Cyclazocine: comparison to hydromorphone and interaction with cocaine.

Kappa-opioid agonists produce neurobiological and behavioral effects opposite to those of cocaine and may be useful for the treatment of cocaine dependence. To evaluate the kappa- and mu-agonist effects of cyclazocine and to test whether cyclazocine pretreatment would attenuate the effects of cocaine, healthy, male and female, experienced opiate and cocaine users (n = 13) were enrolled in a two-phase study. In Phase 1, placebo, cyclazocine (0.2, 0.4 and 0.8 mg) and the mu-agonist hydromorphone (5 and 15 mg) were administered orally in six 4.5-hour sessions separated by at least 72 h. In Phase 2, cocaine (100 mg intranasal) was given 2 h after oral pretreatment with cyclazocine (0, 0.1, 0.2, 0.4, 0.8 and 0 mg, in that order) in each of six sessions conducted daily Monday to Friday and the following Monday. Physiological, subjective and behavioral measures were collected in each session. Nine participants completed Phase 1; eight completed Phase 2. Hydromorphone (15 mg) produced prototypic mu-agonist effects. Cyclazocine exhibited only modest kappa-like effects. Cyclazocine also had only modest, non-dose-related effects on response to cocaine. However, cocaine effects were consistently lower on the last administration (cyclazocine 0 mg pretreatment) following 4 days of cyclazocine pretreatment, compared to the first administration (0 mg pretreatment). This finding is unlikely to be fully attributable to cocaine tolerance and is not accounted for by pharmacokinetic changes; plasma concentrations of cocaine were not altered by cyclazocine. This study is suggestive but not strongly supportive for the use of kappa-opiate drugs to diminish acute effects of cocaine administration or for the use of these kappa agonists in drug abuse treatment applications.

Enadoline, a selective kappa opioid agonist: comparison with butorphanol and hydromorphone in humans.

RATIONALE: The availability of the highly selective and specific kappa opioid agonist enadoline provides an opportunity to explore the function of kappa receptors in humans and their potential utility as a target for substance abuse pharmacotherapy development. OBJECTIVES: The purpose of this study was to characterize the pharmacodynamic effects of enadoline, a selective kappa agonist, and to compare it with butorphanol, a mixed mu/kappa agonist, and hydromorphone, a mu agonist, in humans. METHODS: Pilot evaluation (n=3) served to establish intramuscular doses of enadoline (20, 40, 80, and 160 microg/70 kg), butorphanol (1.5, 3, 6, and 12 mg/70 kg), and hydromorphone (1.5, 3, and 6 mg/70 kg) of comparable activity. These acute doses were examined under double-blind, placebo-controlled and constrained randomized conditions with a minimum of 72 h between tests in volunteers with polysubstance abuse histories (n=6). Physiological and subject- and observer-rated measures were collected 30 min before and for 4 h after administration. RESULTS: Enadoline significantly increased measures of sedation, confusion and dizziness, produced visual distortions and feelings of depersonalization, and increased urinary output. The highest dose (160 microg/70 kg) was not tolerated and led to psychotomimetic effects. Hydromorphone produced prototypic mu opioid effects including respiratory depression, miosis, and euphoria. Butorphanol was most similar to hydromorphone and shared few effects with enadoline. CONCLUSIONS: These results are discussed with respect to the potential use and safety of kappa agonists for clinical indications.

Effect of intravenous injection speed on responses to cocaine and hydromorphone in humans.

RATIONALE: It is commonly accepted that the relative abuse liability of drugs is positively related to the rate of delivery to the central nervous system; however, few controlled studies have tested this hypothesis in humans. OBJECTIVES: The aims of this study were to evaluate systematically the effects of modifying intravenous infusion speed on the pharmacodynamic responses related to abuse liability and toxicity of intravenous cocaine and hydromorphone. METHODS: Twelve experienced opiate and cocaine users completed this 3-week inpatient study. After completing a safety session, participants were tested on 9 separate test days with intravenous cocaine (30 mg/70 kg), hydromorphone (3 mg/70 kg), and placebo, each administered under double-blind and randomized conditions at infusion rates of 2, 15, and 60 s. Dependent outcome measures included a range of physiological, subjective, and observer-rated measures, and continuous electrocardiographic monitoring was conducted for safety monitoring. RESULTS: Subjective responses to cocaine (for example, "high," "liking") were significantly greater when cocaine was infused more rapidly. Physiological responses to cocaine were largely unaltered with no evidence of increased toxicity with faster infusion speeds. None of the effects of hydromorphone were altered by varying the speed of infusion. CONCLUSIONS: This study provides empirical evidence for the commonly accepted belief that the abuse liability of cocaine can be enhanced by increasing the rate of the intravenous infusion; this principal may not hold true for opioids but further work would be required to rule this out. The data also indicate that moderate doses of cocaine can be administered over a range of infusion speeds commonly used in experimental settings without appreciably altering the apparent medical risks.

C cells in normal thyroid aspirates.

OBJECTIVE: To quantify C cells in normal thyroid aspirates. STUDY DESIGN: Smears of 18 glands from patients with no thyroid disease, 8 women and 10 men aged on average 52.8 years, were analyzed. Five samples were aspirated from the upper, middle and lower thirds of each lateral lobe and from the isthmus. Smears were stained with anticalcitonin monoclonal antibody. RESULTS: C cells were detected in all specimens, ranging in number from 3 to 19 per gland, with 53.4% of the cells in the right lobe, 42.8% in the left lobe and 3.7% in the isthmus. The aspirates from the right lobe had 0-13 cells in the upper third, 0-9 in the middle third and 0-3 in the lower third. In the left lobe aspirates there were 0-7 cells in the upper third, 0-6 in the middle third and 0-2 in the lower third. One to two C cells were observed in the isthmus in only four cases. CONCLUSION: It is possible to determine the presence of C cells in normal thyroids and confirm studies conducted on histologic material; the cells were more frequently detected in the middle and upper third and mainly on the right side. They were rare in the isthmus. The search for C cells in thyroid aspirates is of great importance because it permits one to confirm rapidly, precisely and minimally invasively cases suspected of C cell hyperplasia, a preneoplastic condition that precedes the development of medullary carcinoma. In addition, the method shows numerical changes in these cells in such conditions as Hashimoto's thyroiditis and colloid goiter, in which the present results could serve as a control.

[Glucose-6-phosphate dehydrogenase deficiency in 2 girls]. / Défice de glicose-6-fosfato desidrogenase em duas crianças do sexo feminino.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common erythrocyte enzymopathy, affecting over 400 million people worldwide. Portugal is a low prevalence country, but immigrants from endemic regions are common, particularly in the south of the country. In the present study, we report the laboratory findings observed in two black proband children with low G6PD enzyme activity (23 and 18%). The study also included their first-degree relatives. Both biochemical parameters (enzyme activity, electrophoretic mobility and cytochemical test) and genetic determinations (mutation and haplotype characterisation) were performed.

Drug tasting may confound human drug discrimination studies.

Unpublished observations suggested that some subjects in human drug discrimination studies acquired a drug versus placebo discrimination by tasting the capsule contents. To evaluate the prevalence of this behavior and to develop approaches to circumvent this problem, 30 normal human subjects participated in a drug discrimination study in which the study capsules (i.e., lactose and lactose + quinine) could be discriminated by tasting the capsule contents but were otherwise pharmacologically indistinguishable. Twenty percent of the subjects significantly discriminated between the capsules; this discrimination was disrupted by employing thorough mouth checks following capsule administration. Based on these findings, we recommend that human drug discrimination studies incorporate procedures that minimize the possibility of drug tasting by requiring consumption of sufficient fluid in combination with rigorous mouth checks to ensure capsule swallowing.

Mouse strain differences in the behavioral effects of corticotropin-releasing factor (CRF) and the CRF antagonist alpha-helical CRF9-41.

The effect of the corticotropin-releasing factor (CRF) antagonist alpha-helical CRF9-41 (alpha H CRF9-41; 25 and 50 micrograms) was examined in four strains of mice (BALB/C, NIH Swiss, CF-1, and CD) in the elevated plus-maze anxiolytic test and found to significantly increase percent open arm activity in only the BALB/C mice. A marginal anxiolytic response was obtained in NIH Swiss, while no effect of the antagonist was noted in CF-1 or CD mice in this test. Diazepam (1-4 mg/kg IP) significantly increased percent open arm activity in all four mouse strains. Thus, all strains were sensitive to the effects of a known anxiolytic in this test. The locomotor-suppressing effect of the agonist CRF was assessed in the four strains of mice. While CRF suppressed locomotor activity in each of the strains, the peptide was more efficacious and more potent in the BALB/C strain than in any of the other three strains. The behavioral differences in responsiveness to CRF and the antagonist alpha H CRF9-41 could not be explained on the basis of differential binding of CRF to forebrain membranes in the four mouse strains. These data suggest that the BALB/C mouse is more sensitive to the behavioral effects of CRF and its antagonist than other strains and may be a useful strain for examining the effects of CRF and/or stress.

Examination of the D2/5-HT2 affinity ratios of resolved 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles: an enantioselective approach toward the design of potential atypical antipsychotics.

Enantiomers of several N-substituted 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles were obtained by the resolution of 2-fluoro-5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indole and 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indole followed by N-alkylation. These, as well as the racemates, were evaluated for their affinity for the 5-HT2 and D2 receptors. Those compounds possessing the 7S,10R stereochemistry were consistently recognized by the 5-HT2 and D2 receptors as the eutomer. 2-Fluoro-11-[4-(4-fluorophenyl)-4-oxobutyl]-5,6,7,8,9,10-hexahydro-7S,10 R- iminocyclohept[b]indole [(7S,10R)-8] had the highest affinity for the 5-HT2 receptor (Ki = 0.80 nM), while its distomer (7R,10S)-8 was the most selective member of this class of bridged gamma-carbolines (D2/5-HT2 = 562). Incorporation of a benzoyl or isosteric benzisoxazole moiety tethered by a four-carbon spacer to a bridged gamma-carboline nucleus, possessing the 7S,10R absolute configuration, produced high affinity ligands for the 5-HT2 and D2 receptors.

NPC 16377, a potent and selective sigma-ligand. II. Behavioral and neuroprotective profile.

6-[6-(4-Hydroxypiperidinyl)hexyloxy]-3-methylflavone HCI, (NPC 16377), a potent and highly selective sigma-site ligand, was evaluated in tests predictive of antipsychotic and neuroprotective potential and for toxicity. Like haloperidol, clozapine and remoxipride, and the sigma-ligands BMY 14802, ifenprodil and rimcazole, NPC 16377 reversed amphetamine-induced hyperactivity and apomorphine-induced climbing in mice. Additional evidence for antipsychotic activity was obtained in rats with NPC 16377, clozapine, BMY 14802, ifenprodil, haloperidol and rimcazole, all of which reduced conditioned avoidance responses at doses that did not reduce escape behavior. NPC 16377 did not induce catalepsy in mice, suggesting a decreased liability for producing extrapyramidal side effects. NPC 16377 extended survival time for mice exposed to a hypoxic environment. In a model of global ischemia using conscious gerbils, NPC 16377 prevented damage to hippocampal CA1 neurons after either intraperitoneal or oral administration. NPC 16377 did not disrupt prepulse inhibition or block the disruption of prepulse inhibition induced by the phencyclidine site-selective ligand (+)MK-801. In rats trained to discriminate phencyclidine from saline, NPC 16377 did not substitute for the psychotomimetic. These data are consistent with the notion that selective sigma-agents may possess antipsychotic and neuroprotective activities. Moreover, the results from prepulse inhibition and drug discrimination experiments suggest that NPC 16377 is devoid of phencyclidine-like effects.

NPC 16377, a potent and selective sigma-ligand. I. Receptor binding, neurochemical and neuroendocrine profile.

6-[6-(4-Hydroxypiperidinyl)hexyloxy]-3-methylflavone HCI (NPC 16377), a structurally novel compound, was found to be a highly potent and selective ligand for sigma-sites. Although 5-fold less potent than haloperidol and 2-fold less potent than ifenprodil to inhibit 1,3-di-o-tolylguanidine binding, NPC 16377 (IC50 = 36 nM) was more potent than alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinyl butanol (BMY 14802), rimcazole and the atypical antipsychotic, clozapine. A similar rank order of potency was observed when [3H](+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperdine was used as the radioligand. Like BMY, rimcazole and clozapine, NPC 16377 (IC50 = 2671 nM) had low affinity for dopamine type 2 receptors. Additionally, the compound was only weakly active in 35 additional receptor binding assays including those for serotonin2 and serotonin1C receptors. In vivo, NPC 16377 potently inhibited the binding of [3H]-(+)-N-allylnormetazocine to sigma sites after both intraperitoneal and oral administration. At doses 30-fold in excess of the ID50 to inhibit [3H](+)N-allylnormetazocine, NPC 16377 failed to displace [3H]raclopride from dopamine type 2 binding sites. Unlike haloperidol, BMY 14802, ifenprodil and clozapine, behaviorally effective doses of NPC 16377 did not increase dopamine turnover in the frontal cortex, nucleus accumbens or corpus striatum of rats. In contrast, each of these agents increased circulating levels of both adrenocorticotropin and corticosterone, but only NPC 16377 decreased circulating plasma levels of prolactin. The results of the current study are consistent with the notion that NPC 16377 is a potent, selective and orally active sigma site ligand. At behaviorally relevant doses the compound produces neuroendocrine effects both similar to, and different from, neuroleptics, other sigma-ligands and atypical antipsychotics, while having no effect on dopamine turnover. Given these data, NPC 16377 should prove to be a useful compound to explore further the physiological and functional significance of sigma-sites in brain.

1,3,8-trisubstituted xanthines. Effects of substitution pattern upon adenosine receptor A1/A2 affinity.

A series of 11 8-substituted xanthines having three different substitution patterns on the 1- and 3-positions [pattern a (R1 = R3 = CH2CH2CH3), b (R1 = CH2CH2CH3, R3 = CH3), and c (R1 = CH3, R3 = CH2CH2CH3)] was prepared. These compounds were assessed for affinity and selectivity in binding to adenosine A1 and A2 receptors. Compounds with greatest affinity at the A1 receptor had the 1,3-substitution pattern a. With one exception, compounds with pattern a also exhibited the most potent binding at the A2 receptor; however, several compounds with pattern c were equipotent at the A2 receptor with those having pattern a. Additionally, the substituents on the 1- and 3-positions of these 8-substituted xanthines were equally important for determining maximum affinity to the A1 receptor, while the substituent at the 3-position is more important than the substituent at the 1-position for potency at the A2 receptor. As a result of this, it is possible to maximize selectivity for the A1 receptor by choice of the 1- and 3-position substituents. However, the R1/R3 substitution pattern required for maximum A1 selectivity is also dependent upon the substituent in the 8-position in a manner which is not fully understood.

Footshock-induced freezing behavior in rats as a model for assessing anxiolytics.

A number of chemically distinct anxiolytics were examined for effects on defensive behavior (foot-shock-induced freezing) in rats. Central nervous system acting drugs which are not anxiolytics were also studied. Animals were injected with a drug or vehicle (IP) prior to being placed in a chamber with a grid floor through which two footshocks were delivered. Behavior was observed during the pre-shock period (2 min) and for 4 min after the second footshock. The effects of the following drugs on the duration of footshock-induced freezing were studied: diazepam (DZP); 2-amino-4,5-(1,2-cyclohexyl)-7 phosphonoheptonic acid (NPC 12626); 3-((+/-)-2-carboxypiperazine-4-yl)-propyl-l-phosphonic acid (CPP); [(+)-5-methyl-10-11,dihydroxy-5H-dibenzo(a,d)cyclohepten-5,10- imine (MK-801); buspirone hydrochloride (BUS); DL-amphetamine sulfate (AMP); haloperidol (HAL); ethyl-beta-carboline-3 carboxylate (beta-CCE). Compounds which reduced the duration of footshock-induced freezing included DZP, BUS, and the competitive NMDA antagonists NPC 12626 and CPP. The non-competitive NMDA antagonist, MK-801, had no effect on the response. The highest dose of amphetamine tested also reduced footshock-induced freezing. However, amphetamine-treated animals did not locomote or rear after footshock, suggesting fear of the environment. Animals injected with DZP, NPC 12626, CPP or buspirone spent at least 1.4 of the 4 post shock minutes locomoting. Haloperidol had no effect on freezing at the doses tested. beta-CCE tended to increase the duration of footshock-induced freezing.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism of acrylonitrile to cyanide. In vitro studies.

In liver fractions from Sprague-Dawley rats, the metabolism of acrylonitrile (VCN) to cyanide (CN-) was localized the microsomal fraction and required NADPH and O2 for maximal activity. The biotransformation of VCN to CN- was characterized with respect to time, microsomal protein concentration, pH, and temperature. Metabolism of VCN was increased in microsomes obtained from phenobarbital-, Aroclor 1254-, or 3-methylcholanthrene-treated rats (479%, 414%, and 142% of control, respectively) and decreased with CoCl2 treatment (54% of control). The KM estimated for VCN with the phenobarbital (54.8 +/- 9.5 mM) or Aroclor 1254 (40.9 +/- 4.1 mM) preparation was lower than the control (190.7 +/- 19.7 mM). Addition of SKF 525-A or CO to incubation mixtures inhibited VCN metabolism. Addition of the epoxide hydratase inhibitor, 1,1,1-trichloropropane 2,3-oxide, decreased the formation of CN- from VCN. Addition of glutathione, cysteine, D-penicillamine, or 2-mercaptoethanol enhanced the release of CN- from VCN. These findings indicate that VCN is metabolized to CN- via a cytochrome P-450-dependent mixed-function oxidase system.