Enzymatic kinetics regarding reversible metabolism of CS-0777, a sphingosine 1-phosphate receptor modulator, via phosphorylation and dephosphorylation in humans.

1. CS-0777, a candidate compound for autoimmune diseases, becomes phosphorylated active metabolite, M1, by fructosamine 3-kinase (FN3K), FN3K-related protein (FN3K-RP); and M1 is reverted back to CS-0777 by alkaline phosphatase (ALP) in the body. We performed enzyme kinetic analysis of phosphorylation of CS-0777 by FN3K, FN3K-RP, human erythrocytes and human platelets; and dephosphorylation of M1 by various ALP isozymes and human liver, kidney, lung and small intestine microsomes. 2. The Michaelis constants of human FN3K, FN3K-RP and erythrocytes for CS-0777 phosphorylation were in the range from 498 µM to 1060 µM. FN3K inhibitor, 1-deoxy-1-morpholinofructose, suppressed only about 20% of CS-0777 phosphorylation activity in human erythrocyte lysate. Immunodepletion of FN3K and FN3K-RP decreased M1 formation activity by about 25% and 50%, respectively, in human erythrocyte lysate. 3. The Michaelis constants of four human ALPs and microsomes were in the range from 10.9 µM to 32.1 µM. The ALP inhibitor, levamisole, suppressed over 50% of M1 dephosphorylation activity in liver, kidney and lung microsomes. 4. FN3K-RP is expected to take a prominent role in the phosphorylation of CS-0777 in human erythrocytes; dephosphorylation of M1 was observed in all ALPs and human tissue microsomes examined, with a similar affinity towards M1 among them.

In vitro and in vivo efficacies of novel carbazole aminoalcohols in the treatment of cystic echinococcosis.

OBJECTIVES: Cystic echinococcosis (CE), caused by the cestode Echinococcus granulosus, is a worldwide chronic zoonosis. Current chemotherapeutic options are limited to albendazole and mebendazole, which only exert parasitostatic effects and have to be administered at high dosages for long periods. In an effort to find alternative treatment options, the in vitro and in vivo efficacies of novel carbazole aminoalcohols were evaluated. METHODS: Carbazole aminoalcohols were tested against E. granulosus protoscoleces in vitro and metacestodes ex vivo. The in vivo chemotherapeutic effect of representative compounds was assessed in experimentally infected mice. Oral and intravenous pharmacokinetic profiles were determined in mice. RESULTS: The carbazole aminoalcohols exhibited potent protoscolicidal activity with LC50 values ranging from 18.2 to 34.3 µM. Among them, compounds 2 and 24 killed all ex vivo cultured metacestodes at concentrations of 34.3 and 30.6 µM. In vivo studies showed that oral administration of compounds 2 and 24 (25 mg/kg/day) for 30 days led to reductions of 68.4% and 54.3% in parasite weight compared with the untreated group (both groups: P < 0.001). Compound 2 (25 mg/kg/day) and compound 24 (50 mg/kg/day) induced significantly higher cyst mortality rates in comparison with that of the albendazole group (both groups: P < 0.01). Analysis of cysts collected from compound 2- or 24-treated mice by transmission electron microscopy revealed a drug-induced structural destruction. The structural integrity of the germinal layer was lost, and the majority of the microtriches disappeared. Pharmacokinetic profiling of compounds 2 and 24 revealed low clearance and decent oral bioavailability (>70%). CONCLUSIONS: Our study identifies carbazole aminoalcohols as a class of novel anti-CE agents. Compounds 2 and 24 represent promising drug candidates in anti-CE chemotherapy.

Identification of ß-Amino alcohol grafted 1,4,5 trisubstituted 1,2,3-triazoles as potent antimalarial agents.

In a quest to discover new drugs, we have synthesized a series of novel ß-amino alcohol grafted 1,2,3-triazoles and screened them for their in vitro antiplasmodial and in vivo antimalarial activity. Among them, compounds 16 and 25 showed potent activity against chloroquine-sensitive (Pf3D7) strain with IC50 of 0.87 and 0.3 µM respectively, while compounds 7 and 13 exhibited better activity in vitro than the reference drug against chloroquine-resistance strain (PfK1) with IC50 of 0.5 µM each. Compound 25 showed 86.8% in vivo antimalarial efficacy with favorable pharmacokinetic parameters. Mechanistic studies divulged that potent compounds significantly boosted p53 protein levels to exhibit the antimalarial activity.

Pharmacokinetics and disposition of CS-0777, a sphingosine 1-phosphate receptor modulator, in rats and monkeys.

1. Disposition and metabolism of CS-0777 (1-{5-[(3R)-3-amino-4-hydroxy-3- methylbutyl]-1-methyl-1H-pyrrol-2-yl}-4-(4-methylphenyl) butan-1-one), a selective sphingosine 1-phosphate receptor-1 modulator under development for autoimmune conditions was investigated following oral and/or i.v. bolus administration to rats and monkeys. 2. After oral administration of [14C]CS-0777, CS-0777 was well absorbed in rats and monkeys with total recoveries of over 90% of the dose, majorly in feces. CS-0777 and phosphorylated pharmacologically active metabolite of CS-0777 (M1) were highly bound to plasma proteins among rats, monkeys and humans (>93%). 3. The structures of 12 metabolites were identified and phosphorylation and two hydroxylation pathways were proposed as primary metabolism. In the blood of rats and monkeys, the major metabolite was M1 and a few phosphorylated metabolites were also detected. Meanwhile, in urine and feces of rats and monkeys, not phosphorylated, but oxidized CS-0777 metabolites and/or those various conjugated metabolites were observed. This suggests that CS-0777 and its oxidized metabolites would be phosphorylated in the body, but their phosphorylated metabolites would revert back to their dephosphorylated form again then be further metabolized and finally eliminated from the body. 4. Pharmacokinetic analysis using a reversible metabolism model revealed that the clearance of phosphorylation was larger than the clearance of dephosphorylation and elimination.

Influence of the Relative Enamel Abrasivity (REA) of Toothpastes on the Uptake of KOH-soluble and Structurally Bound Fluoride.

PURPOSE: To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of KOH-soluble and structurally bound fluoride into enamel. MATERIALS AND METHODS: Bovine enamel samples were randomly allocated to 6 groups (n=36 per group). Groups A to C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes (1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva=1:3), while the remaining samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined and statistically compared by Scheffe's post-hoc tests. RESULTS: REA value and mode of application (immersion or brushing) had no significant influence on the amount of either kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in the other groups. CONCLUSION: The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes. Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound fluoride into enamel.

1-Aryl-2-((6-aryl)pyrimidin-4-yl)amino)ethanols as competitive inhibitors of fatty acid amide hydrolase.

A series of 1-aryl-2-(((6-aryl)pyrimidin-4-yl)amino)ethanols have been found to be competitive inhibitors of fatty acid amide hydrolase (FAAH). One member of this class, JNJ-40413269, was found to have excellent pharmacokinetic properties, demonstrated robust central target engagement, and was efficacious in a rat model of neuropathic pain.

Substituted 7-amino-5-thio-thiazolo[4,5-d]pyrimidines as potent and selective antagonists of the fractalkine receptor (CX3CR1).

We have developed two parallel series, A and B, of CX3CR1 antagonists for the treatment of multiple sclerosis. By modifying the substituents on the 7-amino-5-thio-thiazolo[4,5-d]pyrimidine core structure, we were able to achieve compounds with high selectivity for CX3CR1 over the closely related CXCR2 receptor. The structure-activity relationships showed that a leucinol moiety attached to the core-structure in the 7-position together with α-methyl branched benzyl derivatives in the 5-position displayed promising affinity, and selectivity as well as physicochemical properties, as exemplified by compounds 18a and 24h. We show the preparation of the first potent and selective orally available CX3CR1 antagonists.

Pharmacological effects of CS-0777, a selective sphingosine 1-phosphate receptor-1 modulator: results from a 12-week, open-label pilot study in multiple sclerosis patients.

CS-0777 is a selective sphingosine 1-phosphate receptor-1 modulator under investigation for treatment of multiple sclerosis (MS). We conducted an open-label, pilot study in 25 MS patients to assess the safety, pharmacokinetics, pharmacodynamics and exploratory efficacy of oral CS-0777 (0.1, 0.3 and 0.6 mg), administered once weekly or every other week for 12 weeks. CS-0777 resulted in a pronounced, dose-dependent decrease in lymphocytes and CD4 T cell subsets, which returned to baseline within 4 weeks after the last dose. Overall, CS-0777 was safe and well-tolerated. These results require confirmation in a double-blind, placebo-controlled and adequately powered phase 2 study in MS.

Purification and identification of activating enzymes of CS-0777, a selective sphingosine 1-phosphate receptor 1 modulator, in erythrocytes.

CS-0777 is a selective sphingosine 1-phosphate (S1P) receptor 1 modulator with potential benefits in the treatment of autoimmune diseases, including multiple sclerosis. CS-0777 is a prodrug that requires phosphorylation to an active S1P analog, similar to the first-in-class S1P receptor modulator FTY720 (fingolimod). We sought to identify the kinase(s) involved in phosphorylation of CS-0777, anticipating sphingosine kinase (SPHK) 1 or 2 as likely candidates. Unlike kinase activity for FTY720, which is found predominantly in platelets, CS-0777 kinase activity was found mainly in red blood cells (RBCs). N,N-Dimethylsphingosine, an inhibitor of SPHK1 and -2, did not inhibit CS-0777 kinase activity. We purified CS-0777 kinase activity from human RBCs by more than 10,000-fold using ammonium sulfate precipitation and successive chromatography steps, and we identified fructosamine 3-kinase (FN3K) and fructosamine 3-kinase-related protein (FN3K-RP) by mass spectrometry. Incubation of human RBC lysates with 1-deoxy-1-morpholinofructose, a competitive inhibitor of FN3K, inhibited ∼10% of the kinase activity, suggesting FN3K-RP is the principal kinase responsible for activation of CS-0777 in blood. Lysates from HEK293 cells overexpressing FN3K or FN3K-RP resulted in phosphorylation of CS-0777 and structurally related molecules but showed little kinase activity for FTY720 and no kinase activity for sphingosine. Substrate preference was highly correlated among FN3K, FN3K-RP, and rat RBC lysates. FN3K and FN3K-RP are known to phosphorylate sugar moieties on glycosylated proteins, but this is the first report that these enzymes can phosphorylate hydrophobic xenobiotics. Identification of the kinases responsible for CS-0777 activation will permit a better understanding of the pharmacokinetics and pharmacodynamics of this promising new drug.

Development of ß-amino alcohol derivatives that inhibit Toll-like receptor 4 mediated inflammatory response as potential antiseptics.

Toll-like receptor 4 (TLR4) induced proinflammatory signaling has been directly implicated in severe sepsis and represents an attractive therapeutic target. Herein, we report our investigations into the structure-activity relationship and preliminary drug metabolism/pharmacokinetics study of ß-amino alcohol derivatives that inhibit the TLR4 signaling pathway. Lead compounds were identified from in vitro cellular examination with micromolar potency for their inhibitory effects on TLR4 signaling and subsequently assessed for their ability to suppress the TLR4-induced inflammatory response in an ex vivo whole blood model. In addition, the toxicology, specificity, solubility, brain-blood barrier permeability, and drug metabolism of several compounds were evaluated. Although further optimizations are needed, our findings lay the groundwork for the future drug development of this class of small molecule agents for the treatment of severe sepsis.

Antagonists of the calcium receptor. 2. Amino alcohol-based parathyroid hormone secretagogues.

When administered as a single agent to rats, the previously reported calcium receptor antagonist 3 elicited a sustained elevation of plasma PTH resulting in no increase in overall bone mineral density. The lack of a bone building effect for analogue 3 was attributed to the large volume of distribution (V(dss)(rat) = 11 L/kg), producing a protracted plasma PTH profile. Incorporation of a carboxylic acid functionality into the amino alcohol template led to the identification of 12 with a lower volume of distribution (V(dss)(12) = 1.18 L/kg) and a shorter half-life. The zwitterionic nature of antagonist 12 necessitated the utility of an ester prodrug approach to increase overall permeability. Antagonist 12 elicited a rapid and transient increase in circulating levels of PTH following oral dosing of the ester prodrug 11 in the dog. The magnitude and duration of the increases in plasma levels of PTH would be expected to stimulate new bone formation.

Antagonists of the calcium receptor I. Amino alcohol-based parathyroid hormone secretagogues.

Functional screening of the former SmithKline Beecham compound collection against the human calcium receptor (CaR) resulted in the identification of the amino alcohol-based hit 2 (IC(50) = 11 microM). Structure-activity studies of 2 focused on the optimization of the right- and left-hand side aromatic moieties as well as the amino alcohol linker region. Critical to the optimization of this antagonist template was the discovery that the chirality of the C-2 secondary alcohol played a key role in enhancing both CaR potency as well as selectivity over the beta-adrenergic receptor subtypes. These SAR studies ultimately led to the identification of 38 (NPS 2143; SB-262470A), a potent and orally active CaR antagonist. Pharmacokinetic characterization of 38 in the rat revealed that this molecule had a large volume of distribution (11 L/kg), which resulted in a prolonged systemic exposure, protracted increases in the plasma levels of PTH, and an overall lack of net bone formation effect in a rodent model of osteoporosis.

Use of an exposure-response model to aid early drug development of an oral sphingosine 1-phosphate receptor modulator.

Pharmacokinetic (PK) and exposure-response modeling of a selective sphingosine 1-phosphate receptor-1 modulator (CS-0777) was conducted in an iterative process to guide early clinical development decisions. A model based on preclinical data from monkeys was extrapolated to humans to support a single ascending dose (SAD) study. The model was updated after each cohort, providing guidance on both maximal inhibition and time to recovery for lymphocyte counts. A 2-compartment PK model with first-order absorption and elimination was found to describe the monkey and human datasets. The relationship between lymphocyte counts and active metabolite (M-1) concentrations was modeled via an indirect response model, whereby M-1 inhibited the reentry of lymphocytes to the circulation. The indirect-response model based on SAD data had an Imax of approximately 85% and an IC50 of 0.24 ng/mL. Additionally, based on SAD data, similar models were developed for lymphocyte subsets, including CD4 cells. Subsequently, simulations were utilized to design a multiple ascending dose study with adaptive dosing regimens that would meet targeted pharmacodynamic (PD) response thresholds (eg, minimum 40% reduction in lymphocytes) while maintaining CD4 counts above a reasonable safety threshold. In conclusion, model-based development and use of adaptive designs for dose optimization can reduce the time and number of subjects needed in early clinical development.

Toxicity and bioavailability of copper herbicides (Clearigate, Cutrine-Plus, and copper sulfate) to freshwater animals.

In designing aquatic herbicides containing copper, an important goal is to maximize efficacy for target species while minimizing risks for nontarget species. To have a margin of safety for nontarget species, the concentration, duration of exposure (i.e., uptake), and form (i.e., species) of copper used for herbicidal properties should not elicit adverse effects on populations of nontarget species. To determine the potential for risk or adverse effects (conversely the margin of safety), data regarding the comparative toxicity of copper-containing herbicides are crucial. A series of comparative toxicity experiments was conducted, including baseline estimates of toxicity (LC50s, LOECs), sensitive species relationships (thresholds and exposure-response slopes), and bioavailability of toxic concentrations and forms of copper 7 days after initial herbicide application. Aqueous 48-h toxicity experiments were performed to contrast responses of Daphnia magna Strauss, Hyalella azteca Saussure, Chironomus tentans Fabricius, and Pimephales promelas Rafinesque to copper herbicides: Clearigate(R), Cutrine(R)-Plus, and copper sulfate. D. magna was the most sensitive aquatic animal tested for all three herbicides; 48-h LC50s for organisms exposed to Clearigate, Cutrine-Plus, and copper sulfate were 29.4, 11.3, and 18. 9 microg Cu/L, respectively. In terms of potency (calculated from the linearized portion of the exposure-response curves, which included 50% mortality), D. magna was the most sensitive animal tested. Organisms exposed to Clearigate, Cutrine-Plus, and copper sulfate had exposure-response slopes of 2.55, 8.61, and 5.07% mortality/microg Cu/L, respectively. Bioavailability of Clearigate and Cutrine-Plus was determined by comparing survival data (LC50s) of test organisms exposed to herbicide concentrations during the first and last 48-h of a 7-day exposure period. Even in these relatively simplified water-only exposures, a transformation of copper to less bioavailable species over time was observed with a 100-200% decrease in toxicity (i.e., an increase in 48-h LC50s) for all four test animals. This series of laboratory experiments provides a worst-case scenario for determining the risk associated with the manufacturer's recommended application rates of Clearigate (100-1,000 microg Cu/L), Cutrine-Plus (200-1,000 microg Cu/L), and copper sulfate (100-500 microg Cu/L) in natural waters for four nontarget freshwater animals.

The effect of chlorhexidine acetate on the corneal penetration of sorbitol from an arnolol formulation in the albino rabbit.

The effect of chlorhexidine acetate on the corneal penetration of sorbitol was evaluated in vitro using the enucleated pigmented rabbit cornea mounted in a modified Ussing chamber. Sorbitol penetrated the cornea poorly when compared with arnolol, a beta blocker. Sorbitol penetration was improved 85% by 0.01% chlorhexidine acetate, 2.9 times by 0.1% EDTA, and 9.6 times by stripping the corneal epithelium prior to the start of the experiment. By comparison, 0.01% chlorhexidine acetate and stripping the corneal epithelium improved the corneal penetration of arnolol only 30% and 74%, respectively, whereas stripping the corneal epithelium did not affect the corneal penetration of chlorhexidine acetate. Collectively, the above findings indicate that changes in corneal integrity may dramatically affect the corneal penetration of some inert excipients in ophthalmic formulations. Such a possibility must be considered carefully in the selection of excipients.

Enamel fluoride uptake affected by site of application: comparing sodium and amine fluorides.

In enamel fluoride uptake studies, the most frequently sampled site is the middle third of the buccal surface. Because different parts of the enamel surface vary in fluoride concentration, the present study investigated fluoride uptake at contrasting sites using two different topical agents. One was a neutral aqueous solution of sodium fluoride containing 2% w/w of fluoride, and the second was an aqueous solution of two amine fluorides containing 1% w/w of fluoride. The enamel of 10 pairs of clinically sound extracted human premolars was etched initially and after treatment with one of these agents on the cervical and middle thirds of the buccal surface and on the proximal surface, yielding the pre- and post-treatment fluoride concentrations of these sites at depths of 5 and 10 microns from the surface. Enamel treated with the amine F solution had significantly higher fluoride uptakes at all sites compared to the NaF-treated specimens. The differences in uptake from the two agents varied with site, being smallest for the buccal middle third enamel and greatest for the proximal enamel. It is suggested that these results relate to possible differences in enamel maturation or to the presence of initial proximal caries, and the greater affinity of amine fluoride for porous enamel. The findings emphasise the importance of obtaining site-specific data in the study of fluoride in enamel.

Human plasma fluoride levels following intake of dentifrices containing aminefluoride or monofluorophosphate.

After single, oral doses, 8 h profiles of fluoride (F) concentrations in plasma were determined in healthy human volunteers. Bioavailability of F from four dentifrices with either aminefluoride (AMF) or monofluorophosphate (MFP) was compared with that of NaF. There were no significant differences with respect to F availabilities, plasma F peak levels and plasma F profiles between NaF and the dentifrices tested, regardless of the F compound, F content or further ingredients. From the pharmacokinetic data it is concluded that dentifrices with 0.02 per cent F or less markedly decrease the risk of inducing plasma F concentrations that might disturb enamel mineralization, even if large quantities of dentifrice are ingested by small children.

[Bioavailability of heptaminol in healthy subjects]. / Untersuchungen zur Bioverfügbarkeit von Heptaminol bei Probanden.

In ten healthy volunteers the plasma and urine concentrations of heptaminol (Heptylon) were determined by high-performance liquid chromatography after intravenous administration of 250 mg heptaminol and oral intake of 2 x 150 mg heptaminol in tablet form, and the pharmacokinetic parameters were calculated. Heptaminol was rapidly and entirely absorbed following oral administration of heptaminol. Mean plasma peak concentrations of 1.6 mg/l were reached after 1.8 h, the area under the plasma concentration-time curve was equal to that after intravenous administration. The dominant terminal plasma half-life was 2.5-2.7 h. The total clearance amounted to 700 ml/min, and nearly all the dose given was recovered unchanged in urine within 24 h, indicating renal elimination by glomerular filtration and tubular secretion without metabolization.