Pharmacological studies of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101). (4). Enzyme induction (author's transl)]

The effect of M7310U, a new non-steroidal analgesic anti-inflammatory agent, on liver microsomal drug-metabolizing enzymes was investigated. Rats were treated orally with M73101 (100, 200, 500 mg/kg), henylbutazone (PZ, 200 mg/kg), aminopyrine (AM, 100 mg/kg) or phenobarbital sodium (PB, 100 mg/kg) once daily for 2 weeks and then were observed for 2 weeks during which treatment was not given. On treatment with M73101, PZ, AM and PB, the liver enlarged but was restored to normal 1 week after the last administration. The rate of increase in the case of M73101 was lower than that seen with the reference compounds. M73101 markedly increased the content of microsomal protein, cytochrome P-450 or b5 and NADPH cytochrome C reductase, aniline hydroxylase and AM demethylase activity, but these increments returned to the normal level 1 week after the last administration. The serum concentration of M73101 after repeated administration (200 mg/kg, p.o.) for 1 week was lower than that after a single administration. Furthermore, M73101 increased Vmax for both aniline hydroxylase and AM demethylase, whereas it increased Km only for aniline hydroxylase. M73101 did not enhance the lipid peroxidation. Our observations suggest that the enlargement of rat liver seen with M73101 was due to the induction of drug-metabolizing enzymes and that this agent can probably be classified as a phenobarbital-type inducer.     

Pharmacological studies of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101). (5) Action of M73101 on the central nervous system (author's transl)

M73101 decreased spontaneous locomotor activity in both mice and rats and prolonged sleeping time induced by hexobarbital in mice. There was no evidence of cataleptogenic action, anti-tremorine action and antagonistic effect on reserpine-induced hypothermia in mice. M73101 did not inhibit convulsions induced by maximal electroshock and pentylenetetrazol but slightly inhibited the convulsion induced by strychnine in mice. Moreover, M73101 depressed only the monosynaptic action potential in intact and spinal cats, indicating that this compound exerts an inhibitory action on spinal function. On the EEG of rabbits, M73101 produced an arousal pattern in the spontaneous EEG and inhibited the recruiting response, but had no marked influence on the EEG arousal response, augmenting response and hippocampal afterdischarge. The arousal pattern in the spontaneous EEG induced by M73101 and the inhibitory action of this compound on the recruiting response were absent in the cerveau isolé preparation of the rabbit, indicating that M73101 may stimulate the brainstem reticular formation and that the inhibition of recruiting response may be related to the stimulatory effect. These properties of M73101 on the central nervous system are similar to those seen with aminopyrine though the potency was weaker. M73101 like aminopyrine showed no marked activity on the motor function.     

Pharmacological studies of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101). (2). Anti-inflammatory activity (author's transl)]

The anti-inflammatory activity and the mode of action of M73101, a new non-steroid analgesic anti-inflammatory agent, were investigated in experimental animals and compared with those of reference drugs. M73101 inhibited the increase in vascular permeability induced by acetic acid and its activity was more potent than that of phenylbutazone. M73101 showed a marked inhibitory effect against rat paw edema induced by various phlogistic agents (carrageenin, dextran, histamine, serotonin and bradykinin) and the activities were equal to or more potent than those of aminopyrine, mepirizole and tiaramide HCl. M73101 also inhibited the edema induced by mustard, scalding and anti-rat rabbit serum in rats. In addition, the anti-edematous effect of M73101 on carrageenin-induced rat paw edema was not influenced by spinalectomy or adrenalectomy, indicating that the anti-inflammatory action of M73101 was not mediated by the central nervous system and the adrenals. Local and oral administration of M73101 inhibited significantly the leucocyte migration into the fluid of CMC pouch in rats and the activity was more potent than phenylbutazone, suggesting that the anti-inflammatory effect of M73101 was due to the direct action at the inflamed site. On the other hand, M73101 did not show any marked activities on the experimental chronic inflammatory models. From these results, it is suggested that M73101 may be useful for clinical application as a basic analgesic, anti-inflammatory drug with remarkable anti-inflammatory activity in acute and subacute cases. The mechanism of the anti-inflammatory action of M73101 probably involves inhibition of an increase in vascular permeability and leucocyte migration.     

Pharmacological studies of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101). (3). General pharmacological actions (author's transl)]

General pharmacological actions of M73101, a new non-steroidal analgesic anti-inflammatory drug were investigated in mice, rats, guinea pigs, rabbits, cats and dogs. Intravenous administration of M73101 produced a slight transient fall in blood pressure, an increase in heart rate and a respiratory stimulation, but no remarkable change in the electrocardiogram. The contraction induced by epinephrine in the isolated ear vessels of rabbits relaxed by M73101. In the isolated trachea of guinea pigs, M73101 relaxed the contraction induced by histamine. Furthermore, M73101 inhibited the bronchoconstriction by histamine but not by bradykinin in guinea pigs. These properties of M73101 on the tracheal smooth muscle were similar to those seen with aminopyrine but different from those seen with aspirin which inhibited only the contraction by bradykinin in vivo, suggesting that M73101 is a compound with properties similar to basic non-steroidal anti-inflammatory drugs. M73101 inhibited the intestinal propulsion in mice and also the gastrointestinal movement in rats and dogs. Moreover, M73101 showed a spasmolytic activity on the isolated ileum of guinea pigs, but such was not due to any specific antagonistic action on the chemical mediators. On the other hand, M73101 had no effect on the isolated uterus and vas deferens of rats. M73101, unlike aminopyrine and phenylbutazone, slightly increased urine volume and electrolytes excretion in rats, indicating that this compound probably does not produced edema. M73101 showed no significant pharmacological activities on the blood sugar level, blood coagulation, platelet aggregation, methemoglobin formation and local irritation.     

Chronic toxicity test of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101) in beagle dogs (author's transl)]

Male and female dogs, aged 17--21 months, were administered orall M 73101 (0, 60, 120 and 240 mg/kg/day), a new analgesic and antiinflammatory drug, for 27 weeks, and following recovery test was carried out for 5 weeks. Dead animals were not found throughout the experimental period. Body weight gain, and food and water consumption were not affected due to M 73101 administration. Except for a slight increase of vomitting in the highest dose, there were no abnormal symptoms. Biochemical examination showed the slight increase in serum alkaline phosphatase activity and free cholesterol level. Pathological examination revealed a dose-dependent increase of liver weight and hypertrophy of hepatocytes due to proliferation of smooth endoplasmic reticulum. In addition, mitochondria became irregularly large in the highest dose. There were no abnormal findings in the gastro-intestinal tracts except for an erosion of gastric mucosa, which was noted in a female dog treated 240 mg/kg/day of M 73101. From these results, it was suggested that the maximum non-toxic dose was 60 mg/kg/day or less, and the greatest safety dose was 120 mg/kg/day in beagle dogs.     

Reproduction study of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101) in rabbits. Administration of M73101 during the period of major organogenesis (author's transl)]

M73101 and aspirin were evaluated for the effects on prenatal development of progeny in JW-NIBS strain rabbits. Pregnant females were given orally M73101 (0, 50, 120 and 300mg/kg/day) or aspirin (200mg/kg/day) on days 6 to 18 of gestation. They were sacrificed on days 29 of pregnancy and their fetuses were examined for abnormalities. The results were summarized as follows: 1. During the dosing period, females received 300mg/kg of M73101 showed pronounced body weight depression and decrease in food and water intake. But after the dosing period, these influences were not seen. Females received aspirin did not show such phenomena. 2. There were no adverse effects on number of implants, litter size, fetal mortality or fetal weight, and no malformed fetuses attributable to the drugs were seen in each group.     

Teratological study of 4-ethoxy-2-methyl 5-morpholino-3(2H)-pyridazinone (M73101) in mice and rats (author's transl)]

M73101 was given orally to pregnant mice (0, 100, 400 and 800 mg/kg/day) and rats (0, 100, 300 and 600mg/kg/day) during the major organogenesis to assess the influences of prenatal and postnatal development of progeny. There were no apparent effects of M73101 on litter size, fetal mortality or sex ratio in both species, although slight decrease in body weight occurred in fetuses of mice and rats exposed to the largest dose. No external, internal or skeletal malformations attributable to M73101 were observed in mouse and rat fetuses. No apparent influences of M73101 on postnatal development of mouse or rat offspring were seen.     

Reproduction study of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101) in rats (II). Administration of M73101 during the period of major organogenesis (author's transl)]

Pregnant female rats were given orally M73101 (0,100,250 and 600 mg/kg) or aspirin (225 mg/kg) on gestational days 7 to 17. About two-thirds of treated females in each group were sacrificed at day 21 of pregnancy and their fetuses were examined for abnormalities. The remaining females were allowed to deliver spontaneously in order to observe postnatal development of their offspring. The results were summarized as follows: 1. No significant effects of M73101 on number of the corpora lutea, litter size, fetal mortality, fetal weight or sex ratio were observed, but aspirin exhibited the intrauterine deaths and growth retardation in fetuses. 2. No external, internal or skeletal malformations attributable to M73101 were seen in fetuses, although aspirin caused malformations of various organ systems. 3. No apparent effects of M73101 on F1 generation were observed on postnatal development including emotionality, learning ability and reproductive performance. There were no adverse influences of M73101 on postnatal development of F2 generation. Aspirin, however, showed adverse effects on postnatal survival, growth, emotionality and mating performance of F1 generation.     

Synthesis and evaluation of the analgesic and anti-inflammatory activity of new 3(2H)-pyridazinone derivatives

A series of 6-substituted-3(2H)-pyridazinone derivatives were synthesized and evaluated for analgesic and anti-inflammatory activities. The structures of these new pyridazinone derivatives were confirmed by their IR, 1H-NMR spectra and elementary analysis. Analgesic and anti-inflammatory activities of the title compounds have been evaluated. Four of the ten tested compounds possessed significant analgesic effects in the phenylbenzoquinone-induced writhing test (PBQ test). The most active derivatives 8a, 8b, 8d, 8e were void of gastric ulcerogenic effect or acute toxicity at the maximal dose (200 mg/kg p.o.). In the carrageenan-induced paw edema model, compound 8d (6- [4- (2-fluorophenyl) piperazin-1-yl]-3(2H)-pyridazinone) showed anti-inflammatory activity similar to that of the standard drug indometacin (CAS 53-86-1). A significant dependence of the anti-inflammatory effect on the substituents was observed; The pharmacological study of these compounds confirms that modification of the chemical group at position 6 of the 3(2H)-pyridazinone ring influences analgesic and anti-inflammatory activities.     

Synthesis and evaluation of analgesic, anti-inflammatory and antioxidant activities of new 6-acyl-3-alkyl-5-methyl-2(3H)-benzoxazolones

A new series of 6-acyl-3-alkyl-5-methyl-2(3H)-benzoxazolones have been obtained starting from 5-methyl-2(3H)-benzoxazolone. All the compounds have been characterized by IR, 1H-NMR and mass spectroscopy. The new compounds were screened for analgesic and anti-inflammatory activities and ulcerogenic effect. The in vitro antioxidant capacity of the synthesized compounds were tested by the nitric oxide radical scavenging assay. Most of the compounds showed antiinflammatory activity. Among them, 3-[4-(4-fluorophenyl)piperazinomethyl] -6-(3-chlorobenzoyl)-5-methyl-2(3H)-benzoxazolone (3j) was found more potent than the reference drug indometacin (CAS 53-86-1) with 41.66% decrease in edema. Compared with the control, some of the compounds exhibited analgesic effects. Similar to the anti-inflammatory activity results, compound 3j showed the highest analgesic profile with 48.56% inhibition. No active hemorragic focus was observed in the microscopic evaluation in the ulcerogenic effect studies of the tested compounds. 6-(3-Chlorobenzoyl)-5-methyl-2(3H)-benzoxazolone (2b) and 3-[4-(4-fluorophenyl-piperazino)methyl]-6-(3-chlorobenzoyl)-5-methyl-2(3H)-benzoxazolone (3j) showed nearly maximum antioxidant activity compared to ascorbic acid (CAS 50-81-7) with IC50 values of 27.6 and 30.1 microg/mL, respectively.     

Synthesis of some new 2,6-disubstituted-3(2H)-pyridazinone derivatives and investigation of their analgesic, anti-inflammatory and antimicrobial activities

In this study, 12 new 3(2H)-pyridazinone derivatives carrying 4-substituted phenylpiperazinylethyl moiety on lactam nitrogen were synthesized and their chemical structures were confirmed by ¹H-NMR, mass, and elemental analysis. Analgesic and anti-inflammatory activities of the synthesized compounds were evaluated in mice. Among the synthesized compounds, compound 9c showed the best analgesic and anti-inflammatory activities without causing any gastric effect in stomachs of tested animals. In addition, the synthesized compounds were screened for their antibacterial and antifungal activities against some pathogenic strains.     

Pharmacological profile of mofezolac, a new non-steroidal analgesic anti-inflammatory drug

Pharmacological activities of mofezolac were investigated in experimental animal models and compared with those of indomethacin, ibuprofen, mefenamic acid, aspirin and aminopyrine. Mofezolac showed a potent suppression of various writhing models in mice or rats; and its potency was slightly lower than that of indomethacin, but was higher than those of the other reference drugs. Thus, mofezolac was especially active against chemically induced writhing and also in the phenylquinone induced intraperitoneal dye leakage reaction in mice. Mofezolac also has a potent inhibitory activity on the algesic responses induced by the mechanical stimulus of the inflammed tissue. Mofezolac exhibited a therapeutic effect comparable to indomethacin in the urate synovitis in dogs. Considering the anti-inflammatory and antipyretic actions, mofezolac was obviously less effective than indomethacin, and its potency was similar to that of ibuprofen. The ulcerogenic effect of mofezolac on the gastric mucosa was far weaker than that of indomethacin. In in vitro studies, the prostaglandin biosynthesis and platelet aggregation were inhibited to the same extent by both mofezolac and indomethacin. Accordingly, it may be considered that the actions of mofezolac are due to the inhibition of cyclooxygenase. Our result suggest that mofezolac can be a useful drug that shows a rapid pain-relieving activity in acute inflammations.     

In vitro properties of 5-(benzylsulfonyl)-4-bromo-2-methyl-3(2H)-pyridazinone: a novel permeability transition pore inhibitor

Despite the increasing implication of the permeability transition pore (PTP) in the pathophysiology of neurodegenerative diseases, few selective PTP inhibitors have been reported so far. Here, we evaluate the pharmacological properties of a novel PTP inhibitor, BBMP (5-(benzylsulfonyl)-4-bromo-2-methyl-3(2H)-pyridazinone). This drug was discovered from the screening of a compound library against the PTP using a functional assay with isolated mitochondria. Similarly to cyclosporin A, the drug prevented Ca2+-induced permeability transition and mitochondrial depolarization. BBMP appeared more potent that minocycline in both swelling and membrane potential assays displaying pIC50 values of 5.5+/-0.1 and 5.6+/-0.0, respectively. Unlike minocycline, BBMP dose-dependently prevented DNA fragmentation induced by KCl 25/5 mM shift and serum deprivation in cerebellar granule neurons with a pIC50 of 5.7+/-0.6. The inhibition of PTP-mediated cytochrome c release observed in isolated mitochondria at 10 and 100 microM may explain its neuroprotective properties in vitro. These data suggest that the mitochondrial PTP is potentially involved in neuronal cell death and that PTP inhibitors, like BBMP, may possess a therapeutic potential in neurodegenerative disorders.