[Reproductive and developmental toxicity studies of prulifloxacin (NM441)(1)--A fertility study in rats by oral administration]

A study of fertility and fetal development of prulifloxacin, a new antibacterial agent, was conducted in Sprague-Dawley rats. Male rats were given the drug orally from 63 days before mating to the end of the mating period. Female rats were given from 14 days before mating to day 7 of pregnancy. The dose levels for both males and females were 0 (control), 30, 170 and 1000 mg/kg. The females were sacrificed on day 20 of pregnancy for examination of their fetuses. In the 170 mg/kg group, water consumption increased in the female rats, and food consumption decreased and the cecum increased in weight and was enlarged in the males and the females. In the 1000 mg/kg group, body weight gain was suppressed in the males, and food consumption decreased, water consumption increased and cecum increased in weight and enlarged in the males and the females. Moreover, this dose caused white spots and rough surface of the kidney in the males. Prulifloxacin had no adverse effects on reproductive function of the parent animals, and also on development of the fetuses. These results show that the NOAEL of prulifloxacin are 30 mg/kg for general toxicity in parent animals, 1000 mg/kg for reproductive function of parent animals and for development of fetuses.

[Reproductive and developmental toxicity studies of prulifloxacin (NM441)(3)--A teratogenicity study in rabbits by oral administration]

A study of the effect of prulifloxacin, a new antibacterial agent, during the period of organogenesis was conducted in New Zealand White rabbits. Female rabbits were given prulifloxacin orally at dose levels of 0 (control), 10, 30 and 100 mg/kg from day 6 to 18 of pregnancy. Female rabbits were sacrificed on day 29 of pregnancy for examination of their fetuses. In the 30 mg/kg group, food and water consumption decreased. In the 100 mg/kg group, soft stool was observed and body weight gain, food consumption and water consumption decreased. Premature delivery (2/16) occurred and enlargement of cecum and increased weight of cecum were observed. The number of fetal death increased in the 100 mg/kg group. However, prulifloxacin had no effects on the number of corpora lutea, implantations and live fetuses, and on body weight, placental weight, sex ratio, and external, visceral and skeletal development of live fetuses. These results show that the NOAEL of prulifloxacin are 10 mg/kg for general toxicity in mother animals, 30 mg/kg for pregnancy of mother animals and for development of fetuses.

[A photoallergenicity study of prulifloxacin (NM441) in guinea pigs]

Photoallergenicity of prulifloxacin, a new antibacterial agent, was examined using guinea pigs compared with those of the other quinolone antibacterial drugs, ofloxacin (OFLX), lomefloxacin (LFLX), ciprofloxacin (CPFX), enoxacin (ENX) and nalidixic acid (NA). Prulifloxacin and other drugs were orally administered at minimal phototoxic doses 1 hr before UVA (18 J/cm2) irradiation. This photosensitization procedure was daily repeated for 5 days. On 16 days after the final sensitization, the animals were challenged with UVA (18 J/cm2) after the administration of correspondent substances at maximal non-phototoxic doses. Photoallergic reactions were induced by OFLX (40 mg/kg), LFLX (3 mg/kg), CPFX (170 mg/kg) and ENX (80 mg/kg), but were not observed in prulifloxacin (170 mg/kg) and NA (30 mg/kg). These results show that photoallergenicity of prulifloxacin were less severe than those of the other quinolone antibacterial drugs under the conditions of this study.

[A 4-week oral toxicity study of prulifloxacin (NM441) in rats followed by a 4-week recovery test]

A repeated dose toxicity study of prulifloxacin, a new antibacterial agent, was conducted in Sprague-Dawley rats. Male and female rats were given the test material orally for 4 weeks at doses of 0 (control), 30, 300 and 3000 mg/kg. After discontinuation of the treatment, a 4-week recovery test was also conducted. There was one case of death in the 3000 mg/kg group. Grayish green and soft feces, unkempt fur, transient deep respiration and decreased body weight gain were observed in the 3000 mg/kg group. Decreased food consumption and increased water intake were seen in the 300 and 3000 mg/kg groups. Ophthalmoscopic examination failed to show any abnormalities related to the treatment. In urinalysis, crystalline substance in the urinary sediments, cloudy urine and decreased Na+ excretion were observed in the 300 and 3000 mg/kg groups. Increased urine volume, lowered urine specific gravity and decreased K+ and Cl- excretions were seen in the 3000 mg/kg group. Hematologic examination showed decreased Hb, Ht, MCV and MCH and increased WBC in the 3000 mg/kg group. Blood chemical examination revealed increased BUN and decreased K+ and Cl- in the 3000 mg/kg group, and decreased K+ and gamma-globulin in the 300 mg/kg group. Pathological changes caused by the treatment were as follows. Cecal weight was increased in all dose groups. Cecal distention and swelling of its absorptive cells were seen in the 300 and 3000 mg/kg groups. In kidney, tubular nephrosis with crystalline substance was observed in the 300 and 3000 mg/kg groups, and its organ weight was increased in the 3000 mg/kg group. The above-mentioned changes were reversible except for decreased gamma-globulin, increased BUN and urine volume, and lowered urine specific gravity. Ulcer and small cavities associated with proliferation of fibrous tissue in the femoral articular cartilage were observed in the 3000 mg/kg group at the end of recovery period of 4 weeks. Plasma levels and urinary concentrations of active metabolite of the test material were increased in all dose groups with dose-related manner, whereby no sex difference was observed. No effects caused by the repeated dosing were seen in the plasma concentrations. Increased cecal weight in the 30 mg/kg group was considered to be attributable to the pharmacological effect of the test material. The results show that the NOAEL of prulifloxacin is 30 mg/kg for 4-week repeated dose toxicity in rats.

[Single and 4-week oral toxicity studies of prulifloxacin (NM441) in aged dogs]

Single-dose and repeated dose toxicity studies of prulifloxacin, a new antibacterial agent, were conducted in aged beagle dogs. I. A single-dose toxicity study Prulifloxacin was administered orally to aged female dogs at a single dose of 2500 and 5000 mg/kg. No death occurred in any group. Vomiting was observed in one of two animals at 2500 mg/kg and in both animals at 5000 mg/kg 3-4 hr after dosing. At 5000 mg/kg, vomiting was observed in both animals after feeding on the day after dosing. One animal also showed soft stool. Thereafter, no abnormalities were observed in any animal. No test article related changes were noted in food consumption, water consumption, body weight or pathological examination in any group. The results show that the lethal dose of prulifloxacin is judged to be greater than 5000 mg/kg in aged female dogs. II. A repeated dose toxicity study Aged male and female dogs were given the test article orally for 4 weeks at doses of 0 (control), 20, 100 and 500 mg/kg. No death occurred in any group. At 500 mg/kg, vomiting was observed every day or intermittently throughout the dosing period and salivation was observed almost every day from day 6 to the end of the dosing onward. Decreases or lack of food and water consumption, and decrease of body weight were noted at 500 mg/kg. At 100 mg/kg, slight decreases in food consumption and body weight were noted in the females. No abnormalities were noted in ophthalmoscopic or electrocardio-graphic examination. In urinalysis, decreases in Na+, K+ and Cl- concentrations and the total excretion amount were noted mostly at 500 mg/kg. A low specific gravity was noted in males at 500 mg/kg. In hematology and serum biochemistry, high GPT, BUN and creatinine, and decreases in WBC were noted in both sexes at 500 mg/kg. A high GOT was noted in males, and low Cl- in females at 500 mg/kg. At 100 mg/kg, a high GPT was noted. Rough surface in the kidney and chronic interstitial nephritis (basophilic change of tubule, atrophy of tubule, thickening of tubular basement membrane, interstitial mononuclear cell infiltration, interstitial focal fibrosis) were increased at 500 mg/kg. No toxicological findings were seen in the 20 mg/kg group. The results show that the NOAEL of prulifloxacin is 20 mg/kg for 4-week repeated dose toxicity in aged dogs.

[Mutagenicity studies of prulifloxacin (NM441) and the active metabolite (NM394)]

The mutagenicity of prulifloxacin, a new antibacterial agent, was investigated by the reverse mutation test in bacteria, the chromosomal aberration test in cultured cells, and the micronucleus test in mice. In addition, NM394, an active metabolite of prulifloxacin, was examined for mutagenicity in the chromosomal aberration test in cultured cells. The reverse mutation test was performed at dose range of 0.0078-0.25 micrograms/plate using Salmonella typhimurium strains (TA100, TA1535, TA98, and TA1537), and Escherichia coli (WP2uvrA). Prulifloxacin did not increase revertant colonies significantly in any of the test strains with or without metabolic activation system (S9 mix). The chromosomal aberration tests were carried out in cultured Chinese hamster lung cells (CHL/IU). Prulifloxacin increased aberrant cells without S9 mix, and NM394 also induced chromosomal aberrations. In human lymphocytes, no significant increases of the frequencies of cells with chromosomal aberrations were observed at dose range of 5-320 micrograms/ml with or without S9 mix. The micronucleus test was conducted at doses of 625-5000 mg/kg in the bone marrow cells of Slc : ddY male mice. There were no significant increases in the frequencies of micronucleated polychromatic erythrocytes.

[Single-dose toxicity studies of prulifloxacin (NM441) in mice, rats and dogs and the active metabolite (NM394) in rats]

Single-dose toxicity studies of prulifloxacin, a new antibacterial agent, were conducted in mice, rats and dogs. In addition, a single-dose toxicity study of (+/-)-6-fluoro-1-methyl-4-oxo-7- (1-piperazinyl)-4H-[1,3]thiazeto[3,2-a]quinoline- 3-carboxylic acid (NM394), an active metabolite of prulifloxacin, was performed in rats. Prulifloxacin was administered orally, intraperitoneally (i.p.) or subcutaneously (s.c.) to mice and rats, and orally to dogs. NM394 was administered intravenously (i.v.) to rats. When prulifloxacin was administered orally or s.c., LD50 values were more than 5000 mg/kg in both sexes of mice and rats; when it was administered i.p., LD50 values were 1757 mg/kg in male mice, 1652 mg/kg in female mice, 915 mg/kg in male rats, and 1076 mg/kg in female rats. The lethal doses of this drug were more than 5000 mg/kg in both sexes of dogs by the oral route. The LD50 values of NM394 were 226 mg/kg in male rats and 238 mg/kg in female rats by the i.v. route. In mice, the major clinical signs observed following the administration of prulifloxacin were sedation, oligopnea, abnormal gait, piloerection, closed eye and tremor by the i.p. route and a scab at the site of injection by the s.c. route; in rats, decreased spontaneous locomotor activity by any of the three routes, oligopnea, lacrimation, hypothermia, piloerection and abnormal gait by the i.p. route, and a scab at the site of injection by the s.c. route; and in dogs, vomiting, reddening of the skin, and loose stool by the oral route. When NM394 was administered i.v., rats showed clonic convulsion and dyspnea. The site of injection was hyperemic, swollen and necrotic. Mice showed a decrease in body weight or an inhibition in weight gain when prulifloxacin was administered i.p. and rats showed the same effects when prulifloxacin or NM394 was administered by any of the above-mentioned routes. Macroscopic findings detected following the i.p. administration of prulifloxacin in mice were pale color of the liver and spleen, thickening of the liver, and adhesion of intra-abdominal organs; and in rats, hydrothorax, congestion and edema of the lung, adhesion of intra-abdominal organs, swelling of the kidney accompanied by fine yellowish-white foci, and atrophy of the testis. When NM394 was administered i.v. to rats, congestion of the lung was macroscopically observed.

[Renal toxicity of prulifloxacin (NM441) in rats]

Renal toxicity of prulifloxacin, a new antibacterial agent, was investigated in rats of both sexes. The animals were given prulifloxacin orally for 28 days at a dose of 3000 mg/kg. Tubular nephrosis in which crystalline substances appeared primarily within tubules was observed from the second day of administration, and a large number of brown circular crystals were found in the urinary sediment from the first day of administration. Electron microscopic observation revealed a close resemblance of the ultrastructural characteristics between the intratubular crystalline substance and the urinary brown circular crystal, and the tubules were occasionally occluded by the crystalline substances. Infrared spectral analysis and X-ray microanalysis indicated that the brown circular crystal consisted of NM394, an active metabolite of prulifloxacin. These results suggested that NM394, which was filtered into the primary urine, may be precipitated as crystals on the process of water reabsorption in the tubules. And then most of the crystals would be washed out as crystalluria particles, and some of crystals retained and caused the obstructive uropathy.

[A 4-week oral toxicity study of prulifloxacin (NM441) in dogs followed by a 4-week recovery test]

A repeated dose toxicity study of prulifloxacin, a new antibacterial agent, was conducted in beagle dogs. Male and female dogs were given the test material orally for 4 weeks at doses of 0 (control), 30, 150 and 750 mg/kg. After discontinuation of the treatment, a 4-week recovery test was also conducted. Feces containing white material were seen in the 150 and 750 mg/kg groups. Salivation, prone, lateral or sitting position, gait disturbance, and locomotor depression were observed in the 750 mg/kg group. In this dose group, decreased body weight and food and water consumptions were also observed. There were no treatment-related effects on survival. Ophthalmoscopic and electrocardiographic examinations and urinalysis failed to show any abnormalities related to the treatment. Hematologic examination showed decreased WBC in the 750 mg/kg group. Blood chemical examination revealed increased GPT and alpha 2-globulin in the 750 mg/kg group. Pathological changes caused by the treatment were as follows. Rarefaction of matrix, cavitations and erosions in humeral and femoral articular cartilages, and inflammatory cell infiltration in synovium were seen in the 150 and 750 mg/kg groups. Focal hemorrhage in synovium was also observed in the 750 mg/kg group. In kidney, regeneration of tubular epithelium, inflammatory cell infiltration, fibrosis and crystalline substance in the tubular lumen were observed in the 750 mg/kg group. The above-mentioned changes were satisfactorily reversible except for the changes in the humeral and femoral articular cartilages and in the kidney. Plasma levels and urinary concentrations of active metabolite of the test material were increased in all dose groups with dose-related manner, whereby no sex difference was observed. No effects caused by the repeated dosing were seen in the plasma concentrations. Toxicological findings were not observed in the 30 mg/kg group. The results show that the NOAEL of prulifloxacin is 30 mg/kg for 4-week repeated dose toxicity in dogs.

Testicular degeneration induced in rat offspring by maternal treatment with sobuzoxane

Pregnant rats were orally administered sobuzoxane (an antitumor drug) during various days of gestation and the testicular development of their offspring was examined histopathologically on day 21 after birth. When 15.6 to 250 mg/kg of sobuzoxane was given every day from day 7 to 17 of gestation, seminiferous tubules devoid of spermatogonia and/or spermatocytes were found in a dose related manner. The critical period for testicular degeneration was identified to be day 13 and 14 of gestation by single administration experiments and single treatment with 15.6 to 250 mg/kg of sobuzoxane on day 14 of gestation gave a dose-dependent incidence of the tests abnormality. These results suggest that the testis abnormality in offspring from dams treated with sobuzoxane is due to inhibition of the proliferation of primordial germ cells during testis organogenesis.

Effects of DNA topoisomerase inhibitors on nonhomologous and homologous recombination in mammalian cells

To study the involvement of DNA topoisomerases in recombination in mammalian cells, we used gene transfer assays to examine the effects of DNA topoisomerase inhibitors on nonhomologous (illegitimate) and homologous recombination. The assays were performed by transfecting adenine phosphoribosyltransferase-deficient (APRT-) CHO cells with plasmids carrying the wild-type or mutant aprt genes and by treating the cells with the inhibitors, followed by subsequent cultivation to select for APRT-positive (APRT+) colonies. Treatments with DNA topoisomerase II inhibitors such as VP-16, VM-26, ICRF-193 resulted in a 3- to 5-fold stimulation of integration of both closed-circular and linearized plasmids carrying the wild-type aprt gene into the recipient genome through nonhomologous recombination. The same treatments also increased 6- to 9-fold and 3-fold the number of APRT+ recombinant colonies that were generated by cotransfecting two closed-circular plasmids with nonoverlapping defective aprt genes and their linearized equivalents, respectively. However, this cotransfection assay involved intrinsically nonhomologous recombination processes; normalization of the frequencies by dividing them with those of the above nonhomologous recombination revealed 2-fold enhancement of homologous recombination events between the circular mutant genes but not between the linear ones. In contrast, DNA topoisomerase I inhibitor, camptothecin, showed no such effect on either recombination. From these results, we discuss the function of DNA topoisomerases on recombination in mammalian cells.

[Synergism of sobuzoxane in combination with doxorubicin against leukemia P388 in mice]

AIM

To study the antitumor activity of sobuzoxane (Sob) in combination with doxorubicin (Dox) and the effect of Sob on Dox-induced cardiotoxicity.

METHODS

DBA/2 mice bearing transplanted leukemia P388 were given i.v. Dox 2 mg.kg-1.d-1 for 3 d, 4 mg.kg-1.d-1 for 1 d combined with ig Sob 20, 40 mg.kg-1.d-1 for 7 d. The increase in life span (ILS) of each group was recorded in 30 d. The myocardium of moribund mice was examined by transmission electron microscopy.

RESULTS

The ILS of combination therapeutic groups of Sob with Dox was 48.7%, 57.3%, 59.0%, and 62.4% respectively, which were 30%-90% higher than the sum of ILS of two groups treated with Dox and Sob separately (P < 0.01). The ultrastructural injury of cardiomyocytes of P388-bearing mice caused by combination chemotherapy with Dox plus Sob was markedly attenuated compared with Dox alone.

CONCLUSION

Sob with Dox exhibited an antitumor synergistic effect on leukemia P388, and the cardiotoxicity of Dox was reduced by Sob.

GR127935: a potent and selective 5-HT1D receptor antagonist

GR127935 is the most potent 5-HT1D receptor antagonist yet described, possessing nanomolar affinity at human 5-HT1D receptors. Sumatriptan-induced contractions of the dog isolated basilar artery and saphenous vein are antagonised by GR127935 in an insurmountable manner indicative of its slow dissociation from the 5-HT1D receptor. 5-HT1D receptor-mediated hypothermia and rotational behaviour in guinea-pigs are antagonised potently, and with long duration, by GR127935, administered by a variety of routes. GR127935 also blocks central 5-HT1D autoreceptors in vitro and in vivo. GR127935 has much lower affinity at other 5-HT, and non-5-HT, receptors. In functional studies, GR127935 fails to affect 5-HT2 receptor-mediated 'wet dog shakes' in guinea-pigs and 5-HT1A receptor-mediated inhibition of 5-HT release in rat dorsal raphé nucleus. The compound has a good safety profile in all species tested. It is concluded that GR127935 is a useful pharmacological tool to characterise 5-HT1D receptor function.

Elucidation of the protein kinase C-dependent apoptosis pathway in distinct subsets of T lymphocytes in MRL-lpr/lpr mice

MRL-lpr mice are severely impaired in the Fas pathway of apoptosis induction. We here evaluate another pathway of apoptosis induction in MRL-lpr mice which is protein kinase C (PKC) dependent. Despite the defect of the Fas pathway, apoptosis developed during culture in vitro in splenic T lymphocytes from MRL-lpr mice more extensively than in T lymphocytes from MRL-(+/+) mice. Apoptosis induction in the former cells was then found to be greatly promoted by PKC inhibitor H-7, and partially prevented by PKC activator phorbol 12-myristate 13-acetate (PMA). High sensitivity to H-7, but not to PKA inhibitor HA 1004, of these cells for apoptosis induction was confirmed by detailed time course and dose-dependency experiments of the drug effect. Population analysis showed that both CD4+ T lymphocytes and CD8+ T lymphocytes from MRL-lpr mice were highly sensitive to H-7, whereas CD8+ T lymphocytes, but not CD4+ T lymphocytes, from MRL-(+/+) mice were susceptible to the reagent. Interestingly, B220+ Thy-1+ CD4-CD8- T lymphocytes from MRL-lpr mice were most sensitive to H-7 for apoptosis induction. Correspondingly, the membrane-translocated activated PKC-alpha level in splenic T lymphocytes from MRL-lpr was more extensively up-regulated by PMA than in splenic T lymphocytes from MRL-(+/+). These results suggest that some signal consistently activates PKC in MRL-lpr T lymphocytes, and this event is needed for survival of these cells. On the other hand, CD4+ CD8+ thymocytes were deleted by apoptosis in culture with PMA, whether these thymocytes were from MRL-lpr mice or MRL-(+/+) mice. This finding suggested that the apoptosis induction pathway linked to PKC activation is intact in CD4+ CD8+ thymocytes from the Fas-defective MRL-lpr mice. We conclude from these results that the PKC-dependent signal pathways for either cell death or cell activation are intact or even accelerated in lpr mice, which could both compensate for the loss of the Fas pathway and promote the generation of autoreactive T lymphocytes.

Some pharmacological properties and cumulative, subchronic and chronic toxicity of 9-methyl-2-[3-(4-phenyl-1-piperazinylpropyl)] -1,2,3,4-tetrahydro-beta-carbolin-1-one (B-193)

The cumulative, subchronic and chronic toxicity of B-193 were studied on the rats and mice. It was found that this compound exerted weak tendency to cumulation in the body. Only the highest doses of B-193 (70, 40 mg/kg po for 12 weeks) caused the increase of animals mortality. Studies on subchronic and chronic toxicity have demonstrated, that B-193 administrated po or ip for 3 weeks, and po for 12 weeks, in general, neither affects the body weight gain nor the mass and morphology of heart, liver and kidneys, as well as spontaneous locomotor activity of animals. The weak depressant effect of B-193 on peripheral blood morphology was seen only after 3 weeks po or ip treatment with this compound. The moderate effect of B-193 on activity of alanine and aspartate transaminases (A1At and AspAt) and serum protein level found after 3 weeks of treatment, was no longer observed after 12 weeks of treatment. This could indicate that above effects of B-193 are reversible.

3-substituted piperazinomethyl benzoxazolinones. Analgesic and anti-inflammatory compounds inhibiting prostaglandin E2

Fourty-three new benzoxazolinone derivatives having a piperazinomethyl group at the third position of the ring were synthesized by using appropriate benzoxazolinones and 4-substituted piperazines via a Mannich reaction. The structures of the compounds were elucidated by spectral data and microanalyses. Analgesic activities were evaluated by a modified Koster test. All compounds, except 7, 14, 21, 32, and 41, showed analgesic activity higher than that of acetylsalicylic acid. The compounds were also screened for their anti-inflammatory activity using a carrageenan paw edema test, and those exhibiting high anti-inflammatory activity were investigated for their ability to inhibit prostaglandin E2 induced paw edema. The results of anti-inflammatory testing indicated that most of the compounds were more active than indometacin. Ulcerogenic activities of the compounds were also studied and no gastrointestinal bleeding was observed at the 100 mg/kg dose level.

Lipidosis of the dorsal root ganglia in rats treated with an almitrine metabolite

Toxic effects of a detriazinyl metabolite of almitrine (DTMA) were evaluated in rats and on cultured rat macrophages. In rats daily treated with DTMA for 16 weeks, spastic gaits with heel-lifting appeared, and lamellated and/or crystalloid bodies formed in sensory neurons, satellite cells, Schwann cells, and vascular endothelial cells of the dorsal root ganglia. The lysosomal lamellated bodies, which were not induced by almitrine, were produced also in cultured rat macrophages exposed to over 1 x 10(-5) M DTMA.

NMDA receptors are involved at the ventrolateral nucleus tractus solitarii for termination of inspiration

The purpose of the present study was to determine whether blockade of excitatory amino acid receptors at the ventrolateral nucleus of the tractus solitarius would influence respiratory activity. This was done by microinjecting excitatory amino acid receptor antagonists into the ventrolateral nucleus of the tractus solitarius of alpha-chloralose-anesthetized animals while monitoring respiratory activity using a Fleisch pneumotachograph and arterial blood pressure and heart rate. Bilateral microinjection of the NMDA receptor antagonist, 3-[(R)-carboxypiperazin-4-yl]-propyl-1- phosphomic acid (CPP), 5.62 nmol per side, produced an increase in inspiratory duration (+4 +/- 1.6 s, n = 8) which progressed to an apneustic pattern of breathing. Similar results were obtained with CPP microinjected into the ventrolateral nucleus of the tractus solitarius of three vagotomized animals. Bilateral microinjection of a second NMDA receptor antagonist, 2-amino-7-phosphono-heptanoic acid (AP7), 562 nmol per side, produced qualitatively similar effects on respiration as seen with CPP. In contrast, blockade of non-NMDA receptors with 6-cyano-7-nitroquinoxaline-2,3-dione (CNXQ), 0.125 nmol per side, had very little effect on respiration. Activation of NMDA receptors at the ventrolateral nucleus of the tractus solitarius with bilateral microinjection of NMDA, 39 pmol, produced a large increase in expiratory duration (+11 +/- 3 s, n = 8), and apnea during the expiratory phase of the respiratory cycle in half of the animals studied. Similar results were obtained with D,L-alpha-amino-3-hydroxy-5-methyl-4-isoxazol-proprionate (AMPA). These results indicate that an endogenous excitatory amino acid released at the ventrolateral nucleus of the tractus solitarius and acting at the NMDA receptor, plays a significant role in respiratory timing.

Some analogues of 1,4-disubstituted piperazines as hypnotic and sedative agents

Preparation, analytical data, and biological properties such as acute toxicity, influence on spontaneous and amphetamine induced locomotor activity, hypnotic activity, influence on hexobarbital narcosis and anticonvulsant activity of new analogues of pyrimidyl piperazines--ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]-3-oxopropanoate (4), 1-[4-(2-pyrimidyl)-1-piperazinyl]-1,3-butandione (5), ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]butanoate (6) and 1-[4-(2-pyrimidyl)-1-piperazinyl]-2-acetyl-1-hexanone (7)--are reported.

Amphoteric drugs. I. Synthesis and antiallergic activity of [4-(diphenylmethoxy)piperidino]-, [4-(diphenylmethyl)piperazinyl]- and [4-(diphenylmethylene)piperidino]alkanoic acid derivatives

A simple method of transforming classical antihistaminics into nonsedative antiallergic agents with strong effects in rat models is described. Various [4-(diphenylmethoxy)piperidino]- (series A), [4-(diphenylmethyl)piperazinyl]-(series B) and [4-(diphenylmethylene)piperidino]alkanoic acid derivatives (series C) were synthesized and examined for antiallergic activities and effects on the central nervous system (CNS), in comparison with the corresponding N-methyl derivatives (1a--c). N-Alkylcarboxylic acids (5a--c) showed stronger inhibitory effects on compound 48/80-induced lethality in rats than the corresponding N-methyl derivatives (1a--c). In particular, N-alkylcarboxylic acids (5a) in series A exhibited approximately 100-fold stronger inhibitory effects than 1a, and were the least effective in prolonging the sleeping time on hexobarbital-induced anesthesia in mice in all series. As a result of chemical modification in series A, it was found that introduction of a methyl group at the para-position on one benzene ring in the (diphenylmethoxy)piperidine system effectively reduced CNS side-effects without reducing antiallergic activity. (+)-3-[4-[(4-Methylphenyl)phenylmethoxy]piperidino]propionic acid ((+)-5l), an optically active isomer of 5l, exhibited a stronger antiallergic effect (ED50 = 0.17 mg/kg, p.o.) than ketotifen and terfenadine in the 48 h homologous passive cutaneous anaphylaxis (PCA) test, and moreover exhibited no CNS side-effects, such as prolongation of the sleeping time on hexobarbital-induced anesthesia, at an oral dose of 30 mg/kg. Compound (+)-5l was thus proved to be a promising candidate as a nonsedative antiallergic agent.