Ferrihemoglobin and kidney lesions in rats produced by 4-aminophenol or 4-dimethylaminophenol

4-Dimethylaminophenol hydrochloride (DMAP), 20 mg/kg i.V., was found to oxidize in rats as much as 50% of the hemoglobin to ferrihemoglobin but did not cause kidney lesions. 4-Aminophenol hydrochloride, 400mg/kg i.V., oxidized only 25% of the hemoglobin and produced large tubular necroses. In highly toxic doses only, e.g., twice the LD₅₀, DMAP also produced tubular necroses.

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Abbreviations Used DMAP 4-Dimethylaminophenol hydrochloride - AP 4-Aminophenol hydrochloride     

Effects of 4-dimethylaminophenol,Co2EDTA,or NaNO2 on cerebral blood flow and sinus blood homeostasis of dogs in connection with acute cyanide poisoning

The effects of the cyanide antidotes DMAP, Co₂EDTA, and NaNO₂ on cerebral blood flow (CBF) and cerebral blood gases were investigated in connection with acute poisoning of dogs by cyanide. The substances were injected intravenously. Local CBF as measured with thermocouples in the cingulum increased by 100–200% after a non-lethal dose of KCN (1 mg/kg) and by 50% after injection of NaNO₂ (15 mg/kg), that oxidized some 20% of the total hemoglobin to ferrihemoglobin. Co₂EDTA (10 mg/kg) induced a decrease in local CBF of 30% and in brain temperature of 0.5°C. The temperature diminished also after poisoning by KCN, but it rose by 0.15°C after the administration of NaNO₂. Local CBF and sinus sagittalis blood flow increased by 60–160% for about 15 min, and the brain temperature decreased by 0.4–0.5°C when DMAP (3.25 mg/kg) or Co₂EDTA (15 mg/kg) was injected 1 min after poisoning by cyanide (4 mg/kg), a dose that always caused respiratory arrest. Immediately after injection of DMAP the brain temperature rose transiently by 0.1–0.2°C. Co₂EDTA did not exert such an effect. In the sinus sagittalis blood of artificially ventilated animals pCO₂ decreased rapidly by 10–20 mmHg after poisoning and approached the initial level after treatment with DMAP or Co₂EDTA. The highest value of pO₂ was about 80 mmHg and 50 mmHg after injection of DMAP and Co₂EDTA, respectively; thereafter pO₂ declined to 20 mmHg or 40 mmHg at 20 min. The lactate concentration increased by 60–70% without tendency to return to normal.     

Circulation,respiration, and blood homeostasis in cyanide-poisoned dogs after treatment with 4-dimethylaminophenol or cobalt compounds

The effects of intravenously injected 4-dimethylaminophenol-HCl (DMAP), Co₂EDTA, and Co(histidine)₂ on the survival rate and several physiological parameters were studied on dogs after acute intravenous poisoning with the double lethal dose of potassium cyanide.All dogs survived when the antidotes were administered 1 min after poisoning. When the therapy began 4 min after poisoning more dogs were rescued in the DMAP group than in the cobalt groups. DMAP, Co₂EDTA, and Co(histidine)₂ restored circulation and respiration of the surviving animals in a similar manner.The increase in the plasma concentrations of glucose and lactate was much higher in the Co₂EDTA group than in the DMAP group. The injection of Co₂EDTA produced a sharp rise in the lactate-to-pyruvate ratio. The lactate-to-pyruvate ratio stayed unchanged for some 15 min after injection of DMAP before also rising. The total dose of KCN (4 mg/kg) was bound to the ferrihemoglobin formed by DMAP. The arterial pO₂ increase, caused by liberation of oxygen from oxyhemoglobin during the formation of ferrihemoglobin, was less when the cyanide could act on the tissues for a longer period of time before the therapy with DMAP began.DMAP is more appropriate for the therapy of cyanide poisoning than Co₂EDTA, since the latter adds its inhibitory effects on the metablism to those of cyanide.     

Biotransformation of 4-dimethylaminophenol in the dog

4-Dimethylaminophenol (DMAP), after an i.v. injection, quickly forms ferrihemoglobin by catalytic transfer of electrons from ferrohemoglobin to oxygen. This reaction is rapidly terminated by covalent binding of oxidized DMAP to the reactive SH-groups of hemoglobin and to reduced glutathione within the red cells, and by conjugation with glucuronic or sulfuric acid presumably in the liver. Fifteen min after i.v. injection of DMAP, 3.25 $\text{mg}\text{kg}$, ¹⁴C-labeled in the ring, no intact DMAP was detected in the blood. The concentrations of metabolites in the blood were as follows: 33 μM DMAP covalently bound to hemoglobin. 30 μM S,S,S-(2-dimethylamino-5-hydroxy-1,3,4-phenylene)-Tris-glutathione (Tris-IGS)-DMAP) 90 per cent of it located within the red cells, 5 μM DMAP-glucuronide, and 22 μM DMAP-sulfate. Within 3 days, 90 per cent of the radioactivity was excreted in the urine, 4 per cent in the faeces. In the 24 hr urine, 25 per cent of the DMAP injected was excreted as DMAP-sulfate, 15 per cent as DMAP-glucuronide, and 23 per cent as DMAP-thioethers, mainly as S,S,S-(dimethylamino-5-hydroxy-1,3,4-phenylene)-Tris-cysteine. When DMAP, ¹⁴C-labeled in the methyl groups, was administered 11 per cent of the radioactivity was excreted in the urine as dimethylamine. It is concluded that most of the thioethers found in the urine derived from Tris-(GS)-DMAP which had been produced within the red cells indicating an important role of the red cells on biotransformation of DMAP.     

Toxicological studies of a new cephamycin, MT-141. II. Its subacute toxicity in rats

In this subacute study, male and female rats were administered with 100, 200, 400, 800 and 1,600 mg/kg/day of MT-141 through an intramuscular (i.m.) route or with 50, 100, 200, 400 and 800 mg/kg/day through an intravenous (i.v.) route for 30 days. MT-141 did not cause lethal effect on male and female rats even at the high dosage of 1,600 mg/kg/day i.m. (approx. one-6th of LD50) and 800 mg/kg/day i.v. (approx. one-8th of LD50). Histopathological findings revealed that MT-141 induced slight local irritation at the sites of i.m. and i.v. injection. Only at a high dose of 1,600 mg/kg/day i.m., MT-141 reduced significantly the gain of body weight in male rats, which was closely related to the decrease of food intake. A slight decrease in serum Cr. and Glc. was observed in male rats at the doses more than 200 mg/kg/day i.m. and a slight decrease of liver weight at the doses more than 800 mg/kg/day i.m., while a slight increase of serum CPK, GOT, A1-P and LDH was perceived at the doses more than 800 mg/kg/day i.m. The distention of cecum was induced by the doses more than 400 mg/kg/day i.m. but histopathological findings revealed no abnormality in the cecum. These results suggest that MT-141 at the dosage level of 1,600 mg/kg/day i.m. causes nonspecific slight toxicity based on the disturbance of nourishment in male rats. In female rats given 100 to 1,600 mg/kg/day i.m., MT-141 at the high doses induced a slight increase of serum GOT, LDH and CPK and distention of the cecum. It is assumed from these results that MT-141 at the dosage level of 1,600 mg/kg/day causes nonspecific slight toxicity in female rats. In male rats given 50 to 800 mg/kg/day through an i.v. route, the level of serum Glc. and Cr. and the liver weight slightly decreased at the doses more than 200 mg/kg/day i.v. The cecum distended at the doses more than 100 mg/kg/day i.v. The dose of 800 mg/kg/day i.v. increased the activity of LDH and CPK in the serum. In female rats, MT-141 raised slightly the level of serum GOT, A1-P, LDH and CPK even at the doses more than 400 mg/kg/day i.v., reduced the liver weight at the dose of 800 mg/kg/day i.v. and distended the cecum at the all doses. These results suggest that MT-141 at the dosage level of 800 mg/kg/day i.v. induces nonspecific slight toxicity in male and female rats.(ABSTRACT TRUNCATED AT 400 WORDS)     

Toxicological studies on a new cephamycin, MT-141, IV. Its acute toxicity in beagle dogs

The acute toxicity of MT-141 was studied in adult Beagle dogs with intravenous (i.v.) or intramuscular (i.m.) administration to obtain following results. MT-141 at the doses ranging from 2,500 to 7,500 mg/kg i.v. caused no effect on life, bodyweight, food intake, eyeground and ECG in male and female Beagle dogs. MT-141 produced an increase in water intake, urine volume, WBC and LAP and a decrease in Lymph., U-Na, U-K and OP, but any histopathological change was not caused in the organs and tissues. It is suggested that these changes in blood, serum and urine are due to mechanical and transient effects induced by infusing a large volume of hypertonic solution of MT-141 into cephalic vein. When 1,000 or 2,000 mg/kg of MT-141 was injected into the muscles of hind legs, the hind legs had difficulty in walking. It is very probable that this change was due to mechanical effects induced by injecting a hypertonic solution of MT-141 at a rate of 70--130 ml/dog. An injection of 1,000 or 2,000 mg/kg i.m. of MT-141 changed activity of GPT, GOT and CPK in the serum within the limit of physiological variations but did not caused any effect on the other toxicological parameters such as bodyweight, food intake, water intake, urine volume, eyeground examination, ECG and histopathological examination. It is concluded from the above-mentioned results that MT-141 at the dose of 2,500--7,500 mg/kg i.v. or 1,000--2,000 mg/kg i.m. has no significant toxicity in Beagle dogs.     

Metabolic pathways of the anti-hypertensive agent, N-(2,5-dimethyl-1H-pyrrol-1-yl)-6-(4-morpholinyl)-3-pyridazinamine hydrochloride. II: Studies in the dog

The metabolic fate of a new anti-hypertensive, 1-pyrrolyl-pyridazinamine, was studied in male Beagle dogs given both p.o. and i.v. doses of the 14C-labelled drug (1 mg/kg). The compound given as a single i.v. injection disappeared from the central compartment with a half-life of about 0.9 h. Plasma levels of total 14C were represented mostly by metabolites. Eight urinary metabolites designated as metabolites I, II and XI-XVI were purified and their structures assigned by means of u.v., i.r., n.m.r. and mass spectrometry. Quantitatively the primary metabolic attack involved the morpholine moiety of the molecule which undergoes oxidative opening. A minor pathway afforded the cleavage of the pyrrole followed by chemical rearrangements to form six-membered sidnone-like products or a triazole derivative. The major (XIII) and three minor metabolites were studied for their antihypertensive activity in rats and were shown to be inactive.     

Influence of curcumin on cyclosporin-induced reduction of biliary bilirubin and cholesterol excretion and on biliary excretion of cyclosporin and its metabolites

We investigated the ability of curcumin, which can be extracted from different Curcuma species, to prevent cyclosporin-induced reduction of biliary bilirubin and cholesterol excretion, and its influence on biliary excretion of cyclosporin (CS) and its metabolites in the bile fistula model in rats. I.v. injection of curcumin (25 and 50 mg/kg) after 30 min increased dose-dependently basal bile flow (30 microliters/kg/min) up to 200%, biliary bilirubin excretion (3000 pmol/kg/min) up to 150%, and biliary cholesterol excretion (22 nmol/kg/min) up to 113%. CS (30 mg/kg) reduced bile flow to 66% and biliary excretion of bilirubin and of cholesterol to 33% of the basal value 30 min after i.v. injection. I.v. administration of curcumin (25 and 50 mg/kg) 30 min after CS increased bile flow dose dependently again to 130% for 1 hour and biliary excretion of cholesterol and of bilirubin to 100% of the basal value for 30 and 150 min, respectively. Injection of curcumin 15 min before CS prevented the CS-induced drop of bile flow at 50 mg/kg and reduction of biliary bilirubin excretion already at 25 mg/kg until the end of the experiment (180 min). The CS-induced reduction of biliary cholesterol excretion, however, was not prevented by curcumin. Finally, the biliary excretions of CS (1200 ng/kg/min) and its metabolites (1200 ng/kg/min) were slightly reduced by curcumin at a dose of 50 mg/kg (to 83% of the initial values). The clinical importance of these controversial effects remains to be shown.     

大黄酸在大鼠和比格犬体内的吸收动力学研究

目的：研究中药大黄的活性蒽醌单体大黄酸（rhein）在SD大鼠和Beagle犬体内的吸收动力学特征,为临床的进一步研究提供基础参数和依据。方法：采用HPLC-荧光检测法分别测定SD大鼠和Beagle犬在灌胃及静脉注射两种给药途径下单次给予不同剂量的大黄酸药物后,两种动物血浆样品中的大黄酸经时曲线过程并计算相应的药代动力学参数及绝对生物利用度。结果：SD大鼠灌胃及静脉注射高、中、低剂量大黄酸后,AUC与剂量间呈一定的线性关系（r〉0.99）,灌胃及静脉注射3个剂量下的半衰期结果相似。在上述研究范围内大黄酸在大鼠体内的药代动力学行为近似是线性的。用面积法,算得高、中、低3个剂量下大黄酸在大鼠体内的绝对生物利用度分别为16.4%、23.8%、19.4%。对6只Beagle犬进行随机交叉试验,静脉注射大黄酸真溶液（0.4mg/kg）和灌胃大黄酸混悬液（20mg/kg）,算得静注及灌胃后药物的消除半衰期分别为（1.77±0.93）、（3.25±0.80）h,Beagle犬体内的绝对生物利用度为（49.7±7.4）%。对Beagle犬组（6只）和SD大鼠灌胃3剂量组（18只）各只动物生物利用度进行方差分析,结果显示差异具有统计学意义（P〈0.01）。结论：大黄酸在不同动物间吸收存在一定的种属差异,吸收程度在Bea-gle犬体内略高于在大鼠体内。     

Pharmacokinetics, enterohepatic circulation and biotransformation of [2-3H]-9,9-Dimethylacridane-10-carboxylic acid S-(2-dimethylamino) thiolethyl ester in the rat and dog

Dogs receiving a 7.5 mg/kg oral or i.v. dose of tritium labelled 9,9-dimethylacridane-10-carboxylic acid S-(2-dimethylamino)thiolethyl ester (DMA) as the methane sulfonate salt (DMA-MS) excreted 86-95% of the radioactivity within 6 days. A similar recovery was obtained for rats receiving 300 mg/kg orally of 15 mg/kg i.v. In both species, approximately 66% of the dose was excreted in the feces as metabolites. Absorption of the oral dose was shown to be 80% and 100% for the rat and dog, respectively. Up to 47% of an i.v. dose was excreted in the bile of rats and an efficient enterohepatic circulation process insues. The parent drug is rapidly metabolized in the tissues yielding at least 6 polar metabolites which contribute to relatively long plasma half-lives in the order of 40 h for dogs and 58-90 h for rats. An atypical increase in plasma radioactivity following an i.v. dose could be rationalized in view of these results. Metabolite profiles were examined in plasma, urine, bile and feces and found to be qualitatively similar. Des-methyl-DMA and DMA-N-oxide were identified as two minor metabolites.     

Development of tolerance to the anticonvulsant effect of diazepam in dogs

In dogs the development of tolerance to the anticonvulsant effect of diazepam was followed by weekly determinations of the convulsive threshold for pentetrazole, 10-15 min after intravenous (i.v.) injection of 0.25 or 0.5 mg/kg diazepam. As soon as after 1 week of oral treatment with diazepam, 0.25 or 0.5 mg/kg three times daily (t.i.d.), the pentetrazole threshold showed a decline or even a fall to the control level in spite of unaltered or rising concentrations of diazepam and its active metabolites. Tolerance also developed when the dogs were treated with chlorazepate, 2 mg/kg t.i.d., between the weekly diazepam injections for threshold determination. The results favor a functional type of tolerance since there was no indication of a more rapid inactivation of diazepam. Treatment with desmethyldiazepam (2 mg/kg i.v. for threshold determination and oral treatment with the desmethyldiazepam precursor chlorazepate, 2 mg/kg t.i.d.) did not produce tolerance. In further experiments in dogs anesthetized, relaxed with suxamethonium and ventilated, a spike-wave activity in the EEG was induced and maintained by an injection and subsequent infusion of pentetrazole. Out of 6 dogs, receiving 4-5 i.v. injections of 0.25-0.5 mg/kg diazepam, 2 showed the phenomenon of acute tolerance, i.e. the effect of the drug on the spiking activity in the EEG became less from one injection to the next, and thus paralleled a situation which may be observed during treatment of clinical status epilepticus. No acute tolerance was observed in corresponding experiments with desmethyldiazepam.     

Biotransformation of 4-dimethylaminophenol in man

1. The biotransformation of 4-dimethylaminophenol (DMAP) was studied on six healthy male volunteers. After i.v. injection of 3.2 mg DMAP-HCl/kg the metabolites were analyzed in the 24 h urine with an isotope dilution technique.
2. For the isotope dilution technique the ¹⁴C-labeled metabolites were synthetized from ¹⁴C-DMAP. ¹⁴C-DMAP-glucuronide was produced in isolated hepatocytes and purified.
3. Two thirds of the DMAP applied were identified in the 24 h urine: 40% DMAP-glucuronide, 12% DMAP-sulfate, and 15% DMAP-thioethers. About 65% of the thioether fraction consisted of S,S,S-(2-dimethylamino-5-hydroxy-1,3,4-phenylene)tris-cysteine and 3% of the corresponding N-acetyl derivative.
4. As compared to dogs and rats humans produced more glucuronide at the expense of sulfate whereas thioether formation was equal in man and dog.

     

Metabolic disposition and pharmacokinetics of pelrinone, a new cardiotonic drug, in laboratory animals and man

The metabolic disposition of pelrinone, a cardiotonic drug, was studied in mouse, rat, rabbit, dog, monkey and man. Pelrinone was rapidly and extensively absorbed in rodents, dogs, monkeys and man. Except in rabbits, the major portion of the serum radioactivity was due to parent drug. Pelrinone was moderately bound to human serum proteins and weakly bound to serum proteins from animals. Radioactive compounds were rapidly eliminated from rat tissues with the highest concentrations found in organs associated with absorption and elimination. After a 1.0 mg/kg i.v. dose, the rapid elimination of pelrinone from mouse, rat and dog serum precluded estimation of an elimination half life (t1/2). However, after higher oral or i.v. doses, a more prolonged elimination phase was apparent and the t1/2 of pelrinone ranged from 8-10 h in rodents and dogs. In human subjects given escalating oral or i.v. doses of pelrinone, the elimination t1/2 was independent of dose and averaged 1-2 h. The serum AUC of pelrinone was linearly dose-related following oral doses up to 20 mg/kg in dogs and 100 mg in man. In mice, a greater proportional increase in AUC occurred between oral doses of 2-100 mg/kg while in rats, the serum AUC increased in less than proportional manner from 10-200 mg/kg p.o. In all species, radioactive compounds were excreted mainly in the urine. No metabolites were detected in dog and human urine while small amounts of unconjugated metabolites were excreted in mouse and rat urine.     

Metabolism and excretion of paclitaxel after oral administration in combination with cyclosporin A and after i.v. administration

The objective of this study was to compare the quantitative excretion of paclitaxel and metabolites after i.v. and oral drug administration. Four patients received 300 mg/m2 paclitaxel orally 30 min after 15 mg/kg oral cyclosporin A, co-administered to enhance the uptake of paclitaxel. Three weeks later these and three other patients received 175 mg/m2 paclitaxel by i.v. infusion. Blood samples, urine and feces were collected up to 48-96 h after administration, and analyzed for paclitaxel and metabolites. The area under the plasma concentration-time curve of paclitaxel after i.v. administration (175 mg/m2) was 16.2 +/- 1.7 microM x h and after oral administration (300 mg/m2) 3.8 +/- 1.5 microM x h. Following i.v. infusion of paclitaxel, total fecal excretion was 56 +/- 25%, with the metabolite 6alpha-hydroxypaclitaxel being the main excretory product (37 +/- 18%). After oral administration of paclitaxel, total fecal excretion was 76 +/- 21%, of which paclitaxel accounted for 61 +/- 14%. In conclusion, after i.v. administration of paclitaxel, excretion occurs mainly in the feces with the metabolites as the major excretory products. Orally administered paclitaxel is also mainly excreted in feces but with the parent drug in highest amounts. We assume that this high amount of parent drug is due to incomplete absorption of orally administered paclitaxel from the gastrointestinal tract.     

Pharmacokinetics of cyanide in poisoning of dogs,and the effect of 4-dimethylaminophenol or thiosulfate

Cyanide in blood, plasma, and urine of dogs after administration of K¹⁴CN was determined with the isotope dilution technique. The addition of large amounts of inactive KCN as soon as possible to a sample to be analyzed inhibited the decrease of the original cyanide concentration.After administration of several lethal doses of cyanide into the stomach or by slow intravenous infusion a concentration of about 40 M cyanide in plasma was found at the moment of respiratory arrest. Since 60% of the cyanide in plasma was bound to proteins the concentration of free cyanide which stopped respiration was about 16 M.Quick formation of ferrihemoglobin by i.v. injection of 4-dimethylaminophenol after plasma cyanide had risen to or above 40 M decreased the cyanide concentration in plasma and restored respiration, while cyanide was accumulated in red cells by formation of ferrihemoglobin cyanide.Equilibrium constants calculated for the reaction between ferrihemoglobin and cyanide in vivo indicated that the reaction approached equilibrium in a few minutes.Up to 60% of the radioactive cyanide absorbed was found as non-cyanide radioactivity in the urine.Abbreviations Used DMAP 4-Dimethylaminophenol hydrochloride - HbFe²⁺ Ferrohemoglobin - HbFe³⁺ Ferrihemoglobin - HbFe³⁺CN^– Ferrihemoglobin cyanide - C_a Molarity of all radioactive compounds calculated on the assumption that one mole cyanide yields one mole metabolite - NCR Molarity of non-cyanide radioactive compounds calculated on the assumption that one mole cyanide yields one mole of metabolite (C_a-[CN^–])     

Pharmacological effects of the antianxiety compound suriclone and its principal metabolites

The pharmacodynamic effects of 4-methyl-1-piperazinecarboxylic acid ester with (+/-)-6-(7-chloro-1,8-naphthyridin-2-yl)-2,3,6,7-tetrahydro-7-h ydr oxy-5H-p- dithiino[2,3-c]pyrrol-5-one (suriclone, RP-31264) and its principal metabolites M1 and M2 on respiration, cardiovascular system, autonomic nervous system, smooth muscle and other physiological parameters were investigated in various animal species. Suriclone, 1 mg/kg i.v., increased the amplitude of respiratory movement, decreased the respiratory rate and blood pressure and increased the heart rate in conscious rabbits. The respiratory and depressor effects were more evident in pentobarbital anesthetized rabbits. In anesthetized dogs, suriclone, 0.05 or 0.5 mg/kg i.v., produced essentially the same effects as seen in the anesthetized rabbits. The ECG pattern was not significantly changed in any animal. Such effects on respiration and on the cardiovascular system of metabolites M1 and M2 in the rabbits were weak. In the isolated guinea-pig atria, suriclone, 10(-6) g/ml, had no effect but increased contractility and decreased heart rate at a high concentration of 10(-5) g/ml. Both M1 and M2 had weak effects. Suriclone had no action on flow rate of the perfusate through the blood vessels of the isolated rabbit ear. In anesthetized dogs, suriclone 0.5 mg/kg i.v., did not affect the responses to vagal stimulation or to pre- and postganglionic stimulation of cardiac ganglion. Suriclone instilled onto the eye or i.v. had no appreciable effect on pupillary diameter or the miotic response in rabbits, but an abnormal oculogyration was evoked when the drug was given i.v. at 1 mg/kg. M1 or M2 had no such effect. Suriclone did not exert analgesic effects in mice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of 4-dimethylaminophenol in rat kidneys,isolated rat kidney tubules and hepatocytes

1. Addition of 4-dimethylaminophenol (DMAP) to suspensions of isolated rat kidney tubules increased extracellular lactate dehydrogenase (LDH) at concn. which did not markedly affect gluconeogenesis. ATP content was also decreased by DMAP but this did not occur until the membrane became permeable to LDH. There was no similar leakage of the mitochondrial enzyme glutamate dehydrogenase.

2. After i.v. injection of DMAP to rats in doses which did not inhibit gluconeogenesis, kidney glutathione was decreased and the urinary LDH was increased. DMAP was irreversibly bound to tissue in rat, with the highest binding in the kidney. The highest binding occurs in those tissues in which DMAP causes necrosis.

3. In isolated rat hepatocytes, DMAP caused toxic effects which were similar but less extensive than occur on addition of DMAP to kidney tubules. The formation of acid-soluble metabolites was higher in isolated rat hepatocytes (20 nmol/mg protein) than in rat kidney tubules (4 nmol/mg protein). DMAP-glucuronide and DMAP-sulphate comprised the major acid-soluble metabolites in both preparations; conjugates of DMAP with glutathione or cysteine were also found.     

A novel quinolinone diuretic, M12285, and its activation mechanism through sulfate conjugation.

The diuretic activity of a quinolinone oxime diuretic, M12285, was examined after renal arterial, i.v. and portal injection in rats. M12285 injected into the renal artery at a dose of 1 mg/kg caused no diuretic effect, whereas i.v. and portal injections induced marked diuresis dose dependently. The minimum effective dose with portal injection was lower (1 mg/kg) than that with i.v. injection (3 mg/kg) and the start of the effect was faster with portal injection. These results indicated that some metabolic modification in the liver is necessary for the diuretic activity to appear. Accordingly, we performed in situ rat liver perfusion with M12285 and obtained several metabolites. Renal arterial injection of each fractionated metabolite of M12285 revealed that all the diuretic activity derived from one of these metabolites. From IR and 1H-nuclear magnetic resonance (1HNMR) measurements, the chemical structure of this active metabolite was assumed to be a sulfate-conjugated form of M12285 at the oxime moiety. Based on this tentative chemical structure, we synthesized the oxime sulfate of M12285 (potassium salt, M17000) and confirmed the identity of IR and 1HNMR spectra. Administration of M17000 into the renal artery induced apparent diuresis in a dose-dependent manner in both rats and dogs. These results indicate that the oxime sulfate of M12285 is responsible for the diuretic activity of M12285. Therefore, we synthesized several derivatives of M17000 and confirmed their possible therapeutic value as a novel family of diuretics, namely quinolinone oxime sulfonic acids.     

Pharmacokinetics and bioavailability of ciramadol,a new analgesic

Healthy male volunteers participated in two studies of the pharmacokinetics of ciramadol, an investigational analgesic. For the dose-proportionality study, subjects received single i.v. doses of 15, 30, or 60 mg of ciramadol on three separate occasions. Serum samples and urine were collected 48 hr after each dose. Overall mean kinetic values for ciramadol were: volume of distribution, 1.5 liters/kg; elimination half-life, 3.7 hr; total clearance, 4.9 ml/min/kg. Clearance did not change systematically with dose. Mean 48-hr urinary excretion was 40% of the dose as the intact drug, with another 24% excreted as ciramadol conjugates; these were dose-independent. For the bioavailability study, subjects received a 30-mg dose of ciramadol i.v., i.m., or orally on three separate occasions. The mean absolute systemic availability of the i.m. dose was 98%; the absolute availability of the oral dose was 82%. Peak serum concentration of 235 and 155 ng/ml were attained at 0.27 and 1.5 hr after the i.m. and oral doses, respectively.     

Gastric emptying in diabetic gastroparetic dogs: ffects of SK-951,a novel prokinetic agent

We examined whether delayed gastric emptying could be produced by diabetes in dogs. Diabetes was produced by a single injection of streptozotocin (30 mg/kg i.v.), and diabetic hyperglycemia was observed from 2 to 15 months after injection. The plasma acetaminophen concentration, which is an indirect indicator of the gastric emptying rate, was delayed in 2 of 5 diabetic dogs from 15 months after the induction of diabetes. The effects of SK-951, a benzofuran derivative, on delayed gastric emptying were also examined in diabetic gastroparetic dogs in comparison with those of cisapride. SK-951 (1 mg/kg i.v.) significantly enhanced delayed gastric emptying in diabetic dogs, but cisapride (1 mg/kg i.v.) had no effect. In addition, SK-951 increased the plasma glucose levels in a manner correlated with its effect on gastric emptying. The present study suggested that SK-951 may be useful in the treatment of diabetic gastroparesis.