Plasma free captopril concentrations during short and long term treatment with oral captopril for heart failure

Get reliable laboratory findings - how to recognize the deceptive effects of angiotensin-converting enzyme inhibitor therapy in the laboratory diagnostics of sarcoidosis?

OBJECTIVES

Serum angiotensin-converting enzyme (ACE) is the only biomarker routinely used in the laboratory diagnostics of sarcoidosis, and ACE inhibitor (ACEi) drugs are among the most prescribed drugs worldwide. Taking ACEi can mislead medical teams by lowering ACE activity, delaying diagnosis and giving a false impression of disease activity of sarcoidosis. We aimed to develop a simple method to detect the presence of ACEi drugs in samples, to investigate the ACEi medication-caused interference and consequences in a retrospective study.

METHODS

ACE activity and the level of ACE inhibition were determined for 1823 patients with suspected sarcoidosis. These values were compared with the therapeutic information at the first and follow-up visits.

RESULTS

A total of 302 patients had biochemical evidence of an ACEi drug effect during diagnostic ACE activity testing. In their case, ACE activity was significantly lower (median(IQR): 4.41 U/L(2.93-6.72)) than in patients not taking ACEi (11.32 U/L(8.79-13.92), p<0.01). In 62 sarcoidosis patients, the ACEi reduced ACE activity to the reference range or below. Only in 40 % of the cases was the medication list recorded in the outpatient chart and only in 3 cases was low ACE activity associated with ACEi use. 67 % of the repeated ACE activity measurements were also performed during ACEi therapy.

CONCLUSIONS

Our study revealed that the use of ACEi is common in patients with suspected sarcoidosis. The ACE activity lowering effect of ACEi drugs may escape the attention of medical teams which can lead to diagnostic errors and unnecessary tests. Nevertheless, these pitfalls can be avoided by using a method suggested by our team.

Development and evaluation of physiologically based pharmacokinetic drug-disease models for predicting captopril pharmacokinetics in chronic diseases

The advancement in the processing speeds of computing machines has facilitated the development of complex physiologically based pharmacokinetic (PBPK) models. These PBPK models can incorporate disease-specific data and could be used to predict pharmacokinetics (PK) of administered drugs in different chronic conditions. The present study aimed to develop and evaluate PBPK drug-disease models for captopril after incorporating relevant pathophysiological changes occurring in adult chronic kidney disease (CKD) and chronic heart failure (CHF) populations. The population-based PBPK simulator Simcyp was used as a modeling and simulation platform. The visual predictive checks and mean observed/predicted ratios (ratio_(Obs/pred)) of the PK parameters were used for model evaluation. The developed disease models were successful in predicting captopril PK in all three stages of CKD (mild, moderate, and severe) and CHF, as the observed and predicted PK profiles and the ratio_(obs/pred) for the PK parameters were in close agreement. The developed captopril PBPK models can assist in tailoring captopril dosages in patients with different disease severity (CKD and CHF).

Medications for Hypertension Change the Secretome Profile from Marrow Stromal Cells and Peripheral Blood Monocytes

Marrow stromal cells (MSCs) are in different stages of clinical trials for stroke patients. MSCs are proposed to promote recovery through the release of secretomes that modulate the function of beneficial immune cells. The majority of stroke patients have comorbidities including hypertension, for which they are prescribed antihypertensive medications that might affect the function of MSCs, when they are administered in stroke patients. Here, we studied the effects of common antihypertensive medications on the secretomes of human MSCs and their modulation of human monocytes (Mo) derived from stroke patients. MTT assay was used to assess the proliferation of MSCs after they were exposed to increased levels of antihypertensive medications. MSCs were exposed to the following medications: atenolol, captopril, and losartan. Monocytes were isolated from stroke patients with NIHSS ranging from 11 to 20 and from healthy controls. MSC-Mo cocultures were established, and a secretome profile was analyzed using the Magpix Multiplex cytokine array from Luminex technology. The linear mixed-effect model was used for statistical analysis. All analyses were performed using SAS 9.4, and p values less than 0.05 were considered significant. At clinically relevant levels, there was no change in MSC proliferation after exposure to atenolol, captopril, or losartan. Atenolol increased IL-1RA in stroke-Mo and decreased IL-8 secretion from MSCs indicating an anti-inflammatory effect of atenolol on secretomes of these cells. Captopril increased IL-8 from stroke-Mo and increased IL-6, IL-8, and MCP-1 secretions from MSCs. Captopril also increased IL-6 secretion from cocultures of stroke-Mo and MSCs indicating a strong proinflammatory effect on MSCs and their interaction with Mo. Atenolol increased the secretion of IL-8 and MCP-1 while captopril increased the secretion of IL-6 and MCP-1 from MSCs. Losartan decreased the release of IL-6 from MSCs. Losartan reduced MCP-1 and TNF-α from stroke-Mo and reduced IL-8 from cocultures of stroke-Mo and MSCs. Our results show that antihypertensive medications such as atenolol, captopril, and losartan, at concentrations comparable to doses prescribed for patients hospitalized for acute stroke, modulate the secretome profile of MSCs and their modulatory effects on target immune cells. Our results suggest that stroke trials involving the use of intravenous MSCs should consider the effect of these antihypertensive drugs administered to stroke patients.

Once daily dosing of enalapril in congestive heart failure

Enalapril 40 mg or tolerated dose was given once daily to 21 patients with congestive heart failure (CHF), NYHA class III, in addition to treatment with digoxin and/or diuretics. After an 8-week open period, 19 patients were randomized to continue enalapril or to receive a placebo in a double-blind manner. After the first enalapril dose of 10 mg, maximal reduction of blood pressure (BP) occurred after 4 hours (mean 34/17 mmHg; p less than 0.001). No further reduction was found after higher doses. After the open period significant improvement was shown as judged by NYHA class (p less than 0.01), stroke volume (p less than 0.05), maximal working capacity (p less than 0.05), heart volume (p less than 0.01) and maximum rate pressure product (RPPmax) (p less than 0.001). Urinary aldosterone markedly decreased (p less than 0.01), whereas serum potassium and serum creatinine slightly increased (p less than 0.05). At the end of the blind period enalapril was superior to placebo concerning NYHA class (p less than 0.01), heart volume (p less than 0.05) and RPPmax (p less than 0.05). Other parameters, including aldosterone in urine, did not differ between the groups. Carry-over effects may have diminished the differences between enalapril and placebo. Diarrhoea (n = 5) and hypotension (n = 5) were the most common side-effects. Overall, enalapril was well tolerated and seems to be useful in single daily doses in the treatment of CHF.

Clinical and neurohumoral differences between spirapril and captopril in mild to moderate chronic congestive heart failure

BACKGROUND

This study was done to determine whether the difference in duration of action of the long-acting angiotensin-converting enzyme (ACE) inhibitor spirapril compared with the short-acting ACE inhibitor captopril affects clinical efficacy in patients with congestive heart failure.

METHODS AND RESULTS

The effects on exercise capacity, neurohumoral status, and quality of life were studied in 20 patients with mild to moderate congestive heart failure in a double-blind, randomized, comparative study in parallel groups with a duration of 12 weeks. All assessments during the study were performed in the morning, before intake of the study medication, to avoid the expected peak effect of the ACE inhibitors used. Mean peak oxygen consumption (peak Vo2) was 17.4 mL/min/kg (range, 14.2-19.9 mL/min/kg) and mean left ventricular ejection fraction was 28% (range, 13-40%). Exercise duration in the captopril group showed a significant increase after 12 weeks (P < .05) of treatment compared with the spirapril group. Peak oxygen consumption tended only to increase in the captopril-treated patients compared with the spirapril-treated patients. Serum ACE activity was significantly different between the two treatment groups during treatment (P < .0001) and showed only a significant decrease in the spirapril group. There was no difference in improvement of quality of life between the two treatment groups.

CONCLUSIONS

This study showed that the effects of the ACE inhibitors spirapril and captopril on exercise capacity are not related to the degree of inhibition of serum ACE activity.

Pharmacokinetic-pharmacodynamic model relating spiraprilat plasma concentrations to systemic and regional hemodynamic effects in congestive heart failure

The aim of this study was to investigate the relations between the plasma concentrations of spiraprilat (the active metabolite of the angiotensin-converting enzyme inhibitor spirapril) and its effects on plasma converting enzyme activity (PCEA), pulmonary capillary wedge pressure (PCWP), and brachial blood flow (BBF), after a single oral administration of 6 mg of spirapril in eight patients with severe congestive heart failure (CHF). Concentrations and effects were determined before and repeatedly during 48 h after drug intake. A sigmoid model was fitted to individual observations. Maximal effects, concentrations inducing half-maximal effects, and Hill coefficients were -99 +/- 2%, 3.9 +/- 1.9 ng/ml, and 2.4 +/- 0.7 for PCEA inhibition, -15 +/- 8 mm Hg, 11.8 +/- 9.2 ng/ml, and 2.6 +/- 1.3 for PCWP decrease, and 36 +/- 19 ml/min, 13.8 +/- 7.6 ng/ml, and 3.3 +/- 1.0 for BBF increase. In severe CHF, although a 14 ng/ml plasma concentration of spiraprilat may induce a 95% inhibition of PCEA, a 30 ng/ml plasma concentration is mandatory to normalize PCWP and BBF. This concentration corresponds to the peak achieved after a 6-mg oral dose of spirapril.

Evidence for norepinephrine cardiotoxicity mediated by superoxide anion radicals in isolated rabbit hearts

Catecholamines have been demonstrated to be cardiotoxic. Besides hemodynamic alterations, oxygen free radicals generated by the auto-oxidation of catecholamines might contribute to their deleterious effects. We examined the influence of exogenous norepinephrine (NE), after inhibiting functional alterations by alpha and beta-adrenoceptor blockade, on acute regional ischemia (MI).

METHOD

We used isolated electrically-driven rabbit hearts with depleted catecholamine stores (reserpine 7.0 mg/kg i.p. 16-24 h before preparation, Langendorff, constant pressure: 70 cm H2O, Tyrode solution, Ca2+ 1.8 mmol/l, 37 degrees C, 185-200 beats/min). Repetitive MI, separated by a reperfusion period of 50 min, was induced by coronary artery branch ligature and quantitated from epicardial NADH-fluorescence photography. Starting after a reperfusion period of 20 min, isolated hearts were treated with NE (10(-6) M), in the presence of propranolol (10(-6) M), phentolamine (10(-6) M) and vitamin C (3 x 10(-8) M) in the perfusion buffer to prevent the functional effects of NE. The influence of the free radical scavenger superoxide dismutase (SOD) (30 U/ml) or captopril (10(-6) M) on MI was also examined.

RESULTS

Left ventricular pressure or coronary flow were not significantly affected by either treatment (p > 0.05). Epicardial NADH-fluorescence area and intensity were, however, significantly enhanced by NE (+22%) (P < 0.05), although propranolol, phentolamine and vitamin C had no significant influence on MI (P > 0.05). SOD had no significant effect on MI in control hearts (P > 0.05) but completely prevented MI enlargement by NE (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative properties of angiotensin-converting enzyme inhibitors: relations with inhibition of tissue angiotensin-converting enzyme and potential clinical implications

This review summarizes the evidence indicating that local synthesis of angiotensin II, and interference with this process by inhibition of angiotensin-converting enzyme (ACE), may be important in the treatment of hypertension. Inhibition of tissue converting enzyme generally has a stronger correlation with the hemodynamic effects of ACE inhibitors than inhibition of ACE in plasma. Reported differences in the ability of ACE inhibitors to penetrate tissues and to bind to the converting enzyme may be closely related to the relative lipophilicity of these agents. Finally, correlation of data from clinical studies with results provided by laboratory experimentation suggests that the efficacy of different ACE inhibitors in hypertensive patients may be predicted from differences among the actions of these drugs in vitro and in whole animals.

A lack of effect of captopril on platelet aggregation in patients with congestive heart failure

We have studied the acute and chronic effects of an ACE inhibitor (captopril) on platelet function and the renin-angiotensin system in patients with congestive heart failure. Plasma concentrations of angiotensin II fell significantly after a single dose of captopril (25 mg) and during long-term treatment with captopril (2 weeks, 75 mg/day). Plasma renin activity increased significantly after both the single and repeated doses. Captopril did not affect ADP-induced platelet aggregation or concentrations. It seems unlikely that circulating angiotensin II affects ADP-induced platelet aggregation in patients with congestive heart failure.

Sublingual administration of captopril versus nitroglycerin in patients with severe congestive heart failure

Angiotensin-converting enzyme inhibition has proven to be a successful approach for the long-term treatment of patients with congestive heart failure. This investigation compared the acute hemodynamic changes after sublingual administration of the angiotensin-converting enzyme inhibitor captopril with those after nitroglycerin. A total of 24 patients with severe left heart failure (New York Heart Association classes III and IV) were given 25 mg captopril and 0.8 mg nitroglycerin sublingually in this randomized, cross-over study. Hemodynamic monitoring revealed a clear improvement in pre- and afterload parameters for both drugs (P less than 0.01 and P less than 0.001), while captopril induced a higher increase in cardiac index (+49.2% vs. +25%), stroke volume index (+53.5% vs. +25.7%), and stroke work index (+55% vs. +28%) than nitroglycerin (P less than 0.001). Although not statistically significant, the onset of change for most hemodynamic parameters was measured earlier after nitroglycerin (after 12-19 vs. 16-22 minutes). Captopril revealed later peak effects (after 47-84 vs. 25-55 minutes, P less than 0.001) and a longer sustained improvement in hemodynamic values (return to baseline values after 117-162 vs. 68-120 minutes, P less than 0.001). No side effects occurred after either captopril or nitroglycerin in this study. Thus, these results indicate there is an early improvement in hemodynamic parameters after the sublingual administration of both drugs in patients with severe congestive heart failure, and that captopril induces a more pronounced and prolonged improvement than nitroglycerin.

Effects of cardiovascular disease on pharmacokinetics

The pathophysiologic changes occurring in cardiovascular disease can affect the kinetics of drugs in several different ways. The present review examines these modifications and the underlying mechanisms. The kinetics of specific agents, such as antiarrhythmic, antihypertensive, cardiotonic, and other drugs are considered, and the clinical implications are outlined. The clinician should be aware of these modifications, because they require an adjustment of the dosage regimen. A rational basis for a correct therapeutic choice can be provided by adequate knowledge of these modifications.

Hemodynamic effects of lisinopril after long-term administration in congestive heart failure

To determine whether acute effects of the angiotensin converting enzyme inhibitor lisinopril are maintained during long-term therapy, 19 patients were studied using right-sided heart catheterization before an initial randomized dose of lisinopril and again after 12 weeks of maintenance lisinopril therapy. During initial evaluation, lisinopril produced significant decreases in mean systemic arterial pressure, pulmonary artery wedge pressure, systemic vascular resistance, mean pulmonary arterial pressure, mean right atrial pressure and pulmonary vascular resistance, and concomitant increases in cardiac index and stroke volume index. After 12 weeks of therapy with lisinopril, the dosage of which was titrated to produce optimal relief of symptoms of congestive heart failure (CHF), repeat hemodynamic studies revealed persistent significant reductions in baseline systemic arterial pressure, pulmonary artery wedge pressure, mean pulmonary arterial pressure and systemic vascular resistance. However, the increases in cardiac index and stroke volume index were not statistically significant. To determine if further acute hemodynamic changes occur during long-term therapy, the patients were readministered a dose of lisinopril. This caused further decreases in systemic arterial pressure, mean pulmonary arterial pressure, pulmonary artery wedge pressure, systemic vascular resistance and mean right atrial pressure, and an increase in cardiac index. Lisinopril did not change stroke work index at either initial or rechallenge study. This study indicates that in patients with CHF treated with lisinopril, acute hemodynamic effects persist after 12 weeks of therapy, and acute hemodynamic response continues to occur upon drug readministration.

Angiotensin-converting enzyme inhibitors. Relationship between pharmacodynamics and pharmacokinetics

The inter-relationship between the pharmacokinetic and pharmacodynamic behaviour of ACE inhibitors is reviewed. First, some of the methods which have been used to assess the pharmacodynamics of ACE inhibitors in humans are presented. They include humoral assays (e.g. ACE activity in plasma, renin activity, etc.), haemodynamic changes (blood pressure, total peripheral resistance, etc.) and agonist challenges (angiotensin I infusions). Subsequently a pharmacokinetic-dynamic model is described, based on biochemical processes obtained after ACE inhibition, which seems to be useful for the interpretation of the complex processes. The various correlations between plasma drug concentration on the one hand and plasma ACE activity, angiotensin II concentration in plasma or blood pressure on the other, are discussed on the basis of this model. From the model obtained it becomes obvious that under many circumstances the release of the inhibitor from ACE binding is the step which in fact determines the pharmacodynamically relevant elimination rate of the drug at low concentrations, whereas at high concentrations the elimination of the drug is mainly dependent on kidney (and/or liver) elimination rate. The dynamic-kinetic correlations are then presented for some ACE inhibitors in various disease states: arterial hypertension, heart failure, old age, renal failure, liver disease. In a final section the kinetic and dynamic relevance of interactions of ACE inhibitors with food and other drugs is described (e.g. prostaglandin inhibitors, diuretics, digoxin and cimetidine). Despite the great body of literature which deals with the kinetic and/or dynamic properties of ACE inhibitors, precise knowledge of the relationship between their kinetic and dynamic behaviour is rather limited and there is a clear need for further studies to elucidate this complex topic, thereby improving therapeutic possibilities with these useful new compounds.

Captopril. An update of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension and congestive heart failure

Captopril is an orally active inhibitor of angiotensin-converting enzyme (ACE) and has been widely studied in the treatment of patients with mild to moderate essential hypertension, severe hypertension not responsive to conventional diuretic/beta-adrenoceptor blocker/vasodilator regimens, and patients with chronic congestive heart failure refractory to treatment with a diuretic and digitalis. In patients with mild or moderate essential hypertension, titrated low doses of captopril used alone or in conjunction with a diuretic are similar in efficacy to usual doses of hydrochlorothiazide, chlorthalidone, or beta-adrenoceptor blocking drugs, as well as to the other ACE inhibitors. In addition, captopril improved well-being to a greater extent than methyldopa or propranolol in a study designed specifically to determine the effect of treatment on the quality of life of patients with mild or moderate essential hypertension. The earlier demonstrated efficacy of captopril, used with a diuretic and often also with a beta-adrenoceptor blocking drug, in the treatment of severe hypertension refractory to conventional 'triple therapy' has been confirmed in more recent trials which illustrate the generally marked antihypertensive effect of captopril-containing regimens in such patients. Results of initial trials in patients with scleroderma are promising, with control of hypertension and stabilization of renal function in these patients when treated at an early stage of the disease. Several comparative and long term trials of captopril in patients with chronic congestive heart failure refractory to treatment with a diuretic/digitalis regimen clearly demonstrate that initial haemodynamic improvement is maintained and correlates with clinical benefit. A tendency for overall clinical response to captopril to be better than the response to prazosin, hydralazine, nisoldipine or enalapril has been reported. Results of a multicentre comparison with digoxin and placebo indicate that captopril is a suitable alternative to digoxin in patients with mild to moderate heart failure who are receiving maintenance diuretic therapy. The tolerability of captopril has now been studied in many thousands of patients involved in formalized trials and the early impression of poor tolerability can no longer be justified. The use of generally lower dosages of captopril in patients with normal or slightly impaired renal function has resulted in a generally low incidence of rash (0.5 to 4%), dysgeusia (0.1 to 3%), proteinuria (0.5%), neutropenia (0.3% during first 3 months) and symptomatic hypotension (0.1 to 3%). Cough is an infrequent but troublesome effect resulting from ACE inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics of captopril in healthy subjects and in patients with cardiovascular diseases

Captopril, the first orally active inhibitor of angiotensin-converting enzyme, is used widely in the treatment of hypertension and congestive heart failure. The pharmacokinetics of this agent have been studied extensively in healthy subjects and in patients with hypertension, congestive heart failure, and chronic renal failure. Captopril contains a sulphydryl group and binds readily to albumin and other plasma proteins. The drug also forms mixed disulphides with endogenous thiol-containing compounds (cysteine, glutathione), as well as the disulphide dimer of the parent compound. These components in blood and urine are measured collectively as total captopril. Because of the reversibility of the formation of these inactive disulphides, total captopril may serve as a reservoir of the pharmacologically active moiety, and thus contribute to a duration of action longer than that predicted by blood concentrations of unchanged captopril. To measure free or unchanged captopril concentrations, a chemical stabiliser must be added to the biological samples to prevent the formation of captopril disulphides ex vivo. In healthy subjects given captopril intravenously, the body clearance of captopril and steady-state volume of distribution were about 0.7 L/h/kg and 0.8 L/kg, respectively. The elimination half-life of unchanged captopril was approximately 2 hours. The primary route of elimination of captopril is the kidney. The renal clearance of unchanged captopril exceeds the glomerular filtration rate, due to active tubular secretion of the drug. In healthy subjects, about 70 to 75% of an oral dose is absorbed and the bioavailability of captopril is approximately 65%. Peak blood concentrations are reached about 45 to 60 minutes after oral administration. The bioavailability of captopril is not altered by age or concomitant medications including diuretics, procainamide, allopurinol, cimetidine or digoxin. However, the co-administration of food or antacids, or probenecid with captopril has been shown to diminish the bioavailability of the latter and decrease its clearance, respectively. The decreased bioavailability of captopril when taken with meals does not significantly alter clinical responses to the drug. Over a wide range of oral (10 to 150 mg) and intravenous doses (2.5 to 10 mg) captopril had linear kinetics in healthy volunteers. In healthy subjects with normal renal function and patients with congestive heart failure given captopril 3 times daily, blood concentrations of total captopril accumulated, whereas those of unchanged captopril did not. Severe renal insufficiency was associated with an accumulation of both unchanged and total captopril.(ABSTRACT TRUNCATED AT 400 WORDS)

Intravenous captopril treatment in patients with severe cardiac failure

The effect of intravenous captopril was studied in 26 patients with severe chronic heart failure. Fourteen patients received a 25 mg intravenous bolus dose and 12 patients were given a series of incremental intravenous doses over the range 0.3125-45 mg. After the 25 mg bolus dose there was a rapid reduction in systemic vascular resistance and systemic blood pressure. The effect was greatest five minutes after the dose when cardiac output was increased by 20%. Mean right atrial pressure and pulmonary end diastolic pressure fell more slowly and reached their nadir 60 minutes after administration. Plasma free captopril concentration was significantly correlated with percentage reduction in systemic vascular resistance 15 minutes after the bolus injection, but was not correlated with either changes in right atrial or pulmonary artery pressures. With the series of incremental doses there was a progressive fall in systemic vascular resistance until a cumulative dose of 5.0 mg was reached; beyond this there was no further significant change. The rapid response to intravenous captopril indicates that it may be useful in the treatment of patients with severe heart failure who require intensive treatment. After intravenous injection of captopril haemodynamic responses in patients with heart failure were greatest at plasma concentrations of 100 g/ml to 150 ng/ml. This is considerably higher than the plasma free captopril concentrations found after conventional oral doses of captopril.