Ropivacaine inhibits leukocyte rolling, adhesion and CD11b/CD18 expression.

Ropivacaine, a new local anesthetic, is currently being investigated for the treatment of ulcerative colitis, with promising results so far. The aim of this study was to examine anti-inflammatory properties of ropivacaine with regard to its effects on vascular permeability and inflammatory leukocyte behavior in vivo. The effects on leukocyte rolling, firm adhesion and vascular permeability were examined in the hamster cheek pouch microvasculature via intravital microscopy, and the effects on leukocyte adhesion molecules were examined in vitro by means of flow cytometry. In large venules, leukocyte adhesion induced by topical leukotriene B4 (LTB4) was almost completely inhibited during the combined application of ropivacaine and LTB4. The spontaneous rolling leukocyte flux was reduced by 72%, the rolling leukocyte fraction by 47% and the total leukocyte flux, which reflects blood flow, by 47%. In postcapillary venules, ropivacaine abolished rolling and LTB4-induced firm adhesion of leukocytes. LTB4 challenge also resulted in increased plasma exudation that was almost completely inhibited by ropivacaine. Moreover, ropivacaine inhibited the tumor necrosis factor alpha-induced up-regulation of CD11b/CD18 and L-selectin shedding by human leukocytes in vitro. Our results suggest that ropivacaine exerts anti-inflammatory activity, and this appears to be mediated to a significant extent by inhibition of both leukocyte rolling and adhesion.

Correlation between chemical structure, receptor binding, and biological activity of some novel, highly active, 16 alpha, 17 alpha-acetal-substituted glucocorticoids.

The affinity for the glucocorticoid receptor in rat skeletal muscle of some glucocorticoids with a new type of 16 alpha, 17 alpha-acetal substituent has been estimated and correlated to the glucocorticoid activities in three in vivo systems in rats. Budesonide (an approximately 1:1 mixture of the C(22) epimers of 11 beta, 21-dihydroxy-16 alpha, 17 alpha-[(22R,S)-propylmethylenedioxy]-pregna-1,4-diene-3,20-dione) and the isolated (22R)- and (22S)-epimers bound to the same binding site as the potent glucocorticoids dexamethasone (DEX) or triamcinolone 16 alpha, 17 alpha-acetonide (TA), but with even higher affinity than DEX or TA, despite the lack of a 9 alpha-fluoro atom in budesonide and its epimers. The (22R)-epimer was twice as active as the (22S)-epimer, 4 times more active than TA, and 14 times more active than DEX. The introduction of a 9 alpha-fluoro atom slightly decreased the binding affinity of the (22R)-epimer of budesonide, in contrast to the positive effect of 9 alpha-fluorination of, e.g., 16 alpha, 17 alpha-acetonides. The negative influence of 9 alpha-fluorination of the (22R)-epimer was partially reversed in the 6 alpha, 9 alpha-difluorinated (22R)-epimer. Nevertheless, the fluorinated compounds were more active than DEX and TA (8 and 11 times more active than DEX, and 2 and 3 times more active than TA, in case of the 9 alpha-fluoro- and 6 alpha, 9 alpha-difluoro-derivatives of the (22R)-epimer, respectively). Budesonide is metabolized mainly to 16 alpha-hydroxyprednisolone (11 beta, 16 alpha, 17 alpha, 21-tetrahydroxy-pregna-1,4-diene-3,20-dione) and 6 beta-hydroxy-budesonide. Both metabolites were very weak competitors for the ligand-binding sites on the receptor (3% and 6% of the affinity of DEX, respectively). The affinity for the receptor in vitro was closely correlated to the topical glucocorticoid activity in vivo for the 12 steroids compared (r = 0.98; R = 0.98), which supports the contention that in vitro tests for receptor affinity are useful when screening for agonists among steroids with the present type of structures. The results on receptor-ligand interaction are in accordance with X-ray crystallographic data available for some steroids.

Influence of 16 alpha, 17 alpha-acetal substitution and steroid nucleus fluorination on the topical to systemic activity ratio of glucocorticoids.

The use of topical glucocorticosteroid therapy on large skin areas or in the lung is sometimes restricted by the occurrence of unwanted, general corticoid actions owing to a profound systemic absorption. To decrease this risk potent glucocorticoids with an enhanced ratio between their topical and their systemic glucocorticoid potencies are wanted. Therefore, structure-activity studies were performed in rat models to investigate what influences the type of substitution in the 16 alpha, 17 alpha-acetal group and the introduction of fluorine in the 9 alpha- or the 6 alpha, 9 alpha-positions have on the topical and the systemic activities, respectively. The introduction of an unsymmetrical 16 alpha, 17 alpha-acetal group (named acetal type B) markedly enhanced the topical anti-inflammatory potency compared with that of the conventional 16 alpha, 17 alpha-acetonide group (named acetal type A). Both acetal types had a similar systemic glucocorticoid potency, however, 9 alpha-Fluoro and especially 6 alpha, 9 alpha-difluoro substitution, on the other hand, enhanced the systemic glucocorticoid activity more than they raised the topical anti-inflammatory potency. Optimal topical to systemic activity ratio was obtained with a nonhalogenated corticoid of acetal type B structure. This compound, budesonide, had at least the same high topical anti-inflammatory potency as fluocinolone acetonide but was about 10 times less potent than this reference to induce systemic glucocorticoid actions. Its lower systemic activity is probably due to a more rapid biotransformation in the liver.

Development of new glucocorticosteroids with a very high ratio between topical and systemic activities.

The very potent topical anti-inflammatory glucocorticosteroids (GCS) most widely used are either 17 alpha-esters of halogenated 16-methyl-17 alpha-hydroxycorticosteroids (e.g. beclomethasone 17 alpha, 21-dipropionate = BDP) or 16 alpha, 17 alpha-acetals of halogenated 16 alpha, 17 alpha-dihydroxy corticosteroids (e.g. triamcinolone acetonide = TA). The purpose of the present investigation was to increase the ratio between the topical anti-inflammatory (TAIP) and the systemic potencies (SP) of GCS 16 alpha, 17 alpha-acetals, as such compounds are not biotransformed in the lung. Structure-activity investigations in rodents showed that fluoro substituents in positions 6 alpha or 9 alpha or both 6 alpha, 9 alpha 9 alpha increased SP more than TAIP. On the other hand, nonsymmetrical 16 alpha, 17 alpha-acetal substitution increased TAIP more than SP. The best TAIP:SP ratio was obtained with budesonide, which contains this new type of acetal substituent, but has no halogen atoms in the steroid nucleus. In the rat and the mouse budesonide has a 5--10 times better TAIP:SP ratio than 16 alpha, 17 alpha-acetonides, like TA, as well as 17 alpha-ester GCS, like BDP. The improved ratio for budesonide is probably due to a high intrinsic GCS activity at the site of application combined with an effective inactivation by biotransformation after systemic absorption. The importance of the inactivation in the liver was verified by experiments in which the biotransformation capacity of the liver was blocked by SKF-525 A.