RESUMO
Twenty-one patients with heart failure (New York Heart Association [NYHA] class II to IV) received a 24-hour infusion of enoximone followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I to III received an 0.5 mg/kg bolus, followed by a maintenance infusion of 2.5, 5.0, or 10.0 micrograms/kg/min. Group IV patients received a maintenance infusion of 5.0 micrograms/kg/min without a loading dose. Serial assessment of hemodynamics, plasma levels of enoximone and enoximone sulfoxide, and ventricular ectopy were performed. Enoximone produced a clinically significant increase in cardiac index, and a decrease in mean pulmonary artery wedge pressure and systemic vascular resistance in all groups. Enoximone mildly increased heart rate, and had a minimal effect on mean arterial pressure. There was no statistically significant change in ventricular ectopy during the infusion. Significant hemodynamic improvement was noted at even the lowest infusion rate, and did not increase in linear fashion at higher infusion rates. In patients who did not receive an initial loading bolus of 0.5 mg/kg, the increase in cardiac index was delayed by approximately 1 hour. Plasma concentrations of both enoximone and its major metabolite continued to rise throughout the 24-hour infusion in group III (10.0 micrograms/kg/min), rather than reaching steady state as predicted by the terminal exponential half-lives of these compounds. This is suggestive of nonlinear pharmacokinetics and indicates a potential for excessive accumulation of enoximone and its metabolite during prolonged infusion. These findings may have important implications in guiding the intravenous administration of enoximone.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Insuficiência Cardíaca/tratamento farmacológico , Hemodinâmica/efeitos dos fármacos , Imidazóis/farmacologia , Imidazóis/farmacocinética , Inibidores de Fosfodiesterase/farmacologia , Inibidores de Fosfodiesterase/farmacocinética , Idoso , Relação Dose-Resposta a Droga , Avaliação de Medicamentos , Enoximona , Feminino , Humanos , Infusões Intravenosas , MasculinoRESUMO
Enoximone is a phosphodiesterase inhibitor, which has been studied extensively for use in the management of patients with moderate-to-severe heart failure. The authors have studied the absorption and disposition kinetics of enoximone and its primary metabolite, enoximone sulfoxide, after both single oral doses of enoximone and at steady-state after short-term chronic oral therapy. A total of ten patients (two female, eight male) with moderate-to-severe heart failure (NYHA class II-IV) were enrolled into the study after giving written informed consent. The plasma levels of enoximone sulfoxide were greater than those of enoximone at all sampling times. The peak enoximone sulfoxide plasma concentrations ranged from 3.5 to 17.3 times the peak enoximone plasma levels for individual patients. The average steady-state plasma concentrations for enoximone were 115 +/- 40 ng/mL and 190 +/- 78 ng/mL for 50 mg every 8 hours and 100 mg every 8 hours dosage regimens, respectively. The absorption and disposition kinetics of enoximone were found to be significantly variable between patients. The authors also evaluated the relationship between dose administered and steady-state plasma levels as well as the relationship between the observed and predicted steady-state plasma levels. The authors found a linear relationship between the dose that was administered and the accrued plasma levels, as well as a good correlation between the predicted and observed steady-state levels. Although these data confirm previous reports that the sulfide metabolite of enoximone accumulates extensively in the plasma during oral therapy, reaching levels much higher than those of enoximone, these data do not support previous suggestions that the disposition of enoximone is nonlinear.
Assuntos
Cardiotônicos/farmacocinética , Insuficiência Cardíaca/metabolismo , Imidazóis/farmacocinética , Administração Oral , Adulto , Idoso , Cardiotônicos/administração & dosagem , Cardiotônicos/uso terapêutico , Enoximona , Feminino , Meia-Vida , Insuficiência Cardíaca/tratamento farmacológico , Humanos , Imidazóis/administração & dosagem , Imidazóis/sangue , Imidazóis/uso terapêutico , Masculino , Taxa de Depuração Metabólica , Pessoa de Meia-Idade , Fatores de TempoRESUMO
Twenty-one patients with heart failure (NYHA class II-IV) received a 24-hour infusion of enoximone, followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I-III received a 0.5 mg/kg bolus, followed by a maintenance infusion of 2.5, 5.0 or 10.0 micrograms/kg/minute. Group IV patients received a maintenance infusion of 5.0 micrograms/kg/minute without the bolus. Serial assessments of haemodynamics, plasma levels of enoximone and enoximone sulphoxide, and ventricular ectopy were performed. Enoximone produced a significant increase in cardiac index (28.1-46.7%) and a decrease in mean pulmonary artery wedge pressure (6.4-35.7%) and systemic vascular resistance (34.7-78.9%). Enoximone had minimal effect on heart rate and blood pressure. In patients who did not receive an initial bolus of 0.5 mg/kg, haemodynamic changes were delayed by approximately 1 hour. Significant haemodynamic improvement was noted at even the lowest infusion rate and did not increase in linear fashion at higher infusion rates. During infusion of enoximone at 10.0 micrograms/kg/minute, both enoximone and its sulphoxide accumulated non-linearly and did not achieve a steady state. No significant adverse effects were noted in these patients. Enoximone infusion at rates greater than 5.0 micrograms/kg/minute may confer minimal additional haemodynamic benefit, while resulting in significant accumulation of enoximone and enoximone sulphoxide. Ventricular ectopy did not increase significantly in most patients.
Assuntos
Cardiotônicos/farmacocinética , Hemodinâmica/efeitos dos fármacos , Imidazóis/farmacocinética , Cardiotônicos/farmacologia , Enoximona , Insuficiência Cardíaca/tratamento farmacológico , Humanos , Imidazóis/farmacologia , Infusões Intravenosas , Rim/efeitos dos fármacosRESUMO
Sixty-five patients with symptomatic, drug-refractory, sustained ventricular tachycardia or fibrillation were treated with oral sotalol (80 to 480 mg twice daily). Sotalol was withdrawn in 11 patients because of continued inducibility of ventricular tachycardia at the time of follow-up electrophysiologic study. Therefore, the clinical effectiveness of sotalol could be evaluated in 54 patients followed up for 11.5 +/- 6 months (range 0.2 to 25). The actuarial incidence of successful sotalol therapy was 54 +/- 13% at 6 months and 47 +/- 13% at 12 months. In 39 patients who underwent electrophysiologic testing while receiving oral sotalol, the drug prevented the reinduction of ventricular tachycardia/fibrillation in 8 (20%). During follow-up study, arrhythmia recurred in 1 (17%) of 6 patients whose ventricular tachycardia was noninducible with oral sotalol and in 8 (44%) of 18 with inducible tachycardia but who were continued on oral sotalol therapy. Adverse effects were noted in 28 patients (42%), requiring drug withdrawal in 13 (22%) and dose reduction after hospital discharge in 10 (15%). Exacerbation of ventricular arrhythmia occurred in six patients (9%), one of whom had associated hypokalemia. Sotalol is frequently useful in the control of intractable, life-threatening ventricular arrhythmias, and its efficacy appears to be predicted by programmed stimulation. However, there is a high rate of limiting side effects, which precludes its use in a large number of patients, and a substantial risk of arrhythmia exacerbation.
Assuntos
Arritmias Cardíacas/tratamento farmacológico , Sotalol/uso terapêutico , Administração Oral , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/terapia , Resistência a Medicamentos , Cardioversão Elétrica , Eletrofisiologia , Cardiopatias/induzido quimicamente , Ventrículos do Coração , Humanos , Recidiva , Sotalol/efeitos adversosRESUMO
The chemical and pharmacologic properties, pharmacokinetics, drug interactions, clinical efficacy, adverse effects, and dosage of propafenone are reviewed. Propafenone is a class IC antiarrhythmic agent that is structurally similar to the beta blockers but that has only weak beta-blocking and calcium-channel-blocking activity. It is well absorbed after oral administration, but systemic bioavailability is only 12% after a 300-mg dose. Among extensive metabolizers (greater than 90% of the United States population), bioavailability seems to vary nonlinearly with dose and increases substantially with food; these effects are not seen in poor metabolizers. Elimination is primarily hepatic, with a mean elimination half-life after oral administration of 5.5 hours in extensive metabolizers and 17.2 hours in poor metabolizers. The relationship between plasma propafenone concentration and clinical response varies considerably among individual patients; therefore, plasma concentrations have limited usefulness in predicting efficacy or electrophysiologic effects. Propafenone is effective in treating ventricular tachycardia and in suppressing premature ventricular complexes (PVCs). It is less effective in the treatment of refractory ventricular tachycardia. Concurrent administration of digoxin, warfarin, or metoprolol with propafenone has been shown to increase the serum concentrations of those three drugs, while cimetidine slightly increases the propafenone concentrations. Additive pharmacologic effect can occur when lidocaine, procainamide, and quinidine are combined with propafenone. Overall, 21% to 32% of patients experience adverse effects, with 3% to 7% of these serious enough to warrant discontinuing therapy. The most common adverse effects are dizziness or lightheadedness, metallic taste, and nausea and vomiting; the most serious adverse effects are proarrhythmic events.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Propafenona , Humanos , Propafenona/efeitos adversos , Propafenona/farmacocinética , Propafenona/farmacologiaAssuntos
Liderança , Equipe de Assistência ao Paciente , Autoritarismo , Humanos , Satisfação no EmpregoRESUMO
Thirteen patients with drug-resistant, life-threatening ventricular arrhythmias and inducible sustained ventricular tachycardia (VT) at electrophysiologic study received moricizine HC1 (ethmozine), 10 mg/kg/day orally. Eight patients underwent electrophysiologic study before and after drug administration; the arrhythmia became noninducible in one. In five other patients, spontaneous sustained VT occurred after 1 to 5 days of drug therapy, and one patient had a worsening of arrhythmias on ethmozine. Ethmozine prolonged infranodal conduction time (HV interval) (51.4 +/- 13.8 msec to 69.3 +/- 17.7 msec [mean +/- SD]), PR interval (201 +/- 28.1 msec to 244 +/- 62.2 msec), and QRS interval (123 +/- 27 msec to 147 +/- 32 msec). Ventricular refractory periods were not consistently affected, and only the one patient who became noninducible had an increase in effective ventricular refractory period (280 to 310 msec). The drug had no significant effect on sinus cycle length or sinus node recovery time, atrial conduction or refractoriness, or atrioventricular nodal refractoriness. Ethmozine had no effect on radionuclide ejection fraction (25.5 +/- 12.7% to 28.2 +/- 13.8%) or cardiac index (2.4 +/- 0.7 to 3.0 +/- 0.6 ml/min/m2) and caused no significant changes in mean aortic, right atrial, pulmonary arterial, or pulmonary capillary wedge pressures. Although the drug is well tolerated and produces no untoward hemodynamic effects, ethmozine is relatively ineffective in patients with sustained VT refractory to conventional antiarrhythmic agents.
Assuntos
Antiarrítmicos/uso terapêutico , Hemodinâmica/efeitos dos fármacos , Fenotiazinas/uso terapêutico , Taquicardia/tratamento farmacológico , Adulto , Idoso , Pressão Sanguínea/efeitos dos fármacos , Débito Cardíaco/efeitos dos fármacos , Estimulação Cardíaca Artificial , Eletrocardiografia , Eletrofisiologia , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Moricizina , Fenotiazinas/sangue , Volume Sistólico/efeitos dos fármacos , Taquicardia/fisiopatologiaRESUMO
Propafenone disposition kinetics were studied after intravenous and oral doses in patients with ventricular arrhythmias. Plasma concentration-time data were fit to a two-compartment model for all but one patient, whose data required fitting to a three-compartment model. The model-independent calculated values of clearance, steady-state volume of distribution, and terminal t1/2 were 11.2 +/- 4.8 ml/min/kg, 3.6 +/- 2.1 l/kg, and 5.0 +/- 3.6 hr. After 5 days on oral propafenone, elimination t1/2 was 6.2 +/- 3.3 hr. The longer t1/2s and the estimates of steady-state bioavailability above 100% suggests that clearance decreases during chronic oral dosing. Considerable intersubject variability was noted in all disposition parameters.
Assuntos
Antiarrítmicos/metabolismo , Arritmias Cardíacas/metabolismo , Propiofenonas/metabolismo , Adulto , Idoso , Feminino , Meia-Vida , Humanos , Cinética , Masculino , Pessoa de Meia-Idade , PropafenonaRESUMO
Sixteen patients with ventricular tachycardia (VT) or nonfatal cardiac arrest were treated with propafenone (P), 900 mg/day. Electrophysiologic studies were performed before and during therapy with P. All patients had inducible sustained VT at the baseline study. During P therapy, VT was not inducible in 1 patient, was unsustained in 1 and was harder to induce in 2 patients. P increased the cycle length of VT from 307 +/- 67 to 382 +/- 107 ms. Five patients began outpatient therapy with P, including 2 in whom VT was slowed to less than 125 beats/min. Two are arrhythmia-free during follow-up of 2 and 8 months. P significantly increased intraatrial conduction time (from 44 +/- 12 to 72 +/- 22 ms), AH interval (from 115 +/- 36 to 152 +/- 45 ms), HV interval (from 55 +/- 18 to 92 +/- 42 ms), QRS duration (from 140 +/- 36 to 180 +/- 48 ms) and QT interval (from 402 +/- 30 to 459 +/- 60 ms). P increased atrial (from 247 +/- 36 to 288 +/- 38 ms) and ventricular (from 249 +/- 20 to 277 +/- 32 ms) effective refractory periods, Sinus cycle length did not change, but the corrected sinus node recovery time increased (from 162 +/- 85 to 821 +/- 1,607 ms). P aggravated arrhythmias in 4 patients. The plasma P concentration, measured either at the time of electrophysiologic studies of when therapy was discontinued, was 753 +/- 428 ng/ml. P suppressed ventricular ectopic beats in 33% and increased them in 1 patient. P has antiarrhythmic activity against VT similar to that of other antiarrhythmic drugs and has potential for serious adverse effects in some patients.
Assuntos
Antiarrítmicos/uso terapêutico , Propiofenonas/uso terapêutico , Taquicardia/tratamento farmacológico , Administração Oral , Antiarrítmicos/administração & dosagem , Antiarrítmicos/efeitos adversos , Cateterismo Cardíaco , Estimulação Cardíaca Artificial , Ensaios Clínicos como Assunto , Eletrocardiografia , Frequência Cardíaca/efeitos dos fármacos , Humanos , Propafenona , Propiofenonas/administração & dosagem , Propiofenonas/efeitos adversos , Recidiva , Taquicardia/fisiopatologiaRESUMO
We determined the efficacy, pharmacokinetics, and plasma concentration-response relationships of propafenone, a promising new antiarrhythmic drug. Thirteen patients with frequent and complex ventricular premature beats were studied after receiving four increasing doses, during drug washout and during a randomized double-blind placebo-controlled trial, to evaluate the optimal dose in each patient. A nonlinear relationship was found between propafenone dose and steady-state mean concentration with a 10-fold increase in drug concentration as dose increased threefold from 300 to 900 mg/day. There was great intersubject variability in elimination half-life (mean 6 hr, range 2.4 to 11.8), steady-state mean concentration on 900 mg/day of propafenone (mean 1008 ng/ml, range 482 to 1812), and "therapeutic" plasma concentration (mean 588 ng/ml, range 64 to 1044). The interaction of these three parameters in individual patients determined the duration of the antiarrhythmic action of propafenone during washout (mean 11.5 hr, range 4 to 22). There was a greater than 90% reduction of ventricular premature beats in 10 subjects during dose ranging and in seven during double-blind crossover. Side effects requiring discontinuation of the drug occurred in three patients and included apparent worsening of arrhythmias in two. We conclude that propafenone effectively suppresses ventricular arrhythmias and that nonlinear drug accumulation and intersubject variability in elimination of half-life, steady-state mean plasma concentration, and therapeutic concentration indicate a need for individual therapy.
Assuntos
Antiarrítmicos/administração & dosagem , Propiofenonas/administração & dosagem , Adulto , Idoso , Antiarrítmicos/sangue , Arritmias Cardíacas/tratamento farmacológico , Aspartato Aminotransferases/sangue , Relação Dose-Resposta a Droga , Eletrocardiografia , Feminino , Meia-Vida , Humanos , Cinética , Masculino , Pessoa de Meia-Idade , Propafenona , Propiofenonas/efeitos adversos , Propiofenonas/sangueRESUMO
"Purple toes" syndrome and a generalized skin eruption developed in a 73-year-old woman who was taking warfarin sodium (Coumadin) as well as antiarrhythmic agents after a stroke. Both the rash and the discoloration of her feet were apparently related to use of warfarin and gradually resolved after discontinuation of the drug.