Johannes Schneider

Analgesic effects of 1′,1′ dimethylheptyl-Δ8-THC-11-oic acid (CT3) in mice

Abstract The metabolic pathway leading to carboxylic acid derivatives of cannabinoids was discovered more than twenty years ago. While these compounds showed no cannabimimetjc activity, subsequent work documented several biological responses both in vitro and in vivo for the THC acids. These include inhibition of eicosanoid synthesis, antiedema effects, antagonism to PAF actions, inhibition of leucocyte adhesion and anti nociception. In this report we present data further characterizing the analgesic properties of the title substance which is a potent synthetic member of this group. CT3 was effective in the mouse hot plate assay at 48 °C showing an ED-50 of 4.31(3.37–5.83) mg kg when administered i.v (10% Cremophor EL in saline). When given by gavage in peanut oil, it resulted in 30–40% MPE (maximum possible effect) at 10 mg kg with the effect persisting for up to 5 hours. A more potent response was observed in the mouse p-phenylquinone writhing test. When given i.v., it showed an ED-50 of 1.24 (0.84–1.75) mg kg . However, no activity was found with oral administration either in peanut oil or Cremophor EL. At 10 mg kg i.v., a 100% inhibition of the writhing response was seen. The mouse formalin antinociception test was also studied in animals that received CT3 (4.64 mg kg ) I.V. Using three behavioral parameters for activity. The drug showed decreases in each category when compared with vehicle/formalin treated mice. The formalin effect showed a typical two phase, time related, response in which CT3 caused a 64% reduction in the early phase and a 48% reduction in the late phase in a composite score of nociception. Interestingly, it did not alter motor function in the rota rod procedure at 4.64 mg kg i.v.

Time course of IL-6 and TNFα release during endotoxin-induced endotoxin tolerance in rats

Abstract Development of endotoxin tolerance in rats induced by repeated application of low dosages of endotoxin is associated with repeatable IL-6 formation, reversible drop in white blood cells, pronounced consumption of platelets, gradual formation of α2M as an example of acute phase proteins, and flattening TNFα formation. In the status of full tolerance the TNF α release is completely eliminated. Inhibition of TNFα biosynthesis and induction of acute phase protein formation by IL-6 are discussed as possible factors in the development of endotoxin tolerance.

Characterisation of tramadol, morphine and tapentadol in an acute pain model in Beagle dogs

OBJECTIVE To evaluate the analgesic potential of the centrally acting analgesics tramadol, morphine and the novel analgesic tapentadol in a pre-clinical research model of acute nociceptive pain, the tail-flick model in dogs. STUDY DESIGN Prospective part-randomized pre-clinical research trial. ANIMALS Fifteen male Beagle dogs (HsdCpb:DOBE), aged 12-15 months. METHODS On different occasions separated by at least 1 week, dogs received intravenous (IV) administrations of tramadol (6.81, 10.0 mg kg(-1) ), tapentadol (2.15, 4.64, 6.81 mg kg(-1) ) or morphine (0.464, 0.681, 1.0 mg kg(-1) ) with subsequent measurement of tail withdrawal latencies from a thermal stimulus (for each treatment n = 5). Blood samples were collected immediately after the pharmacodynamic measurements of tramadol to determine pharmacokinetics and the active metabolite O-demethyltramadol (M1). RESULTS Tapentadol and morphine induced dose-dependent antinociception with ED50-values of 4.3 mg kg(-1) and 0.71 mg kg(-1) , respectively. In contrast, tramadol did not induce antinociception at any dose tested. Measurements of the serum levels of tramadol and the M1 metabolite revealed only marginal amounts of the M1 metabolite, which explains the absence of the antinociceptive effect of tramadol in this experimental pain model in dogs. CONCLUSIONS AND CLINICAL RELEVANCE Different breeds of dogs might not or only poorly respond to treatment with tramadol due to low metabolism of the drug. Tapentadol and morphine which act directly on μ-opioid receptors without the need for metabolic activation are demonstrated to induce potent antinociception in the experimental model used and should also provide a reliable pain management in the clinical situation. The non-opioid mechanisms of tramadol do not provide antinociception in this experimental setting. This contrasts to many clinical situations described in the literature, where tramadol appears to provide useful analgesia in dogs for post-operative pain relief and in more chronically pain states.

Heparin and the thrombin inhibitor argatroban enhance fibrinolysis by infused or bolus-injected saruplase (r-scu-PA) in rabbit femoral artery thrombosis

Enhancement by anticoagulation of thrombolysis with infused or bolus-injected saruplase (r-scu-PA) has been studied using heparin and the thrombin inhibitor argatroban. In a rabbit femoral artery thrombosis model infusion of saruplase (3 - 12 mg/kg, 60 min) caused a dose-dependent thrombolysis. Reperfusion rate after infusion of 3 mg/kg saruplase alone was 3/6, reperfusion time 42 +/- 3 min and reocclusion rate 2/3; final patency rate at 120 min was 17%. Combination of 3 mg/kg saruplase with heparin (150 U/kg + 100 U/kg.hr i.v.; 5.3-fold PTT-prolongation) resulted in a reperfusion rate of 6/6 after a reperfusion time of 39 +/- 7 min; reocclusion rate was 3/6 and final patency rate was 50%. Argatroban (1 mg/kg + 3 mg/kg.hr i.v.; 2.3-fold PTT prolongation) in combination with saruplase resulted in a reperfusion rate of 6/6 after 26 +/- 5 min; no reocclusion occured and final patency rate was 100% (p less than 0.05 vs saruplase alone). Bolus injection of 6 mg/kg saruplase achieved reperfusion in 5/6 arteries after 15 +/- 3 min, but reocclusion rate was 4/5; final patency rate was 17%. Combination of bolus-injected saruplase with heparin resulted in a reperfusion rate of 4/6 after 8 +/- 3 min and no reocclusion occured; patency rate was 67%. With combination of argatroban and bolus-injected saruplase 6/6 arteries were reperfused after 8 +/- 3 min; reocclusion was prevented and final patency rate was 100% (p less than 0.05 vs saruplase-bolus alone). Systemic fibrinogenolysis was more pronounced with bolus injection than infusion of saruplase. The results indicate that arterial thrombolysis with saruplase can be enhanced by heparin and the thrombin inhibitor argatroban. The bolus injection of saruplase resulted in persistent reperfusion when simultaneous anticoagulation was performed. Despite less PTT prolongation, enhancement of saruplase-induced thrombolysis was more effective with argatroban than with heparin in rabbit femoral artery thrombosis.

Extravasation of leukocytes assessed by intravital microscopy: Effect of thalidomide

Abstract.Objective and Design: Thalidomide is very effective in the treatment of idiopathic aphthous stomatitis, characterized by recurrent focal intramucosal leukocytic vasculitis. The mode of action of thalidomide in this clinical entity may include inhibition of the extravasation of leukocytes. Therefore, we studied the effect of thalidomide on different steps of leukocyte migration by intravital microscopy.¶Material: Male Syrian golden hamsters were used.¶Treatment: Leukocyte migration in buccal mucosa of the hamster cheek pouch was elicited by the local application of lipopolysaccharide (LPS, 20 μg/ml) or murine tumor necrosis factor-α (muTNF-α, 10 ng/ml). (+)-Thalidomide (20–200 mg/kg i.p.) was administered 60 min before the local application of LPS or muTNF-α. Dexamethasone (2 × 1.0–10 mg/kg i.p.) was administered 18 h and 60 min before topical LPS application.¶Methods: The numbers of rolling, firmly adherent and migrating leukocytes were estimated by intravital microscopy up to 165 min after the topical applications of LPS or muTNF-α and evaluated by an interactive image analysis software.¶Results: Thalidomide (20–200 mg/kg i.p.) dose-dependently inhibited LPS-stimulated perivenular leukocyte migration by up to 87 ± 5% and muTNF-α-induced leukocyte migration by up to 78 ± 4%. Dexamethasone (2 ± 1.0–10 mg/kg i.p.) inhibited LPS-stimulated leukocyte migration by up to 85 ± 13%. (+)-Thalidomide (200 mg/kg i.p.) inhibited LPS-stimulated rolling by 80 ± 5% and reduced the number of firmly adherent leukocytes by about 40%. Dexamethasone (2 × 10 mg/kg i.p.) did not reduce the number of rolling leukocytes but inhibited leukocyte adherence by 72 ± 9%.¶Conclusions: These results show that (+)-thalidomide predominantly inhibits leukocyte rolling and thus differs from the glucocorticoid dexamethasone. The inhibition of LPS- or muTNF-α-induced leukocyte extravasation by thalidomide may account for some of its clinical activities.

Fibrin-specific lysis of microthrombosis in endotoxemic rats by saruplase

The dissolution by the fibrinolytic agent saruplase of microthrombi due to disseminated intravascular coagulation (DIC) has been studied in anesthetized rats. The intravenous infusion of E. coli lipopolysaccharide (endotoxin) for 4 hours (total dose: 25 mg/kg) induced marked thrombocytopenia and hypofibrinogenemia. DIC-related microthrombosis, detected as increased deposition of 125I-labelled human fibrin, was found in the liver and the kidneys, but not in the lungs, the heart, the mesenterium, the spleen and the M. rectus abdominis of endotoxemic rats. Treatment with 1-20 micrograms/kg.min saruplase, that was infused concomitantly with endotoxin, dose-dependently and significantly reduced endotoxin-induced microthrombosis in the liver and the kidneys by 85 resp. 88%. When saruplase (20 micrograms/kg.min) was administered only during the last two hours of endotoxin infusion, liver microthrombosis was still significantly dissolved by 69%, whereas renal microthrombosis was insignificantly reduced by 34%. The inhibition of endotoxin-induced microthrombosis took place in the same dosage range as the shortening of the euglobulin clot lysis time in normal rats by saruplase as a measure of its fibrinolytic activity. Saruplase did not modify thrombocytopenia and hypofibrinogenemia in endotoxemic rats. Saruplase per se did not affect plasma fibrinogen levels. Thus, in a fibrin-selective dose range saruplase is able to dissolve microthrombosis associated with DIC in endotoxemic rats.

Comparison of the protective effects by human and bovine superoxide dismutase against ischemia- and reperfusion-induced impairment of kidney function in anesthetized rats

In a rat model of ischemia- and reperfusion-induced kidney damage, the protective effects of human superoxide dismutase produced by genetic technology (hum-SOD) were compared to those of bovine superoxide dismutase (bov-SOD). The intravenous infusion of hum-SOD and bov-SOD, started concomitantly with the kidney reperfusion after a 60-min (or 30-min) period of ischemia, significantly improved the renal function (inulin and p-amino-hippuric acid clearance rates) as compared to the vehicle-treated control group. In contrast, inactive apoenzyme of superoxide dismutase (Apo-SOD) did not improve the impaired renal function after the kidney reperfusion. Therefore, the kidney protection by hum-SOD and bov-SOD may reasonably be ascribed to their specific enzymatic function--scavenging of oxygen radicals. In this respect, hum-SOD proved to be as effective as bov-SOD. To our knowledge this is the first report on a direct pharmacologic comparison of superoxide dismutases from natural and recombinant origin.

The prostacyclin analogue taprostene and recombinant human superoxide dismutase increase the permanent survival rate of endotoxemic rats.

The permanent survival rate of endotoxemic rats was studied. In 40 untreated control rats the survival rate 7 days after the endotoxin administration was 33%. The survival rate was increased to 40% with recombinant human superoxide dismutase (r-HSOD), to 55% (p less than 0.05) with the prostacyclin analogue Taprostene and to 70% (p less than 0.01) with the combination of r-HSOD and Taprostene (20 rats for each treatment group). r-HSOD and Taprostene provide significant and permanent protection in rat endotoxic shock.

Analgesic and antitussive properties of EM 405

EM 405 [l-p-chlorbenzyl-2-dimethyl-amino-methylcyclohexen-l,2] is a new compound with antioedematic activity in acute and chronic inflammation models [1]. The compound has no influence on arachidonic acid metabolism and differs in various aspects from the antiinflammatory action profile of non-steroidal antiinflammatory drugs. Here we report on its antitussive and analgesic properties, the latter being of potential benefit in states of acute and chronic inflammation.

Thrombin inhibitory and clot-specific fibrinolytic activities of the urokinase variant, M23 (rscu-PA-40 kDa/Hir)

The recombinant bifunctional urokinase variant, M23 (rscu-PA-40 kDA/Hir), comprising the kringle and protease domain of single-chain urokinase-type plasminogen activator and a C-terminal fragment of hirudin in one single-chain molecule, was evaluated for its thrombin-inhibitory and fibrinolytic properties in vitro and in vivo. M23 inhibited thrombin-activated coagulation of human blood and thrombin-induced aggregation of human platelet rich plasma in a concentration-dependent manner. The ADP-induced aggregation of human platelet rich plasma was not influenced by M23. In contrast, recombinant single-chain urokinase-type plasminogen activator (saruplase) inhibited neither blood coagulation nor platelet rich plasma aggregation. M23 and saruplase both lysed radiolabelled human thrombi immersed in human plasma (Chandler Loop system) with equal potency. However, there was a significantly lower systemic generation of plasmin (measured as consumption of alpha 2-antiplasmin) by M23 compared to saruplase. In anaesthetized non-heparinized rabbits, experimental femoral artery thrombosis was treated with intravenous bolus injections of M23 or saruplase (6 mg/kg, each). Thrombolytic restoration of arterial blood perfusion was significantly higher in M23- than in saruplase-treated rabbits. Plasma fibrinogen concentrations were decreased markedly in saruplase-treated animals, but remained at significantly higher levels in M23-treated rabbits. In conclusion, the bifunctional molecule, M23, showed thrombin inhibitory and fibrinolytic properties in human in vitro systems and exerted superior thrombolytic effects to saruplase in rabbit femoral artery thrombosis. In vitro and in vivo data indicate that the fibrinolytic activity of M23 is highly clot-specific.