Observations on the pharmacological properties of inflammatory exudate

Modifications in the regression of the acute inflammation caused by a beta-adrenergic effect unbalanced by the alpha-component ("biased beta-effect")

A biased beta-adrenergic effect was produced either by blocking the alpha-adrenergic component of endogenous catecholamines using phentolamine or by application of isoproterenol. Both experimental conditions led to a prolongation of the lymphocyte phase of the inflammatory process. A beta-bias also curbed the activity of a substance (or substances) inhibiting the ingress of lymphocytes into the site of inflammation (subcutaneously injected Sephadex) around the fourth and fifth day after the onset of inflammation. This lack in activity is evidently connected with the prolonged lymphocyte phase.

Anti-inflammatory and related properties of 2-(2,4-dichlorophenoxy)phenylacetic acid (fenclofenac)

Fenclofenac was shown to possess anti-inflammatory, antinociceptive and antipyretic properties as measured by tests in rats that detect clinically active compounds. In a chronic test for assessing anti-inflammatory activity (established adjuvant arthritis), it was approximately equipotent to alclofenac, fenoprofen calcium and phenylbutazone, more potent than acetylsalicylic acid and ibuprofen, but was less potent than diclofenac sodium, indomethacin, ketoprofen and naproxen. In contrast, the potency of fenclofenac in acute tests for anti-inflammatory, antinociceptive and anti-pyretic activity was generally lower, the drug being approximately equipotent to acetylsalicylic acid in such tests. The anti-inflammatory activity of fenclofenac was not mediated via the pituitary-adrenal axis or a counter-irritant action. Fenclofenac was shown to have remarkably low gastric ulcerogenic potential, both acutely and chronically.

The possible occurrence of endogenous anti-inflammatory substances in the blood of injured rats

1 Using the carrageenin rat paw oedema test as an assay, an attempt has been made to confirm the presence of anti-inflammatory activity in the blood of rats with a chronic inflammatory lesion induced by a polyester sponge, and to relate such activity to the systemic anti-inflammatory effect exerted in situ by the lesion. In addition, plasma from rats given acetic acid intraperitoneally has been examined for anti-inflammatory properties. 2 The activity of serum obtained from sponge-bearing adrenalectomized Wistar rats did not differ significantly from that obtained from animals without implants. Furthermore, implanted sponges exerted no systemic anti-inflammatory effect. 3 Similar experiments were performed in sponge-bearing adrenalectomized Sprague-Dawley rats, plasma instead of serum being examined for anti-inflammatory activity. The plasma removed from such animals possessed no anti-inflammatory activity, whilst implanted sponges exerted a small, yet significant, systemic inhibitory effect. 4 When the irritancy of sponge implants was augmented with croton oil, more marked systemic anti-inflammatory effects were observed. However, the plasma obtained from rats injured in this manner exerted no anti-inflammatory effect. 5 No anti-inflammatory activity could be detected in plasma samples obtained from rats treated with doses of acetic acid capable of producing pronounced systemic anti-inflammatory effects. 6 It was concluded that the induction of these inflammatory lesions in rats does not appear to lead to a detectable release of endogenous anti-inflammatory substances into the circulation.

Prostaglandins and the anti-inflammatory activity of a human plasma fraction in carrageenan-induced paw oedema in the rat

A fraction prepared from normal human plasma inhibits the swelling of the acute carrageenan-induced paw oedema in the rat. Treatment of the animals with prostaglandin E1, arachidonic acid or with substances which either block the formation of prostaglandins or antagonize their action showed that these mediators are concerned in the development of the paw oedema. The anti-inflammatory effect of the plasma fraction in the carrageenan reaction does not involve a specific interference with the prostaglandin system. The plasma fraction is not an inhibitor of the action of SRS-A on the guinea-pig ileum.

Anti-inflammatory and irritant effects of a fraction from normal human plasma

1 By the use of carrageenan-induced rat paw oedema assay the anti-inflammatory activity of a fraction isolated from normal human plasma has been measured after its intravenous, intraperitoneal and oral administration. Its effects in the dextran-induced rat paw oedema and the systemic dextran anaphylactoid reaction in the rat were also studied.2 The fraction showed marked anti-inflammatory activity in the carrageenan test after intravenous administration and a smaller but still significant activity when given intraperitoneally, but was inactive orally after the administration of a larger dose. It was active in the dextran-induced paw oedema test but not against the anaphylactoid reaction.3 A comparison between its anti-inflammatory and irritant properties revealed no correlation when each parameter was determined in relation to dose. The fraction did not affect the blood pressure of the anaesthetized rat.4 These findings are discussed in relation to the existence of a natural anti-inflammatory substance or substances in human plasma.

Anti-inflammatory activity in human plasma

Pooled human plasma contains a fraction, separable by ultrafiltration and column chromatography, which possesses anti-inflammatory activity in the carrageenan oedema test in the rat, may be partially purified by solvent extraction, has an apparent molecular weight below 1000, and is resistant to acid and proteolytic digestion.

A substance showing experimental anti-inflammatory activity has been isolated from human serum (McArthur, Smith & Freeman, 1972). The present paper describes a much simpler preparation of this material from pooled human plasma, its partial purification by extraction with acetone and ethanol, its ultrafiltration through several membranes, and its resistance to acidic, proteolytic and thermal degradation. A preliminary account of part of this work has been published (Elliott, Ford-Hutchinson & others, 1973).

Separation of irritancy from the anti-inflammatory component of inflammation exudate

The anti-inflammatory component found in inflammation exudates has been purified by Sephadex gel filtration and preparative polyacrylamide electrophoresis. Highly purified material produces no greater irritancy upon injection than 0.9% sodium chloride.

Relationship between the anti-inflammatory and irritant properties of inflammatory exudate

1. Using the rat paw oedema assay procedure a comparison was made between the anti-inflammatory and irritant properties of the inflammatory exudate obtained from polyester sponges implanted subcutaneously in adrenalectomized rats. Where necessary, comparison was also made with a known counter-irritant, carrageenin.2. A significant correlation between the anti-inflammatory and irritant properties of sponge exudate was observed when each parameter was determined in relation to dose. A similar result was obtained with carrageenin.3. A comparison of the two activities of sponge exudate samples harvested at various times following sponge implantation did not give a significant correlation although in each case significant anti-inflammatory activity was accompanied by marked irritation.4. Time-effect curves of the two activities of sponge exudate showed a significant correlation over the time period examined. However, no such correlation was obtained using carrageenin.5. Both activities of sponge exudate were retained following dialysis.6. These findings are discussed in relation to a counter-irritant mode of action for sponge exudate.