Captopril: an update review of its pharmacological properties and therapeutic efficacy in congestive heart failure

Repurposing of Chronically Used Drugs in Cancer Therapy: A Chance to Grasp

Despite the advancement in drug discovery for cancer therapy, drug repurposing remains an exceptional opportunistic strategy. This approach offers many advantages (faster, safer, and cheaper drugs) typically needed to overcome increased challenges, i.e., side effects, resistance, and costs associated with cancer therapy. However, not all drug classes suit a patient's condition or long-time use. For that, repurposing chronically used medications is more appealing. This review highlights the importance of repurposing anti-diabetic and anti-hypertensive drugs in the global fight against human malignancies. Extensive searches of all available evidence (up to 30 March 2023) on the anti-cancer activities of anti-diabetic and anti-hypertensive agents are obtained from multiple resources (PubMed, Google Scholar, ClinicalTrials.gov, Drug Bank database, ReDo database, and the National Institutes of Health). Interestingly, more than 92 clinical trials are evaluating the anti-cancer activity of 14 anti-diabetic and anti-hypertensive drugs against more than 15 cancer types. Moreover, some of these agents have reached Phase IV evaluations, suggesting promising official release as anti-cancer medications. This comprehensive review provides current updates on different anti-diabetic and anti-hypertensive classes possessing anti-cancer activities with the available evidence about their mechanism(s) and stage of development and evaluation. Hence, it serves researchers and clinicians interested in anti-cancer drug discovery and cancer management.

Association between angiotensin-converting enzyme inhibitors and the risk of lung cancer: a systematic review and meta-analysis

BACKGROUND

The association between the use of angiotensin-converting enzyme inhibitors (ACEIs) and lung cancer risk remains controversial. This study evaluated the association between the use of ACEIs and lung cancer risk.

METHODS

Records from five databases were searched from inception to 26 January 2022. Clinical studies involving persons aged ≥18 years with at least one year of follow-up and reporting adverse events, including lung cancer, were recorded with separate outcome reports supplied for the ACEIs and control groups. Data were extracted independently by three authors and pooled using a random-effects model. The primary outcome was lung cancer development. Odds ratios (ORs) with 95% confidence intervals (CIs) and lung cancer-related morbidity were calculated.

RESULTS

Of 2400 records screened, 13,061,226 patients were included from seven cohort studies and four case-control studies. Pooled results showed that ACEIs use was linked to increased lung cancer risk (OR 1.19, 95% CI 1.05-1.36; P = 0.008), with high heterogeneity (I2 = 98%).

CONCLUSIONS

ACEI usage is a greater risk factor for lung carcinogenesis than angiotensin receptor blocker use, especially in Asian patients. Further randomised controlled trials are needed to confirm the causal association between the use of ACEIs and lung cancer risk.

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).

High content screening identifies licoisoflavone A as a bioactive compound of Tongmaiyangxin Pills to restrain cardiomyocyte hypertrophy via activating Sirt3

BACKGROUND

Cardiac hypertrophy is a prominent feature of heart remodeling, which may eventually lead to heart failure. Tongmaiyangxin (TMYX) pills are a clinically used botanical drug for treating multiple cardiovascular diseases including chronic heart failure. The aim of the current study was to identify the bioactive compounds in Tongmaiyangxin pills that attenuate cardiomyocytes hypertrophy, and to investigate the underlying mechanism of action.

METHODS AND RESULTS

The anti-hypertrophy effect of TMYX was validated in isoproterenol-induced cardiac hypertrophy model in C57BL/6 mice. After TMYX treatment for 2 weeks, the heart ejection fraction and fractional shortening of the mice model was increased by approximately 20% and 15%, respectively, (p < 0.05). Besides, TMYX dose-dependently reduced the cross section area of cardiomyocytes in the angiotensin-II induced hypertrophy H9c2 model (p < 0.01). Combining high content screening and liquid chromatography mass spectrometry, four compounds with anti-cardiac hypertrophy effects were identified from TMYX, which includes emodin, licoisoflavone A, licoricone and glyasperin A. Licoisoflavone A is one of the compounds with most significant protective effect and we continued to investigate the mechanism. Primary cultures of neonatal rat cardiomyocytes were treated with a hypertrophic agonist phenylephrine (PE) in the presence or absence of licoisoflavone A. After 48 h of treatment, cells were harvested and mitochondrial acetylation was analyzed by western blotting and Image analysis. Interestingly, the results suggested that the anti-hypertrophic effects of licoisoflavone A depend on the activation of the deacetylase Sirt3 (p < 0.01). Finally, we showed that licoisoflavone A-treatment was able to decrease relative ANF and BNP levels in the hypertrophic cardiac cells (p < 0.01), but not in cells co-treated with Sirt3 inhibitors (3-TYP) (p > 0.05).

CONCLUSION

TMYX exerts its anti-hypertrophy effect possibly through upregulating Sirt3 expression. Four compounds were identified from TMYX which may be responsible for the anti-hypertrophy effect. Among these compounds, licoisoflavone A was demonstrated to block the hypertrophic response of cardiomyocytes, which required its positive regulation on the expression of Sirt3. These results suggested that licoisoflavone A is a potential Sirt3 activator with therapeutic effect on cardiac hypertrophy.

Photoluminescent coral-like carbon-branched polymers as nanoprobe for fluorometric determination of captopril

The authors describe the synthesis of fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus. Uric acid and phosphoric acid act as nitrogen and phosphorus sources, respectively. The PCNBPs have a coral-like branched structure, are cross-connected, and < 20 nm in skeleton diameter. Their blue fluorescence, best measured at excitation/emission wavelengths of 330/425 nm, is quenched by mercury (II) ions due to the specifically restricted rigid conformation caused by the interaction of phosphorus, nitrogen, and oxygen groups on the surface of the PCNBPs. Fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (CAP) in the range 50 nM to 40 μM concentration range. Fluorescence recovery is attributed to the effectively specific interactions between the thiol group of CAP and Hg(II). The method was applied to the determination of the concentration of Cap in pharmaceutical samples, and recoveries were between 97.6 and 105.1%. Graphical abstract Fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus are described. Their fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (Cap) in the range 50 nM to 40 μM concentration range.

Laser induced thermal lens microscopy for highly sensitive determination of captopril

In this work, a combined flow injection-photo thermal lens microscopy (FI-PTLM) system was used for highly sensitive determination of captopril as an angiotensin-converting enzyme inhibitor. Captopril has no absorption in the visible range, but due to its thiol group could interact with gold nanoparticles (GNPs). GNPs, because of their surface plasmon resonance (SPR), have absorption in the visible range, but their interaction with a low concentration of captopril shows no effective change in UV-Vis spectrophotometry because their aggregation is slight. On the contrary, at the same condition, the PTLM with a visible light source enables sensitive measurement of this compound. The thiol group of captopril binds to the surface of GNPs and decreases the SPR. At the optimum condition in the focal volume of 2.68 fL (f=10^-15), the obtained range of linearity was 50-800 nM. The developed method was successfully applied for the determination of captopril in human serum and pharmaceutical samples.

The Specific α1-Adrenergic Receptor Antagonist Prazosin Influences the Urine Proteome

Urine, reflecting many changes in the body, is a better source than blood for biomarker discovery. However, even under physiological conditions, the urine proteome often varies. Understanding how various regulating factors affect urine proteome helps link changes to urine proteome with urinary biomarkers of physiological conditions as well as corresponding diseases. To evaluate the possible impact of α1-adrenergic receptor on urine proteome, this study investigated effects of the specific inhibitor prazosin on the urine proteome in a rat model by using tandem mass tagging and two-dimensional liquid chromatography-tandem mass spectrometry. A total of 775 proteins were identified, approximately half of which were influenced by prazosin treatment, indicating that the sympathetic nervous system exerts a significant impact on urine proteome. Eight significantly changed proteins were previously annotated as urinary candidate biomarkers. Angiotensinogen, haptoglobin, and beta-2 microglobulin, which were reported to be associated with blood pressure, were validated via Western blot. Prazosin is widely used in clinical practice; thus, these protein changes should be considered when studying corresponding diseases such as hypertension, post-traumatic stress disorder and benign prostatic hyperplasia. The related physiological activities of α1-receptors, controlling blood pressure and fear response might significantly affect the urine proteome and warrant further biomarker studies.

Effect of captopril and telmisartan on methotrexate-induced hepatotoxicity in rats: impact of oxidative stress, inflammation and apoptosis

Methotrexate (MTX) is a commonly used antineoplastic and anti-rheumatoid drug whose efficacy is limited by its hepatotoxicity. The aim of this study was to investigate the possible protective role of captopril (100 mg/kg/day, p.o. for seven days), an angiotensin converting enzyme inhibitor, and telmisartan (10 mg/kg/day p.o. for seven days), an angiotensin II receptor blocker with peroxisome proliferative receptor gamma (PPARγ) agonism, in a model of MTX (single dose 20 mg/kg i.p. at the fifth day) induced hepatotoxicity in rats. Results of the present study revealed MTX-induced hepatotoxicity as demonstrated by increased level of liver enzymes and confirmed by histopathology. Pretreatment with captopril or telmisartan produced a significant hepatic protection manifested as a significant (p < 0.05) decrease in serum levels of alanine transferase (ALT) and aspartate transferase (AST) and alkaline phosphatase (ALP) enzymes; hepatic malondialdehyde (MDA) and total nitrites and nitrates (NOx) levels; as well as a significant increase in hepatic superoxide dismutase (SOD) activity. In addition, there was a remarkable improvement in the histopathological features and a significant reduction in the expression of COX-2, iNOS and caspase-3 enzymes as compared with the MTX group. We recommend considering captopril/Telmisartan, if tolerated and not contraindicated, as preferable antihypertensive agents in patients receiving MTX in their chemotherapy protocols.

Highly Improved Electrooxidation of Captopril on Copper Hexacyanoferrate/Ordered Mesoporous Carbon-Modified Glassy Carbon Electrode

Using an electrochemical polymerization process, a copper hexacyanoferrate/ordered mesoporous carbon-modified glassy carbon electrode (CuHCF/OMC/GCE) was prepared. The performance of CuHCF/OMC was compared with that of CuHCF and the properties of the new material were improved. A sensor for sensitive detection of captopril was developed based on CuHCF/OMC-modified glassy carbon electrode. The composition and morphology of the as-prepared CuHCF/OMC products were characterized by energy-dispersive X-ray spectroscopy and scanning electron microscopy. The electrochemical behaviour and electrocatalytic performance of the CuHCF/OMC-modified glassy carbon electrode towards the oxidation of captopril were evaluated by cyclic voltammetry. Results showed that the CuHCF/OMC-modified electrode exhibits two well-defined redox peaks. The linear range for the detection of captopril was from 1.0 × 10–5 to 2.7 × 10–3 M, with a correlation coefficient of 0.999, and the detection limit was 1.2 × 10–6 M based on a signal-to-noise ratio of 3.

Clinical evaluation of imidapril in congestive heart failure in dogs: results of the EFFIC study

OBJECTIVES

The clinical efficacy and safety of imidapril were evaluated in dogs that presented with mild to severe congestive heart failure (New York Heart Association stage II to IV) by comparing the success rate of imidapril with a positive control by a non-inferiority approach.

METHODS

This good, clinical practice compliant, multicentre study (EFFIC study) enrolled 142 client-owned dogs and was conducted in 20 locations in France, Belgium and Germany. Dogs of various breed, age and weight were included in the study. These dogs were randomised into two groups that were treated for 84 days with either the test product, imidapril, or the positive control, benazepril, and followed up in parallel over this period. Both treatments were administered at a dose of 0.25 mg/kg once a day with the possibility of doubling this dose to 0.5 mg/kg if considered necessary from a clinical point of view. In addition, concomitant treatment was given to dogs presenting with pulmonary oedema and/or ascites, supraventricular tachyarrhythmia and/or dilated cardiomyopathy. The evolution of the New York Heart Association stage and the "functional signs" score were evaluated as primary efficacy criteria.

RESULTS

The success rate in the imidapril group was 66 compared with 68 per cent in the benazepril group. Regarding safety, 35 dogs in each group experienced at least one adverse event. Nine dogs in each group experienced at least one serious adverse event. The difference between these results was not statistically significant.

CLINICAL SIGNIFICANCE

Imidapril is as efficacious and safe as the reference product, benazepril.

Cardiovascular drugs for the newborn

This article reviews the various cardiovascular drugs for newborns, including antiarrhythmics, antihypertensives, inotropes, and pulmonary vasodilators. Antiarrhythmic drugs are classified according to their mechanisms of action, such as effects on ion channels, duration of repolarization, and receptor interaction, which help with understanding the effects of individual antiarrhythmic drugs and selection of drugs for specific arrhythmias. Drug treatment for hypertension should start with a single drug from one of the following classes: ACE inhibitors, angiotensin-receptor antagonists, beta-receptor antagonists, calcium channel blockers, or diuretics. The inotropic drug should be selected according to its specific pharmacologic properties and the specific cardiovascular abnormality to be corrected. An effective pulmonary vasodilator must dilate the pulmonary vasculature more than the systemic vasculature.

Comparison of the efficacy and tolerability of telmisartan 40 mg vs. enalapril 10 mg in the treatment of mild-to-moderate hypertension: a multicentre, double-blind study in Taiwanese patients

The purpose of this randomised, double-blind, double-dummy, parallel-group study was to evaluate the efficacy and tolerability of telmisartan 40 mg once daily vs. enalapril 10 mg once daily in 147 Taiwanese patients with mild-to-moderate essential hypertension (diastolic blood pressure [DBP] 90-109 mmHg). After 6 weeks' treatment, telmisartan produced a significantly greater reduction from baseline in the primary endpoint of trough seated DBP compared with enalapril 10 mg (11.7 vs. 8.7 mmHg, respectively; p = 0.02). Numerically greater reductions compared with baseline in seated systolic blood pressure (SBP), standing DBP, and standing SBP were achieved with telmisartan compared with enalapril. Also, numerically greater proportions of patients achieved blood pressure control (DBP/systolic blood pressure [SBP] <90/140 mmHg) and responded to treatment (reduction from baseline in trough seated DBP > or = 10 mmHg and/or post-treatment DBP <90 mmHg; reduction from baseline in trough seated SBP > or = 10 mmHg and/or post-treatment SBP <140 mmHg) with telmisartan 40 mg compared with enalapril 10 mg. Although both treatments were well tolerated, the incidence of cough was markedly lower with telmisartan 40 mg (8.5%) than with enalapril 10 mg (18.4%) in this population of Taiwanese hypertensive patients.

Intensive blood pressure reduction is beneficial in patients with impaired cardiac function coexisting with chronic renal insufficiency

Both in CHF (congestive heart failure) and CRI (chronic renal insufficiency), blood pressure reduction is beneficial for preservation of cardiac and renal function. However, it is uncertain how much blood pressure reduction is appropriate in patients with both CHF and coexisting CRI. In the present study, we examined whether intensive blood pressure reduction is more beneficial in these patients than the usually accepted level of reduction. Thirty-five men and 21 women of average age 63+/-5 years suffering from both CHF and CRI were selected from 316 patients attending the Kidney Disease Center of Saitama Medical School Hospital. All participants had an ejection fraction (EF) of less than 55% as determined by echocardiography. Renal function was evaluated by 24-h creatinine clearance (GFR), and a GFR of less than 50 ml/min was regarded as indicating renal insufficiency. Patients were divided into 2 groups according to the target blood pressure: in group I, blood pressure (BP) was lowered to less than 120/75 mmHg and in group II, blood pressure was lowered to less than 130/80 but more than 121/76 mmHg. The daily doses of basic antihypertensive agents were amlodipine 5 to 20 mg, benazepril 2.5 to 5 mg, guanabenz 2 to 8 mg and furosemide 20 to 60 mg. At the end of a 2-year follow-up period, the BP in group I was controlled at the level of 118+/-4/73+/-3 mmHg with good maintenance of EF (46+/-4 to 60+/-4%) and GFR (44+/-4 to 40+/-3 ml/min). In group II, BP was maintained at 128+/-4/81+/-2 mmHg, accompanied by a reduction of EF (46+/-4 to 42+/-3%) and a significant reduction of GFR (44+/-3 to 35+/-3 ml/min). These results suggest that intensive blood pressure reduction might be beneficial in cases complicated by cardiorenal failure.

Determination of captopril in biological samples by high-performance liquid chromatography with ThioGlo 3 derivatization

Captopril, a well-known angiotensin converting enzyme (ACE) inhibitor, is widely used for treatment of arterial hypertension. Recent studies suggest that it may also act as a scavenger of free radicals because of its thiol group. Therefore, the present study describes a rapid, sensitive and relatively simple method for the detection of captopril in biological tissues with reverse-phase HPLC. Captopril was first derivatized with ThioGlo 3 [3H-Naphto[2,1-b]pyran,9-acetoxy-2-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl-3-oxo-)]. It was then detected by fluorescence-HPLC using an Astec C(18) column as the stationary phase and a water:acetonitrile:acetic acid:phosphoric acid mixture (50:50; 1 mL/L acids) as the mobile phase (excitation wavelength, 365 nm; emission wavelength, 445 nm). The calibration curve for captopril was linear over a range of 10-2500 nM and the coefficient of variation acquired for the within- and between-run precision for captopril was 0.5 and 3.8%, respectively. The detection limit of captopril with this method was found to be 200 fmol/20 microL injection volume. Its relative recovery from biological samples was determined to the range from 93.3 to 105.3%. Based on these results, we believe that our method is advantageous for captopril determination.

Efficacy and safety of spirapril in mild-to-moderate hypertension

Spirapril is a new angiotensin-converting enzyme (ACE) inhibitor. It is a prodrug with a resorption of about 50%. The active metabolite spiraprilat reaches maximal plasma concentration within 2-3 h after oral administration. Spirapril can be administered once daily because of its long duration of action caused by an elimination half-life of about 40 h. It undergoes renal and hepatic elimination. In contrast to other ACE inhibitors it has a narrow dose range; therefore, the recommended dose is 6 mg for most patients without the need for dose titration. Spirapril has no relevant drug interactions. In several studies, spirapril was given to patients with mild-to-moderate essential hypertension at doses of 1-24 mg/day. There was an identical blood pressure lowering effect at doses of 6-24 mg/day; doses of 1-3 mg/day were less effective. Twenty-four-hour blood pressure monitoring showed a trough:peak ratio up to 0.84. In studies comparing the effect of spirapril with enalapril, lisinopril, trandolapril or captopril, spirapril was at least as effective as the other substances. Besides treating uncomplicated mild-to-moderate essential hypertension, spirapril can be used in patients with diseases accompanying hypertension such as heart and renal diseases, diabetes mellitus, and lipid disturbances. Possible advantages of spirapril compared to other ACE inhibitors are the dual mechanism of elimination, the lack of need for dose titration and a low incidence of cough.

Determination of captopril in human serum by high performance liquid chromatography using solid-phase extraction

A rapid, simple and sensitive assay was developed for determination of captopril in human serum. We employed silica gel cartridge for efficient extraction of captopril adduct from human serum. Captopril was trapped with p-bromophenacyl bromide (pBPB) to give captopril-pBPB adduct. A 4-ml benzene extract of 1 ml acidified serum was passed through 1 ml silica gel cartridge. Potential interfering compounds were removed with 4-ml benzene wash. The captopril-pBPB adduct was eluted with 0.5 ml acetonitrile. Of this acetonitrile solution (100 microliters) was injected on an ODS reverse phase HPLC column (chromatography conditions; mobile phase; acetonitrile-water-acetic acid (225:270:5, v/v/v), flow rate; 1 ml min-1, detection; UV at 263 nm). It is found that this method is accurate and does not require time consuming evaporation-concentration steps. Recovery exceeds 94% and analytical responses are linear over captopril concentration range from 50 up to 1000 ng ml-1. The coefficients of variation from 108 ng ml-1 to 605 ng ml-1 varied between 3.7-7.7% and the relative error did not exceed 3.7%. Therefore, this method can be used for routine clinical monitoring and in pharmacokinetic studies of captopril.

Chemiluminescence flow-injection analysis of captopril applying a sensitized rhodamine 6G method

A flow-injection analysis with chemiluminescence detection is described for the determination of captopril based on the photochemical reaction with cerium(IV) in sulphuric acid medium yielding a strong chemiluminescent signal which can be sensitized by some fluorescers. The proposed procedure has a linear application range of 1 x 10(-6) - 2 x 10(-4) M (r = 0.997) with a detection limit of 2 x 10(-7) M, an RSD of 2.8% at 1 x 10(-6) M captopril, and a sample measurement frequency of 500 h-1. The method was used for the simple and rapid determination of captopril in a pharmaceutical preparation.

Determination intestinal metabolism and permeability for several compounds in rats. Implications on regional bioavailability in humans

PURPOSE

To investigate the regional differences in small intestinal (SI) metabolism and permeability for several compounds and to ascertain the potential significance of these differences on the reported reductions in regional bioavailability in humans.

METHODS

The regional SI metabolism and permeability of captopril, didanosine (ddI), mannitol, ofloxacin and zidovudine (ZDV) were investigated in rats using a Single Pass Perfusion (SPIP) procedure or intestinal homogenates.

RESULTS

ddI was metabolized to a greater extent in the upper SI whereas captopril was metabolized to a greater extent in the lower SI. Relatively low homogenate concentrations resulted in significant degradation of captopril in the upper and lower SI. All other compounds were stable and changes in the buffer system or the initial concentration did not affect the results. The SI permeabilities of all compounds, with the exception of mannitol, decreased linearly with respect to SI location and the slopes of the corresponding normalized regression lines were not significantly different.

CONCLUSIONS

It has been reported that captopril and ddI demonstrate regional intestinal bioavailability in several species including humans. The current results suggest that the reported reduction in the lower SI bioavailability of captopril may be a result of a reduction in permeability and an increase in intestinal metabolism whereas for ddI, the reduction in the lower SI bioavailability appears to be attributable to a reduction in intestinal permeability. Other factors such as luminal metabolism may also significantly effect regional differences in the intestinal bioavailability of ddI or captopril. Based on these results, a strong possibility exists that ofloxacin and ZDV may also demonstrate regional differences in intestinal bioavailability.

Comparison of the safety and efficacy of delapril with captopril in outpatients with congestive heart failure

In this study delapril and captopril were compared in outpatients with congestive heart failure (CHF), New York Heart Association (NYHA) classes III and IV, in a double-blind study of efficacy and safety. Efficacy was evaluated by monitoring changes in the NYHA classification, exercise work, hemodynamic parameters, Kostuk's classification, and clinical signs and symptoms. Safety was monitored by a variety of laboratory tests, including renal and hepatic function, urinalysis, routine hematology testing, and the reporting of adverse events. Analysis of the data obtained revealed that delapril and captopril exhibit equal efficacy over the dosage ranges studied. There was a greater improvement of NYHA classification in terms of CHF signs and symptoms and ergometric workload in the delapril group; however, this did not reach statistical significance. The safety of the 2 drugs was also comparable, with no significant differences in any of the parameters measured at the start and end of the study. There was no statistically significant difference in the reporting of adverse events between the 2 drugs, although the sample size studied was small. There were no significant differences between the 2 drugs in terms of their effects on arterial blood pressure and no difference between prestudy and post-treatment arterial blood pressure measurements.

Captopril: determination in blood and pharmacokinetics after single oral dose

The study describes a specific, precise, sensitive and accurate method for determination of unchanged captopril, an angiotensin-converting enzyme inhibitor, in human plasma. Captopril was stabilized by forming an adduct with p-bromophenacyl bromide and this adduct was measured by high-performance liquid chromatography with UV detection. The standard curve was linear over a range of 30-800 ng ml-1. The average yield of derivatization of the unchanged captopril was 73.6% and the recovery of captopril-adduct reached 93.1%. The limit of detection was 15 ng ml-1, while the quantitative limit was 30 ng ml-1. Inter- and intra-assay RSD was below 9%, but inter- and intra-assay accuracy was below 8%. On the basis of elaborated method, a single-dose pharmacokinetics in 12 men, in two doses (25 and 50 mg of captopril) has been investigated. The comparison of the pharmacokinetic parameters obtained from both doses of the drug have been made.

Application of an electrochemical detector with a graphite electrode to liquid chromatographic determination of penicillamine and captopril in biological samples

A high-performance liquid chromatographic determination of penicillamine and captopril in rat serum, liver and kidney samples is described. An electrochemical detector with a graphite working electrode at a potential of +0.9 V vs the Ag/AgCl reference electrode is used for the detection system. Linear responses of the peak height to the amount of samples injected were obtained in a range of 0.1-500 ng on-column and 0.5-500 ng on-column for penicillamine and captopril with correlation coefficients of 0.997 and 0.995, respectively. Detection limits at a signal-to-noise ratio of 3 were 20 and 300 pg for penicillamine and captopril, respectively. The graphite electrode has a long lifetime of about 4 months with continuous use, even with the high voltage supplied. The analytical application of this method to the determination of penicillamine and captopril in biological samples was successful.

Bioavailability and pharmacokinetics of a fixed combination of delapril/indapamide following single and multiple dosing in healthy volunteers

The study objective was to obtain detailed information on the bioavailability and pharmacokinetics of the new fixed combination of delapril and indapamide following single and multiple dosing. For this reason, the study was performed in two parts, separated by a medication-free period of at least 7 days. In the single dose part, one tablet, containing 30 mg delapril and 2.5 mg indapamide, was administered to 12 male volunteers; in the multiple dose part, the volunteers received one tablet of the test preparation, once daily over 7 days. Following single and on the last day of the multiple dosing regimen, blood samples were withdrawn and serum concentrations of delapril and its metabolites M1, M2 and M3 and whole blood concentrations of indapamide were quantified by means of HPLC methods. In addition, urine samples were collected following single and multiple dosing for evaluation of the cumulative amount of delapril and its metabolites M1-M3 excreted in urine. For the area under the curve, calculated from time 0 to infinity (AUC(0-infinity)) the study revealed, following single dosing, mean values of delapril and its metabolites M1, M2 and M3 of 281, 2178, 739 and 716 h.ng/ml, respectively; for indapamide the mean value was 1597 h.ng/ml. The corresponding mean values found after multiple dose administration were 272, 2071, 857 and 598 h.ng/ml for delapril and its metabolites, respectively and 1536 h.ng/ml for indapamide. Evaluation of the cumulative amount of delapril and its metabolites M1-M3 excreted in urine (Ae) demonstrated mean values following single dosing (observation period 36 h) of 705, 4521, 454 and 4203 micrograms, respectively; the corresponding values after multiple dose administration (observation period 24 h) of the test preparation were 655, 4679, 469 and 4801 micrograms, respectively. The most important pharmacokinetic parameters AUC(0-infinity) and Ae were statistically compared by analysis of variance (ANOVA) and 90% confidence intervals were calculated. It may be concluded from the results of this study, that the bioavailability and pharmacokinetic parameters of the test preparation after single dosing and after multiple doses correspond well. The undesired side effects observed are known to occur after administration of the test preparation. The occurrence was a little more frequent after multiple dose application in comparison with the single dose administration.

Acceptability of perindopril in mild-to-moderate chronic congestive heart failure. Results of a long-term open study in 320 patients

The long-term acceptability of perindopril in mild-to-moderate chronic heart failure (CHF) was evaluated in a multicenter open study. A total of 320 patients with a mean age of 62 +/- 1 years and CHF of New York Heart Association (NYHA) class I (2 patients), II (204 patients), or III (114 patients) were included after a 2-week run-in period during which time vasodilators were stopped and diuretic and/or digoxin therapy stabilized. Perindopril treatment was started at 2 mg, increasing to 4 mg once daily after 2 weeks if supine systolic blood pressure remained > 100 mm Hg. After this dose titration period, follow-up visits were scheduled at monthly intervals for the first 3 months, then at 3-month intervals with a maximum period of follow-up being 30 months. At the time of analysis, mean duration of treatment was 276 days and 208 patients were treated > or = 6 months. Of the 320 patients, 10 (3.1%) died, 9 (2.8%) were withdrawn for worsening heart failure, and 38 (11.9%) for nonfatal adverse events, including cough (2.8%), dizziness or orthostatic discomfort (1.9%), angina pectoris (1.6%), and cutaneous signs (1.3%). Exercise test duration increased from 516 +/- 14 to 659 +/- 19 sec after 6 months of treatment (p < 0.01). At 6 months, 55.6% of patients improved by at least 1 NYHA class. Supine systolic blood pressure decreased slightly from 137 +/- 2 to 132 +/- 1 mm Hg (p < 0.01) and plasma creatinine levels remained stable from 100 +/- 2 to 102 +/- 2 mumol/liter after 6 months of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal functional alterations induced by angiotensin-converting enzyme inhibitors in heart failure

OBJECTIVE

To review the effects of angiotensin-converting enzyme (ACE) inhibitors on renal pathophysiology and the compensatory mechanisms involved in heart failure. A clinical application of the use of these agents in the setting of concomitant heart failure and renal insufficiency also is presented.

DATA SOURCES

A MEDLINE search was conducted using the terms heart failure, congestive; renal insufficiency; and angiotensin-converting enzyme inhibitors.

STUDY SELECTION

All applicable animal and human trials were reviewed.

DATA SYNTHESIS

Advances in the management of heart failure have led to new insights into the complex pathophysiology of this condition, particularly the favorable clinical effects noted with the ACE inhibitors. The net effect of ACE inhibitors on the renin-angiotensin system in patients with heart failure is to augment renal blood flow to a greater extent than cardiac output. Glomerular filtration rate is either unchanged or decreased by ACE inhibition. Sodium excretion is augmented primarily by alterations in glomerular hemodynamic parameters. ACE inhibitors may alter renal tubular function, both directly and indirectly, leading to increased diuresis and natriuresis.

CONCLUSIONS

Although ACE inhibitors exert beneficial pharmacodynamic effects on the renal bed in patients with heart failure, clinical consideration of volume and neurohormonal status prior to institution of therapy is prudent.

Importance of long-acting angiotensin-converting enzyme inhibitors for congestive heart failure

The renin-angiotensin system (RAS) has both localized and systemic effects in the pathophysiology of heart failure. These may lead to structural changes in the heart and blood vessels as well as to more disseminated symptomatology, including vasoconstriction and both salt and water retention. In association with other neurohormonal mechanisms, such as the sympathetic nervous system, these latter effects result in an elevated work load for the heart. The increase in neurohormonal activity, seen in some patients with heart failure, may result in a loss of circadian variation in heart rate and blood pressure and deprive the heart of a needed reduction in work load during the night. The suppression of such neurohormonal activity through the use of long-acting angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril, provides a means of controlling such symptoms. In comparison with short-acting ACE inhibitors, such long-acting suppression of the RAS may have a number of advantages. These include a more sustained increase in exercise duration, improvement in left ventricular ejection fraction, and, speculatively, a better influence on patient mortality.

Effects of once-daily benazepril therapy on exercise tolerance and manifestations of chronic congestive heart failure. The Benazepril Heart Failure Study Group

The effects of the long-acting angiotensin-converting enzyme inhibitor benazepril hydrochloride on exercise tolerance and signs and symptoms of congestive heart failure (CHF) were evaluated in a double-blind, multicenter, placebo-controlled clinical trial. Patients with chronic New York Heart Association class II to IV symptoms of CHF and an ejection fraction by radionuclide scanning of less than or equal to 35% were randomized in a 2:1 ratio to treatment with ascending doses of oral benazepril (n = 114) or placebo (n = 58) once daily, while continuing to receive background therapy with digoxin and diuretics. After randomization, patients were evaluated clinically every 2 weeks during a 12-week, double-blind treatment period. Maximal exercise tolerance was measured before and at specified time points after randomization by graded treadmill exercise testing. At week 12, mean exercise time increased 95 +/- 12 (SEM) seconds in the group receiving benazepril, whereas the increase was 37 +/- 18 seconds in the group receiving placebo (p less than 0.01 for the difference between the groups). There was also greater improvement in overall clinical status and in the signs and symptoms of CHF in benazepril-treated patients than in control subjects. There were 3 deaths in placebo-treated patients and none in benazepril-treated patients (p less than 0.05); the overall incidence of adverse effects was identical in the 2 groups. Benazepril is a well-tolerated angiotensin-converting enzyme inhibitor that provides clinically important improvement in exercise tolerance and in signs and symptoms when given once daily to patients with CHF receiving background therapy with digoxin and a diuretic.

The clinical pharmacology of angiotensin converting enzyme inhibitors in chronic heart failure

ACE inhibitors (ACEIs) have now been shown to improve symptoms and survival in patients with mild, moderate and severe chronic heart failure. Their mechanism of action is thought to be a combination of RAAS suppression and augmentation of bradykinin and prostaglandins. Although ACE inhibitors improve hemodynamics post myocardial infarction, we do not yet have consistent data on their effects on symptoms or survival in these particular patients. One other potential benefit is their effects on reperfusion injury and free radicals. As yet only minor differences have been found to exist between different ACEIs but increasing attention is now being focussed in this direction.

Cholestatic jaundice associated with captopril therapy

Captopril has attained widespread use as an effective agent in the treatment of heart failure and hypertension. Dermatological, renal and haematological toxicity associated with its use has been widely described and is usually well recognized. There have been comparatively few reports implicating it as causing hepatic drug reactions. Most descriptions have emphasized strongly cholestatic features, although a mixed hepatocellular cholestatic picture and predominant hepatocellular reactions have been reported. Between November 1972 and June 1990 only five cases of possible Captopril-associated hepatic dysfunction were reported to the Australian Adverse Drug Reaction Advisory Committee. Cases reported suggest equal sex distribution, latent period to development of abnormality between 1 week and 20 months, with slow resolution of jaundice and biochemical abnormality from 1 week to 6 months after withdrawal of the drug. One case of hepatic coma and death with massive acute hepatic necrosis on biopsy has been reported. Not uncommonly the accompanying systemic features suggest a syndrome of drug hypersensitivity. We report a case of Captopril-induced cholestatic jaundice in which the abnormality occurred 2 weeks after commencement of the drug and resolved slowly upon discontinuation. The case illustrates two important points: first, the importance of taking a full history, obtaining detailed information about previous drug administration in patients admitted with jaundice; and second, in the case of Captopril-induced liver disease, the jaundice may persist for many weeks after drug withdrawal.

A large-scale trial of captopril for mild to moderate heart failure in the primary care setting

A large-scale, prospective, 8-week, office-based study was conducted to evaluate the effects of adding captopril to a therapeutic regimen of diuretic and digoxin or diuretic alone in the management of patients with mild to moderate congestive heart failure (CHF). A total of 2218 primary care physicians evaluated 6669 patients over the study period for efficacy parameters, which included changes in a modified New York Heart Association (NYHA) functional classification, symptomatology, and daily activity levels. Overall, 63.8% of evaluated patients improved with regard to functional ability, with 19% improving two or more modified NYHA classes. Symptoms of CHF, including dyspnea on exertion, fatigue, and orthopnea and signs, including rales and peripheral edema, were reduced in 86% of these patients: 41.5% demonstrated mild improvement; 30.0%, moderate improvement; and 14.5%, marked improvement. Three parameters, with which patients reported having difficulty at study entry, were assessed serially to evaluate changes in functional capacity; 78.5% of patients reported an increased walking distance, 72.3% had increased capacity for climbing stairs, and 60.2% had improved capacity for individual recreational activities. Adverse experiences were reported in 18.1% of all patients; 4.9% of patients withdrew from the study because of an adverse effect. Combination therapy with captopril and diuretic for CHF was shown to be safe and effective regardless of patient age (less than 70 years vs. greater than or equal to 70 years), duration of heart failure (less than 1 year vs. greater than 1 year), presence of digoxin treatment, or the dosing schedule employed.(ABSTRACT TRUNCATED AT 250 WORDS)

Which vasodilator drug in patients with chronic heart failure? A randomised comparison of captopril and hydralazine

1. Fifty patients with symptoms due to chronic heart failure despite diuretic therapy were randomised to receive additional treatment with either hydralazine or captopril. The dose was titrated; 24 received hydralazine and 26 captopril up to a maximum daily dosage of 225 mg and 75 mg respectively. Forty-three patients had coronary heart disease and seven dilated cardiomyopathy. 2. Dyspnoea and tiredness were assessed using a visual analogue scale (0-100) before and during 12 weeks' treatment. Captopril produced a significantly greater reduction in breathlessness (F = 31.6, P less than 0.001) and tiredness (F = 65.8, P less than 0.001) compared with hydralazine. 3. There was an increase in treadmill exercise time during treatment with both hydralazine (from 5.5 (3.47-7.53) min to 6.9 (4.87-8.93) min), and captopril (from 5.0 (3.05-6.95) min to 7.8 (5.85-9.75) min), but the degree of improvement was significantly greater in the patients treated with captopril (F = 7.4, P less than 0.001). 4. There was no significant change in right ventricular ejection fraction (from 27.9 (19.3-36.5)% to 28.7 (20.1-37.3)%) or left ventricular ejection fraction (from 22.2 (14.2-30.2)% to 23.9 (15.9-31.9)%) during treatment with hydralazine. However, both right and left ventricular ejection fraction increased significantly during treatment with captopril (from 27.1 (18.9-35.3)% to 32.0 (23.8-40.2)%, P less than 0.05; and from 25.0 (17.2-32.8)% to 29.6 (21.8-37.4)%, P less than 0.05 respectively). 5. These results suggest that in patients with symptoms due to chronic heart failure despite diuretic therapy, treatment with captopril produces a greater symptomatic and haemodynamic improvement than treatment with hydralazine.

Pharmacology of angiotensin-converting enzyme inhibitors as a guide to their use in congestive heart failure

The pharmacokinetics of the angiotensin-converting enzyme (ACE) inhibitors are difficult to assess for several reasons. First, these compounds exert their influence by inhibiting an intermediary enzyme of a cascade of enzymatic events, whose rate-limiting enzyme (renin) is not directly affected by ACE inhibition. Second, renin and angiotensin I accumulate during ACE inhibition and a change in the dose of an ACE inhibitor could produce sudden shifts of angiotensin I to angiotensin II. Third, components of the circulating renin system require the interaction of several organ systems and effector sites. Fourth, the kinetics of ACE inhibitors can be influenced by the organ systems responsible for drug absorption, metabolism and excretion, and the functional status of these systems can be affected by the heart failure process. Fifth, at least some portion of the cardiovascular effects of ACE inhibitors is influenced by the contributions of other systems whose physiologic effects may be of importance in some patients with congestive heart failure. Sixth, the potential impact of tissue-bound ACE is not yet fully understood. Finally, for appropriate drug dosing, the effects of aging on the heart failure process, the extent of renin system activity, and the disposition of ACE inhibitors need to be considered. Because of their complex pharmacokinetics, treatment with ACE inhibitors has been guided by their pharmacodynamic and clinical characteristics.

Endocrinologic Warfare: The Role of Angiotensin-Converting Enzyme Inhibitors in Congestive Heart Failure

The angiotensin-converting enzyme (ACE) inhibitors represent the gold standard of vasodilator therapy for congestive heart failure through blunting of the endocrinologic manifestations of heart failure. The future role of these agents may be in the asymptomatic and mild stages of heart failure. ACE inhibitors have been shown to decrease morbidity and mortality with the natural history of this disease being altered. The future will bring many new ACE inhibitors to market, with the challenge for physicians and pharmacists to understand the important distinctions of each specific agent. © 1990 by W.B. Saunders Company.

Tissue renin-angiotensin systems in the heart and vasculature: possible involvement in the cardiovascular actions of converting enzyme inhibitors

The existence of independently functioning local renin-angiotensin systems in a number of tissues has been firmly established by biochemical and functional evidence and, most recently, by the demonstration of genetic messages for components of the renin-angiotensin systems, such as renin and angiotensinogen, in several organs. In this review, local renin-angiotensin systems in the heart and vascular walls are described and the contribution of a local inhibition of converting enzymes to the cardiovascular actions of converting enzyme inhibitors is discussed. Most of the studies cited support the hypothesis that an inhibition of cardiac converting enzyme may be involved in the beneficial hemodynamic and metabolic actions of converting enzyme inhibitors in cardiovascular disease, such as hypertension and congestive heart failure, independent of the circulating renin-angiotensin system. Local effects on cardiac converting enzyme may contribute to the ability of converting enzyme inhibitors to reduce cardiac hypertrophy. Similarly, local converting enzyme inhibition in the vascular wall may not only constitute a mechanism involved in the antihypertensive effects of converting enzyme inhibitors, but may also contribute to the regression of hypertension-induced vascular hypertrophy. In addition to reduced local angiotensin II generation, converting enzyme inhibition may engender a potentiation of the local effects of kinins. This mechanism may be more important to the cardiovascular actions of converting enzyme inhibitors than initially thought.

Angiotensin-converting enzyme inhibitors and renal function

The effects of angiotensin-converting enzyme (ACE) inhibitors on renal hemodynamics vary widely depending on the preexisting physiologic and pathologic state of the kidneys. Although some studies of ACE inhibitors in primary essential hypertension have demonstrated increases in glomerular filtration rate (GFR) and effective renal plasma flow in patients with renal impairment, other studies have not shown these same beneficial results. The difference may involve the choice of ACE inhibitor used in the investigations, but controlled comparison trials are needed to determine whether this is the case. The use of ACE inhibitors in renovascular hypertension remains controversial. ACE inhibition can interfere with the autoregulation of GFR mediated by angiotensin II and may lead to deterioration of renal function, especially in patients with bilateral renal artery stenosis or stenosis of a solitary kidney. Additionally, ACE inhibitors have been shown to cause a decline in GFR in the kidney affected by the stenosis, whether or not clinically apparent renal insufficiency occurs. Although the functional impairment associated with ACE inhibitors in renal artery stenosis has generally been reversible following removal of the drug, the consequences of a long-term reduction in GFR are unknown. Treatment of stable congestive heart failure (CHF) with ACE inhibitors can result in enhancement of GFR and reduction of sodium and fluid retention, thus improving the clinical state. However, in patients with decompensated cardiac failure, renal perfusion pressures may already be at or near the autoregulatory breakpoint and ACE inhibition may cause deterioration of renal function. In general, ACE inhibitors can be used safely in CHF if they are initiated cautiously, with adjustment of ACE inhibitor and diuretic dosages to avoid systemic hypotension and sodium and fluid depletion. In studies comparing the agents, enalapril and lisinopril have both been shown to cause higher incidences of renal function deterioration than has captopril. These findings suggest that the more complete or sustained ACE inhibition seen with the longer-acting agents may be detrimental to renal function in patients with CHF. The use of ACE inhibitors in the treatment of proteinuria is the newest area of research with these agents. At present it appears that ACE inhibitors reduce urinary protein excretion the most effectively in diabetic patients with mild proteinuria and in hypertensive patients with renal insufficiency and proteinuria due to glomerular disorders. More study is needed to determine whether these agents can reduce the rate of renal failure progression and to define the patient populations expected to benefit most.(ABSTRACT TRUNCATED AT 400 WORDS)

Short term haemodynamic effects of converting enzyme inhibition before and after eating in patients with moderate heart failure caused by dilated cardiomyopathy: a double blind study

The haemodynamic changes that follow a meal can mimic the response to a vasodilator drug. To avoid overestimating the beneficial effects of treatment in uncontrolled studies, measurements of haemodynamic function are usually performed with patients in the fasting postabsorptive state. But such recordings are not representative of the resting patient during daily life. In this double blind placebo controlled study the short term haemodynamic effects of enalapril were assessed during 12 hours in 19 patients with moderate heart failure caused by dilated cardiomyopathy. The patients ate lunch and dinner and were studied in the absorptive and postabsorptive phases. In the placebo group systemic vascular resistance, mean arterial pressure, and the rate-pressure product fell significantly (5-16%) after lunch. Four hours after lunch the haemodynamic function had returned to baseline--that is the postabsorptive state. Enalapril, accentuated the haemodynamic effects during the absorptive state producing a larger post-prandial fall in mean arterial blood pressure and rate-pressure product and changes in the absorptive phase were maintained into the post-absorptive phase. Pulmonary wedge pressure fell significantly after treatment with enalapril. These overall changes during the study period indicated that enalapril reduced the preload and afterload on the heart--over and above the reduction produced by eating. These findings suggest that the effects of enalapril given at rest to patients with moderate heart failure unload the heart and enhance the reduction of afterload induced by meals.