No abstract

The arachidonic acid (AA)-induced ear edema model in the mouse has been demonstrated as an effective in vivo experimental tool to screen compounds showing anti-inflammatory activity. Since neutrophil influx is a component of the inflammatory reaction, we have modified this assay by quantitating myeloperoxidase (MPO) levels which reflect neutrophil accumulation in the edematous biopsies of the mouse ear. Our work has shown that orally administered 5-lipoxygenase inhibitors, dual inhibitors (CO/LO), and steroids dose-dependently inhibit both edema formation and MPO activity, whereas oral activity is not seen with NSAID's. There is a good correlation between the inhibition of edema formation and of MPO activity by these compounds. Thus, measurement of MPO, in addition to the AA-induced edema in the mouse ear, can provide another parameter to profile potential anti-inflammatory compounds.

A series of carboxy-substituted cinnamides were investigated as antagonists of the human cell surface leukotriene B4 (LTB4) receptor. Binding was determined through measurement of [3H]LTB4 displacement from human neutrophils. Receptor antagonism was confirmed through a functional assay, which measures inhibition of Ca2+ release in human neutrophils. Potent antagonists were discovered through optimization of a random screening hit, a p-(alpha-methylbenzyloxy)cinnamide, having low-micromolar activity. Substantial improvement of in vitro potency was realized by the attachment of a carboxylic acid moiety to the cinnamide phenyl ring through a flexible tether, leading to identification of compounds with low-nanomolar potency. Modification of the benzyloxy substituent, either through ortho-substitution on the benzyloxy phenyl group or through replacement of the ether oxygen with a methylene or sulfur atom, produced achiral antagonists of equal or greater potency. The most potent compounds in vitro were assayed for oral activity using the arachidonic acid-induced mouse ear edema model of inflammation. Several compounds in this series were found to significantly inhibit edema formation and myeloperoxidase activity in this model up to 17 h after oral administration. Representatives of this series have been shown to be potent and long-acting orally active inhibitors of the LTB4 receptor.

No abstract

Hartman, H.B., J.E. Roehr, B.L. Kotyuk, R.W. Kosley, Jr., R.J. Cherill, W.W. Petko, and P.G. Conway: HP 663: A novel compound for the treatment of glaucoma. Drug Dev. Res. 12:197-209, 1988. Various studies suggest that the 7-dihydroxypropionyl derivative of forskolin, HP 663, effectively lowers intraocular pressure (IOP) by a novel mechanism. Biochemically, HP 663 stimulates rat striatal adenylate cyclase and displays an affinity for forskolin binding sites similar to that of forskolin. Following topical administration this compound lowers IOP in both New Zealand White (NZW) and Dutch Belt (DB) rabbits. In NZW rabbits, concentrations from 0.05 to 2.0% in a buffered hydroxypropylmethylcellulose (HPMC) vehicle produce significant reductions in outflow pressures of 35-45% for 5-6 hr. Additionally, HP 663 is soluble in this vehicle up to a concentration of 0.25%. As mentioned, HP 663 also reduces IOP in DB rabbits; however, this response is not significant until a concentration of 1% is attained. The effect on aqueous humor inflow was indirectly determined by studying the rate of IOP recovery following rapid i.v. infusion of 20% NaCI. In NZW rabbits, HP 663 significantly reduced aqueous humor inflow as shown by a 40% decrease in the IOP recovery rate compared to control. Tolerance also does not appear to develop to the IOP lowering effects of HP 663 in NZW rabbits. This compound is still capable of significantly lowering IOP following twice daily treatment for 21 consecutive days. Following topical administration of concentrations which effectively lower IOP, HP 663 exhibits no significant effects on heart rate or blood pressure of NZW rabbits. Therefore, this compound does not appear to exhibit a potential for peripheral side effects after topical application. Based on the results of the present study, HP 663 appears to be a potent activator of adenylate cylase and may provide a novel and effective treatment for glaucoma.