Acute haemodynamic comparison of amrinone and pirbuterol in chronic heart failure. Additional effects of isosorbide dinitrate

Spectral Properties Echoing the Tautomerism of Milrinone and Its Application to Fe3+ Ion Sensing and Protein Staining

Knowledge on the spectral properties of the tautomers of milrinone (MLR) in solvents and solid-state, as well as under light conditions is of critical importance from both theoretical and practical points of view. Herein, we investigated the spectral properties of MLR in different conditions using UV-Vis and fluorescence spectroscopies. The experimental results demonstrated that MLR can undergo the tautomerization reaction induced by solvent polarity, light and pH, eliciting four tautomeric structures (enol, keto, anion, and cation forms). The interesting multi-functional groups in MLR enable it to coordinate with metal ions or to recognize gust molecules by H-bonding. In the use of MLR as an excited-state intermolecular proton transfer (inter-ESPT) fluorescent probe, a highly sensitive and selective analysis of Fe³⁺ was developed, which offered a sensitive detection of Fe³⁺ with the detection limit of 3.5 nM. More importantly, MLR exhibited the ability of anchoring proteins and led to the recognition-driven turn-on inter-ESPT process, highlighting the potential for the probe to image proteins in electrophoresis gels. The spectral experimental results revealed the possible degradation mechanism, so that we can better understand the side effects of oral preparations. The use of the available drug as an inter-ESPT fluorescent probe is simple and accurate, providing a good method for Fe³⁺ ion sensing and protein staining.

Comparison of the initial hospitalization costs between the patients treated with dobutamine and the patients treated with amrinone for acute decompensated heart failure in a Japanese institute

OBJECTIVES

Phosphodiesterase (PDE) III inhibitor therapy is effective for treatment of acute decompensated heart failure (ADHF). Nevertheless, this drug is expensive than conventional inotropic agent dobutamine. We compared total medication costs of the patients treated with PDE III inhibitor amrinone therapy to that of the patients treated with conventional dobutamine therapy during initial hospitalization.

METHODS

We analyzed 160 consecutive patients with ADHF admitted to our hospital. Shock, dehydration, severe infection, multiple organ failure, and mild heart failure (New York Heart Association class IIs) were not eligible for the study. Ninety-seven patients were divided into two groups: 1) DOB group treated with dobutamine therapy; and 2) AMR group treated with amrinone therapy. Total medication costs and cost for hospital room charge were calculated based on their usage during the initial hospitalization for each patient. Group comparison was done between the DOB and AMR groups.

RESULTS

Length of stay was longer in the DOB group than in the AMR group. Mean calculated cost of intravenous drugs was higher in the DOB group (173,186 +/- 239,147 yen) than in the AMR group (63,145 +/- 47,223 yen, P < 0.05). Total medication costs were higher in the DOB group than in the AMR group. Cost for hospital room charge was higher in the DOB group than in the AMR group.

CONCLUSIONS

In the treatment of ADHF, appropriate therapy even with expensive drugs makes total medication costs less expensive comparing with conventional therapy with cheaper drugs during initial hospitalization.

Effect of Cyclodextrin Nanocavity Confinement on the Photorelaxation of the Cardiotonic Drug Milrinone

We report on steady-state UV-visible absorption, emission, and picosecond emission studies of milrinone (MIR) drug in neutral water and complexed to cyclodextrins (alpha-, beta-, gamma-CD and dimethyl-beta-CD (DM-beta-CD)). The results reveal that MIR forms a 1:1 inclusion complex with CD. Upon encapsulation the emission intensity increases and the fluorescence lifetime changes from approximately 65 ps to 240-350 ps, indicating a confinement effect of the nanocages on the photophysical behavior of the drug. Due to its methyl groups, the DM-beta-CD complex shows the largest effect. The time-anisotropy experiments support the formation of 1:1 inclusion complexes and indicate motion of the drug inside the nanocavity. Furthermore, results of PM3 calculations combined with spectral and dynamical data show that the drug is not fully embedded into the cavities, and the conformation of the included complex explains the relatively short lifetimes and low emission quantum yields of these entities.

Combination of positive inotropic and vasodilating substances in congestive heart failure

Therapy combining vasodilators and inotropic agents is considered to be one of the most powerful means of improving cardiac function in patients with congestive heart failure (CHF). The vasodilators enhance the effectiveness of inotropic agents by providing a reduction in preload and/or afterload. Inotropic drugs with different mechanisms of action, such as digitalis glycosides, ephedrine, dopamine, dobutamine, ibopamine, terbutaline, salbutamol, pirbuterol, prenalterol, amrinone, and milrinone, have been tested in combination with vasodilators with a predominant effect on preload (nitrates, molsidomine), with a predominant effect on afterload (hydralazine, nifedipine), or with a balanced action on both arterial and venous beds (nitroprusside, prazosin, captopril), showing positive results. The problem of the combination of digitalis glycosides and vasodilators with different sites of action has been considered by our group. In 42 patients with CHF, digoxin (DIG, 0.01 mg/kg intravenously) was tested in combination with molsidomine (MLS, 4 mg sublingually) (12 patients), a nitrate-like agent with a predominant vasodilating action on the capacitance vessels, nifedipine (NFP, 10 mg sublingually) (22 patients), a Ca2+ antagonist drug with a predominant action on the resistance vessels, and captopril (CPT, 25 mg orally) (8 patients), an ACE inhibitor with a balanced effect on both preload and afterload. The combination DIG plus MLS caused a reduction in left ventricular filling pressure (LVFP) greater than that achieved with either agent alone. The hemodynamic improvement was obtained without side effects, in spite of the striking fall in preload. We stress that this investigation was performed on patients with CHF following acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic effects of intravenous perfusion of amrinone in increasing doses in 12 patients with severe heart decompensation]

Twelve patients with severe heart failure were given amrinone by intravenous infusion in doses rising from 1 to 2, 3 and 4 mg X min-1, the interval between each dose being 30 min. The total cumulative dose was 300 mg over 120 min. Haemodynamic measurements were started the day before treatment to take into account nycthemeral fluctuations in haemodynamics and the possible effects of maintenance treatments and meals, all factors which might influence the baseline values. When given at a rate of more than 2 mg X min-1, amrinone significantly improved cardiac function (p less than 0.001). The mean pulmonary capillary pressure fell from 24.1 +/- 5.3 to 13.7 +/- 8.6 mmHg, and the cardiac index rose from 1.75 +/- 0.40 to 2.51 +/- 0.32 1 X min-1 X m-2. Heart rate and blood pressure were not significantly modified. No adverse reaction was observed during the infusion and the following 24 hours. Thus, intravenous amrinone proved effective in patients with severe heart failure, with maximal effects being obtained in doses of 3 mg X min-1.

Myocardial pharmacodynamics of dopamine, dobutamine, amrinone and isoprenaline compared in the isolated rabbit heart

The isolated spontaneously beating rabbit heart was used for comparing the myocardial effects of isoprenaline, dobutamine, dopamine and amrinone. Both isoprenaline and dobutamine produced a progressive concentration-dependent increase in contractility from 100% to a maximum of about 200% (pD2 7.81 and 7.01, respectively) as measured by the increase in isotonic contraction rate. The simultaneous augmentations in contraction amplitude reached maxima of about 127 and 143% (pD2 7.83 and 7.05) for each of the drugs and the heart frequency rose to 202 and 162% (pD2 7.80 and 6.63), respectively. The accompanying oxygen consumption increased from 100 to 194% (pD2 7.70) for isoprenaline and to only 177% (pD2 6.36) for dobutamine. Coronary flow rate rose to 153 and 134%, respectively. Dopamine increased the contraction rate to 181% (pD2 6.26), contraction amplitude to about 122% (pD2 6.25) and heart rate to 162% (pD2, 5.85), while oxygen consumption rose to a maximum of 202% (pD2 5.69). Coronary flow rate rose to 156%. In contrast amrinone produced an unexpected slowly progressing decrease in contraction rate and contraction amplitude to about 66% (pD2 4.45 and 4.01, respectively). Oxygen consumption increased to 159% (pD2 4.10) and coronary flow rate to 210%. The positive inotropic effect of dobutamine thus equalled that of isoprenaline but with a distinct lower concomitant increase in heart frequency and oxygen consumption which may reflect a better myocardial efficiency during the action of dobutamine.

Intravenous use of amrinone for the treatment of the failing heart

Amrinone, a new nonadrenergic, nonglycosidic agent with combined positive inotropic and vasodilating properties, was approved recently for parenteral use in the treatment of left ventricular failure. Its mechanism of action is mediated primarily by selective phosphodiesterase fraction III inhibition, although at high doses alterations of calcium transport may occur. Acute hemodynamic changes produced by amrinone include augmentation of cardiac output and decreases in pulmonary capillary wedge pressure, right atrial pressure and systemic vascular resistance. Heart rate and blood pressure remain unaltered. Myocardial oxygen consumption declines concomitantly with the decrease in systolic wall tension. The efficacy of amrinone is comparable to that of dobutamine and dopamine. Synergistic interactions with catecholamines and vasodilators are described. Adverse effects are minimal, with dosage limited predominantly by decreases in filling pressures.

Pirbuterol. A preliminary review of its pharmacological properties and therapeutic efficacy in reversible bronchospastic disease

Pirbuterol is a beta-adrenoceptor agonist which differs structurally from salbutamol in the substitution of a pyridine ring for the benzene ring. In common with salbutamol, pirbuterol demonstrates both bronchodilatory and cardiovascular effects. Generally, improvements of up to 25% are noted in forced expiratory volume in 1 second (FEV1) [versus baseline or placebo] in asthmatic patients treated with pirbuterol for several months. In individual 12-week double-blind comparative studies, pirbuterol aerosol appeared similar to orciprenaline (metaproterenol) aerosol, and orally administered pirbuterol appeared similar to orally administered salbutamol in bronchodilator efficacy. However, well-designed long term comparative studies are needed to more clearly define the comparative efficacy of pirbuterol and alternative beta-adrenoceptor agonists.

Effects of intracoronary and intravenous amrinone infusions in patients with cardiac failure and patients with near normal cardiac function

The effects of intracoronary and intravenous infusions of amrinone were studied to distinguish the drug's direct cardiac actions from its peripheral vascular and neuroendocrine properties. Intracoronary infusions of amrinone were found to have no haemodynamic effect other than producing a slight reduction in the left ventricular ejection fraction and some suggestion of coronary vasodilatation in patients with impaired left ventricular function. They did not improve contractility, cardiac output, or filling pressures and had no significant effect on myocardial metabolism, although therapeutic concentrations of the drug were detected in coronary sinus blood. Intravenously administered amrinone reduced filling pressures and improved the cardiac index in all patients, but haemodynamic improvements were most pronounced in the patients with the worst cardiac function. These changes were accompanied by improvements in the indices of contractility only in patients in whom alterations in concentrations of free fatty acid, glycerol, and glucose suggested peripheral catecholamine release. In the patients with the best basal cardiac function intravenously administered amrinone produced a reduction in myocardial work and evidence of myocardial ischaemia, as a result of excessive reduction of coronary perfusion pressure and increased heart rate, without any appreciable increase in cardiac index. It is concluded that, at the concentrations of the drug that can be achieved in man without adverse effects, amrinone has no direct positive inotropic effect. Haemodynamic changes are predominantly the result of vasodilatation, although catecholamines may be released in some patients.

Assessment of the inotropic and vasodilator effects of amrinone versus isoproterenol

The hemodynamic effects of graded-dose infusions of amrinone (maximal dose 30 micrograms/kg/min) (10 patients) and isoproterenol (maximum dose 4 micrograms/min) (11 patients) were assessed in patients with a range of left ventricular (LV) function. LV ejection fraction ranged from 0.13 to 0.77 (mean +/- standard deviation 0.47 +/- 0.23) among the patients who received amrinone and from 0.24 to 0.77 (mean 0.52 +/- 0.18) among those who received isoproterenol. Peak-dose amrinone produced a reduction in LV filling pressure (from 15 +/- 10 to 10 +/- 7 mm Hg, p less than 0.001), but no significant change in heart rate, cardiac output, mean aortic pressure, total systemic vascular resistance (TSVR) or LV dP/dt max. In contrast, peak-dose isoproterenol produced a similar reduction in LV filling pressure (from 17 +/- 12 to 13 +/- 13 mm Hg, p less than 0.05), but also caused increases in heart rate, cardiac output and LV dP/dt max and decreases in mean aortic pressure and TSVR (p less than 0.001). The absolute change in cardiac output and stroke volume correlated closely with the change in TSVR in response to amrinone (r = -0.90, p less than 0.001 and r = -0.84, p = 0.002, respectively), but not in response to isoproterenol. Although isoproterenol produced a marked increase in cardiac output and LV dP/dt max (not explained by heart rate changes alone) in all patients, amrinone produced an increase in cardiac output only in those with markedly elevated LV filling pressures (who had a reduction in TSVR), and an increase in LV dP/dt in a minority.

Comparison of the effects of amrinone and sodium nitroprusside on haemodynamics, contractility, and myocardial metabolism in patients with cardiac failure due to coronary artery disease and dilated cardiomyopathy

The effects of intravenous amrinone and sodium nitroprusside on haemodynamic indices, left ventricular contractility, and myocardial metabolism were compared in patients with cardiac failure. All patients received one dose of each drug and some received serial doses. Eight patients had dilated cardiomyopathy and six coronary artery disease, but the responses to the two drugs were independent of the aetiology of cardiac failure. Both drugs lowered left ventricular end diastolic pressure and aortocoronary sinus oxygen difference and increased cardiac index and left ventricular efficiency; these effects were dose related. Although the effects of the drugs on peripheral blood substrate concentrations were different, those on myocardial substrate metabolism were identical. Pressure derived indices of contractility in each group of patients were unaltered by either drug. After amrinone administration increases in cardiac index were related to plasma amrinone concentration, but alterations in contractility were not. In four individual patients increases in contractility were associated with alterations in plasma metabolite concentrations, which suggested that catecholamine release had occurred. For the groups of patients as a whole, however, amrinone had effects which did not differ significantly from those of the pure vasodilator, nitroprusside. There was no evidence that amrinone had a direct positive inotropic effect since no dose related changes in indices of contractile function could be established.

Non-additive positive inotropic effects of amrinone and ouabain on cat papillary muscles

Amrinone has been shown to produce haemodynamic benefits in digitalis-treated patients. Since amrinone is a positive inotropic agent on isolated heart muscle, these benefits may mean that amrinone increases the maximal ouabain-induced increase in force of contraction, without causing toxicity. We have therefore measured, in cat right ventricular papillary muscles, the inotropic effects of ouabain, amrinone alone and amrinone with a maximally effective, non-toxic ouabain concentration (2 X 10(-7) M). Ouabain is much more potent than amrinone (EC50-values: ouabain, 8 X 10(-8) M, amrinone, 1-2.8 X 10(-3) M). The highest amrinone concentration used (6 X 10(-3) M) produced a significantly lower increase in force of contraction than ouabain (2 X 10(-7) M) in the same muscles. After ouabain (2 X 10(-7) M) produced a stable effect, no further increase in force of contraction was observed with any amrinone concentration. Sustained arrhythmias were observed in five of six muscles at 3 X 10(-3) M amrinone with ouabain (2 X 10(-7) M), but in only one of these muscles with amrinone 3 X 10(-3) M alone. Since the positive inotropic effects of amrinone are not additive with those from a maximally effective ouabain concentration, the haemodynamic benefits seen in patients are probably due to non-cardiac effects of amrinone such as vasodilatation.

Amrinone. A preliminary review of its pharmacological properties and therapeutic use

Amrinone is a bipyridine derivative with positive inotropic effects and vasodilatory properties. However, in the clinical setting of congestive heart failure, the relative contribution of these factors remains a matter of conjecture. Its mode of action appears to be related to alterations in extracellular and intracellular calcium balance, probably mediated by increased levels of tissue cyclic adenosine monophosphate and possibly involving a sodium-dependent pathway. Clinical experience has mostly been short term and is limited to a relatively small number of patients with severe congestive heart failure, refractory to conventional treatment. Amrinone rapidly improves cardiac performance by decreasing systemic vascular resistance (afterload), decreasing the determinants of left ventricular filling pressure (preload) and improving the cardiac contractility. Improvements in exercise performance and clinical symptomatology occur without an increase in heart rate or decrease in mean arterial pressure. Amrinone has been compared with dopamine, dobutamine, pirbuterol and prazosin in preliminary short terms studies in patients with severe congestive heart failure, although more studies are needed before any relative clinical advantages or disadvantages can be ascribed to amrinone. Initial experience suggests that the addition of vasodilators such as hydralazine and isosorbide dinitrate to amrinone therapy may confer additional haemodynamic benefits. Preliminary medium term studies suggest that tolerance to the haemodynamic effects of amrinone does not usually occur, but long term studies are needed to determine whether amrinone alters the normal progression of the disease and whether overall mortality is affected. Amrinone has usually been administered as intravenous bolus doses (totalling 1.5 to 3.6 mg/kg/day) and/or continuous intravenous infusion, with varied results. Generally, an oral dose greater than the intravenous dose is required to achieve an equivalent level of response. Reversible, usually asymptomatic, thrombocytopenia occurs in about 20% of patients treated with amrinone. Arrhythmias and gastrointestinal disturbances have been reported, but wider clinical experience is required to determine the side effect profile of the drug.