Activity of bepridil and other anti-anginals on cardiovascular modifications engendered by conditioned anxiety in the dog.

The action of bepridil (5 mg/kg), perhexilene (5 mg/kg) propranolol (0.5 mg/kg), dipyridamole (0.5 mg/kg), amiodarone (10 mg/kg), pentaerythritol tetranitrate (40 microgram/kg) and nitroglycerine (40 microgram/kg) on cardiovascular manifestations of auditory-inducted emotional stress has been investigated in the conscious dog. Bepridil, perhexilene and propranolol considerably reduce tachycardia provoked by the anxiogenic stimulus, with nitroglycerin exerting an attenuated effect and the others with no significant effect on this parameter. Beppridil, nitroglycerin, perhexilene, propranolol and pentaerythritol all significantly reduce the elevation of the Robinson index, the first four with the same intensity. Only amiodarone and dipyridamole are without effect on this parameter of cardiac workload. Finally, none of the products under investigation significantly reduces systolic hypertension, associated with the induction of conditioned anxiety.

Cardiovascular pharmacology of bepridil (1[3 isobutoxy 2 (benzylphenyl) amino] propyl pyrrolidine hydrochloride) a new potential anti-anginal compound.

In dogs intravenous bepridil (2.5 mg/kg) increased coronary sinus blood flow and PVO2. Arterial pressure was briefly lowered, and heart rate was slowed in animals with intact or denervated hearts, or after propranolol administration. Ventricular inotropism was reduced at higher doses. Bepridil (5 mg/kg i.v.) showed a partial antagonist activity on isoprenaline cardiovascular effects (or cardiac sympathetic stimulation effects) i.e. tachycardia, increase in left dP/dt max. and diastolic hypotension. The antitachycardia activity was particularly pronounced. It was found to be non-competitive. It was also found to be non-specific since glucagon, theophylline- and papaverine-induced tachycardia were also reduced. The continuous infusion of high doses of bepridil did not cause any disturbance in atrio-ventricular or intraventricular conduction. In rats, after 50 mg/kg/day p.o., bepridil did not alter myocardial noradrenaline levels.

Consequence of solubility alteration by salt effect on dissolution enhancement and biological response of a solid dispersion of an experimental antianginal drug.

Improvement of dissolution of a poorly water-soluble experimental antianginal drug has been obtained by solid dispersion preparation. Its solubility decreased with rising chloride ion concentration and biological responses in dogs varied with the gastrointestinal administration site. A correlation seemed to exist between the apparent solubility and the heart rate activity.

Influence of hypercapnia on the cerebrovascular activities of some drugs used in the treatment of cerebral ischemia.

The effects of twelve substances on local cerebral blood flow (LCBF) were studied in the normocapnic and hypercapnic conscious rabbit. In normocapnia, an increase in LCBF was observed after naftidrofuryl (NAF), cinnarizine (CI), viquidil (VI) and heptaminol acefyllinate (HA). The LCBF was only slightly increased or unchanged after hydrogenated ergot alkaloids (HEA), cyclandelate (CY), hexobendine (HE), ifenprodil (IF), piridoxilate (PI), vincamine (VC) and xantinol niacate (XN). It was reduced by theophylline (TH). In hypercapnia, a more pronounced increase in LCBF than in normocapnia was seen with CY, HE, NAF, and VI and a decrease or lesser effect with HA, IF, VC and XN. The decrease in LCBF with TH was enhanced by hypercapnia. The effects of CI, HEA and PI were not modified. The therapeutic implication of these modifications of drug effects by hypercapnia, is discussed.

General pharmacological properties of a new non-opiate antitussive: zipeprol (3024 CERM). I. Action on respiratory function and acute toxicity.

1-(2-Methoxy-2-phenyl)-ethyl-4-(2-hydroxy-3-methoxy-3-phenyl)-propyl-iperazine-dihydrochloride (zipeprol, Respilene) is a substance of non-phenanthrenic chemical structure. In the cat, it antagonised cough induced by stimulation of the superior laryngeal nerve or by direct mechanical excitation of the sensitive tracheo-bronchial receptors. The efficacy of zipeprol after enteral administration made it possible both to establish good intestinal absorption and to rank it favourably in relation to several major antitussive reference products; codeine, codethyline, dextromethorphan, diphenhydramine and pentoxyverine. The activity of zipeprol was superior or equal to that of all these substances, excdept codeine. The antitussive properties appeared to be due to a central action. Other properties have been demonstrated which suggest at least a supplementary mechanism in the inhibition of cough, in addition to the central action. These consisted of slight antihistamine and anticholinergic properties, marked local-anesthetic potency and bronchospasmolytic activity. This latter property was demonstrated by the inhibition of histamine and serotonin induced bronchospasm in the guinea-pig. In vitro, using human sputum, zipeprol had a mucolytic action, shown by a decrease in sputum vis viscosity and lysis of DNA and AMPS fibrils. In the dog, at high doses, zipeprol unlike codeine, did not inhibit central stimulation of respiration by hypercapnia, in addition no modification of ventilatory dynamics or blood gases was seen. On the basis of these results, zipeprol can be considered as possessing no respiratory depressant effect even in the upper ranges of its antitussive doses.

General pharmacological properties of a new non-opiate antitussive: zipeprol (3024 CERM). II. Actions on the cardiovascular system, intestinal transit and central nervous system.

The effects of 1-(2-methoxy-2-phenyl)-ethyl-4-(2-hydroxy-3-methoxy-3-phenyl)-propyl-piperazine-dihydrochloride (zipeprol, 3024 CERM, Respilene), a new nonopiate antitussive agent, have been studied on the cardiovascular system, intestinal function and the central nervous system. Most of these studies were performed comparatively with reference antitussives, particularly codeine, whose activites in these fields are the basis of its undesirable side effects. In the dog, zipeprol showed no hypotensive or cardiac-depressant activity. It did not alter pulmonary arterial pressure. An important antiarrhythmic action was apparent in studies on rhythm disturbances induced by ouabain and coronary ligation. Intestinal function, measured by the recording of peristaltic movements in the dog and the speed of intestinal transit in the rat, was not modified by the product. Zipeprol showed no characteristic action on the central nervous system. Analgesic activity was seen only at doses just below toxic levels. Finally in the rat and the mouse, no evidence of physical dependence was seen after prolonged treatment. This together with the absence of chemical similarity to the morphinics, leads to exclude the possibility of zipeprol treatment leading to addiction. The results of these studies allow zipeprol to be clearly distinguished from the opiate antitussives.

Pharmacological properties of 2-(2-chloro-p-toluidino)-2-imidazoline-nitrate (tolonidine), a new antihypertensive agent. II. Action on cardiac contraction, circulatory parameters, autonomic receptors and diuresis.

Tolonidine, 2(2-chloro-p-toluidino)-2-imidazoline-nitrate, is a substance chemically related to clonidine. In the anesthetized dog, tolonidine administered i.v. decreased the amplitude of ventricular contractions, reduced aortic blood flow and increased peripheral vascular resistances. In the bivagotomized pithed rat, tolonidine induced a long-lasting increase in blood pressure with no secondary hypotension, thus suggesting peripheral sympathomimetic properties, however, contractions of seminal vesicles in vitro were not obtained. The product proved to have no peripheral sympatholytic or parasympatholytic properties. In the dog and the rat, diuresis was hardly changed. These properties are closely related to those of clonidine, which was studied comparatively. A general discussion is proposed at the end of a third article.

Pharmacological properties of 2-(2-chloro-p-toluidino)-2-imidazoline-nitrate (Tolonidine), a new antihypertensive agent. I. Action on blood pressure and heart rate.

Tolonidine, 2-(2-chloro-p-toluidino)-2-imidazoline-nitrate, a substance structurally related to clonidine, was studied for its effects on blood pressure and heart rate in anesthetized or conscious, normotensive or hypertensive animals (mainly dogs). In all cases, blood pressure was lowered by tolonidine. Initial short-lasting hypertension was observed after each i.v. administration. Heart rate was markedly lowered irrespective of the experimental process. Comparison with clonidine, guanethidine and mecamylamine in hypertensive anesthetized or unanesthetized animals made it possible to place tolonidine with respect to these reference antihypertensive drugs. A close relationship essentially appears between the effects of both derivatives of imidazoline: tolonidine and clonidine, tolonidine being, however, active at higher doses. The analysis of these results will appear at the end of a series of three articles.

Pharmacological properties of 2-(2-chloro-p-toluidino)-2-imidazoline-nitrate (tolonidine), a new antihypertensive agent. III. Action on the secretions of the digestive tract and on the central nervous system, acute toxicity.

The pharmacological properties of 2-(2-chloro-p-toluidino)-2-imidazoline-nitrate (tolonidine) a new synthetic derivative of imidazoline are reported in a series of three successive articles. This compound has been shown to possess hypotensive and antihypertensive properties. After i.v. administration, the hypotensive phase was preceded by hypertension related to the potent direct alpha-sympatheticomimetic properties of the product. This pressor response, which was not seen after oral administration, was accompanied by a marked decrease in cardiac output and a significant increase in peripheral vascular resistance. The hypotensive action of the product was due to a drop in cardiac output probably reinforced by a decrease in vasoconstrictor sympathetic tone due to a central action. Whatever the route of administration, tolonidine slowed heart rate independently of blood pressure variations, due essentially to an increase in vagal tone. In studies of diuresis, liquid and salt loss were observed in the cat, not in the dog. At doses which induce a drop in blood pressure tolonidine did not produce a reduction in pilocarpine-induced salivary secretion and only partially inhibited gastric secretion. In the central nervous system, tolonidine produced a sedation which first appeared at doses having an antihypertensive effect but which was only fully apparent with increased doses. A decrease in the release of cerebral amines, serotonin and noradrenaline by tolonidine is proposed. Tolonidine was compared with three other antihypertensive agents: clonidine, which is structurally related, and guanethidine and mecamylamine, which are structurally unrelated and have a different mode of action. A close resemblance of the pharmacological properties of tolonidine and clonidine was established due to the chemical relationship between the two substances.

[Influence of moderate normoxic hypercapnia on the autoregulation of the cerebral circulation in the unanesthetized rabbit]. / Influence d'une hypercapnie normoxique modérée sur l'autorégulation de la circulation cérébrale chez le lapin non anesthésié

In the unanesthetized rabbit autoregulation of cerebral blood flow was evaluated by continuous recording of local cerebral blood flow during progressive hypotension induced by exsanguination. Under hypercapnia induced by CO2, 8 per cent in air, autoregulation was not suppressed but an increase of the threshold under which autoregulation disappears was noted.