Antiinflammatory, analgesic, and antipyretic activities of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H-pyrazol o[3, 4-d]pyrimidine-2-carboxylate (AA-2379), a novel non-acidic agent.

The antiinflammatory, analgesic, and antipyretic activities of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H-pyrazolo[ 3, 4-d]pyrimidine-2-carboxylate (AA-2379), a novel non-acidic agent, were examined. 1. AA-2379 had a potent antiinflammatory activity; 3-25 mg/kg, p.o. of the compound inhibited rat carrageenin-, bradykinin-, trypsin-, formalin-, dextran-, and nystatin-induced paw edema; mouse traumatic edema; and rat croton oil pouch inflammation by about 30%. The compound at 25-50 mg/kg, p.o. also inhibited the vascular permeability induced by histamine, serotonin, and bradykinin. 2. AA-2379 had an analgesic activity; the ID50 values in mouse phenylquinone-induced writhing were 10.1 mg/kg, p.o. and the compound at 12.5 mg/kg, p.o. inhibited dog urate arthritis. 3. AA-2379 at 3-10 mg/kg, p.o. showed antipyretic activity in febrile rats and rabbits. 4. AA-2379, at 500 mg/kg, p.o. was not ulcerogenic in rats. 5. These data show that AA-2379 is more active than non-acidic antiinflammatory agents, such as tiaramide and aminopyrine.

Study on the receptor subtypes mediating the analgesic action of an enkephalin analog, Tyr-D-Met(O)-Gly-EtPhe-NHNHCOCH3.AcOH (EK-399).

The analgesic action of the enkephalin analog EK-399 (Tyr-D-Met(O)-Gly-EtPhe-NHNHCOCH3.AcOH) and the subtypes of the opiate receptors mediating the action were studied. The analgesic effect of subcutaneously injected EK-399 was ten times as potent as that of morphine in the rat tail flick test. EK-399 had a longer latency time and duration time than morphine. The analgesic action of EK-399 injected into the rat spinal subarachnoid space was about 800 (1800 in molar ratio) times as potent as that of morphine in the hot plate test. EK-399 had high affinities for both mu and delta opiate receptors in the rat brain receptor binding assay. The apparent pA2 values with naloxone were 7.65 for morphine and 5.98 for EK-399 in the rat tail flick test; the difference was significant. A cross tolerance between EK-399 and morphine was examined in the rat tail flick test. Although morphine tolerant rats showed no tolerance to EK-399, EK-399 tolerant rats showed a clear tolerance to morphine. These results indicate that EK-399 has a potent and long lasting analgesic effect via opiate receptors in rats. In addition to mu-receptors, delta-receptors may be involved in its analgesic mechanism.

Spinal antinociceptive effects of adenosine compounds in mice.

The effects of injecting ATP, ADP, AMP, adenosine and adenine intrathecally on the pain response induced by the injection of substance P (10 ng/mouse) intrathecally were studied. All the compounds except adenine inhibited the pain response in a dose-related manner. The ED50 values of ATP, ADP, AMP and adenosine were 2.10, 0.93, 0.88 and 0.48 micrograms/mouse, respectively. Pretreatment with theophylline at a dose of 100 mg/kg p.o. markedly diminished all the antinociceptive effects. The effect of adenosine was not affected by s.c. injection of naloxone. These results suggest the existence of adenosine receptors which modulate spinal nociceptive sensory processing, independently of the endogenous opiate system.

[Effects of ipriflavone (TC-80, an anti-osteoporotic drug) on acute and chronic pain].

The effects of TC-80 on acute and chronic pain in rats and mice were examined. Single oral administration of TC-80 at 50-300 mg/kg was not analgesic in the phenylquinone writhing, acetic acid writhing, and hot plate tests in mice or the tail flick test in rats. Three-weeks administration of TC-80 in a dose of 100 mg/kg/day, p.o., to rats had no analgesic action in the acetic acid writhing and tail flick tests. When TC-80 was given orally in a dose of 100 mg/kg/day for 3 weeks to rats with adjuvant arthritic chronic pain, analgesic effects were observed 2 weeks after the start of administration in males and in ovariectomized estrone-supplemented females; the effect seen in the females was statistically significant. Changes in the bones of the hind paws were examined radiologically, and synovitis, periosteal new bone formation and bone destruction were examined histopathologically in the females. These variables were improved by treatment with TC-80 for 3 weeks. It is concluded that TC-80 has no analgesic effect, but may inhibit chronic pain by anti-osteoporotic action on bone disease.

[Re-evaluation of the carrageenin-induced abscess model as a screening method for anti-inflammatory agents].

For the simple assay of anti-inflammatory agents and the analysis of their mode of action, the early inflammatory reactions of the carrageenin abscess model in rats were studied by determining abscess (exudate) weight, vascular permeability measured by extravascular dye leakage, protein, prostaglandins (PGs), and DNA (an index of leucocyte infiltration). Subcutaneous injection of 0.5 ml of 2% carrageenin in the dorsal sacral region of rats induced an edema with an initial weak phase (3 hr) followed by a second pronounced phase, reaching a maximum (2.3 g) at 15 hr and declining steadily thereafter. During the first 15 hr, there was a good correlation between the edema formation and changes in the increased vascular permeability, and also the PGE contents in the exudate paralleled the permeability, but thereafter, these components did not follow the same time course. The marked increase in DNA content in the exudate started after a lag time of a few hr in correspondence with the second accelerated edema formation. The edema formation was effectively inhibited by indomethacin and dexamethasone given simultaneously with the irritant injection; maximum inhibition with indomethacin (2 mg/kg, p.o.) was 36% at 15 hr and 48% with dexamethasone (0.1 mg/kg, p.o.) at 9 hr. Indomethacin very significantly affected exudate PGE levels and vascular permeability, rather than suppressing the edema formation. When the treatment was initiated at 9 hr after injury, it was not effective in reducing the weight of the 24-hr abscess, whereas it had significant effect on the PGE concentration. Dexamethasone did not exert significant effect on the PGE levels despite its potent and steady anti-edematous activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacology of 4-benzyol-1-indancarboxylic acid (TAI-901) and 4-(4-methylbenzoyl)-1-indancarboxylic acid (TAI-908).

Pharmacological studies on the derivatives of 1-indancarboxylic acid yielded 4-benzoyl-1-indancarboxylic acid (TAI-901) and 4-(4-methylbenzoyl)-1-indancarboxylic acid (TAI-908). The relative potency (R.P.) of TAI-901 and TAI-908 assessed in parallel line assays (indomethacin - 1) demonstrated that both compounds were highly analgesic against various noxious stimuli induced in experimental animals. R.P. values of TAI-901 were 1.0, 1.7, 4.4 and 2.8 in the phenylquinone writhing, acetic acid writhing, adjuvant arthritic pain and urate arthritic pain tests, respectively. R.P. values of TAI-908 were 1.6, 2.0, 4.7 and 7.0, respectively, in these tests. Both compounds were more inhibitory than indomethacin against acute inflammation, but less inhibitory against chronic inflammation. The inhibitory activities of TAI-901 and TAI-908 on the prostaglandin biosynthesis by microsomes of rabbit renal medulla were 2.2 and 2.6 times that of indomethacin. TAI-901 was 1/3.8 1/7.1, and TAI-908 was 1/16.7 and 1/12.5 as toxic as indomethacin in male rats and mice, respectively.

Optical isomerization of R(-)-clidanac to the biologically active S(+)-isomer in guinea-pigs.

Optical isomerization of clidanac (RS-6-chloro-5-cyclohexyl-1-indancarboxylic acid, I), an anti-inflammatory drug having a chiral centre in its molecule, was evaluated in guinea-pigs. After oral administration of R(-)-I, the biologically active S(+)-isomer was detectable in the plasma, in the early stages. At 3 h after dosing R(-)-I, the plasma contained above 90% of the S(+)-isomer. Little conversion of S(+)-I to R(-)-I was observed. This may account for the equivalent in vivo activities of R(-)- and S(+)-I in this species. Determination of the enantiomeric composition required derivatization of the enantiomers to their diastereomeric amides after which thin layer chromatography (t.l.c.) was used for the separation. The quantitative determination of the compounds so-separated was accomplished by in situ measurements of the u.v.-reflectance. The t.l.c.-u.v.-densitometric procedure was also used to determine the plasma concentration of I.

Inhibition of prostaglandin biosynthesis by clidanac and related compounds: structural and conformational requirements for PG synthetase inhibition.

The inhibition of prostaglandin (PG) biosynthesis by clidanac (6-chloro-5-cyclohexyl-1-indancarboxylic acid, TAI-284), its metabolites and some analogues has been examined using various microsomal preparations as enzyme source. Clidanac and some analogues were among the most potent inhibitors. The (+)-isomer of clidanac was shown to be 1000 times more potent than the (-)-isomer in inhibiting PG synthetase activity. The cis-3'-hydroxyl metabolite which retains anti-inflammatory activity comparable to that of clidanac had much less inhibitory activity. Structure-activity studies with clidanac analogues showed that the position of halogen substitution in 1-indancarboxylic acid is of considerable significance for the conformational requirement for binding to the enzyme.

Effects of some anti-rheumatic agents on copper-catalyzed thermal aggregation of gamma globulin.

Gerber has shown that specific anti-rheumatics, D-penicillamine and aurothiomalate, inhibit copper(II)-catalyzed thermal aggregation of human gamma globulin. Various anti-rheumatics were tested for the activity. Steroidal and non-steroidal anti-inflammatory agents were almost ineffective, while a new non-steroidal anti-inflammatory agent, TAI-284 (6-chloro-5-cyclohexyl-1-indancarboxylic acid), was found to be one half as active as aurothiomalate. The structure-activity relationship of TAI-284 derivatives and the mode of action of TAI-284 were investigated.