Identification of Cyanamide-Based Janus Kinase 3 (JAK3) Covalent Inhibitors.

Ongoing interest in the discovery of selective JAK3 inhibitors led us to design novel covalent inhibitors that engage the JAK3 residue Cys909 by cyanamide, a structurally and mechanistically differentiated electrophile from other cysteine reacting groups previously incorporated in JAK3 covalent inhibitors. Through crystallography, kinetic, and computational studies, interaction of cyanamide 12 with Cys909 was optimized leading to potent and selective JAK3 inhibitors as exemplified by 32. In relevant cell-based assays and in agreement with previous results from this group, 32 demonstrated that selective inhibition of JAK3 is sufficient to drive JAK1/JAK3-mediated cellular responses. The contribution from extrahepatic processes to the clearance of cyanamide-based covalent inhibitors was also characterized using metabolic and pharmacokinetic data for 12. This work also gave key insights into a productive approach to decrease glutathione/glutathione S-transferase-mediated clearance, a challenge typically encountered during the discovery of covalent kinase inhibitors.

Novel broad-spectrum and long-acting parenteral cephalosporins having an acyl cyanamide moiety at the C-3 terminal: Synthesis and structure-activity relationships.

A series of novel 7ß-[2-(2-aminothiazole-4-yl)-2-(Z)-(alkoxyimino)acetamido]-cephalosporins having pyridinium-linked acyl cyanamide at the C-3 position were prepared and their antibacterial activities and pharmacokinetics profiles were evaluated. Most of the compounds exhibited potent antibacterial activities against penicillin-resistant Streptococcus pneumoniae (PRSP) and ß-lactamase non-producing penicillin-resistant Haemophilus influenzae (BLNAR). Introduction of a propenyl group between the cephalospoin core and the side chains at the C-3 position improved the pharmacokinetics profile. Among these compounds, 7ß-[2-(2-aminothiazole-4-yl)-2-(Z)- (alkoxyimino)acetamido]-3-(pyridin-1-ium-1-yl)prop-1-en-1-yl)cephalosporins (32j) showed well-balanced antibacterial activity against S. pneumoniae and H. influenzae which included resistant strains and also other Gram-positive or Gram-negative pathogens. Furthermore, 32j showed a long half-life comparable to that of Ceftriaxone in mice and monkeys.

The adverse effects of hydrogen cyanamide on human health: an evaluation of inquiries to the New Zealand National Poisons Centre.

INTRODUCTION: Hydrogen cyanamide is used in New Zealand to induce bud break in kiwifruit vines. The aim of this investigation was to evaluate the calls received by the New Zealand National Poisons Centre (NZNPC) attributed to acute hydrogen cyanamide exposure, and to ascertain the clinical effects of such exposures. METHODS: Call data from the NZNPC telephone collection databases regarding human hydrogen cyanamide exposures were analyzed retrospectively for the years 1990-2006. RESULTS: There were 68 human exposures, 69% were male and 22% female; 88% were adults and there were no suicide attempts. Common exposure routes were inhalation (56%) and skin contact (28%). The workplace accounted for 45% of calls. The predominant toxic effects were nausea and vomiting (29%), headache (22%), contact dermatitis (19%), and erythema (18%). DISCUSSION: Reported symptoms and signs were consistent with the expected effects of hydrogen cyanamide exposure. Other reports of similar exposures describe higher degrees of illnesses among workers using hydrogen cyanamide, which might have been because of lack of training, inadequate access to personal protective equipment, and the absence of engineering controls. CONCLUSIONS: Based on the calls received by the NZNPC, acute exposure to hydrogen cyanamide in the workplace or acute exposure to those living within the vicinity of its use may not pose a significant immediate threat to human health.

Effect of different doses of cyanamide on striatal salsolinol formation after ethanol treatment.

To assess the dose-dependent effect of cyanamide (CY, a potent aldehyde dehydrogenase inhibitor) on salsolinol release in the striatum, rats were treated with CY (25, 50 and 100 mg/kg) plus ethanol (EtOH,1 g/kg) intraperitoneally. Striatal salsolinol was detected using in vivo microdialysis coupled with high-performance liquid chromatography with an electrochemical detector in free-moving rats, and blood acetaldehyde (AcH) and EtOH were detected using the head-space gas chromatographic method. With the increase in the doses of CY following EtOH, the peak concentrations of striatal salsolinol and blood AcH were increased significantly. Our study indicated that the magnitude of striatal salsolinol levels may depend on the concentration of blood AcH, and that there is a correlation between the blood AcH and striatal salsolinol.

Absolute bioavailability and absorption profile of cyanamide in man.

A pharmacokinetic study of cyanamide, an inhibitor of aldehyde dehydrogenase (EC1.2.1.3) used as an adjuvant in the aversive therapy of chronic alcoholism, has been carried out in healthy male volunteers following intravenous and oral administration. Cyanamide plasma levels were determined by a sensitive HPLC assay, specific for cyanamide. After intravenous administration cyanamide displayed a disposition profile according to a two-compartmental open model. Elimination half-life and total plasma clearance values ranged from 42.2 to 61.3 min and from 0.0123 to 0.0190 L.kg-1.min-1, respectively. After oral administration of 0.3, 1.0, and 1.5 mg/kg x +/- SEM values of Cmax, tmax (median) and AUC were 0.18 +/- 0.03, 0.91 +/- 0.11, and 1.65 +/- 0.27 micrograms.ml-1; 13.5, 13.5, and 12 min; and 8.59 +/- 1.32, 45.39 +/- 1.62, and 77.86 +/- 17.49 micrograms.ml-1.min, respectively. Absorption was not complete and the oral bioavailability, 45.55 +/- 9.22, 70.12 +/- 4.73, and 80.78 +/- 8.19% for the 0.3, 1.0, and 1.5 mg/kg doses, respectively, increased with the dose administered. The models that consider a first-order absorption process alone (whether with a fixed or variable bioavailability value as a function of dose) or with loss of drug due to presystemic metabolism (with zero-order or Michaelis-Menten kinetics) were simultaneously fitted to plasma level data obtained following 1 mg/kg i.v. and 0.3, 1.0, and 1.5 mg/kg oral administrations. The model that best fit the data was that with a first-order absorption process plus a loss by presystemic metabolism with Michaelis-Menten kinetics, suggesting the presence of a saturable first-pass effect.

Pharmacokinetics and oral bioavailability of carbimide in man.

A pharmacokinetic study of carbimide, an inhibitor of aldehyde dehydrogenase, used as an adjuvant in the aversive therapy of chronic alcoholism, has been carried out in male human volunteers for intravenous and oral administration. Carbimide plasma concentrations were determined by a sensitive and specific high performance liquid chromatographic method. The intravenous doses administered were 0.1, 0.3, 0.6, and 1 mg kg-1 and linear pharmacokinetics were observed for this dose range. Elimination half-life and total plasma clearance values ranged from 42 to 52 min and from 14.4 to 20.5 ml kg-1 min-1, respectively. After oral administration of 1 and 1.5 mg kg-1 of carbimide, elimination half-life values were 75 and 61 min, respectively, being higher than the corresponding value obtained after 0.3 mg kg-1 doses, i.e. 39 min. In all cases, rapid absorption was indicated by tmax values ranging from 10.5 to 15.5 min. Absorption was not complete, the oral bioavailability being 53 per cent and 70 per cent for the 0.3 and 1 mg kg-1 carbimide dose, respectively. The data indicate that there is a first-pass effect for carbimide.

Lack of correlation between pharmacokinetic and pharmacodynamic behaviour of cyanamide in man. A preliminary report.

A pharmacokinetic and dynamic study of cyanamide, an inhibitor of aldehyde dehydrogenase (ALDH) used as an adjuvant in the aversive therapy of chronic alcoholism, has been carried out in man after oral administrations. Cyanamide plasma levels were determined by a sensitive and specific high performance liquid chromatographic assay. Blood ALDH activity were estimated after oral administration of 0.3, 1 and 1.5 mg/kg of cyanamide. One i.v. administration of 1 mg/kg was performed in order to determine the absolute bioavailability and the main pharmacokinetic parameters. Elimination half life and total plasma clearance values were 51.7 8.8 min and 14.4 2.7 mL/kg/min respectively. After oral administrations of 0.3, 1 and 1.5 mg/kg a rapid absorption rate was estimated with a Tmax values range of 10.5 to 15.5 min. The extent of absorption was not complete, oral bioavailability being 53%, 70% and 81% respectively. The presence of a first pass-effect is suggested. The inhibitory activity of cyanamide on blood ALDH reached the maximum value 4 h after its administration and decreased progressively throughout six days period. The cyanamide plasma levels time course did not correlated with the pharmacodynamic time course responses.

[Disulfiram and calcium carbimide. Mode of action, adverse effects and clinical use]. / Disulfiram og kalsiumkarbimid. Virkningsmekanisme, bivirkninger og klinisk bruk.

The alcohol-sensitizing drugs disulfiram and calcium carbimide are often used in the treatment of alcohol problems with the hope of reducing alcohol consumption. These drugs inhibit the liver enzyme acetaldehyde dehydrogenase and, when taken prior to ethanol, produce an acetaldehyde-mediated aversive reaction. However, the drugs are unspecific, and several side effects may be related to their influence on other biochemical processes. These drugs are primarily pharmacological adjuncts and should be used in conjunction with behavioural and psychosocial therapies.

Pharmacokinetics of cyanamide in dog and rat.

A pharmacokinetic study of cyanamide, an inhibitor of aldehyde dehydrogenase (E.C. 1.2.1.3) has been made in the beagle dog and Sprague-Dawley rat. Cyanamide plasma levels were determined by a sensitive high performance liquid chromatographic assay, specific for cyanamide. In the dog, i.v. administration of cyanamide at 1, 2 and 4 mg kg-1, produced a dose-dependent pharmacokinetic behaviour. Statistically significant changes were observed in plasma clearance values (12.6 to 19.7 mL kg-1 min-1), half life values (39 to 61 min) and mean residence times (50 to 79 min). Peak plasma concentrations, after oral administration of 4 mg kg-1 were achieved at 30 min and oral bioavailability was about 65%. In the rat after i.v. or oral administration, cyanamide (2 mg kg-1) had a half life of 30 min, a total plasma clearance of 117 mL kg-1 min-1 and a mean residence time of 26 min. Oral bioavailability was about 69%.

Metabolism of cyanamide to cyanide and an inhibitor of aldehyde dehydrogenase (ALDH) by rat liver microsomes.

Rat liver microsomes, as well as purified catalase, convert the alcohol deterrent agent, cyanamide, to an active inhibitor of AlDH. Whether this enzymatic activation of cyanamide is mediated primarily by catalase present in the microsomes or involves the cytochrome P-450 enzymes is not known. We now report that cyanide is also a product of the microsomal oxidation of cyanamide. Formation of cyanide from cyanamide and rat liver microsomes was time dependent, reaching maximal levels within 5-10 min. Induction of the cytochrome P-450 enzymes by phenobarbital (PB) pretreatment doubled the yield of cyanide, while SKF-525A blocked this PB-induced increase. Administration of 3-aminotriazole (3-AT) to PB-treated rats inhibited the catalatic activity of their microsomes by 98% and substantially reduced cyanide formation. These results suggest that while catalase is responsible in major part for the oxidation of cyanamide to cyanide by uninduced microsomes, the participation of the hepatic cytochrome P-450 enzymes cannot be ruled out in PB-induced microsomes. We propose a metabolic scheme wherein N-hydroxycyanamide is the intermediate product of cyanamide oxidation, which then decomposes to yield the observed product, cyanide. By deduction, the second product of this decomposition is postulated to be nitroxyl (HNO), which may be the active AlDH inhibitor.