Haemodynamic evaluation of ibopamine in severe congestive heart failure

Acute effect of ibopamine and isosorbide mononitrate on blood volume distribution in congestive heart failure

In order to compare ibopamine (IBO), a dopamine congener, with isosorbide mononitrate (ISMN) and to study their interaction in effects on the capacitance vasculature in congestive heart failure (CHF), a prospective, randomized, placebo-controlled, double-blind clinical trial was performed in 32 patients with New York Heart Association class II-IV CHF, randomly assigned to receive single oral doses of placebo, 200 mg IBO, 20 mg ISMN, or both IBO and ISMN. After labelling of red cells with 99mTc, changes in regional radioactivity, indicative of changes in blood volume, were recorded using a gamma-camera before and at 30, 60 and 120 min after drug administration. At 30 and 60 min, arterial systolic and pulse pressures were higher with IBO than with ISMN and placebo (for pulse pressure by mean 13.7 mmHg, 95% confidence interval 4.5-23.0 mmHg, at 30 min), probably reflecting an IBO-induced rise in stroke volume at unchanged heart rate and mean arterial pressure. IBO did not change regional radioactivity except for a transient increase of 4.4% (0.5-7.6%) in the thorax at 30 min. This was attenuated by concomitant ISMN treatment since, starting at 30 min, the drug increased radioactivity in the legs, compared with patients not receiving the drug, by 8.0% (95% confidence interval 0.2-15.8%), leading to a fall in thoracic and left ventricular radioactivity at 30 min of 3.4% (0.3-7.0%) and 6.4% (0.8-11.9%), respectively, and a fall of 5.5% (0.5-10.5%) in hepatic radioactivity at 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Ibopamine in chronic congestive heart failure: hemodynamic and neurohumoral effects

Ibopamine is a dopamine-like drug that shows mainly vasoactive properties, predominantly acting on dopamine1-(DA1-) and DA2-adrenoceptors. Ibopamine increases cardiac output, reduces peripheral vascular resistance, and increases renal blood flow, exerting a lesser effect on preload parameters. This hemodynamic improvement is also present even after relatively long-term treatment. There is no evidence of pharmacologic tolerance. In relation to DA2-activation, ibopamine modulates the neurohumoral consequences of heart failure with decreases in plasma renin activity and aldosterone and norepinephrine plasma levels, an effect that can be beneficial in the long-term treatment of heart failure patients.

Single-dose effects of ibopamine hydrochloride on renal function in patients with congestive heart failure

To examine the renal effects of ibopamine HCl we evaluated 15 patients with New York Heart Association Class II-III congestive heart failure and mild renal insufficiency (creatinine clearance [CLcr] = 45-85 ml min-1). Diuretics and vasodilators were withheld and a sodium (Na+)-restricted diet was initiated. All patients exhibited positive Na+ balance at the time of evaluation. Hourly urine volumes, urine chemistries, serum chemistries, PAH and inulin/iothalamate clearances were determined 2 h pre and 4 h post a single 200 mg oral dose of ibopamine. Effective renal plasma flow, creatinine clearance, filtration fraction, and the fractional excretion of sodium and potassium were not significantly altered postdose. A significant increase in urine output and decrease in urine osmolality were seen at all time points postdose. A significant reduction in serum potassium (2 and 3 h) and blood urea nitrogen (1, 3 and 4 h) concentrations occurred. Measurements of glomerular filtration rate by inulin or [125I]-iothalamate produced differing results in the patient groups studied. We conclude that a single dose of ibopamine does not produce significant improvements in renal function in patients with congestive heart failure, mild renal insufficiency and positive sodium balance.

Clinical relevance of long-term therapy with levodopa and orally active dopamine analogues in patients with chronic congestive heart failure

Beneficial effects of long-term treatment with dopamine analogues in patients with congestive heart failure may result from their vasodilating properties, in particular from renal artery vasodilation. Oral application of levodopa results in increased dopamine plasma levels and can improve cardiac performance and renal function in patients with congestive heart failure. A daily levodopa dosage of at least 4 g appears to a prerequisite for long-term response to the drug. Because of frequent side effects including nausea, vomiting, and dyskinesia at this dosage, the clinical usefulness of levodopa seems to be limited to a minority of patients. Ventricular arrhythmias have been shown to increase significantly during long-term levodopa therapy, probably due to stimulation of myocardial beta receptors. Increased ventricular arrhythmias or significant central nervous side effects have not been observed after administration of ibopamine and fenoldopam, which are orally active analogues of dopamine. Both agents exhibit potent arterial vasodilating properties and have been shown to increase cardiac performance in patients with congestive heart failure after short-term administration. The long-term beneficial effects of ibopamine and fenoldopam in the treatment of congestive heart failure have not yet been clarified. However, available results are encouraging and warrant further clinical evaluation of these agents, as well as the development of new analogues of dopamine, in particular of potent vascular dopamine agonists.

Acute haemodynamic effects of ibopamine and dopamine on isovolumic relaxation

The effects of intraduodenal ibopamine (a new orally active inotropic agent claimed to have haemodynamic effects similar to dopamine) on isovolumic relaxation were monitored for 90 min in eight closed-chest anaesthetized dogs. Dopamine and epinine (ibopamine active metabolite) were also infused at graded doses. After 15 min, ibopamine (12 mg/kg) shortened the time constant of isovolumic relaxation, and increased stroke volume and mean aortic pressure. Peak positive dP/dt increased significantly only 10 min later. Heart rate did not change. Dopamine (10 micrograms/kg per min) similarly reduced the time constant, and increased stroke volume, mean aortic pressure, peak positive dP/dt and heart rate. Epinine (10 micrograms/kg per min) caused similar changes in peak positive dP/dt, stroke volume, mean aortic pressure, and accelerated time constant without raising the heart rate. Ibopamine and epinine therefore significantly improved the isovolumic relaxation phase, like dopamine, without however affecting the heart rate.

Effect of dopamine, ibopamine, and epinine on alpha- and beta-adrenoceptors in canine pulmonary circulation

Dopamine has been widely utilized in the treatment of acute congestive heart failure, ibopamine, the diisobutyrate ester of N-methyldopamine (epinine), is a novel inotropic agent that, unlike-dopamine, is orally active. In clinical studies at doses that produce favorable hemodynamic responses, ibopamine and dopamine can evoke a slight and transient increase in pulmonary artery pressure and pulmonary capillary wedge pressure, an effect that is no longer apparent 1 h after administration. We have previously demonstrated in anesthetized dogs that this effect is due to stimulation of alpha-adrenoceptors in the pulmonary circulation by dopamine and ibopamine, as well as by the active form of ibopamine, epinine. The aim of the present investigation was to determine how dopamine, ibopamine, and epinine interact with beta-adrenoceptors in the canine pulmonary circulation, since this activity may serve to offset the alpha-adrenoceptor-mediated pulmonary vasoconstrictor responses. Intraarterial injection of dopamine, ibopamine, and epinine resulted in dose-dependent pulmonary vasoconstrictor responses with a maximum increase of approximately 50-60% above resting pulmonary vascular tone. When animals were pretreated with propranolol (1 mg/kg iv) to block beta-adrenoceptors, pulmonary vasoconstrictor responses to dopamine were unchanged, whereas pulmonary vasopressor responses to ibopamine and epinine were significantly potentiated, especially for epinine. Upon intraduodenal administration of a therapeutically effective dose of ibopamine (i.e. 36 mg/kg) to normal dogs, virtually no pulmonary pressor response was observed. However, administration of this same dose of ibopamine to dogs pretreated with propranolol (1 mg/kg iv) resulted in a marked pulmonary pressor response. These data indicate that epinine, and therefore the parent compound ibopamine, have the capacity to stimulate beta 2-adrenoceptors in the pulmonary circulation to a far greater degree than dopamine, and that this activity serves to offset, at least in part, the alpha-adrenoceptor-mediated pulmonary vasoconstriction that occurs in response to ibopamine.

Ibopamine as a substitute for digitalis in patients with congestive heart failure on chronic digoxin therapy. Smith Kline and French Ibopamine Group

The substitution of digoxin with ibopamine, a new inotropic and vasodilating agent, was evaluated in a multicenter study in 58 patients with mild-to-moderate congestive heart failure, stabilized on diuretics, and digoxin therapy. The study was a parallel, double-blind, randomized trial of four weeks duration in which half of the group continued the pre-study medication (diuretics and digoxin) and half of the group was treated with diuretics and ibopamine (100 mg, three times a day). At baseline evaluation, the two groups were similar for age, sex, underlying cardiac disease, duration of congestive heart failure, symptom score, cardiothoracic ratio, echocardiographic parameters of left ventricular function and exercise tolerance as measured by bicycle ergometry. After four weeks, no clinical deterioration was found in the patients treated with ibopamine in any measured parameter. There were two deaths during the study: a sudden death and one following an acute myocardial infarction. Both patients were on digoxin. This study suggests that in patients with mild-to-moderate congestive heart failure, ibopamine therapy may effectively and safely substitute digoxin therapy for up to four weeks, representing an option for patients requiring inotropic support but are at risk for potential digoxin toxicity.

Noninvasive assessment of diastolic and systolic properties of ibopamine in patients with congestive heart failure

The acute effect of a single oral 100 mg dose of ibopamine on systolic and diastolic left ventricular function in nine patients with congestive heart failure was assessed by quantitative M-mode and pulsed Doppler echocardiography. Echocardiography was performed at baseline and 30, 60, and 120 minutes after ingestion of drug. Indices of systolic and diastolic left ventricular function were derived from digitized tracings of the septal and posterior endocardial surfaces and transmitral and aortic valve velocity profiles. Ibopamine significantly improved systolic function as reflected by a decrease in the preejection period to left ventricular ejection time ratio from 0.57 +/- 0.16 at baseline to 0.47 +/- 0.15 (p less than 0.05) 30 minutes after ingestion of drug. The maximum improvements in stroke volume and cardiac output after ibopamine were from 63 +/- 35 to 72 +/- 40 ml (p less than 0.05) and 4.6 +/- 1.7 to 5.4 +/- 2.1 L/min (p = 0.05), respectively. The contribution of atrial systole to total diastolic filling increased from 32 +/- 10% at baseline to 37 +/- 12% (p less than 0.05) after 30 minutes and persisted for at least 120 minutes. The distribution of diastolic filling was significantly altered after ingestion of ibopamine as reflected by a decrease in the ratio of the time-velocity integrals of left ventricular filling during early diastole and atrial systole (Ei/Ai) from 2.44 +/- 1.08 at baseline to 1.98 +/- 0.97 (p less than 0.05) 30 minutes after drug. The decrease in the Ei/Ai persisted for at least 120 minutes. The duration of the effect of ibopamine on diastolic filling persisted longer than its effect on augmenting systolic function. The positive effect of ibopamine on systolic function makes it a promising drug in the treatment of congestive heart failure.

Early cardiovascular changes with ibopamine: evidence for a biphasic haemodynamic action

1. The haemodynamic effects of ibopamine, an oral dopamine derivative, were studied in eight patients with left ventricular dysfunction using invasive catheterisation techniques. 2. An early rise was seen in the mean right atrial pressure (P less than 0.05), the mean capillary wedge pressure (P less than 0.01) and the mean pulmonary arterial pressure (P less than 0.001) which occurred at 15 min and persisted for 30 min. 3. A second, later, positive chronotropic effect was seen as an increase in the heart rate (P less than 0.05) at 45 min with an increased cardiac output (P less than 0.05) persisting above baseline values at 1 h, but with no change in stroke volume. 4. These results support a biphasic mode of action for ibopamine which may be explained by a time phase difference in alpha- and beta-adrenoceptor stimulatory effects.

Analysis of epinine and its metabolites in man after oral administration of its pro-drug ibopamine using high-performance liquid chromatography with electrochemical detection

Ibopamine (N-methyldopamine O,O'-diisobutyrol ester, hydrochloride) is an ester prodrug of epinine. Epinine is a cardiovascular agent used in congestive heart failure because of its dopaminergic and adrenoreceptor agonist properties. Quantitative analytical methods, using high-performance liquid chromatography coupled with electrochemical detection, were developed for the determination of epinine and its known metabolites in biological media. Epinine was extracted from human plasma and urine via an alumina adsorption procedure; this procedure was also used to estimate epinine conjugates after prior enzymatic hydrolysis. Penicillamine was added to the incubation mixture to inhibit isoquinoline production. Urinary dihydroxyphenylacetic acid levels were obtained using the same alumina adsorption procedure, while a separate analytical procedure utilizing a direct high-performance liquid chromatographic analysis of samples was developed for homovanillic acid and its conjugates. Coefficients of variation for all the assays were below 8%. These methods were used to study the pharmacokinetics and metabolic fate of epinine after oral administration of ibopamine to healthy volunteers.

Effects of long-term therapy with oral ibopamine on resting hemodynamics and exercise capacity in patients with heart failure: relationship to the generation of N-methyldopamine and to plasma norepinephrine levels

N-Methyldopamine (epinine), one of the few modifications of the dopamine (DA) molecule that retains agonist activity at the DA1 receptor, was administered orally as the diisobutyric ester, ibopamine (100, 200, and 300 mg), to 15 patients with congestive heart failure. An increase in cardiac index and decline in systemic vascular resistance was observed with each dose, and these hemodynamic effects persisted for 3 to 6 hr. Small transient increments in right atrial and pulmonary capillary wedge pressures occurred 0.5 hr after ingestion of 200 and 300 mg of ibopamine, but these pressures returned to baseline or lower levels within 30 min. Heart rate and mean arterial pressure were unchanged. Plasma concentrations of epinine peaked 0.5 hr after administration of drug and then declined to minimal levels at 3 hr. Ten patients enrolled in a trial to evaluate the efficacy of long-term therapy with ibopamine; after 8 weeks of treatment, the initial hemodynamic responses to the drug were attenuated and no significant improvement in oxygen uptake at peak exercise was observed. A decline in plasma norepinephrine concentrations, which could be attributed to activation of alpha 2-adrenoceptors and/or DA2 receptors on sympathetic nerves, was observed after initial administration of ibopamine and persisted after long-term drug ingestion; no long-term hemodynamic benefit could be ascribed to the reduction in sympathetic activity.