Rapamycin, a new antifungal antibiotic, was found to inhibit the immune response in rats. It totally prevented the development of two experimental immunopathies (experimental allergic encephalomyelitis (EAE) and adjuvant arthritis (AA)) and the formation of humoral (IgE-like) antibody. It was about half as potent as cyclophosphamide in inhibiting EAE. In AA and on antibody formation, rapamycin and cyclophosphamide were about equipotent, whereas methotrexate was more potent. The immunosuppressant activity of rapamycin appears to be related to inhibition of the lymphatic system.

Etodolac, 1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid, a clinically effective analgesic and antiinflammatory agent, has been resolved via a chromatographic separation of its diastereoisomeric esters with (-)-borneol. The effects of the enantiomers were studied in vitro on prostaglandin synthetase and on adjuvant-induced arthritis in rats. The biochemical and pharmacological results show that virtually all of the effects of etodolac are due to the (+) enantiomer.

A series of 37 1-ethyl- and 1-n-propyl-1, 3, 4, 9-tetrahydropyrano[3, 4-b]indole-1-acetic acids bearing one, or two, substituents on the benzene ring has been synthesized via the acid-catalyzed condensation of a substituted tryptophol with ethyl propionylacetate or ethyl butyrylacetate. Antiinflammatory and ulcerogenic effects were examined and the results show that 1, 8-diethyl-1, 3, 4, 9-tetrahydropyrano[3, 4-b]indole-1-acetic acid (etodolic acid, USAN) is a potent agent, particularly active against a chronic rat model of inflammation (ED50 0.7 + 1-0.1 mg/kg po in the adjuvant arthritis model) and which has a relatively low acute ulcerogenic potential in the same species.

No abstract

The large variation in the severity of the arthritic response of the adjuvant-injected rat often makes it impossible to obtain statistically manageable dose–response curves with anti-inflammatory drugs. Consequently, the relative potency of anti-inflammatory drugs generally was not established. In the present study, with a modification of the therapeutic test, reliable dose–response curves were obtained with seven anti-inflammatory drugs. With this method the "therapeutic" mean effective dose (ED50) and relative potency were calculated by probit analysis. Charles River rats were injected in the left hind paw with adjuvant. On day 14, rats with an injected paw volume of 4–6 ml that increased by at least 0.5 ml between days 10 and 14 were selected for drug treatment. Groups of 6–12 rats with a mean injected paw volume of 5–5.5 ml were formed. Dosing with compounds was started on day 14 and continued daily until day 22 (nine injections). Ninety-four percent of the arthritic control rats showed a further increase in injected paw size between days 14 and 22 (mean, 1.06 ± 0.12 ml) whereas rats dosed with anti-inflammatory compounds showed a dose-related decrease in paw size during the same period. A decrease of 0.5 ml or more between days 14 and 22 was considered to be a therapeutic effect, smaller decreases were taken as no effect. The oral ED50's in milligrams per kilogram were indomethacin, 0.22 ± 0.05; prednisolone, 3.49 ± 1.0; hydrocortisone, 12.4 ± 3.0; phenylbutazone, 13.27 ± 2.7; mefenamic acid 20.10 ± 5.8; aminopyrine, 129.95 ± 25.3; and aspirin, 279.0 ± 24.6. Except for aspirin, the relative potency of the compounds studied by this therapeutic test (chronic) was comparable to that reported for the acute carrageenin assay. Aspirin appears to be markedly less active in chronic inflammation than in acute. This finding is consistent with both experimental and clinical observations.