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This study was conducted in order to evaluate whether or not caffeine has any effect on venlafaxine antinociception in mice in acute application. Swiss albino mice, both male and female, were tested with hot plate analgesiameter set at 52.5 +/- 0.1 degrees C. The mice were divided into four groups receiving saline + saline, caffeine (5 mg/kg) + saline, saline + venlafaxine (70 mg/kg) and caffeine (5 mg/kg) + venlafaxine (70 mg/kg) intraperitoneally. Each animal was tested on hot plate before treatment and 30, 45, 60 min after injections. Venlafaxine produced a significant antinociceptive effect at 30 and 45 min and the effect decreased at 60 min. Caffeine alone showed no significant antinociceptive effect at the applied dose however, it significantly antagonized the antinociceptive effect of venlafaxine at 30 min. As a result, caffeine inhibits the antinociceptive effect of venlafaxine in acute application in mice and this observation provides new evidence that the adenosinergic system may play a significant role in the mechanism of antinociceptive action of venlafaxine. This study raises the possibility that caffeine consumption might influence the effectiveness of venlafaxine in the treatment of pain in humans.

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The interactions on antinociception between a muscarinic agonist arecoline (arec), an anticholinesterase physostigmine (physo) which both cross CNS, and a peripherally acting antimuscarinic hyoscine-N-butyl bromide (hyo), were assessed by tail flick test in mice. All drugs were administered intraperitoneally (i.p.). While hyoscine-N-butyl bromide (0.15 and 4.00 mg/kg, i.p.) did not produce antinociception, physostigmine salicylate (0.3 mg/kg, i.p.) and arecoline hydrobromide (8.00 mg/kg, i.p.) exerted significant antinociceptive effect. In combined applications, physo + hyo (0.075 + 0.15; 0.15 + 0.30; 0.30 + 0.60 mg/kg) and arec + hyo (1.00 + 0.50; 2.00 + 1.00; 4.00 + 2.00; 8.00 + 4.00 mg/kg), respectively, produced significant antinociception and the tail flick latencies produced by physo 0.30 + hyo 0.60 mg/kg and arec 8.00 + hyo 4.00 mg/kg were not significantly different from those of physo 0.30 mg/kg and arec 8.00 mg/kg, respectively, showing that hyo did not antagonise the antinociceptive effects of physo and arec. We believe that combining an centrally acting cholinergic drug applied systemically with a peripherally acting (quaternary amine) antimuscarinic compound might be used as an effective analgesic in clinical practice.

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The calcium channel antagonistic effect of taxine (CAS 12607-93-1) (active principle of leaves of English yew; Taxus baccata L.) was investigated in isolated aorta of rabbit, and its organ selectivity was determined and compared with that of verapamil (CAS 52-53-9) in isolated aorta, atrium and jejunum preparations of rabbits. Taxine (10(-6)-10(-4) g/ml) inhibited concentration-dependently the Ca(2+)-induced contractions of the aorta depolarized by 60 mmol/l K+ in Ca2+ free media. Both taxine (3 x 10(-7)-10(-4) g/ml) and verapamil (10(-10)-10(-7) g/ml) relaxed the aorta, which was precontracted by 60 mmol/l K+, in a concentration-dependent manner. The IC50 of taxine was 4.78 x 10(-6) and that of verapamil 2.45 x 10(-9) g/ml. Similar effects of taxine were observed in the endothelium-denuded aortic strips. Taxine (3 x 10(-8)-10(-5) g/ml) and verapamil (10(-10)-10(-6) g/ml) produced concentration-dependent negative inotropic and chronotropic effects on isolated atrium preparations. The IC50 values of taxine were 3.63 x 10(-7), and 5.75 x 10(-7) g/ml and those of verapamil 2.69 x 10(-9) and 3.71 x 10(-8) g/ml for contraction and rate, respectively. Taxine and verapamil reduced the amplitude of peristaltic movements of the jejunum. The IC50 values were 1.86 x 10(-5) g/ml for taxine and 3.80 x 10(-8) g/ml for verapamil. From these data it was concluded that taxine has calcium channel antagonistic activity. It was found that taxine was about 13 times more selective for the heart than the vessel and 51 times more selective for the heart than the intestine with respect to inotropic effects, and 8 times more selective for the heart than the vessel, and 32 times more selective for the heart than the intestine in regard to chronotropic effects. When compared with relative selectivity between heart and vessel, taxine is about 14 and 126 times more selective for the heart than verapamil with respect to inotropic and chronotropic effects, and taxine is about 4 and 32 times more selective for the heart than verapamil when compared with relative selectivity on the intestine in regard to inotropic and chronotropic effects, respectively.

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Tribulus terrestris L. is an annual plant which has been commonly used in folk medicine as diuretic and against colic pains, hypertension and hypercholesterolemia in Turkey. This study investigated the effects of liophilized saponin mixture of this plant on several smooth muscle preparations in vitro. The liophilized material was obtained from dried and powdered T. terrestris L. by specific extraction method for saponins. Median lethal dose (LD50) of saponin mixture on Swiss albino mice was calculated according to Litchfield-Wilcoxon method via i.p. route. LD50 and its 95% confidence limits were 813 and 739-894 mg.kg-1 respectively. Saponin mixture has caused a significant decrease on peristaltic movements of isolated sheep ureter and rabbit jejunum preparations in a dose-dependent manner (p < 0.05). However it has been observed no effect on isolated rabbit aorta and its contractile response to KCl or noradrenaline (p > 0.05). According to these results it has been suggested that T. terrestris L. or its saponin mixture may be useful on some smooth muscle spasms or colic pains.

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Tetanus is still responsible for many deaths, especially in the developing parts of the world. In this study, the prophylactic effect of ornidazole on experimental tetanus in mice was investigated. The initial minimum lethal dose (MLD) of Clostridium tetani spores was determined in mice and 100 MLD was applied to mice in experiments. Ornidazole was then administered at the dose of 20 mg, 40 mg and 80 mg/kg. In addition, penicillin and horse tetanus serum were also administered to other groups. According to the present results, ornidazole decreased the number of deaths in mice significantly in a dose and drug administration time dependent manner. These results suggest that, together with essential wound care and active immunization, ornidazole (or another nitroimidazole) may be a useful and supportive therapeutic agent in tetanus prophylaxis.

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1. In the present study, thiamphenicol caused a significant fall in ACh-induced frog rectus abdominis muscle contraction peaks and significant rightward shifts of the contractile response curves in a dose-dependent manner. 2. In addition, the maximal ACh response of muscle could not be obtained in presence of thiamphenicol. On the other hand, thiamphenicol did not alter KCl-induced contractions of the muscle at the same concentrations. 3. In contrast chloramphenicol did not cause any significant change in ACh-induced contraction peaks. 4. These results have suggested that thiamphenicol may have a neuromuscular blocking effect on frog rectus abdominis muscle.

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Morphine-ephedrine interaction on analgesia was studied in mice (n = 240) and in post-operative patients (n = 32). It was found that combining morphine and ephedrine enhances analgesia which is not significantly different from the effect of morphine given alone at double dose.

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The acute toxicity of taxine isolated from leaves of yew trees was determined in mice and rats. The drug was used as the sulphate salt. The following LD50 values (mg/kg) and 95% confidence limits were found: mice po 19.72 (16.84-23.09); mice ip 21.88 (19.66-24.35); rats sc 20.18 (18.35-22.20).

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The effects of the sulfate salt of taxine, the alkaloid mixture of the yew (Taxus baccata L.), on membrane currents of enzymatically isolated single ventricular cells of guinea pig were studied under current- or voltage clamp conditions. It was found that the drug inhibits both the sodium (INa) and the calcium current (ICa). The mean decrease of ICa and the maximum rate of rise of the action potential (dV/dtmax), an index of INa, and their standard errors under the influence of 10(-6), 10(-5), 10(-4) g/ml of taxine (control 100%) were 87.1 +/- 2.9, 67.8 +/- 2.8, 24.4 +/- 2.0 for the amplitude of ICa and 75.4 +/- 3.7, 53.3 +/- 7.5, 9.4 +/- 1.1 for dV/dtmax, respectively. Recovery from the effects of taxine is partially possible. Under the influence of taxine, inconsistent effects were observed on the potassium outward current. In conclusion the effect of taxine on the heart results from its ICa and INa inhibiting properties similar to those of other antiarrhythmic drugs.

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