Discovery of JNJ-63576253: A Clinical Stage Androgen Receptor Antagonist for F877L Mutant and Wild-Type Castration-Resistant Prostate Cancer (mCRPC).

Persistent androgen receptor (AR) activation drives therapeutic resistance to second-generation AR pathway inhibitors and contributes to the progression of advanced prostate cancer. One resistance mechanism is point mutations in the ligand binding domain of AR that can transform antagonists into agonists. The AR F877L mutation, identified in patients treated with enzalutamide or apalutamide, confers resistance to both enzalutamide and apalutamide. Compound 4 (JNJ-pan-AR) was identified as a pan-AR antagonist with potent activity against wild-type and clinically relevant AR mutations including F877L. Metabolite identification studies revealed a latent bioactivation pathway associated with 4. Subsequent lead optimization of 4 led to amelioration of this pathway and nomination of 5 (JNJ-63576253) as a clinical stage, next-generation AR antagonist for the treatment of castration-resistant prostate cancer (CRPC).

Synthesis and Characterization of Fluorine-18-Labeled N-(4-Chloro-3-((fluoromethyl-d2)thio)phenyl)picolinamide for Imaging of mGluR4 in Brain.

We have synthesized and characterized [18F]-N-(4-chloro-3-((fluoromethyl-d2)thio)phenyl)-picolinamide ([18F]15) as a potential ligand for the positron emission tomography (PET) imaging of mGluR4 in the brain. Radioligand [18F]15 displays central nervous system drug-like properties, including mGluR4 affinity, potent mGluR4 PAM activity, and selectivity against other mGluRs, as well as sufficient metabolic stability. Radiosynthesis was carried out in two steps. The radiochemical yield of [18F]15 was 11.6 ± 2.9% (n = 7, decay corrected) with a purity of 99% and a molar activity of 84.1 ± 11.8 GBq/µmol. Ex vivo biodistribution studies showed reversible binding of [18F]15 in all investigated tissues including the brain, liver, heart, lungs, and kidneys. PET imaging studies in male Sprague Dawley rats showed that [18F]15 accumulates in the brain regions known to express mGluR4. Pretreatment with the unlabeled mGluR4 PAM compounds 13 (methylthio analogue) and 15 showed significant dose-dependent blocking effects. These results suggest that [18F]15 is a promising radioligand for PET imaging mGluR4 in the brain.

Development of radiolabeled bis(zinc(II)-dipicolylamine) complexes for cell death imaging.

PURPOSE: Although it has been traditionally surmised that phosphatidylserine (PS) externalization is a hallmark of apoptosis, most other non-apoptotic modes of cell death, such as necrosis, are also associated with PS externalization. Bis(zinc-dipicolylamine) (ZnDPA) complexes have been reported to exhibit affinity for PS. The present study aimed to develop novel radiolabeled ZnDPA derivatives for cell death imaging in tumor after treatment with anticancer drugs. METHODS: [125I]IB-EG2-ZnDPA and [99mTc]Tc-MAG3-EG2-ZnDPA were designed and prepared. The stabilities of these radiotracers were determined in 0.1 M phosphate buffer (pH 7.4) or murine plasma at 37 °C, and their 1-octanol/water partition coefficients (logP) were measured. The uptake of radioactivity in cancer cells, which were preincubated in a normal medium or in a medium containing 5-FU, was measured after incubation with radiotracers. Accumulation of [99mTc]Tc-MAG3-EG2-ZnDPA in the tumor was evaluated in tumor-bearing mice treated with or without 5-FU, and then TUNEL staining was performed to detect dead cells in the tumor tissue sections. RESULTS: The radiochemical purities of [125I]IB-EG2-ZnDPA and [99mTc]Tc-MAG3-EG2-ZnDPA exceeded 95%. Although [125I]IB-EG2-ZnDPA gradually decomposing with time, more than 90% of [99mTc]Tc-MAG3-EG2-ZnDPA remained in its intact form in phosphate buffer through 6 h of incubation. Neither [125I]IB-EG2-ZnDPA nor [99mTc]Tc-MAG3-EG2-ZnDPA decomposed so much after 6-h incubation in murine plasma. [125I]IB-EG2-ZnDPA could not specifically recognize PS on the cell surface because of its high lipophilicity. Conversely, [99mTc]Tc-MAG3-EG2-ZnDPA accumulated in cancer cells after treatment with an anticancer drug both in vitro and in vivo, and its accumulation was correlated with the number of TUNEL-positive cells. However, the biodistribution of [99mTc]Tc-MAG3-EG2-ZnDPA was not suitable for imaging because of its low accumulation in tumor and high uptake in abdomen organs. CONCLUSION: [99mTc]Tc-MAG3-EG2-ZnDPA could be useful for the early detection of treatment effects after chemotherapy. Since the signal-to-noise ratio is not enough for single photon emission computed tomography imaging, further modification is needed to improve its biodistribution and affinity for PS.

[Preventive therapy with mexidol in toxic damage to the heart]. / Preventivnaia terapiia meksidolom toksicheskogo povrezhdeniia serdtsa.

The purpose of this study was to efficacy of mexidol in the prevention of toxic damage to the heart in acute pancreatitis. MATERIAL AND METHODS: The paper presents the results of experimental studies conducted on 30 adult mongrel adult dogs, which simulated acute focal pancreatic necrosis. We studied the influence of mexidol in the complex therapy for changes in the qualitative and quantitative composition of the lipid tissue structures of the heart, the intensity of processes of lipid peroxidation, antioxidant capacity, phospholipase A2 activity and morphofunctional state of the heart muscle in experimental acute focal pancreatic necrosis. Th. RESULTS AND DISCUSSION: The preventive use of antioxidant drug mexidol in complex treatment of acute focal pancreatic necrosis, which limits the development of endogenous intoxication, increased intensity of lipid peroxidation and restores antioxidant capacity, reduces leading to phospholipase activity in tissue structures of the heart, corrigiruet lipid metabolism and morphofunctional state of the heart, and, consequently, toxic damage to the heart during endotoxic.

Positron emission tomography imaging of cardiomyocyte apoptosis with a novel molecule probe [18F]FP-DPAZn2.

Cardiomyocyte apoptosis plays a causal role in the development and progression of heart failure. Currently, there is no effective imaging agent that can be used to detect cardiomyocyte apoptosis in vivo. To target phosphatidylserine (PS) on the surface of the dying cell, we synthesized a novel 18F-labeled Zn2+-dipicolylamine (DPA) analog, [18F]FP-DPAZn2, and evaluated it for noninvasive imaging of cardiomyocyte apoptosis. In vitro, the fluorescence imaging of dansyl-DPAZn2 was suitable for detecting cardiomyocyte apoptosis, which was confirmed by confocal immunofluorescence imaging, terminal dUTP nick-end labeling (TUNEL) assay, and western blot assay. The in vivo biodistribution showed that the uptake ratios of [18F]FP-DPAZn2 in the heart were 4.41±0.29% ID/g at 5 min, 2.40 ± 0.43% ID/g at 30 min, 1.63 ± 0.26% ID/g at 60 min, and 1.43% ± 0.07 ID/g at 120 min post-injection. In vivo, the [18F]FP-DPAZn2 PET images showed more cardiac accumulation of radioactivity 60 min post-injection in acute myocardial infarction (AMI) rats than in normal rats, which was consistent with the findings of a histological analysis of the rat cardiac tissues in vitro. [18F]FP-DPAZn2 PET imaging has the capability for myocardial apoptosis detection, but the method will require improved myocardial uptake for the noninvasive evaluation of cardiomyocyte apoptosis in clinical settings.

[The distribution of mexidol in the rat's brain and its subcellular fractions].

OBJECTIVE: To study the penetration of mexidol through the blood-brain barrier into different brain compartments and cell mitochondria. MATERIAL AND METHODS: The study was carried out on adult male Wistar rats using the drug mexidol ("Farmasoft" Russia). The penetration of mexidol into different compartments of the brain (the cortex, cerebellum, thalamus and medulla) and distribution between mitochondrial and cytoplasmic fractions of the cerebral cortex was studied. The concentration of mexidol in blood plasma and brain tissues was measured using HPLC. RESULTS AND CONCLUSION: Mexidol penetrated through the blood-brain barrier into brain compartments of rats with the maximal accumulation in the cortex. In the brain cortex cells, mexidol was identified in the cytoplasmic and mitochondrial fractions.

[Antioxidant agents in neuroprotection treatment of glaucoma].

Purpose was to study efficiency and safety of mexidol in combined therapy in patients with primary open-angle glaucoma (POAG). 94 patients (185 eyes) at the age of 18-75 years old with POAG I-III stages were divided into 3 groups: 50 patients received combined therapy of mexidol 100 mg and picamilon 150 mg, 22 patients received combined therapy of mexidol 300 mg and picamilon 150 mg, 22 patients received only picamilon 150 mg. All medicine was administered qd during 14 or 21 days. Examination included standard ophthalmologic methods, perimetry, electroretinography, retinal and optic nerve heard arterial blood flow. Improvement of visual acuity, perimetric, electrofisiological indicies and increased blood flow velocity of central retinal artery were registrated. Combined mexidol therapy allows improving results in treatment of patients with POAG.

High-sensitivity liquid chromatography-tandem mass spectrometry method for the simultaneous determination of sodium picosulfate and its three major metabolites in human plasma.

Sodium picosulfate (PICO-Na) is a member of the polyphenolic group of stimulant laxatives. Its major metabolites in humans are its active aglycone BHPM (bis-(p-hydroxyphenyl)-pyridyl-2-methane), the monoglucuronide (M1) and the monosulfate (M2) of BHPM. A sensitive, specific and rapid liquid chromatography-tandem mass spectrometry method was established and validated for the simultaneous determination of picosulfate (PICO) and its three major metabolites in human plasma to investigate the pharmacokinetics of PICO and its major metabolites. Following protein precipitation with acetonitrile, chromatographic separation was achieved on a Luna 5u C(18)(2) column using gradient elution starting with 10% of 10mM ammonium acetate followed by increasing percentages of acetonitrile to eliminate interferences due to in-source conversion of the conjugated metabolites. Detection was performed on a tandem mass spectrometer equipped with an electrospray ionization source operated in the positive mode, using the transitions of m/z 438.1→m/z 278.1 for PICO, m/z 278.1→m/z 184.2 for BHPM, m/z 454.1→m/z 184.2 for M1, and m/z 358.1→m/z 184.2 summed with m/z 358.1→m/z 278.1 for M2. Deuterium labeled compounds of the analytes were used as the internal standard, two of which, M1-d(12) and M2-d(12), were synthesized in-house. The method was validated in concentration ranges of 0.150-40.0 ng/mL for PICO and M2, 0.600-160 ng/mL for BHPM, and 0.045-12.0 ng/mL for M1 with acceptable accuracy and precision. The method was successfully applied to characterize the pharmacokinetic profiles of PICO and its metabolites in healthy volunteers after a single oral administration of 5mg PICO-Na.

[The influence of water soluble antioxidant agent (mexidol) on optic nerve and blood flow velocity in ocular and orbital arteries in patients with primary open-angle glaucoma].

The prospective single-blind placebo-controlled randomized trial is devoted to influence of mexidol (2-ethil-6-methil-3-hydroxipiridine succinate) on dynamics of optic nerve electrophysiologic profile and velocity indices of blood flow in ocular and orbital arteries in correlation with changes of retinal photosensitivity, visual acuity and visual field size during course of intravenous mexidol infusions and standard treatment of primary open-angle glaucoma. 2 weeks of intravenous infusions of 300 mg mexidol daily was found to cause depression of optic nerve electrical sensitivity threshold and widening of total visual field (16 mm2 test stimulus) after 14 days of treatment. These effects were not associated with changes of blood flow velocity in ocular and orbital arteries, were transient and came to initial indices 3 months after the end of treatment. Delayed vasotropic effect of mexidol manifested in increase of blood flow velocity in central retinal artery in 90 days after the end of infusions.

Absence of excretion of the active moiety of bisacodyl and sodium picosulfate into human breast milk: an open-label, parallel-group, multiple-dose study in healthy lactating women.

The aim of this study was to determine whether administration of the prodrugs bisacodyl (Bisa) and sodium picosulfate (SPS) leads to excretion of their common active metabolite, bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM), in breast milk. Two groups of 8 healthy lactating women who had stopped breast feeding received multiple doses of Bisa or SPS. Plasma, urine, and breast milk were collected and concentrations of free and total BHPM were determined using validated liquid chromatography/mass spectrometry methods. BHPM remained below the limits of detection in breast milk following single- and multiple-dose administration of Bisa and SPS. First, BHPM plasma concentrations were observed after a lag time of about 3 to 4 h and 4 to 5 h following Bisa and SPS administration, respectively. C(max) was attained approximately 5 h after dosing of Bisa and 9 h after dosing of SPS. BHPM did not accumulate after multiple administrations of Bisa and only slightly accumulated following multiple doses of SPS. About 12% and 13% of Bisa and SPS was excreted as BHPM into urine at steady state. BHPM, the active moiety of Bisa and SPS, was not excreted into human breast milk. Hence, use of Bisa or SPS to treat constipation of breast-feeding women is considered well tolerated with regard to exposing infants to BHPM via breast milk.

In vivo optical imaging of acute cell death using a near-infrared fluorescent zinc-dipicolylamine probe.

Cell death is a fundamental biological process that is present in numerous disease pathologies. Fluorescent probes that detect cell death have been developed for a myriad of research applications ranging from microscopy to in vivo imaging. Here we describe a synthetic near-infrared (NIR) conjugate of zinc(II)-dipicolylamine (Zn²+-DPA) for in vivo imaging of cell death. Chemically induced in vivo models of myopathy were established using an ionphore, ethanol, or ketamine as cytotoxins. The Zn²+-DPA fluorescent probe or corresponding control was subsequently injected, and whole animal fluorescence imaging demonstrated probe uptake at the site of muscle damage, which was confirmed by ex vivo and histological analyses. Further, a comparative study with a NIR fluorescent conjugate Annexin V showed less intense uptake at the site of muscle damage and high accumulation in the bladder. The results indicate that the fluorescent Zn²+-DPA conjugate is an effective probe for in vivo cell death detection and in some cases may be an appropriate alternative to fluorescent Annexin V conjugates.

Discovery, synthesis, and structure-activity relationship development of a series of N-(4-acetamido)phenylpicolinamides as positive allosteric modulators of metabotropic glutamate receptor 4 (mGlu(4)) with CNS exposure in rats.

Herein we report the discovery, synthesis, and evaluation of a series of N-(4-acetamido)-phenylpicolinamides as positive allosteric modulators of mGlu(4). Compounds from the series show submicromolar potency at both human and rat mGlu(4). In addition, pharmacokinetic studies utilizing subcutaneous dosing demonstrated good brain exposure in rats.

[Effect of mexidol on 6beta/free hydroxycortisol ratio. Possibility of CYP3A4 activation].

The influence of mexidol (2-ethyl-6-methyl-3-oxypyridine) after a single peroral administration on the levels of 6beta-hydroxycortisol (6beta-OHC) and free cortisol (FC) in human urine has been evaluated. The 6beta-OHC/FC ratio is increased (approximately 2.96 +/- 0.76 times) against the basal 6beta-OHC/FC ratio during the first 24 hour after drug administration. Data analysis on the second and third day after mexidol administration did not show evident changes in 6beta-OHC/FC ratios. It is suggested that CYP3A4 activation after mexidol administration occurred only during active drug biotransformation and excretion and ceased after full excretion from the human body.

[HPLC-MS determination of 2-ethyl-6-methyl-3-oxypyridine].

An HPLC-ESI-MS method has been developed for determining 2-ethyl-6-methyl-3-oxypyridine (EMO) in human urine upon peroral administration of this substance in form ofmexidol. Various sample preparation (extraction) procedures were tested and compared for evaluating the recovery and matrix effect. Solid-phase extraction procedure followed by derivation with dansyl chloride is proposed as a method of choice. The recovery of analyte was 48.1 +/- 3.4%, and the matrix effect was 99.4 +/- 4.1%. The MS and MS/MS spectra of EMO and its dansyl derivatives are presented and interpreted. The analyses were performed using a mass spectrometer of the ion trap type with electrospray ionization at atmospheric pressure, operating in the regime of positive ion detection.

Sodium picosulfate/magnesium citrate: a review of its use as a colorectal cleanser.

Oral sodium picosulfate/magnesium citrate (CitraFleet; Picolax), consisting of sodium picosulfate (a stimulant laxative) and magnesium citrate (an osmotic laxative), is approved for use in adults (CitraFleet; Picolax) and/or adolescents and children (Picolax) as a colorectal cleansing agent prior to any diagnostic procedure (e.g. colonoscopy or x-ray examination) requiring a clean bowel and/or surgery. It is dispensed in powder form (sodium picosulfate 0.01 g, magnesium oxide 3.5 g, citric acid 12.0 g per sachet), with the magnesium oxide and citric acid components forming magnesium citrate when the powder is dissolved in water. In adult patients, two sachets of sodium picosulfate/magnesium citrate was at least as effective and well tolerated as oral magnesium citrate 17.7 or 35.4 g, or oral polyethylene glycol 236 g in adult patients undergoing a double-contrast barium enema procedure in three large, randomized, comparative clinical studies. In contrast, sodium picosulfate/magnesium citrate was less effective than a sodium phosphate enema preparation in two studies in patients undergoing flexible sigmoidoscopy. A similar number of patients receiving two sachets of sodium picosulfate/magnesium citrate or two 45 mL doses of oral sodium phosphate the day before a double-contrast barium enema procedure achieved satisfactory barium coating and none/minimal faecal residue in one study. However, the data from three of these studies should be interpreted with caution because the administrative regimens used differed from that recommended. Sodium picosulfate/magnesium citrate is also an effective and generally well tolerated colorectal cleansing agent in children and adolescents; the preparation was more effective than oral bisacodyl 0.01 or 0.02 g plus a sodium phosphate enema preparation in this population. Further research is thus required to accurately position sodium picosulfate/magnesium citrate and fully establish its efficacy and tolerability prior to various exploratory or surgical procedures. Nevertheless, oral sodium picosulfate/magnesium citrate provides a useful option in the preparation of the colon and rectum in adults, adolescents and children undergoing any diagnostic procedure (e.g. colonoscopy or x-ray examination) requiring a clean bowel and/or surgery. Oral sodium picosulfate/magnesium citrate acts locally in the colon as both a stimulant laxative, by increasing the frequency and the force of peristalsis (sodium picosulfate component), and an osmotic laxative, by retaining fluids in the colon (magnesium citrate component), to clear the colon and rectum of faecal contents. It is not absorbed in any detectable quantities. Sodium picosulfate is a prodrug: it is hydrolyzed by bacteria in the colon to the active metabolite 4,4'-dihydroxydiphenyl-(2-pyridyl)methane. Sodium picosulfate/magnesium citrate may be associated with a dehydrating effect, as evidenced by a reduction in bodyweight and increased haemoglobin levels; some at-risk patients may experience postural hypotension and older patients may require additional electrolytes. In three large (n >100), randomized, single-blind clinical studies, two sachets of oral sodium picosulfate/magnesium citrate was at least as effective as oral magnesium citrate 17.7 or 35.4 g, or oral polyethylene glycol 236 g as a colorectal cleansing agent in adult patients undergoing a double-contrast barium enema procedure. In contrast, sodium picosulfate/magnesium citrate was less effective than a sodium phosphate enema preparation in two studies in patients undergoing flexible sigmoidoscopy. A similar number of patients receiving two sachets of sodium picosulfate/magnesium citrate or two 45 mL doses of oral sodium phosphate the day before a double-contrast barium enema procedure achieved satisfactory barium coating and none/minimal faecal residue in one study. However, the data from three of these studies should be interpreted with caution because the administrative regimens used differed from that recommended. In children and adolescents, sodium picosulfate/magnesium citrate was significantly more effective as a colorectal cleansing agent than oral bisacodyl 0.01 or 0.02 g plus a sodium phosphate enema preparation in a randomized, single-blind study; dosages were adjusted for age in this study. Oral sodium picosulfate/magnesium citrate is generally well tolerated in adult patients undergoing various investigational colorectal procedures. Adverse events were generally mild to moderate in intensity and mainly gastrointestinal in nature (e.g. abdominal cramps/pain, nausea); other common treatment-emergent adverse events included disturbance of daily activity, headache and sleep disturbance. This combination is at least as well tolerated as oral sodium phosphate or oral polyethylene glycol, with moderate/severe nausea and vomiting occurring less frequently in sodium picosulfate/magnesium citrate recipients than in those receiving oral sodium phosphate, and abdominal bloating/pain and nausea developing less often with sodium picosulfate/magnesium citrate than polyethylene glycol therapy. The incidence of abdominal pain and sleep disturbance in sodium picosulfate/magnesium citrate versus oral magnesium citrate recipients was similar in one study, but significantly lower with sodium picosulfate/magnesium citrate in another. While the incidence of most adverse events was similar in recipients of sodium picosulfate/magnesium citrate and a sodium phosphate enema preparation, more patients receiving sodium picosulfate/magnesium citrate reported moderate/severe flatulence, incontinence and sleep disturbance, and more patients receiving the enema preparation reported rectal soreness. The tolerability profile of sodium picosulfate/magnesium citrate in patients aged >70 years is reportedly similar to that in patients aged <70 years. Abdominal pain also occurred less frequently with sodium picosulfate/magnesium citrate than with oral bisacodyl plus a sodium phosphate enema preparation in children and adolescents.

Pharmacokinetics of the novel nicotinic receptor antagonist N,N'-dodecane-1,12-diyl-bis-3-picolinium dibromide in the rat.

Plasma and brain concentrations of the nicotinic acetylcholine receptor antagonist and blood-brain barrier choline transporter substrate, N,N'-dodecane-1,12-diyl-bis-3-picolinium dibromide (bPiDDB), were analyzed by liquid beta-scintillation spectrometry after administration of [14CH3]bPiDDB to male Sprague-Dawley rats. Plasma concentrations of [14CH3]bPiDDB were determined at 10 time points over 3 h. Absolute plasma bioavailabilities (1, 3, and 5.6 mg/kg s.c.) were 80.3, 68.2, and 103.7%, respectively. bPiDDB (1, 3, and 5.6 mg/kg) gave Cmax values of 0.13, 0.33, and 0.43 microg/ml, respectively, Tmax values of 5.0, 6.7, and 8.8 min, respectively, and t1/2 values of 76.0, 54.6, and 41.7 min, respectively. Mean area under the plasma concentration versus time curve from time zero to infinity (micrograms per minute per milliliter) and mean Cmax (microg/ml) values were dose-dependent (r2=0.9361 and 0.7968, respectively) over the dose range studied. No metabolism of [14CH3]bPiDDB was detected with any dose of bPiDDB administered. Only moderate protein binding (63-65% in plasma and 59-62% in brain supernatant) was observed, which was reversible. Brain concentrations and brain/plasma ratios of bPiDDB after a single 5.6 mg/kg s.c. dose over 5 to 60 min ranged from 0.09 to 0.33 microg/g brain tissue and were maximal at 10 min after injection, representing approximately 0.6% of the administered dose. Brain/blood ratio (0.18 at 5 min to 0.51 at 60 min after injection) was observed, indicating that clearance from brain is slower than clearance from plasma. The results show that bPiDDB is distributed rapidly from the site of injection into plasma, affords good plasma concentrations, and appears to reach brain tissues via facilitated transport by the blood-brain barrier choline transporter to afford therapeutically relevant concentrations in rat brain.

N,N'-Alkane-diyl-bis-3-picoliniums as nicotinic receptor antagonists: inhibition of nicotine-evoked dopamine release and hyperactivity.

The current study evaluated a new series of N,N'-alkane-diyl-bis-3-picolinium (bAPi) analogs with C6-C12 methylene linkers as nicotinic acetylcholine receptor (nAChR) antagonists, for nicotine-evoked [3H]dopamine (DA) overflow, for blood-brain barrier choline transporter affinity, and for attenuation of discriminative stimulus and locomotor stimulant effects of nicotine. bAPi analogs exhibited little affinity for alpha4beta2* (* indicates putative nAChR subtype assignment) and alpha7* high-affinity ligand binding sites and exhibited no inhibition of DA transporter function. With the exception of C6, all analogs inhibited nicotine-evoked [3H]DA overflow (IC50 = 2 nM-6 microM; Imax = 54-64%), with N,N'-dodecane-1,12-diyl-bis-3-picolinium dibromide (bPiDDB; C12) being most potent. bPiDDB did not inhibit electrically evoked [3H]DA overflow, suggesting specific nAChR inhibitory effects and a lack of toxicity to DA neurons. Schild analysis suggested that bPiDDB interacts in an orthosteric manner at nAChRs mediating nicotine-evoked [3H]DA overflow. To determine whether bPiDDB interacts with alpha-conotoxin MII-sensitive alpha6beta2-containing nAChRs, slices were exposed concomitantly to maximally effective concentrations of bPiDDB (10 nM) and alpha-conotoxin MII (1 nM). Inhibition of nicotine-evoked [3H]DA overflow was not different with the combination compared with either antagonist alone, suggesting that bPiDDB interacts with alpha6beta2-containing nAChRs. C7, C8, C10, and C12 analogs exhibited high affinity for the blood-brain barrier choline transporter in vivo, suggesting brain bioavailability. Although none of the analogs altered the discriminative stimulus effect of nicotine, C8, C9, C10, and C12 analogs decreased nicotine-induced hyperactivity in nicotine-sensitized rats, without reducing spontaneous activity. Further development of nAChR antagonists that inhibit nicotine-evoked DA release and penetrate brain to antagonize DA-mediated locomotor stimulant effects of nicotine as novel treatments for nicotine addiction is warranted.

Discovery of a novel nicotinic receptor antagonist for the treatment of nicotine addiction: 1-(3-Picolinium)-12-triethylammonium-dodecane dibromide (TMPD).

Limitations in efficacy and high relapse rates of currently available smoking cessation agents reveal the need for more efficacious pharmacotherapies. One strategy is to develop subtype-selective nicotinic receptor (nAChR) antagonists that inhibit nicotine-evoked dopamine (DA) release, the primary neurotransmitter involved in nicotine reward. Simple alkylation of the pyridino N-atom converts nicotine from a potent agonist into a potent antagonist. The classical antagonists, hexamethonium and decamethonium, differentiate between peripheral nAChR subtypes. Using a similar approach, we interconnected varying quaternary ammonium moieties with a lipophilic linker to provide N,N'-bis-nicotinium analogs, affording a lead compound, N,N'-dodecyl-1,12-diyl-bis-3-picolinium dibromide (bPiDDB), which inhibited nicotine-evoked DA release and decreased nicotine self-administration. The current work describes a novel compound, 1-(3-picolinium)-12-triethylammonium-dodecane dibromide (TMPD), a hybrid of bPiDDB and decamethonium. TMPD completely inhibited (IC(50)=500 nM) nicotine-evoked DA release from superfused rat striatal slices, suggesting that TMPD acts as a nAChR antagonist at more than one subtype. TMPD (1 microM) inhibited the response to acetylcholine at alpha3beta4, alpha4beta4, alpha4beta2, and alpha1beta1varepsilondelta receptors expressed in Xenopus oocytes. TMPD had a 2-fold higher affinity than choline for the blood-brain barrier choline transporter, suggesting brain bioavailability. TMPD did not inhibit hyperactivity in nicotine sensitized rats, but significantly and specifically decreased nicotine self-administration. Together, the results suggest that TMPD may have the ability to reduce the rewarding effect of nicotine with minimal side effects, a pharmacological profile indicative of potential clinical utility for the treatment of tobacco dependence.

Bioavailability of glycyrrhizin from Shaoyao-Gancao-Tang in laxative-treated rats.

Shaoyao-Gancao-Tang (SGT), a traditional Chinese formulation composed of Shaoyao (Paeoniae Radix) and Gancao (Glycyrrhizae Radix), is frequently used in conjunction with laxatives such as sodium picosulfate in colonoscopy to relieve abdominal pains. We have investigated the alterations of the bioavailability of glycyrrhizin when SGT was co-administered with sodium picosulfate and we tried to identify a regimen that might minimize the alterations. Glycyrrhizin is one of the active glycosides in Gancao and SGT and is hydrolysed into the bioactive metabolite, 18 beta-glycyrrhetic acid (GA) by intestinal bacteria following oral administration. We found that the maximum plasma concentration (C(max)) and the area under the mean concentration vs time curve from zero to 24 h (AUC(0-24 h)) of GA from a single dose of SGT administered 5 h after a single pretreatment with sodium picosulfate were significantly reduced to 15% and 20% of the control level in rats, respectively. These reductions were still significant four days after sodium picosulfate pretreatment, but were restored by repetitive administration of SGT following sodium picosulfate pretreatment. Similar reductions and recovery were observed for the glycyrrhizin-metabolizing activity of intestinal bacteria in rat faeces. The results warrant clinical studies for co-administration of laxatives such as sodium picosulfate and SGT.

[Biotransformation of mexidol in inbred BALB/C and C57BL/6 mice].

The pharmacokinetics and biotransformation of mexidol was studied in BALB/C and C57BL/6 mice. The blood plasma contains dealkylated metabolites, and the urine contains glucuronoconjugated derivatives of the drug. The process of glucuronoconjugation more intensively proceeds in C57BL/6 mice than in BALB/C mice.