Comparative effects of drugs on four paw oedema models in the rat

Anti-Inflammatory Potential of Pteropodine in Rodents

Pteropodine (PT) is a component of some plants with potentially useful pharmacological activities for humans. This compound has biomedical properties related to the modulation of the immune system, nervous system, and inflammatory processes. This study addresses the anti-inflammatory and antioxidant capacity of pteropodin in a murine model of arthritis and induced edema of the mouse ear. To evaluate the anti-inflammatory activity, we used the reversed passive Arthus reaction (RPAR), which includes the rat paw edema test, the rat pleurisy test, and a mouse ear edema model. The antioxidant effect of PT was evaluated by determining the myeloperoxidase enzyme activity. PT showed an anti-inflammatory effect in the different specific and non-specific tests. We found a 51, 66 and 70% inhibitory effect of 10, 20 and 40 mg/kg of PT, respectively, in the rat paw edema test. In the pleurisy assay, 40 mg/kg of PT induced a low neutrophil count (up to 36%) when compared to the negative control group, and 20 mg/kg of PT increased the content of lymphocytes by up to 28% and the pleural exudate volume decreased by 52% when compared to the negative control group, respectively. We also found an 81.4% inflammatory inhibition of the edema ear with 0.04 mg/ear of PT, and a significant myeloperoxidase enzyme inhibition by the three doses of PT tested. We conclude that PT exerted a potent anti-inflammatory effect in the acute inflammation model in rodents.

A comprehensive insight into the anti-inflammatory properties of dapsone

The 4,4'-diaminodiphenyl sulfone (DDS), also known as dapsone, is traditionally used as a potent anti-bacterial agent in clinical management of leprosy. For decades, dapsone has been among the first-line medications used in multidrug treatment of leprosy recommended by the World Health Organization (WHO). Shortly after dapsone's discovery as an antibiotic in 1937, the dual function of dapsone (anti-microbial and anti-inflammatory) was elucidated. Dapsone exerts its anti-bacterial effects by inhibiting dihydrofolic acid synthesis, leading to inhibition of bacterial growth, while its anti-inflammatory properties are triggered by inhibiting reactive oxygen species (ROS) production, reducing the effect of eosinophil peroxidase on mast cells and downregulating neutrophil-mediated inflammatory responses. Among the leading mechanisms associated with its anti-microbial/anti-protozoal effects, dapsone clearly has multiple antioxidant, anti-inflammatory, and anti-apoptotic functions. In this regard, it has been described in treating a wide variety of inflammatory and infectious skin conditions. Previous reports have explored different molecular targets for dapsone and provided insight into the anti-inflammatory mechanism of dapsone. This article reviews several basic, experimental, and clinical approaches on anti-inflammatory effect of dapsone.

Central mediators of the zymosan-induced febrile response

BACKGROUND

Zymosan is a fungal cell wall protein-carbohydrate complex that is known to activate inflammatory pathways through the Toll-like receptors and is commonly used to induce fever. Nevertheless, the central mediators that are involved in the zymosan-induced febrile response are only partially known.

METHODS

The present study evaluated the participation of prostaglandins, substance P, endothelin-1 (ET-1), and endogenous opioids (eOPs) in the zymosan-induced febrile response by using inhibitors and antagonists in male Wistar rats.

RESULTS

Both nonselective (indomethacin) and selective (celecoxib) cyclooxygenase inhibitors reduced the febrile response induced by an intraperitoneal (i.p.) injection of zymosan. Indomethacin also blocked the increase in the prostaglandin E2 levels in the cerebrospinal fluid. An intracerebroventricular injection of the neurokinin-1, ETB, and μ-opioid receptor antagonists also reduced the febrile response induced by the i.p. injected zymosan. Moreover, the μ-opioid receptor antagonist CTAP also reduced the febrile response induced by intra-articular injection of zymosan.

CONCLUSIONS

These results demonstrate that prostaglandins, substance P, ET-1, and eOPs are central mediators of the zymosan-induced febrile response.

Dapsone in dermatology and beyond

Dapsone (4,4′-diaminodiphenylsulfone) is an aniline derivative belonging to the group of synthetic sulfones. In 1937 against the background of sulfonamide era the microbial activity of dapsone has been discovered. Shortly thereafter, the use of dapsone to treat non-pathogen-caused diseases revealed alternate antiinflammatory mechanisms that initially were elucidated by inflammatory animal models. Thus, dapsone clearly has dual functions of both: antimicrobial/antiprotozoal effects and anti-inflammatory features similarly to non-steroidal anti-inflammatory drugs. The latter capabilities primarily were used in treating chronic inflammatory disorders. Dapsone has been investigated predominantly by in vitro methods aiming to get more insights into the effect of dapsone to inflammatory effector cells, cytokines, and/or mediators, such as cellular toxic oxygen metabolism, myoloperoxidase-/halogenid system, adhesion molecules, chemotaxis, membrane-associated phospholipids, prostaglandins, leukotrienes, interleukin-8, tumor necrosis factor α, lymphocyte functions, and tumor growth. Moreover, attention has been paid to mechanisms by which dapsone mediates effects in more complex settings like impact of lifespan, stroke, glioblastoma, or as anticonvulsive agent. Additionally, there are some dermatological investigations in human being using dapsone and its metabolites (e.g., leukotriene B₄-induced chemotaxis, ultraviolet-induced erythema). It could be established that dapsone metabolites by their own have anti-inflammatory properties. Pharmacology and mechanisms of action are determining factors for clinical use of dapsone chiefly in neutrophilic and/or eosinophilic dermatoses and in chronic disorders outside the field of dermatology. The steroid-sparing effect of dapsone is useful for numerous clinical entities. Future avenues of investigations will provide more information on this fascinating and essential agent.

Modeling natural anti-inflammatory compounds by molecular topology

One of the main pharmacological problems today in the treatment of chronic inflammation diseases consists of the fact that anti-inflammatory drugs usually exhibit side effects. The natural products offer a great hope in the identification of bioactive lead compounds and their development into drugs for treating inflammatory diseases. Computer-aided drug design has proved to be a very useful tool for discovering new drugs and, specifically, Molecular Topology has become a good technique for such a goal. A topological-mathematical model, obtained by linear discriminant analysis, has been developed for the search of new anti-inflammatory natural compounds. An external validation obtained with the remaining compounds (those not used in building up the model), has been carried out. Finally, a virtual screening on natural products was performed and 74 compounds showed actual anti-inflammatory activity. From them, 54 had been previously described as anti-inflammatory in the literature. This can be seen as a plus in the model validation and as a reinforcement of the role of Molecular Topology as an efficient tool for the discovery of new anti-inflammatory natural compounds.

Inhibition of microsomal prostaglandin E2 synthase-1 as a molecular basis for the anti-inflammatory actions of boswellic acids from frankincense

BACKGROUND AND PURPOSE

Frankincense, the gum resin derived from Boswellia species, showed anti-inflammatory efficacy in animal models and in pilot clinical studies. Boswellic acids (BAs) are assumed to be responsible for these effects but their anti-inflammatory efficacy in vivo and their molecular modes of action are incompletely understood.

EXPERIMENTAL APPROACH

A protein fishing approach using immobilized BA and surface plasmon resonance (SPR) spectroscopy were used to reveal microsomal prostaglandin E(2) synthase-1 (mPGES1) as a BA-interacting protein. Cell-free and cell-based assays were applied to confirm the functional interference of BAs with mPGES1. Carrageenan-induced mouse paw oedema and rat pleurisy models were utilized to demonstrate the efficacy of defined BAs in vivo.

KEY RESULTS

Human mPGES1 from A549 cells or in vitro-translated human enzyme selectively bound to BA affinity matrices and SPR spectroscopy confirmed these interactions. BAs reversibly suppressed the transformation of prostaglandin (PG)H(2) to PGE(2) mediated by mPGES1 (IC(50) = 3-10 µM). Also, in intact A549 cells, BAs selectively inhibited PGE(2) generation and, in human whole blood, β-BA reduced lipopolysaccharide-induced PGE(2) biosynthesis without affecting formation of the COX-derived metabolites 6-keto PGF(1α) and thromboxane B(2) . Intraperitoneal or oral administration of β-BA (1 mg·kg(-1) ) suppressed rat pleurisy, accompanied by impaired levels of PGE(2) and β-BA (1 mg·kg(-1) , given i.p.) also reduced mouse paw oedema, both induced by carrageenan.

CONCLUSIONS AND IMPLICATIONS

Suppression of PGE(2) formation by BAs via interference with mPGES1 contribute to the anti-inflammatory effectiveness of BAs and of frankincense, and may constitute a biochemical basis for their anti-inflammatory properties.

Hyperforin, an Anti-Inflammatory Constituent from St. John's Wort, Inhibits Microsomal Prostaglandin E(2) Synthase-1 and Suppresses Prostaglandin E(2) Formation in vivo

The acylphloroglucinol hyperforin (Hyp) from St. John's wort possesses anti-inflammatory and anti-carcinogenic properties which were ascribed among others to the inhibition of 5-lipoxygenase. Here, we investigated whether Hyp also interferes with prostanoid generation in biological systems, particularly with key enzymes participating in prostaglandin (PG)E₂ biosynthesis, i.e., cyclooxygenases (COX)-1/2 and microsomal PGE₂ synthase (mPGES)-1 which play key roles in inflammation and tumorigenesis. Similar to the mPGES-1 inhibitors MK-886 and MD-52, Hyp significantly suppressed PGE₂ formation in whole blood assays starting at 0.03–1 μM, whereas the concomitant generation of COX-derived 12(S)-hydroxy-5-cis-8,10-trans-heptadecatrienoic acid, thromboxane B₂, and 6-keto PGF_1α was not significantly suppressed up to 30 μM. In cell-free assays, Hyp efficiently blocked the conversion of PGH₂ to PGE₂ mediated by mPGES-1 (IC₅₀ = 1 μM), and isolated COX enzymes were not (COX-2) or hardly (COX-1) suppressed. Intraperitoneal (i.p.) administration of Hyp (4 mg kg⁻¹) to rats impaired exudate volume and leukocyte numbers in carrageenan-induced pleurisy associated with reduced PGE₂ levels, and Hyp (given i.p.) inhibited carrageenan-induced mouse paw edema formation (ED₅₀ = 1 mg kg⁻¹) being superior over indomethacin (ED₅₀ = 5 mg kg⁻¹). We conclude that the suppression of PGE₂ biosynthesis in vitro and in vivo by acting on mPGES-1 critically contributes to the anti-inflammatory efficiency of Hyp.

Ketoprofen in piglets: enantioselective pharmacokinetics, pharmacodynamics and PK/PD modelling

The chiral pharmacokinetics and pharmacodynamics of ketoprofen were investigated in a placebo-controlled study in piglets after intramuscular administration of 6 mg/kg racemic ketoprofen. The absorption half-lives of both enantiomers were short, and S-ketoprofen predominated over R-ketoprofen in plasma. A kaolin-induced inflammation model was used to evaluate the anti-inflammatory, antipyretic and analgesic effects of ketoprofen. Skin temperatures increased after the kaolin injection, but the effect of ketoprofen was small. No significant antipyretic effects could be detected, but body temperatures tended to be lower in the ketoprofen-treated piglets. Mechanical nociceptive threshold testing was used to evaluate the analgesic effects. The piglets in the ketoprofen-treated group had significantly higher mechanical nociceptive thresholds compared to the piglets in the placebo group for 12-24 h following the treatment. Pharmacokinetic/pharmacodynamic modelling of the results from the mechanical nociceptive threshold testing gave a median IC(50) for S-ketoprofen of 26.7 μg/mL and an IC(50) for R-ketoprofen of 1.6 μg/mL. This indicates that R-ketoprofen is a more potent analgesic than S-ketoprofen in piglets. Estimated ED(50) for racemic ketoprofen was 2.5 mg/kg.

Development and validation of a new model of inflammation in the cat and selection of surrogate endpoints for testing anti-inflammatory drugs

In laboratory animals many models of inflammation have been developed for preclinical evaluation of the pharmacological profiles of nonsteroidal anti-inflammatory drugs (NSAIDs). In contrast, in species of veterinary interest, including the cat, NSAIDs have been studied mainly using dose-titration or dose-confirmation studies in clinical subjects. This is due to the scarcity of appropriate animal models and to the associated lack of quantitative validated endpoints describing the magnitude and time course of drug response. Determination of pharmacokinetic/pharmacodynamic (PK/PD) relationships provides a powerful approach for the selection of effective and safe dosage regimens. In this study, a paw inflammation model in the cat was developed for the preclinical evaluation of NSAIDs using PK/PD modelling. Subcutaneous injection of 500 mg kaolin in the paw produced a well-defined and reproducible inflammatory response that lasted 4-5 days. Several endpoints were assessed for their clinical relevance and for their metrological performance (accuracy and reproducibility). Body temperature, lameness scoring, locomotion tests and possibly skin temperature were the most appropriate endpoints for testing the antipyretic, analgesic and anti-inflammatory effects of NSAIDs in the cat.

Anti-inflammatory action of Pluchea sagittalis: involvement of an antioxidant mechanism

Pluchea sagittalis, (Lam.) Cabr., a popular medicinal herb grown in South America, was studied for anti-inflammatory and antioxidant activities. The anti-edema action of P. sagittalis aqueous extract was assayed in different models of inflammation: 1) the mouse ear edema test induced by arachidonic acid and croton oil; 2) the rat hind-paw edema test produced by several inflammatory inductors: carrageenan, dextran, zymosan, platelet-activating factor (PAF) and arachidonic acid; 3) a subacute model based on the rat carrageenan air-pouch granuloma test. Blood leukocyte free radical production was measured by flow cytometry with 2',7'-dichlorofluorescin diacetate (DCFH-DA) in vivo, in rats with induced air-pouch granuloma, and in a model in vitro. stimulating leukocytes with hydrogen peroxide. The aqueous extract of P. sagittalis showed a marked anti-inflammatory effect in both ear edema tests, dextran and carrageenan hind-paw edemas and carrageenan air-pouch model. It also had a potent antioxidant activity in blood leukocytes, both in vivo and in vitro. Our results correlate the reduction of free radical production with the anti-inflammatory effect of this plant.

Percutaneous absorption of ketoprofen. I. In vitro release and percutaneous absorption of ketoprofen from different ointment bases

Ketoprofen (KP) is a potent non-steroidal anti-inflammatory drug which is used for the treatment of rheumatoid arthritis. The oral administration of KP can cause gastric irritation and renal adverse effects. Topical application of the drug can bypass gastrointestinal disturbances and provide relatively consistent drug levels at the site of action. Since the efficacy of an ointment depends on the type of ointment base and the concentration of the drug, four different bases (white petrolatum, cold cream, hydrophilic ointment and Carbopol 940 gel) were used at 1, 3, 5, 7 and 10% concentrations of KP to evaluate the effect of ointment base and concentration. The general rank order of the drug release was found to be: Carbopol gel > hydrophilic ointment > cold cream > white petrolatum. There was a positive correlation between the concentration of KP and release rate for all bases except Carbopol gel. The in vivo percutaneous absorption of KP from different ointment bases at 3% concentration was studied by carrageenan-induced paw edema in mice. The rank order of the percent edema inhibition was as follows: Carbopol gel > or = hydrophilic ointment > cold cream > white petrolatum. There was a good correlation between the in vitro and in vivo results.

Assessment of antiinflammatory agents using 125I-labeled human serum albumin to quantify footpad edema volume in the rat

Intravenously injected human serum albumin, labeled with radioactive iodine ([125I]HSA), accumulates at inflammatory foci in proportion to the volume of the exudate, making it possible to quantify the volume of edema. This paper describes the use of [125I]HSA to measure edema formation in the carrageenin rat-footpad model, both continuously and at a single time point. In assessing antiinflammatory agents, the method was shown to be more sensitive than the most commonly used technique of thickness measurement. Because anesthetics are known to suppress inflammation, the comparative effect of five anesthetic agents on the inflammatory response was determined. Ether was the only anesthetic tested that did not substantially inhibit the accumulation of edema. The technique overcomes many of the limitations of previously used procedures and has the potential to become the method of choice when assessing edema in the rat footpad.

Canine carrageenin-induced acute paw inflammation model and its response to nonsteroidal antiinflammatory drugs

A quantitative method for testing antiinflammatory agents in beagles has been developed, based on measurement of paw inflammation induced by a local injection of carrageenin. Carrageenin [0.5 mL of 2% (wt/vol) in saline] was injected into the plantar region of the hindpaws of pentobarbital-anesthetized beagles. Paw pressure changes registered from a water-filled balloon held on the top of the paw by a light adhesive tape wrapping were monitored for 240 min. In control dogs given 0.5% (wt/vol) methylcellulose (10 mL/kg orally) just before carrageenin, paw pressure increased significantly (p less than 0.05) over eightfold, from 2.9 +/- 0.8 mm Hg (mean +/- SEM, n = 29 paws) at 75 min to 26.0 +/- 3.5 mmHg at 240 min. The increase in paw pressure was significantly inhibited by the cyclooxygenase inhibitors, ibuprofen, indomethacin, and orpanoxin, and partially inhibited by the lipoxygenase inhibitor, phenidone, administered orally before carrageenin injection. Thus this model, with further characterization, could provide a convenient, quantitative way of assessing the efficacy of nonsteroidal antiinflammatory agents in dogs.

Kinins and peritoneal exudates induced by carrageenin and zymosan in rats

1. Kinins were measured by a radioimmunoassay in the inflammatory exudates induced by carrageenin or zymosan in the peritoneal cavity of normal Wistar rats and of kininogen-deficient Brown Norway rats. 2. After administration of carrageenin to normal rats, levels of immunoreactive kinins showed a single peak during the first two hours and then decreased. The presence of kinins preceded and accompanied the exudation of 125I-labelled albumin. Kinins were identified as bradykinin by chromatography. 3. Captopril, an inhibitor of kininase 2, increased the level of kinins and the volume of the exudates after carrageenin treatment. In Brown Norway rats, the volume of the exudates was small and contained little or undetectable amounts of immunoreactive kinins. 4. During zymosan-induced peritonitis, the exudates were devoid of immunoreactive kinins in both species. The volume of the exudates was larger in kininogen-deficient rats than in normal rats. 5. We conclude that in rats, the kinin system is a major factor responsible for the development of the inflammatory reactions induced by carrageenin, but is not involved in the reactions induced by zymosan.

Inhibitory effect 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) on type III allergic (Arthus) reaction

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 non-steroidal, non-acidic agent, markedly inhibits type III allergic (Arthus) reaction; the ID50 values of AA-2379 in the rat reversed passive Arthus pleurisy, the rat active Arthus pleurisy, and the reversed passive Arthus reaction in rat skin were 5-10 mg/kg, p.o., and 30 mg/kg of AA-2379 inhibited the active Arthus reaction in rabbit skin by about 50%. Dexamethasone, but not acidic non-steroidal anti-inflammatory drugs and aminopyrine, inhibited the Arthus reaction. The vascular permeability in the reversed passive Arthus pleurisy is enhanced biphasically in the early response mediated by physiologically active amines, prostaglandins, and leukotrienes, and in the late response mediated by complements and polymorphonuclear leukocytes (PMNs). AA-2379 inhibited the late response more potently than the early one. Furthermore, when given after the early response was reduced, AA-2379 obviously inhibited the late response. Rat zymosan-induced paw edema and mouse zymosan-activated serum-induced peritonitis, mediated by complements, were dose-dependently inhibited by AA-2379; the ID50 values were 11.4 and 10.2 mg/kg, p.o., respectively. The results suggest that AA-2379 differs from non-steroidal anti-inflammatory agents in strongly inhibiting the late response of the Arthus reaction, which associated with PMNs.

The effects of steroidal and nonsteroidal anti-inflammatory agents on uptake of Evans blue in experimental metastasis

The effects of anti-inflammatory drugs on uptake of Evans blue were studied in solitary Walker carcinosarcomas implanted in the livers of Sprague-Dawley rats. Animals were sacrificed at 5 min, 30 min, and 6 hr after administration of the anti-inflammatory drugs and Evans blue, and spectrophotometric measurements of the Evans blue in tumor and normal liver tissue were carried out. Uptake of Evans blue in the tumors was significantly decreased at all time periods after the injection of the following, as compared to controls: steroids (cortisol, methylprednisolone, and triamcinolone), the antihistamine diphenhydramine, and nonsteroidal anti-inflammatory agents (naproxen, ibuprofen, indomethacin, and phenylbutazone). The effects of these drugs on uptake of Evans blue in the normal liver were more variable.

Inhibitory effects of a novel synthetic protease inhibitor, FUT-175, on the paw edema in rats and zymosan-induced complement activation in vitro

FUT-175 inhibited the zymosan-induced rat paw edema in a dose-dependent manner, while indomethacin exhibited no significant activities in this model. FUT-175 also inhibited the decrease in hemolytic complement (CH50) induced by zymosan in vitro, and indomethacin was inactive. These results suggest that FUT-175 has potent in vitro and in vivo inhibitory activity against the activation of the complement system induced by zymosan.

Mast cell amines and the oedema induced by zymosan and carrageenans in rats

Cimetidine and metiamide suppressed the paw swelling induced in rats by low doses of histamine while these H2 antagonists had little effect on the oedema induced by 100 micrograms of histamine and inhibited by mepyramine. When administered 0.5 h before the inflammagens, H2 antagonists reduced the oedema induced by zymosan and iota carrageenan; they had a slight effect on the oedema induced by lambda and kappa carrageenans and no effect on the oedema induced by compound 48/80. When administered 18 h before the inflammagens, cimetidine greatly increased zymosan oedema and slightly increased lambda carrageenan oedema. Mepyramine, methysergide or depletion of the 5-hydroxytryptamine stores in mast cells by pretreatment with reserpine inhibited the oedema induced by compound 48/80 and zymosan but did not affect the oedema induced by lambda and kappa carrageenans. Histamine may play a dual role in inflammatory reactions. Mast cell amines take a part in the development of zymosan oedema though they play a minor role in the oedema induced by the carrageenans.

Further studies of the mechanism of counter irritation by turpentine

The influence of counter irritation by turpentine (0.2 ml) on zymosan- and carrageenan-oedemas was investigated in the rat. Zymosan-oedema was inhibited by mepyramine and methysergide and by leucopenia. It was not modified by captopril and developed normally in kininogendeficient Brown Norway rats. Leucocytes and mast cell amines but not kinins are thus involved in zymosan-oedema. The last phase of this reaction was inhibited by counter irritation alone, but the odema was largely depressed by counter irritation in rats pretreated with mepyramine and methysergide. Carrageenan-oedema was increased by kininase inhibitors and inhibited by leucopenia in normal rats. This inflammatory reaction had a small developement and was not increased by kininase inhibitors in kininogen-deficient BN rats. Leucocytes and kinins participate in the developement of this inflammatory reaction in normal rats while kinins are lacking in deficient rats. Counter irritation depressed carrageenan-oedema in deficient Brown Norway rats and suppressed the potentiating effect of kininase inhibitors in normal rats. Carrageenan oedema was nearly abolished in turpentine-treated leucopenic rats. These results suggest that the anti-inflammatory effect of counter irritation by turpentine could depend on a reduction of leucocyte accumulation into zymosan-oedema and on a reduction of both kinin formation and of leucocyte accumulation into carrageenan-oedema. The significance of T-kininogen as acute phase reactant is discussed.

Pharmacological studies of FUT-175, nafamstat mesilate. I. Inhibition of protease activity in in vitro and in vivo experiments

FUT-175, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate (nafamstat mesilate), a novel synthetic protease-inhibiting agent, was studied to determine its in vitro effects against various proteases and other enzymes, as well as to determine its in vivo protease inhibitory effects. FUT-175 was found to inhibit, in an intense, specific and reversible way, the enzyme activities of trypsin, C1r, C1s, thrombin, kallikrein and plasmin with IC50 values of the order of 10(-6)-10(-8) M. FUT-175 also inhibited complement-mediated hemolysis, including both classical and alternative pathways, sites of inhibition being on C1r and C1s as evidenced by the intermediate-cell technique. In animal model reactions in which the complement system is known to be involved as pathogenetic factors, e.g., Forssman shock, Forssman cutaneous vasculitis, zymosan-induced paw edema, endotoxin shock and local Shwartzman reaction, FUT-175 was highly effective in that, for example, intravenous dosing at 3 mg/kg could completely protect guinea pigs from the lethal Forssman shock. FUT-175 was also found to be effective in trypsin-induced shock in mice, in lethality due to thrombin-thrombosis in mice and in kinin formation in the inflammatory process in rats.

Effects of various substances on two types of inflammatory reaction in animals

The effects of 16 substances, including non-steroidal anti-inflammatory agents, a corticoid, phenols, immunomodulators and gold salts, were studied using two types of acute inflammatory reaction, a non-specific reaction (carrageenan-induced oedema) and an immune reaction (reversed passive Arthus reaction in the rat or active Arthus reaction in the mouse). Results revealed that the active Arthus model appears to be more selective than the passive reversed Arthus model, which is itself less sensitive than the carrageenan model. The active Arthus reaction might be useful for secondary screening of molecules that act on mechanisms modulating the intervention of complement and the various functions of polymorphonuclear leucocytes, and the passive Arthus reaction appears to be more suitable for preliminary screening. The activities of the different substances studied are discussed in terms of their modes of action and toxicity.

Anti-inflammatory effect of LA 2851 and reference drugs on some models of inflammation. Investigation of the mechanism of action

LA 2851 (2-4-diamino-7-methyl-pyrazolo (1,5-a) 1,3,5-triazine), a bronchodilator and antiallergic compound, in type I hypersensitivity, has been tested orally for activity against carrageenan oedema and complement dependent, reverse passive Arthus (RPA) and zymosan oedema in rats. Pharmacokinetic determinations were also realized in order to correlate plasma blood levels and pharmacological activity. LA 2851 was found active in the first test but showed a more marked effect in the immunologically mediated RPA reaction and zymosan oedema. Among reference drugs tested, theophylline showed the same pattern in contrast with non-steroidal anti-inflammatory agents. LA 2851 and theophylline, using a superfused lung preparation, were found ineffective on the synthesis of cyclooxygenase products from arachidonic acid. LA 2851 as theophylline inhibited cAMP phosphodiesterase (PDE) but this inhibition does not seem to be involved in their anti-inflammatory activity since papaverine, a potent inhibitor of PDE, was totally inactive. The activity on RPA and zymosan inflammation was achieved at the drug plasma level in the range of those required to relax the trachea. The same antagonism was obtained with the 2 drugs at a lower plasma level with LA 2851 than with theophylline for the same dose administered (25 mg/kg). LA 2851 and theophylline did not inhibit all the components of the inflammatory process since maximum inhibition did not exceed 60% up to 200 mg/kg and 100 mg/kg respectively.

Quantitation of experimental postsurgical edema

Many oral surgical procedures are followed by varying degrees of edema. Although numerous methods of minimizing swelling have been advocated, no technique has gained complete acceptance. A major problem has been the inability to document the efficacy of suggested treatments convincingly. The present study quantitates edema by measuring differences in percentage of water content between operated and unoperated tissues over a period of one week. Percentage difference in water content peaked by 48 to 72 hours and was followed by gradual resolution. By use of this model system, a steroid-induced, dose-dependent suppression of postsurgical swelling was confirmed.

The role of low dosage prothionamide with and without 4,4'-diamino diphenyl sulphone for use with isoniazid in the treatment of experimental mouse tuberculosis

To determine whether or not low dosage prothionamide (PTH), with or without diamino diphenyl sulphone (DDS), can replace PAS or thiacetazone as the companion drug to isoniazid (INH) in the treatment of tuberculosis, two experiments have been performed in mice. In experiment I the 2-month effectiveness of 25mg/kg INH alone, INH+PTH (25mg/kg) or INH+PTH+DDS (10mg/kg) was investigated. Both PTH-containing regimens were equally effective in preventing the selection of INH-resistant mutants but PTH did not appear to add much to the bactericidal activity of INH. In experiment II the one year effectiveness of similar regimens supplemented by an initial month of streptomycin (SM) was investigated. Again PTH appeared very effective whereas DDS seemed ineffective. Therefore it seems that PTH is likely to be a good companion drug for INH when used in man at the dosage of 5mg/kg which is more or less equivalent to 25mg/kg in the mouse.

Action of gold salts in some inflammatory and immunological models

Several gold salts were compared in kaolin-induced rat paw oedema, u.v. erythema in guinea pigs, delayed type hypersensitivity and humoral immunity in mice, and adjuvant-induced arthritis in the rat. In the latter the additional parameters of serum gold and copper levels and lysosomal enzyme activity were determined. In addition, the in vitro inhibition of several lysosomal enzymes derived from mouse macrophages was studied. The gold compounds examined were aurothiomalate, aurothioglucose, triethylphosphine gold chloride (SK & F 36914) and its glucopyranoside derivative (SK & F D-39162), triphenylphosphine gold chloride and sodium gold chloride dihydrate. SK & F 36914 and SK & F D-39162 has significant activity after oral dosage upon paw kaolin and u.v. erythema in rats and guinea pigs, respectively. Gastric swelling also occurred. In Wistar rats, adjuvant arthritis was little affected by the gold salts but in the Lewis rats there was suppression. In both strains there was less elevation in serum copper levels with treatment by SK & F 36914 and SK & F D-39162, but not by aurothiomalate. None of the compounds had any measurable effect on delayed hypersensitivity or humoral antibody levels in mice. The in vitro activities of cathepsin B1 and cathepsin D were inhibited by all the gold compounds. Reactivity of gold compounds with glutathione and cysteine in vitro was dependent on compound solubility and the nature of the gold ligand. Considerable differences exist between the profiles of activity for the different gold salts evaluated. These observations indicate that some gold salts do possess anti-inflammatory activity with a potency similar to that of indomethacin.