Effects of lomefloxacin and sparfloxacin on human platelet aggregation.

Platelet aggregation is inhibited by high concentrations of most antibiotics. For this reason it is important to evaluate the effects of new antimicrobial agents on platelet aggregation. Lomefloxacin and sparfloxacin are new difluorinated quinolone antimicrobial agents. The aim of this work was to evaluate in vitro the effects of lomefloxacin and sparfloxacin on adenosinediphosphate (ADP) and collagen-induced human platelet aggregation. Our data showed that both antibiotics (lomefloxacin and sparfloxacin) at therapeutic doses did not inhibit in vitro human platelet aggregation. Lomefloxacin, only at the highest tested concentration (1 mg/ml), which is far higher than the clinically achievable one, significantly (P < 0.05) inhibited collagen-induced platelet aggregation. Sparfloxacin also caused inhibition of collagen and ADP-induced human platelet aggregation only at the highest tested concentration (0.01 mg/ml), which is higher than that reached in vivo. These findings suggest that therapeutic doses of lomefloxacin and sparfloxacin do not affect human platelet aggregation.

Evaluation of the effects of pefloxacin on platelet aggregation in vitro and ex vivo in patients suffering from chronic bronchitis.

The effects of pefloxacin on adenosine-diphosphate (ADP) and collagen-induced human platelet aggregation in vitro and ex vivo in patients suffering from chronic bronchitis were investigated. In the in vitro study carried out on platelets from 12 healthy volunteers, pefloxacin had no effect on platelet function even at a concentration of 10 mg/ml, which is 1,500 times higher than that reached in vivo. In the ex vivo study carried out in 10 patients, who received pefloxacin twice daily for 7-10 days as 400 mg oral dose, the drug did not influence platelet aggregation up to 24 hours after administration of the last oral dose.

Serum digoxin levels after concomitant ticarcillin and clavulanic acid administration.

Recently it has been recognized that steady-state serum digoxin concentrations may increase or fall to ineffective levels when the glycoside is administered together with several antibiotics. Our study was designed to assess if serum digoxin levels may be modified by the concomitant use of a ticarcillin and clavulanic acid. The study was carried out in 15 hospitalized patients suffering from exacerbation of their chronic bronchitis without liver disease and renal failure. Serum digoxin levels were not significantly modified by the concomitant use of a ticarcillin and clavulanic acid, although peak digoxin serum concentrations were slightly lower. However, the average time to achieve the maximum concentration and area under the curve over 24 h did not change.

Degradation of acetylcholine in human airways: role of butyrylcholinesterase.

1. Neostigmine and BW284C51 induced concentration-dependent contractions in human isolated bronchial preparations whereas tetraisopropylpyrophosphoramide (iso-OMPA) was inactive on airway resting tone. 2. Neostigmine (0.1 microM) or iso-OMPA (100 microM) increased acetylcholine sensitivity in human isolated bronchial preparations but did not alter methacholine or carbachol concentration-effect curves. 3. In the presence of iso-OMPA (10 microM) the bronchial rings were more sensitive to neostigmine. The pD2 values were, control: 6.05 +/- 0.15 and treated: 6.91 +/- 0.14. 4. Neostigmine or iso-OMPA retarded the degradation of acetylcholine when this substrate was exogenously added to human isolated airways. A marked reduction of acetylcholine degradation was observed in the presence of both inhibitors. Exogenous butyrylcholine degradation was prevented by iso-OMPA (10 microM) but not by neostigmine (0.1 microM). 5. These results suggest the presence of butyrylcholinesterase activity in human bronchial muscle and this enzyme may co-regulate the degradation of acetylcholine in this tissue.

Teicoplanin with other drugs: possible pharmacological interactions.

The contemporaneous employment of two or more drugs may present the risk of modifying the required therapeutic effect or producing adverse reactions. These interactions are of a pharmacokinetic and pharmacodynamic type. Teicoplanin is an antibiotic with a glycopeptide structure, produced by Actinoplanes teichomyceticus, active against both anaerobic and aerobic Gram-positive bacteria that are resistant to various chemotherapeutic drugs (beta-lactam and macrolide antibiotics, tetracyclines, co-trimoxazole). Then the aim of this work was to verify experimentally the possible pharmacological interactions between teicoplanin and oral hypoglycemic (phenformin and glibenclamide), or oral anticoagulant (warfarin) or bronchodilator (theophylline) drugs. Teicoplanin (3-15 mg/kg/die i.p. for 4 days) administration to the rat did not significantly (p > 0.05) modify the glycemia, prothrombin and partial thromboplastin times, the hypoglycemic effect of phenformin (2.5 mg/kg/die os for 4 days) and glibenclamide (0.5 mg/kg/die os for 4 days) or the anticoagulant effect of warfarin (0.5 mg/kg/die os for 4 days); moreover it did not significantly (p > 0.05) modify the pharmacokinetics of aminophylline (5 mg/kg i.v.) on the rabbit. In conclusion our results documented that teicoplanin does not interfere with phenformin, glibenclamide, or sodium warfarin activities nor with aminophylline pharmacokinetics.

Effects of some cephalosporins and teicoplanin on platelet aggregation.

Antibiotics may interfere with platelet (PLT) function, and beta-lactam antibiotics may interact with PLT aggregation, by inhibiting the binding of agonists of this aggregation (such as ADP and collagen) to specific receptor sites. In this study we have evaluated the relative in-vitro antiplatelet effects of some old and new cephalosporins (cefonicid, ceftazidime, ceftriaxone, cefotaxime, cefuroxime and flomoxef) and of teicoplanin, a new glycopeptide antibiotic. All the cephalosporins tested, and also teicoplanin, were found to have the potential to adversely affect human platelet aggregation only at high concentrations which are not achieved in vivo.

Effects of teicoplanin on human platelet aggregation in vitro and ex vivo.

The effects of teicoplanin on adenosine-diphosphate (ADP)-induced human platelet aggregation in vitro and on both ADP- and ristocetin-induced human platelet aggregation ex vivo were investigated. In the in vitro study carried out on platelets from 7 healthy volunteers, teicoplanin had no effect on platelet function even at a concentration (1 mg/ml) 10 times higher than the peak level found in the in vivo state, but at the highest concentration (10 mg/ml), which is 100 times higher than that reached in vivo, it inhibited ADP-induced platelet aggregation. In the ex vivo studies carried out in 10 healthy volunteers, teicoplanin, following single intravenous doses of 400 mg and 800 mg, did not produce any effect on platelet function up to 6 hours after administration. After 12 hours, teicoplanin, when given at 800 mg i.v., reduced ADP-induced platelet aggregation.

Clinical pharmacokinetics of teicoplanin and aminophylline during cotreatment with both medicaments.

The influence of teicoplanin and aminophylline (theophylline ethylenediamine) on their mutual steady-state pharmacokinetics was studied in two parts, namely experimental and clinical studies. The concentrations of teicoplanin and aminophylline (theophylline) were evaluated at several times after intravenous administration of teicoplanin (3 and 15 mg/kg) and aminophylline (5 mg/kg) in 12 rabbits. Ten COPD patients were treated for 5 consecutive days with a short-term intravenous infusion of 240 mg aminophylline twice daily; ten more patients received for 5 days a short-term intravenous infusion of 200 mg teicoplanin twice daily. On the last day, blood samples were taken for teicoplanin and theophylline determination by means of the HPLC method. Subsequently, while aminophylline and teicoplanin were continued at the same dosage, the first ten patients received in addition a short-term intravenous infusion of 200 mg teicoplanin twice daily, and the second ten patients a short-term intravenous infusion of 240 mg aminophylline twice daily. After 5 days the serial assays of serum teicoplanin and theophylline were repeated. Our results demonstrated, in both experimental and clinical studies, no influence of theophylline on the steady-state pharmacokinetics of teicoplanin. Likewise teicoplanin had no significant effect on the steady-state pharmacokinetics of intravenous administration of theophylline in the form of aminophylline.

[Pharmacologic interactions between quinolones and oral hypoglycemic agents. An experimental study on rabbits]. / Interazioni farmacologiche tra chinolonici ed ipoglicemizzanti orali. Studio sperimentale sul coniglio.

The association between antibiotics and oral hypoglycemic agents can determine various pharmacological interactions. The aim of our work has been to verify experimentally the eventual pharmacological interactions that may occur when some quinolones (nalidixic acid, ofloxacin, pefloxacin and sparfloxacin) are administered in association with oral hypoglycemic drugs (phenphormine and glibenclamide). Our results showed that ofloxacin, pefloxacin and sparfloxacin only at high dosages (not used in the human clinic) can increase the phenphormine and glibenclamide hypoglycemic effect. The nalidixic acid, just at therapeutic doses, is able to increase the hypoglycemic effect of the drugs studied.

Cardiovascular and respiratory effects of dermorphin in rats.

The cardiovascular and respiratory effects of dermorphin (D) have been evaluated in freely moving or anesthetized normotensive and spontaneously hypertensive male rats. Intravenously or intracerebroventricularly administration of D produced arterial hypotension with sinus bradycardia and respiratory depression. Naloxone antagonized the effects of D. Atrial natriuretic antipeptide IgG reduced the cardiovascular responses without any significant modification of respiratory response. ICI 174864, naloxonazine and binaltorphimine did not reduce the cardiovascular and respiratory effects. In hypertensive rats D produced more intense and longer cardiovascular effects than those seen in normotensive animals. D effects involve the activation of mu and k opioid receptors for cardiovascular responses and mu 2 opioid receptors for respiratory depression without any significant effect on delta receptors. The release of atrial natriuretic peptide also appears to be involved in the cardiovascular effects of D.

Prenatal and postnatal vanadium exposure in rats: effect on vasomotor reactivity development of pups.

The study has been carried out on albino rats pre and/or postnatally exposed to vanadate (1 and 10 mg/dl). In pups pre- and postnatal or postnatal vanadate exposure significantly decreased on the 30th and 60th day of age the pressor response to 1-noradrenaline, and increased the pressor response to sinus-carotid baroreceptor stimulation and the hypotensive responses to 1-isoprenaline and acetylcholine. The effects were observed at vanadate doses that did not interfere with gestation, maternal and pup body weight, maternal systolic arterial blood pressure during pregnancy, and pup systolic arterial blood pressure. These doses have not determined any macroscopic teratogenic effects.

Interference of prenatal and postnatal exposure to Ca2+-antagonist agents on rat functional development of vascular system.

Exposure to drugs during pregnancy can alter functional development of the vascular system. The present investigation was carried out in order to evaluate the effects of prenatal and postnatal exposure to Ca2+-antagonist (diltiazem, verapamil, and nimodipine) drugs on the development of rat vasomotor reactivity. Studies were carried out on pregnant female albino rats exposed from the first day of pregnancy until weaning to diltiazem and verapamil (6 and 24 mg/kg in their drinking water ad libitum) and nimodipine (3 and 12 mg/kg in their food ad libitum). After weaning, pups were exposed until the 60th day of age to the same treatment as their mothers were. Afterwards, pups from the 60th to 90th day of age were fed with a normal diet. In 30-, 60-, and 90-day-old conscious and anaesthetized pups, we evaluated the following: 1) systolic arterial blood pressure; 2) vasomotor responses elicited by various agents: L-noradrenaline (0.1, 1, and 5 micrograms/kg IV), L-isoprenaline (0.01, 0.1, and 1 micrograms/kg IV), and acetylcholine (0.01, 0.1, and 1 micrograms/kg IV) and by sinus-carotid baroreceptor stimulation; and 3) catecholamine, acetylcholinesterase, and adenosinase plasma levels. Prenatal and postnatal exposure to Ca2+-antagonist drugs significantly (P less than .05) decreased the pressor response to sinus-carotid baroreceptor stimulation and to L-noradrenaline and increased the hypotensive responses to L-isoprenaline and acetylcholine. Moreover, this type of treatment, although it induced a significant (P less than .05) decrease of catecholamine plasma levels, did not modify the acetylcholinesterase and adenosinase plasma levels in 30- and 60-day-old rats. On the 90th day of age, the evaluated parameters were not different from those of control rats. Our results showed that exposure to Ca2+ antagonists during pregnancy and the postnatal period may alter the functional development of rat vasomotor reactivity.

Ureas and amides derived from N-(5-norbornen-2-ylmethyl) bornan-2-exo-amine with antiarrhythmic and other activities.

The synthesis of title compounds by reaction of camphor nitrimine with (5-norbornen-2-yl)methylamine, followed by NaBH4 reduction of the resulting imine to N-substituted isobornylamine (IV) and reaction of (IV) with alkyl and aryl isocyanates or acyl chlorides, is described. Some ureas and amides are endowed with antiarrhythmic activity in rats superior or comparable to that of quinidine, whereas benzamide (V o) showed an appreciable hypoglycemic activity in mice. Moreover, compounds (V) exhibited in general moderate hypotensive, bradycardic and antiinflammatory activities in rats, as well as a weak infiltration anesthesia in mice.

Glutamergic transmission and cardiovascular apparatus in normotensive rats.

The cardiovascular effects induced by L-glutamic acid (G) on the cardiovascular apparatus of normotensive ethyl urethane-anaesthetized rats have been evaluated. (a) When administered i.v. (1 to 100 mg/kg) G induced a transitory and dose-dependent increase of arterial pressure (AP) with very moderate sinus bradycardia. It was antagonized by L-glutamic acid diethyl ester (GDEE, 0.1 to 100 mg/kg i.v.). (b) The intracerebroventricular (i.c.v.) administration of G (third ventricle, right lateral ventricle, posterior hypothalamus and striatum) at a dose of 0.1 to 10 mg/an induced a transitory and dose-dependent increase of AP, abolished by i.c.v. GDEE (1 to 10 mcg/an). (c) G hypertension was reduced by several procedures, i.e. catecholamine depletion, alpha 1, alpha 1 and alpha 2 or beta adrenergic blocks, alpha 2 central adrenergic stimulation, Ca2+ transmembrane or gangliary block, surrenectomy, and spinal transection at C7. (d) Atropine, bilateral vagotomy and sinus carotidal denervation increased G hypertension. (e) Therefore the bradycardia does seem to be due to a reflex-mediated effect via sinus carotid and aortic baroreceptors. (f) These data show that glutamergic transmission also participates through a central mechanism in the regulation of cardiovascular function in rats, via an increase in central sympathetic efferent activity.

Derivatives of 1,2,3,3-tetramethyl-2-azabicyclo[2.2.2]octan-5-trans-ol with antiarrhythmic and other activities. VIII.

The synthesis of some alkyl, aryl thioureas and aryl ureas starting from 5-trans-(3-aminopropoxy)-1,2,3,3-tetramethyl-2-azabicyclo[2.2.2]octane is described. Some thioureas showed a remarkable antiarrhythmic activity besides a weak hypotensive effect in rats and, like some ureas, infiltration anesthesia in mice.

Derivatives of 1,2,3,3-tetramethyl-2-azabicyclo [2.2.2]-octan-5-trans-ol with antiarrhythmic and other activities. VII.

The synthesis of a series of alkyl and aryl ureas (II) starting from 5-trans-(3-aminoproxy)-1,2,3,3-tetramethyl-2-azabicyclo [2.2.2]-octane is described. Some compounds (II) showed appreciable antiarrhythmic activity in rats and infiltration anesthesia in mice, as well as weak hypotensive and bradycardic activities in rats.