 60% and approximately 12% of a single dose of SFN is eliminated in 24 h as the NAC conjugates of SFN and ERN, respectively. The corresponding figures in rats dosed with ERN were approximately 67% and approximately 29%. When the GSH conjugate of SFN was incubated with phosphate buffer (pH 7.4, 37 degrees C), < 1% of the conjugate dissociated to liberate free SFN. On the other hand, the conjugate underwent a facile thiol exchange reaction (> 70% conversion) when incubated in the presence of excess cysteine, thereby acting as an effective carbamoylating agent. It is concluded that SFN undergoes metabolism by S-oxide reduction and dehydrogenation and that GSH conjugation is the major pathway by which the parent compound and its phase I metabolites are eliminated in the rat.

Simultaneous determination of urinary free cortisol and 6beta-hydroxycortisol by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry and its application for estimating hepatic CYP3A induction.

A reversed-phase high-performance liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry (HPLC-APCI-MS-MS) assay was developed to simultaneously determine monkey urinary free cortisol (C) and 6beta-hydroxycortisol (6beta-OHC) in 8 min. Urine sample (0.5 ml) containing fludrocortisone acetate (F-C) as the internal standard was extracted with ethyl acetate for 5 min with an extraction efficiency of 90% and 75% for C and 6beta-OHC, respectively. A Perkin-Elmer Sciex API 3000 triple quadruple instrument was used for mass spectrometric detection and the column eluent was directed to a heated nebulizer probe. The assay was linear over the range 0.25-10 microM for each analyte. The intra- and inter-day relative standard deviation (RSD) over the entire concentration range for both analytes was less than 10%. Accuracy determined at three concentrations (0.8, 2.0 and 8.0 microM) ranged between 95.5 and 108%. The method described herein is suitable for the rapid and efficient measurement of 6beta-OHC/C ratio in Rhesus monkey urine following administration of known hepatic CYP3A inducers and can be used to estimate potential CYP3A induction by drug candidates in the process of early drug development.

Disposition and metabolism of olanzapine in mice, dogs, and rhesus monkeys.

Olanzapine (OLZ) is a novel antipsychotic agent with a high affinity for serotonin (5-HT2), dopamine (D1/D2/D4), muscarinic (m1-m5), adrenergic (alpha 1), and histamine (H1) receptors. The pharmacokinetics, excretion, and metabolism of OLZ were studied in CD-1 mice, beagle dogs, and rhesus monkeys after a single oral and/or intravenous dose of [14C]OLZ. After oral administration, OLZ was well absorbed in dogs (absolute bioavailability of 73%) and to the extent of at least 55% in monkeys and 32% in mice. The terminal elimination half-life of OLZ was relatively short in mice and monkeys (approximately 3 hr) and long in dogs (approximately 9 hr). In mice and dogs, radioactivity was predominantly eliminated in feces; but, in monkeys, the major route of elimination of radioactivity was urine. Dogs and monkeys excreted in urine, respectively, 38% and 55% of the dose over a 168-hr period, whereas the fraction of the dose excreted in urine of mice over the collection period (120 hr) was 32%. OLZ was subject to substantial first-pass metabolism; at the tmax, OLZ accounted for 19%, 18%, and 8% of the radioactivity, in mice, dogs, and monkeys, respectively. The ratio of AUC OLZ to AUC radioactivity was, respectively, 10%, 14%, and 4% in mice, dogs, and monkeys. The principal urinary metabolites in mice were 7-hydroxy OLZ glucuronide, 2-hydroxymethyl OLZ, and 2-carboxy OLZ accounting for approximately 10%, 4%, and 2% of the dose. Metabolites that were present in urine in lesser amounts were 7-hydroxy OLZ, N-desmethyl OLZ, and N-desmethyl-2-hydroxymethyl OLZ. In dogs, the major metabolite accounting for approximately 8% of the dose was 7-hydroxy-N-oxide OLZ. Other metabolites identified were 2-hydroxymethyl OLZ, 2-carboxy OLZ, N-oxide OLZ, 7-hydroxy OLZ, and its glucuronide and N-desmethyl OLZ. The major metabolite in monkey urine was N-desmethyl-2-carboxy OLZ, and accounted for approximately 17% of the dose. In addition, N-oxide-2-hydroxymethyl, 2-carboxyl OLZ, and 2-hydroxymethyl OLZ were identified in monkey urine. Thus, in mice and dogs, OLZ was metabolized through aromatic hydroxylation, allylic oxidation, N-dealkylation, and N-oxidation reactions. In monkeys, OLZ was biotransformed mainly through double oxidation reactions involving the allylic carbon and methyl piperazine nitrogen. Whereas the oxidative metabolic profile of OLZ in animals was similar to that of humans, animals were notable for not forming appreciable amounts of the principal human metabolite (i.e. 10-N-glucuronide OLZ).