Comparative bioavailability study on naproxen betainate sodium salt monohydrate and naproxen sodium salt in healthy volunteers

The S-naproxen betainate sodium salt monohydrate (naproxen-betaNa, CAS 104124-26-7, Aprenin, test drug), and the sodium salt of S-naproxen (reference), were administered to twelve healthy volunteers of both sexes according to a crossover design, in a single dose of one 575 mg capsule of test, containing 342 mg of S-naproxen and two 275 mg tablets of reference, containing 502 mg of S-naproxen. Blood samples were drawn off over a 24-h period before (time 0) and after administration at foreseen time intervals. Naproxen was measured in plasma by a validated HPLC assay with UV detection which was able to detect 1 microgram/ml and proved to be linear in the range 1-100 micrograms/ml. The non-compartmental pharmacokinetic parameters obtained were statistically processed according to the EU guidance note on bioavailability and bioequivalence Cmax, AUC0-24h and AUC0-infinity were normalized to the dose of 502 mg of naproxen and log-transformed before statistical analysis to assess bioequivalence. Dose-normalized values of plasma concentrations encountered with the two formulations proved to overlap, with the exception of the first sampling time which showed naproxen concentrations that were higher with test drug than with reference. The specific test for bioequivalence led to 90% confidence intervals within the 80-125% range with target pharmacokinetic parameters, whereas the time to peak (tmax) observed with the test and reference drugs did not differ to any statistically significant degree when analysed with Wilcoxon's non-parametric test. It is concluded that the test drug should be declared bioequivalent with the reference drug in terms of dose-normalized concentrations, despite the more rapid increase in plasma concentrations of naproxen observed at the first sampling time with test drug.

Dobutamine echocardiography: usefulness of digital image processing

The present study was undertaken in order specifically to evaluate the usefulness of digital image processing so as to enhance the diagnostic power of dobutamine stress echocardiography. For this purpose 44 dobutamine echocardiographic tests, routinely performed in our echo laboratory, were analysed blindly by two observers using traditional videotape recording and digitized image acquisition. The results obtained from both observers show a trend which suggests that the traditional videotape approach provides more true-positive tests than the digitized approach (27/38 vs 23/38 and 24/38 vs 22/38 for the first and second observer, respectively). True-negative test detection was 6/6 with the videotape and 5/6 with the digitized method for both observers. As a consequence of the discrepancies observed between the two modalities, the videotape indicates that it can provide higher diagnostic accuracy than the digitized approach (72 +/- 9% vs 63 +/- 10%). The tests results concordance (positive or negative) between the two modalities of analysis was 66% for both the observers. The inter-observer agreement on the test results was 84% and 80% for the videotape analysis and the digitized analysis, respectively. On the basis of the results, we consider that digitized analysis applied to dobutamine stress echocardiography does not afford significant diagnostic advantages and should not be considered as an alternative option to traditional videotape analysis. However, it may be considered an extremely useful integrative tool since it produces the on-line image evaluation more easily and faster and allows a more practical form of stress test storage.

["Incomplete closure" of the mitral valve: the relationships to valvular regurgitation and to the morphofunctional characteristics of the left ventricle]

OBJECTIVES

The present study was designed in order to evaluate the prevalence of mitral regurgitation in patients with the "incomplete mitral leaflet closure" echocardiographic pattern, to verify whether the amount of "incomplete mitral leaflet closure" is related to the severity of mitral regurgitation and, last, to verify the relation between the "incomplete mitral leaflet closure" and left ventricular morphology and function.

METHODS

We studied 80 patients (14 patients with dilatative cardiomyopathy, 26 patients with coronary artery disease, and 40 patients with hypertensive heart disease or aortic valve disease) showing the "incomplete mitral leaflet closure" pattern, retrospectively selected from a population composed of 1700 consecutive patients routinely examined in our echocardiographic laboratory. In all patients we evaluated the presence and the severity of mitral regurgitation, the morphological and functional parameters of the left ventricle, the systolic diameter of the mitral annulus, the distance between the point of mitral leaflet coaptation and the annular plane, and the incomplete mitral closure area, assuming the last two parameters as indexes of the severity of incomplete closure of the mitral valve.

RESULTS

We observed the presence of mitral regurgitation in 51 out of 80 patients (64%). The valvular insufficiency was considered mild in 78% of the patients. We observed no significant difference between patients with mitral regurgitation and without, as regards the diameter of the mitral annulus, the distance between the point of mitral leaflet coaptation and the annular plane, and the incomplete mitral closure area in different types of heart diseases. The incomplete mitral closure area and the diameter of the mitral annulus showed a significant, although not elevated, correlation with the severity of the mitral regurgitation (r = 0.36 and r = 0.32, respectively). The severity of mitral regurgitation showed significant correlations with all of the left ventricular morphological and functional parameters evaluated. Finally, we observed significant correlations between the incomplete mitral closure area and all of the morphological and functional parameters of the left ventricle.

CONCLUSIONS

On the basis of the results obtained we can conclude that: 1) the "incomplete mitral leaflet closure" pattern does not appear to be a highly specific marker of mitral regurgitation, 2) this pattern appears to be related to the morphology and function of the left ventricle, and 3) the severity of the incomplete mitral valve closure is more easily evaluated by a parameter that takes into account the numerous factors acting on the mitral apparatus, that is the incomplete mitral closure area.

[Myocardial response to ischemia produced by repeated coronary occlusions: an experimental study]

BACKGROUND

The fact that brief repeated episodes of ischemia may induce prolonged functional depression of the left ventricle is still a matter of debate. During an angioplasty several brief (20-90 sec) coronary occlusions are performed, with the potential risk of inducing myocardial jeopardy.

METHODS

We performed 4 repeated LAD occlusions in 7 open chest pigs under general anesthesia and controlled ventilation. The following parameters were evaluated: mean systemic arterial pressure (MAP), left ventricular peak systolic pressure (LVPSP), heart rate (HR), and peak negative and positive dP/dt (dP/dt- and +). Each parameter was measured in the basal state and every 4 sec, in the expiratory phase, during the coronary occlusion, the first min and after 10 min of reperfusion. The percent change from control values for each parameter was also calculated and, by means of the ANOVA test, the differences among the 4 consecutive occlusions for each parameter were tested.

RESULTS

The results showed that: 1) coronary occlusions significantly depressed dP/dt + and -, MAP and LVPSP, while HR did not change; 2) each variable returned to control values within 1 min of reperfusion; 3) the response to ischemia (percent change) was the same in each of the 4 consecutive occlusions for all parameters at every recording time.

CONCLUSIONS

We can conclude that: 1) each experimental coronary occlusion induces a depression of myocardial function that is reversible in 1 min of reperfusion; 2) four repeated 2 minutes coronary occlusions do not induce cumulative effects on myocardial response to ischemia.

Comparative evaluation of three dosages of slow-release isosorbide dinitrate (60, 80, 100 mg) in chronic angina of the aged

In a single-blind, placebo-controlled study the acute and chronic antianginal effects of three slow-release (SR) new formulations of isosorbide dinitrate (ISDN 60, 80, 100 mg) have been comparatively evaluated in a group of aged affected by chronic stable effort-induced angina. Compared to placebo, overall the active dose paritetically improved the effort tolerance up to 24 h after the first assumption. In the time course of the trial (2 and 4 weeks) the resting hemodynamic changes induced by the first dose were partially blunted without affecting the exercise related-parameters. Also if plasma levels of ISDN and of its metabolites did not correlate to the degree of physical improvement, the peak increase in effort tolerance was observed under 100 mg treatment. Mild to moderate transient headache was experienced by 50% of actively treated and by 20% of placebo treated patients and no other serious adverse effects have been noted. One may conclude that ISDN in slow-release formulations of 60-100 mg isan effective, safe and well tolerated medication in the management of angina in the aged.

[Pharmacokinetics of defibrotide in uremic patients undergoing hemodialysis]

Defibrotide pharmacokinetics were studied in 6 voluntary healthy subjects and in 10 uremic patients undergoing dialysis during which (instead of heparin) defibrotide was administered to prevent fibrino-formation in the circuit. Blood concentrations of the drug were assessed (expressed with reference to the residual glycidic deoxyribose) during a standard dialysis using defibrotide, 3.5, 15, 30, 45, 60 and 90 minutes after the defibrotide bolus (200 mg) had been injected into the arterial channel. The half-lives of the alpha and beta plasmatic phases were found to be equal at 3.79 and 41.4 min in dialysed subjects and at 1.13 and 16.54 in healthy volunteers. These results indicate that in uremic patients undergoing dialysis at intervals using defibrotide, a longer time is required to eliminate the drug from the circulation. This variation does not however appear to be significant in terms of the therapeutic use of the drug during dialysis.

[Effects of low-dose diltiazem on isovolumetric relaxation and contraction]

Calcium entry blockers are commonly believed to have a direct negative inotropic effect, but systolic function of the left ventricle (LV) can be improved when the peripheral vasodilator activity of the drug is present. The aim of our study was to evaluate the effect of diltiazem (D) on isovolumic contraction (IC) and relaxation (IR) at a dosage which is not effective on the peripheral vascular bed. We infused 10 micrograms/Kg/min i.v. of D for a 30 min period in to 12 pigs, anesthetized with ethyl urethane (1250 mg/Kg) and under artificial ventilation. The following variables were evaluated: left ventricular systolic (LVSP) and end-diastolic (LVEDP) pressure, peak - and + dP/dt, mean arterial pressure (MAP), heart rate (HR) and double product. The recordings were obtained in the control condition and 5, 10, 15, 20, 25 and 30 minutes after beginning the infusion. The statistical analysis was performed using the one-way ANOVA test. Our results show: 1) a maximal increase in the peak + dP/dt from 2228 +/- 501 to 2448 +/- 576 mmHg/sec (p less than or equal to 0.01) and of the peak . dP/dt from 1262 +/- 260 to 1348 +/- 272 mmHg/sec (p less than or equal to 0.05); 2) and increase in LVSP from 86 +/- 13 to 90 +/- 10 mmHg (p less than or equal to 0.01) and 3) no changes in HR, PAM, LVEDP and double product. As the indices representing afterload and preload (PAM and LVEDP) remained unchanged during the infusion, we suggest that the increase in dP/dt + and - are due to a direct effect of diltiazem on myocardial function.(ABSTRACT TRUNCATED AT 250 WORDS)

[A comparison between mitral and aortic outputs evaluated by Doppler echocardiography in a group of healthy subjects: false regurgitation]

Doppler echocardiography is a potentially useful tool for the non invasive evaluation of cardiac output and, therefore, for the quantitative assessment of valvular regurgitation. The aim of our study was to establish the presence of possible pitfalls in the evaluation of mitral and aortic regurgitant fraction obtained by Doppler echocardiography comparing the cardiac output measured at the level of the mitral and aortic valve. For this purpose 19 healthy volunteers, aged between 14-68 years, were studied. Stroke volume and cardiac output were calculated at the level of the mitral and aortic valve. The methods we used for the measurement of both the mitral and aortic cardiac output had already been validated and presumes that the shape of the valve annulus, is circular. No statistically significant differences were found between the parameters obtained at the two different valvular levels. Furthermore, cardiac output values correlated fairly well (r = 0.83, ESS = 0.78 l/min). In 9 subjects the aortic cardiac output was greater than the mitral one, while in the others mitral cardiac output was greater. The average of the differences between the two cardiac outputs was 0.58 +/- 0.48 l/min with a regurgitation fraction of 9.5 +/- 7.9%. Our results show that the mitral and aortic stroke volume and cardiac output, as measured by Doppler echocardiography (considering a circular shaped valve annulus, are not statistically different and correlate fairly well in our normal subjects. Nevertheless, we observed a certain degree of variability between the mitral and the aortic cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

[First seconds after acute experimental ischemic: changes in isovolumic contraction and relaxation]

The purpose of this study was to answer the following questions: 1) are isovolumic contraction and relaxation affected in a different way by LAD occlusion? 2) Does proximal and distal LAD coronary occlusion induce different changes in isovolumic contraction and relaxation? In 22 pigs, LAD coronary artery was dissected free right after the first or third diagonal branch and occluded by ligation. The following variables were evaluated: left ventricular systolic and end-diastolic pressure; peak - and + dP/dt, mean arterial and pulmonary pressure. All our data were obtained in the first minute following the occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Gas chromatographic evaluation of trapidil and its desethyl metabolite in biological fluids for pharmacokinetic and bioavailability investigations

This paper describes a suitable and cost-saving method for quantitative analysis of trapidil (5-methyl-7-diethylamino-s-triazolo [1,5-a]pyrimidine) and its desethyl metabolite in plasma and urine for pharmacokinetic and bioavailability investigations. Trapidil and desethyl-trapidil were extracted from plasma, concentrated and injected into the gas chromatography without any derivatization process. The authors suggest a series of internal standards. A thermoionic specific detector enables high sensitivity to be achieved, i.e. 20 ng/ml, and good specificity. The method is cost-saving in that it allows about 30 analyses a day to be performed without automatic integrators, and about 50 analyses a day with these integrators.

[Functional evaluation of the autonomic regulation in mitral valve prolapse]

We examined fifty patients aged from 15 to 35 years, mean 23 +/- 5, with mitral valve prolapse (MVP) documented by two-dimensional echocardiography in the apical 4-chamber view as well as in the parasternal-long axis. The patients have been submitted to 4 tests: Valsalva maneuver, standing and exercise test and 24 hours ambulatory ECG monitoring. Fourty-five healthy subjects of similar age and sex served as controls. During the standing test the patients with MVP showed a significantly faster heart rate than the control subjects both in resting and in the standing position; during the exercise test they exhibited higher prevalence of ST segment and T wave abnormalities disappearing at the peak of the exercise. These observations support the hypothesis of a hyperadrenergic state. The greater bradycardia showed during the Valsalva maneuver, the lower heart rate and the higher incidence of bradyarrhythmias and A-V blocks during the sleeping period suggest an increased vagal tone. Our results suggest therefore that in subjects with MVP a dysfunction of both, sympathetic and parasympathetic nervous system is present.

Multicenter study on the clinical efficacy of chronic ibopamine administration

The purpose of this multicenter study was to evaluate the therapeutic efficacy of ibopamine (SB-7505), the 3,4-diisobutyrylester of N-methyldopamine, chronically administered to patients with severe congestive heart failure (CHF) in whom traditional therapy had been ineffective. 55 patients chronically treated with cardiac glycosides and diuretics were assigned to an investigation covering three stages each lasting 7 days. Stage A: continuation of traditional therapy (glycosides and diuretics). Stage B: addition of ibopamine to the glycoside/diuretic therapy. Stage C: withdrawal of ibopamine. Heart rate, blood pressure, body weight, diuresis and 8 target symptoms of CHF (clinical scores) and hematochemical parameters were recorded throughout the three stages. The addition of ibopamine to traditional therapy led to a significant improvement. By contrast, after ibopamine had been withdrawn patients worsened. No hematochemical parameters were modified during the trial. None of the patients experienced any significant side-effects.

Monitored long-term treatment with ibopamine in patients suffering from severe congestive heart failure

50 patients with congestive heart failure underwent monitored long-term treatment aimed at evaluating the effect of ibopamine (SB-7505), the 3,4-diisobutyryl ester of N-methyldopamine, on their condition. Ibopamine was administered alone or in combination with traditional therapy mainly at a dose of 100 mg t.i.d. Clinical scores and NYHA (New York Heart Association) functional classes improved. Biochemical parameters showed no adverse modifications. Mild transient side-effects probably related to ibopamine occurred in two patients.

[Study of the regional contraction of the left ventricle in normal subjects using a two-dimensional echocardiographic technic]

The purpose of this study is to evaluate normal left ventricular regional wall motion pattern in order to answer the two following questions: does wall motion change at different levels of the left ventricle from the base to the apex? does wall motion change among different segments at the same level? Seventy-two normal subjects were submitted to a cross sectional echocardiographic examination and the tape recordings were analyzed by a computerized system. Parasternal short axis views at mitral valve and papillary muscles level were chosen and divided by the computer in 16 areas which were fitted to a more anatomical division, i.e. interventricular septum, anterior, lateral, posterior-lateral, inferior-posterior and inferior walls. From each segment, fractional area changes were obtained. Statistical analyses were carried out by the two way analysis of variance and two paired t test. Wall motion pattern of the normal left ventricle is not uniform either at different levels or among segments at the same level: we conclude that regional wall motion differences of the left ventricle are not necessarily due to abnormal conditions, but might be a normal left ventricular pattern.

Prostacyclin effect on heart rate in the pig

The purpose of this study was to assess the hemodynamic response after prostacyclin infusion into the venous system and into the carotid artery in the pig. During the study the following circulatory variables were studied: mean systemic arterial pressure, mean pulmonary arterial pressure, wedge pressure, heart rate, cardiac output, systolic and diastolic left ventricular pressure, stroke volume, total systemic resistance, total pulmonary resistance, left ventricular stroke work. Our results confirm that prostacyclin is a powerful hypotensive agent. The hypotensive effect seems to be due to a peripheral vasodilatation of arterial and venous vessels. Venous infusion caused only 19% tachycardia, as opposed to 36% caused by arterial infusion for the same percentage of blood pressure reduction. This suggests that prostacyclin probably stimulates cardiopulmonary vagal receptors. The effect of prostacyclin on heart rate, therefore, may be twofold and in opposite directions: one action causing tachycardia secondary to hypotension, and the other inviting bradycardia through direct vagal stimulation.

[Arrhythmias in the mitral valve prolapse syndrome]

Possible connections have been investigated between PVc (premature ventricular contractions) and echocardiographic patterns in 23 patients affected by MVPS. Pansystolic prolapse has been found in 12 cases and mid-systolic prolapse in 11. A correlation has been found between significant ventricular arrhythmias (50 PVc/24 h) and mid-systolic prolapse. These findings suggest the mechanical origin of cardiac rhythm disorders.

Effect of ibopamine on heart rate and spontaneous premature ventricular beats in patients with angina pectoris

Seven male patients suffering from angina pectoris with spontaneous premature ventricular beats were given oral ibopamine 50 mg t.i.d. for 5 consecutive days, after at least 6 days of observation under basal conditions. A number of clinical parameters were explored during the basal and treatment periods, including repeated 24-hour Holter recordings in each case. The heart rate, expressed as mean hourly rate, minimum and maximum values per observation period, and nocturnal value, showed no clinically or statistically significant change with treatment. There was no worsening of pre-existing arrhythmias or chest pain. All other test parameters remained unchanged. This confirms the excellent tolerance of ibopamine in patients with ischaemic heart disease.

Prostacyclin effect on cardiovascular system in man evaluated by echocardiography

This was an echocardiographic study of the cardiovascular effects of prostacyclin (PGI2) infused intravenously to human volunteers at the rate of 20 ng . kg-1 . min-1 for 10 minutes. The following parameters were recorded in the steady state, at one-minute intervals throughout infusion and the ensuing recovery period: systolic, diastolic, and mean blood pressure (SBP, DBP, MBP); heart rate (HR); left ventricle end-diastolic (EDD) and end-systolic diameter (ESD); stroke volume index (SVI); cardiac index (CI); peripheral vascular resistance (PVR); left ventricle fractional shortening (FS) and ejection fraction (EF). We detected a progressive reduction of MBP without any HR modification. MBP reduction was associated with a reduction of PVR and a parallel rise of CI and SVI. There was also an increase of FS and EF reflecting a reduced ESD. We conclude that PGI2 infused in man at the rate stated above causes hypotension reflecting an arterial vasodilating effect; a lack of heart rate reflex response to afterload reduction (probably a nerve-mediated effect of PGI2); and no venous vasodilation, judging from the absence of any change in end-diastolic diameter.

Role of hypotension induced by PGI2 on the control of depth and frequency of breathing

We studied the respiratory response to infusion of prostacyclin (PGI2) in 7 anaesthetized pigs in an attempt to understand whether the changes in pattern of breathing were due to a direct action of the substance or to the concomitant hypotensive effect. The depth and frequency of breathing were analyzed in terms of the threshold-inhibition curve for termination of inspiration (VT/TI relationship) and of bulbo-pontine rhythm, estimated from inspiratory and expiratory time during occlusion of the airways at the end expiratory level (TE/TI relationship). This provide the central respiratory rhythm when the phasic lung volume receives no input from pulmonary stretch receptors. The hypotension induced by PGI2 increased pulmonary ventilation mainly through a change in VT and caused a slight rightward displacement of VT/TI relationship without modifying the slope of the curve. This effect seems to be vagally mediated. PGI2 also changed the bulbo-pontine rhythm. Our results show that PGI2 modifies the vagal discharge and bulbo-pontine rhythm by two opposite mechanisms: hypotension and an apparent direct action on carotid and aortic baroreceptors.

Analysis of hemodynamic and respiratory effects of PGI2 in the pig

Cardiovascular and pulmonary effects of prostacyclin (PGI2) were investigated in the anaesthetized pig before and after vagosympathectomy at 1',2',3',4',5',10',15' and 20' after the beginning of the infusion. The animals were perfused with PGI2,2ug/kg/min for 4 min. We measured the following parameters : mean arterial pressure, heart rate, cardiac output, stroke volume, mean pulmonary arterial pressure, mean wedge pressure, left stroke work, total systemic resistance, total pulmonary resistance, tidal volume, respiratory frequency, minute volume, lung resistance and compliance, end-tidal CO2, transpulmonary pressure. Our findings suggest that the hypotension observed is due to a reduction in total peripheral resistance by a direct effect of PGI2 on the vascular bed without inhibition of the sympathetic nervous system. Prostacyclin does not directly modify cardiac function and produces a decrease in preload by venous dilation. The changes in pattern of breathing are related to the hypotensive effect of PGI2.

[Respiratory effects of PGI-2 in the pig]

In anaesthetised pig the intravenous perfusion of 2 micrograms/Kg/min/4 min of PGI2 induces within 30'' respiratory changes that spontaneously disappear after perfusion. The PGI2 induces a decrease of respiratory frequency while total pulmonary resistance increases significantly. This changes of pattern of breathing are correlated to tonus of vagus nerve and after vagosimpathectomy are not present. The relationship of tidal volume/frequency has been evaluated according to the blood pressure variation.

[Hemodynamics in swine treated with PGI 2]

The hemodynamic response of pig perfused by PGI2 (2 micrograms/kg/mm/4 min) has been studied before and after vagosympathectomy. Prostacyclin produces hypotension, which depends to an reduction of total peripheral resistances, without cardiac involvement. A venous dilatation is also present with reduction of preload and of systolic volume. The authors conclude assessing that prostaciclyn act by peripheral mechanism.

Plasma turnover and excretion of K-strophanthoside-3H in human volunteers after parenteral administration

Pharmacokinetic parameters of K-strophanthoside-3H, a short-acting cardiac glycoside, were investigated in healthy subjects, patients suffering from heart disease, renal failure and in cholecystectomized patients with a biliary T-tube inserted surgically, after parenteral administration of 250 mug of the glycoside. The healthy subjects, patients suffering from heart disease and those with the biliary T-tube showed a dominant half-time for plasma turnover of the glycoside of 15-16 h after the i.v. route and 18-22 h after the i.m. route and cumulative urinary excretion of the drug over a 24 h period of 37-42% (i.v. route) and 32-33% (i.m. route). The volumes of distribution were lower in patients with heart disease and patients with biliary fistula than in the healthy subjects. In patients suffering from renal failure the dominant half-time of plasma turnover was higher (33 h), while cumulative urinary excretion of the glycoside (12%) and the volumes of distribution were lower than in the healthy subjects. A peak of plasma levels 30 min after i.m. administration of K-strophanthoside-3H leads to the conclusion that this glycoside is rapidly absorbed when injected intramuscularly.