Effect of food on the bioavailability of lisinopril, a nonsulfhydryl angiotensin-converting enzyme inhibitor

Pharmacokinetic and Bioequivalence Study of Lisinopril/Hydrochlorothiazide Tablet Under Fasting and Postprandial Conditions in Healthy Chinese Subjects

The objective of this research was to evaluate and compare the pharmacokinetic profiles and safety of lisinopril/hydrochlorothiazide (10 mg/12.5 mg) tablets in the test and reference formulations administered to participants in both fasting and postprandial states and to evaluate the bioequivalence of the 2 products in healthy Chinese volunteers. This study employed a single-center, randomized, open-label, single-dose dosing trial involving a cumulative 96 healthy adult participants (60 in the fasting group and 36 in the postprandial group). Each group comprised 2 sequence sets, and a 2-week washout period was implemented. There were no statistically significant differences in time to maximum concentration and terminal elimination half-life between the test and control groups under fasting and postprandial conditions (P > .05), and the 90% CIs for area under the plasma concentration-time curve and maximum plasma concentration were within the bioequivalence range of 80%-125%. Pharmacokinetic results indicate a large food effect for lisinopril, meaning that there is a loss of approximately 20%-25% of systemic exposure from fasting to postprandial administration for both preparations. The study demonstrated that a single oral dose of generic lisinopril/hydrochlorothiazide is bioequivalent to the reference product and well tolerated, with no significant adverse events observed, and that both products are similarly safe in a cohort of healthy Chinese male and female participants, following administration under fasting and postprandial conditions.

Bioequivalence evaluation and food effect assessment of Lisinopril/amlodipine tablets in healthy Chinese subjects under fasting and fed conditions

PURPOSE

The combination of lisinopril and amlodipine has a marked additional effect on blood pressure and fewer side effects than individual monotherapy. This study was conducted to compare the pharmacokinetic parameters and evaluate the bioequivalence between two Lisinopril/amlodipine tablets in healthy Chinese subjects.

METHODS

A single center, randomized, open-label, single-dose, two-period crossover bioequivalence study was designed in healthy Chinese subjects under both fasting and fed conditions. Blood samples were collected before drug administration and at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 24, 36, 48, 72, 96, 144, 168 h after administration. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to determine the plasma concentration of lisinopril and amlodipine. Maximum concentration (C_max) and area under the concentration-time curve (AUC) were used to evaluate bioequivalence. Adverse events were recorded.

RESULTS

Ninety-two healthy subjects were enrolled, and 75 completed the study. The 90% confidence intervals (CIs) of the ratio of geometric means (GMRs) of C_max, AUC_0-t, and AUC_0-∞ of lisinopril and amlodipine under both fasting and fed conditions fell within the conventional bioequivalence criteria of 0.80-1.25. A high-fat meal appeared to decrease the C_max and AUC of lisinopril. No severe adverse events were observed.

CONCLUSION

The trial demonstrated that the test and the reference lisinopril/amlodipine tablets were bioequivalent and well tolerated in Chinese people under fasting and fed conditions.

TRIAL REGISTRATION

Clinical Trails.gov identifier, NCT04885660 (retrospectively registered in 13/05/ 2021).

Impact of Green Tea Catechin Ingestion on the Pharmacokinetics of Lisinopril in Healthy Volunteers

Lisinopril, a highly hydrophilic long‐acting angiotensin‐converting enzyme inhibitor, is frequently prescribed for the treatment of hypertension and congestive heart failure. Green tea consumption may reduce the risk of cardiovascular outcomes and total mortality, whereas green tea or its catechin components has been reported to decrease plasma concentrations of a hydrophilic β blocker, nadolol, in humans. The aim of this study was to evaluate possible effects of green tea extract (GTE) on the lisinopril pharmacokinetics. In an open‐label, randomized, single‐center, 2‐phase crossover study, 10 healthy subjects ingested 200 mL of an aqueous solution of GTE containing ~ 300 mg of (–)‐epigallocatechin gallate, a major catechin component in green tea, or water (control) when receiving 10 mg of lisinopril after overnight fasting. The geometric mean ratio (GTE/control) for maximum plasma concentration and the area under the plasma concentration‐time curve of lisinopril were 0.289 (90% confidence interval (CI) 0.226–0.352) and 0.337 (90% CI 0.269–0.405), respectively. In contrast, there were no significant differences in time to reach maximum lisinopril concentration (6 hours in both phases) and renal clearance of lisinopril (57.7 mL/minute in control vs. 56.9 mL/minute in GTE). These results suggest that the extent of intestinal absorption of lisinopril was significantly impaired in the presence of GTE, whereas it had no major effect on the absorption rate and renal excretion of lisinopril. Concomitant use of lisinopril and green tea may decrease oral exposure to lisinopril, and therefore result in reduced therapeutic efficacy.

Prediction of lisinopril pediatric dose from the reference adult dose by employing a physiologically based pharmacokinetic model

Background

This study aimed to assess the pediatric lisinopril doses using an adult physiological based pharmacokinetic (PBPK) model. As the empirical rules of dose calculation cannot calculate gender-specific pediatric doses and ignores the age-related physiological differences.

Methods

A PBPK model of lisinopril for the healthy adult population was developed for oral (fed and fasting) and IV administration using PK-Sim MoBI® and was scaled down to a virtual pediatric population for prediction of lisinopril doses in neonates to infants, infants to toddler, children at pre-school age, children at school age and the adolescents. The pharmacokinetic parameters were predicted for the above groups at decremental doses of 20 mg, 10 mg, 5 mg, 2.5 mg, and 1.5 mg in order to accomplish doses producing the pharmacokinetic parameters, similar (or comparable) to that of the adult population. The above simulated pediatric doses were compared to the doses computed using the conventional four methods, such as Young’s rule, Clark’s rule, and weight-based and body surface area-based equations and the dose reported in different studies.

Results

Though the doses predicted for all subpopulations of children were comparable to those calculated by Young’s rule, yet the conventional methods overestimated the pediatric doses when compared to the respective PBPK-predicted doses. The findings of previous real time pharmacokinetic studies in pediatric patients supported the present simulated dose.

Conclusion

Thus, PBPK seems to have predictability potential for pediatric dose since it takes into consideration the physiological changes related to age and gender.

Review on Preclinical and Clinical Evidence of Food (Beverages, Fruits and Vegetables) and Drug Interactions: Mechanism and Safety

Background:

The therapeutic potency and efficacy of drugs can be affected by a patient’s dietary habit. The food composition and their nutritional value interact with drugs that lead to alteration of the therapeutic response of drugs in patients.

Objective:

This present review is an attempt to illustrate clinical reports of food-drug interaction. Further, it also highlights specific interaction mechanism(s) and the safety thereof.

Methods:

Through the search engine “Scopus”; literature on recent advances in food and drug interactions includes almost all therapeutic categories such as antimicrobials, antiviral, antifungal, antihistamines, anticoagulants, non-steroidal anti-inflammatory drugs, and drugs acting on the central nervous system and cardiovascular system.

Results:

Preclinical and clinical studies that have been conducted by various researchers affirm significant drug-food interactions across the various therapeutic categories of drugs. Preclinical studies have documented the effects of food, milk products, alcohols, fruit and vegetables on the drug absorption, metabolizing enzymes and drug transporters. The clinical studies on fruits/vegetables and drugs interactions report significant alteration in therapeutic response.

Conclusion:

Based on the preclinical and clinical reports, it can be concluded that the interaction of food with drug(s) significantly alters their therapeutic potential. The inputs from clinical practitioners to elucidate potential risk of food-drug interaction need to be intensified in order to prevent adverse clinical consequences.

The effect of food on the pharmacokinetics of a dual angiotensin-converting enzyme/neutral endopeptidase inhibitor, M100240

M100240 is a thioester of MDL 100,173, a dual angiotensin-converting enzyme (ACE)/neutral endopeptidase (NEP) inhibitor. Clinical studies have shown that M100240 is capable of decreasing ACE activity and angiotensin II concentrations while increasing plasma renin activity and potentiating the effects of atrial natriuretic peptide. This may result in a unique treatment benefit in disease states characterized by intravascular volume or sodium overload or increased venous pressure. The pharmacokinetics of MDL 100,173 were evaluated in 30 healthy subjects in an open-label, randomized, 2-period crossover design. Subjects received a single oral dose of 50 mg of M100240 administered with a high-fat meal and separately under fasted conditions. Serial plasma concentrations of M100240 and MDL 100,173 were analyzed, and pharmacokinetic parameters were calculated with noncompartmental methods. The intrasubject percent coefficient of variation for MDL 100,173 C(max) and AUC(0-24h) were less than 20%, indicating that this agent is a moderately variable drug. Although AUC(0-24h) was within the protocol-defined range of 80% to 125%, the lower limit of the 90% confidence interval for C(max) fell outside of the 70% to 143% range. Absence of a food effect on the pharmacokinetic profile of 50 mg of M100240 could therefore not be demonstrated. This finding is not surprising based on the documented food effect with the sulfhydryl-containing ACE inhibitor, captopril. Clinical significance of this pharmacokinetic food effect is unlikely, as the magnitude of pharmacodynamic response is probably better correlated with AUC than a single-point determination of C(max). Single oral doses of 50 mg of M100240 were safe and well tolerated under fed and fasted conditions.

Food-drug interactions

Interactions between food and drugs may inadvertently reduce or increase the drug effect. The majority of clinically relevant food-drug interactions are caused by food-induced changes in the bioavailability of the drug. Since the bioavailability and clinical effect of most drugs are correlated, the bioavailability is an important pharmacokinetic effect parameter. However, in order to evaluate the clinical relevance of a food-drug interaction, the impact of food intake on the clinical effect of the drug has to be quantified as well. As a result of quality review in healthcare systems, healthcare providers are increasingly required to develop methods for identifying and preventing adverse food-drug interactions. In this review of original literature, we have tried to provide both pharmacokinetic and clinical effect parameters of clinically relevant food-drug interactions. The most important interactions are those associated with a high risk of treatment failure arising from a significantly reduced bioavailability in the fed state. Such interactions are frequently caused by chelation with components in food (as occurs with alendronic acid, clodronic acid, didanosine, etidronic acid, penicillamine and tetracycline) or dairy products (ciprofloxacin and norfloxacin), or by other direct interactions between the drug and certain food components (avitriptan, indinavir, itraconazole solution, levodopa, melphalan, mercaptopurine and perindopril). In addition, the physiological response to food intake, in particular gastric acid secretion, may reduce the bioavailability of certain drugs (ampicillin, azithromycin capsules, didanosine, erythromycin stearate or enteric coated, and isoniazid). For other drugs, concomitant food intake may result in an increase in drug bioavailability either because of a food-induced increase in drug solubility (albendazole, atovaquone, griseofulvin, isotretinoin, lovastatin, mefloquine, saquinavir and tacrolimus) or because of the secretion of gastric acid (itraconazole capsules) or bile (griseofulvin and halofantrine) in response to food intake. For most drugs, such an increase results in a desired increase in drug effect, but in others it may result in serious toxicity (halofantrine).

Stability and in vitro absorption of captopril, enalapril and lisinopril across the rat intestine

In vitro absorption of three angiotensin converting enzyme (ACE) inhibitors, captopril, enalapril and lisinopril, and their stabilities in aqueous buffer as well as their resistance to intestinal and dermal tissue homogenates were investigated. The results demonstrate that the spontaneous oxidation of captopril, enalapril and lisinopril followed first-order degradation kinetics in McIlvaine's citrate-phosphate buffer. The degradation rates for enalapril and lisinopril were much slower than that for captopril. With the former two ACE inhibitors, the first-order rate constants of breakdown in the presence of dermal homogenate were not significantly different from the control values. Intestinal homogenate increased the decomposition of both of these inhibitors when compared to the enzyme-free control systems. On the other hand, the first-order rates of disappearance of captopril in the presence of both dermal and intestinal homogenates were lower than in the enzyme-free system. The extent of reduction was proportional to the amount of homogenate added. This suggests that tissue homogenates prevent the oxidation of captopril to its disulphide dimer. Transport experiments show that the amounts of ACE inhibitors transferred from solution on the mucosal side increased linearly with incubation time over the 2 hr of study. The rates of transfer from the mucosal side to the serosal side had the following rank order: captopril > enalapril > lisinopril roughly in the ratio 1:1.13:1.27. Addition of harmaline caused a significant reduction in the transfer rate of captopril compared to the control system, which strongly suggests that captopril is transported by a sodium-dependent carrier-mediated process across intestinal tissue.

Decision analysis applied to the selection of angiotensin-converting enzyme inhibitors

Decision analysis is applied to the group of angiotensin-converting enzyme inhibitors, in order to select those which should be included in the hospital formulary and to establish a research method which allows the reproduction of the process with new, related drugs. Captopril, enalapril and lisinopril were the alternatives considered. Evaluation criteria were efficacy, clinical experience, safety, dosage interval, hepatic bioactivation, interactions, dosage forms and cost. A relative weight was assigned through a survey among the hospital's staff. Each alternative was evaluated in relation to all criteria. Sensitivity analysis was applied to validate the method. Enalapril obtained the highest score, followed by lisinopril and captopril. The sensitivity analysis confirms this result. Enalapril is selected for the hospital formulary due to its higher score, although the differences between the three are very small.

Differences in structure of angiotensin-converting enzyme inhibitors might predict differences in action

Angiotensin-converting enzyme (ACE) inhibitors probably work by inhibition of tissue-located ACE, and they differ with regard to their relative ability to inhibit ACE in different organs. This apparent tissue selectivity may stem from either differences in tissue bioavailability or from a different affinity for the enzyme. The affinity of the ACE inhibitor for a particular enzyme is not only determined by the structure of the inhibitor, but also by the structure of the enzyme. ACE enzymes from different tissues may be slightly different, and this may have some bearing on the relative affinities of different ACE inhibitors for ACE from different tissues. The duration of inhibition in a particular tissue reflects not only the affinity of that inhibitor for the tissue enzyme, but also reflects the ease or difficulty with which the active ACE inhibitor is released from that tissue. Whether the beneficial effects of ACE inhibitors on experimentally induced myocardial infarction and reperfusion arrhythmias are due to the presence of a sulfhydryl group or are mainly related to the ACE inhibitor-mediated bradykinin potentiation remains a matter of controversy.

Quinapril: a new second-generation ACE inhibitor

Quinapril is a new non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor. The drug undergoes hepatic hydrolysis into its major active diacid metabolite, quinaprilat, and two minor inactive metabolites. On a weight basis quinaprilat is three times as potent an ACE inhibitor as quinapril. Approximately 60 percent of an oral dose of quinapril is absorbed. In contrast with captopril, the absorption of quinapril is unaffected by food. Peak serum concentrations of quinapril and quinaprilat are achieved within one and two hours, respectively. Approximately 61 percent of an orally administered dose is excreted in the urine, principally as quinaprilat. The elimination half-life of quinaprilat is three hours, but is prolonged up to 11 hours in patients with renal dysfunction. Quinapril dose reduction is recommended in patients with a creatinine clearance of 0.50 mL/sec or less. In the elderly the elimination of quinaprilat is reduced and correlates well with renal function. In patients with cirrhosis the hydrolysis of quinapril to quinaprilat is impaired resulting in lower plasma quinaprilat concentrations and up to a two-fold increase in quinapril half-life. Quinaprilat has a strong binding capacity to tissue ACE allowing for once-daily dosing. The recommended starting dose for quinapril is 20 mg/d. The nature and incidence of adverse reactions to quinapril are similar to those of enalapril and captopril. Quinapril's antihypertensive efficacy is equal to that of captopril and enalapril. A small number of patients with congestive heart failure (CHF) have been treated with quinapril. Preliminary data indicate that quinapril is an equally effective therapeutic alternative to presently available ACE inhibitors in the treatment of CHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical pharmacokinetics of the newer ACE inhibitors. A review

The orally active angiotensin-converting inhibitors (ACE inhibitors) such as captopril and enalapril represent a significant therapeutic advance in the treatment of hypertension and congestive heart failure. Enalapril differs from captopril in several respects. It is a prodrug converted by hepatic esterolysis to the active (but more poorly absorbed) diacid, enalaprilat. Enalaprilat is more potent than captopril, more slowly eliminated and does not possess a sulfhydryl (SH) group. Enalapril was rapidly followed by a number of newer ACE inhibitors, the majority of which are similar to enalapril in that they are prodrugs, converted by hepatic esterolysis to a major active but poorly absorbed diacid metabolite. In one case (delapril) there are 2 active metabolites; in another (alacepril) the prodrug is converted in vivo to captopril. Lisinopril is an exception in that it is an enalaprilat-like diacid but with acceptable oral bioavailability, so that the prodrug route is not employed. The newer ACE inhibitors are at widely different stages of development, and it is not yet clear how many will reach regular clinical use. Of these newer drugs, lisinopril is the longest established and is the subject of the widest published literature. For a number there is as yet little published pharmacokinetic information. A variety of assay methods have been employed to characterise the pharmacokinetics of the ACE inhibitors, including enzymatic techniques, radioimmunoassay and chromatography. The peak plasma concentrations of the prodrugs are generally observed at around 1 hour and those of the diacid metabolites at about 2 to 4 hours. However, there is considerable variation within and between drugs, with benazepril and benazeprilat reaching peak concentrations early and enalapril and enalaprilat typical of later times to peak. Absorption of the active diacids is generally poor, and moderate (typically 30 to 70%) for the prodrugs. The bioavailability of lisinopril is about 25%. It is difficult to talk meaningfully about half-lives of the active drugs. The declines in their plasma concentrations are polyphasic and, if analytical sensitivity allows, active drug may be found at 48 hours or more following administration. This may reflect binding to ACE in plasma. Half-lives of accumulation are of the order of 12 hours; protein binding varies from little (lisinopril) to 90% (benazeprilat). Elimination is mostly renal but there may be biliary elimination for some, such as benazeprilat and fosinopril. The half-lives of the prodrugs are short. Impaired renal function decreases the elimination rate of the diacids.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiotensin-converting enzyme inhibitors: a comparative review

The chemistry, pharmacology, pharmacokinetics, adverse effects, and dosages of the three currently available angiotensin-converting enzyme (ACE) inhibitors are reviewed. This class of agents effectively inhibits the conversion of angiotensin I to the active vasoconstrictor angiotensin II, a hormone that also promotes, via aldosterone stimulation, increased sodium and water retention. The ACE inhibitors, therefore, are capable of lowering blood pressure primarily by promoting vasodilatation and reducing intravascular fluid volume. Captopril, the first orally active, commercially available ACE inhibitor, is a sulfhydryl-containing compound. Captopril was followed by the introduction of enalapril and lisinopril, two non-sulfhydryl ACE inhibitors. The pharmacokinetic profiles of these three ACE inhibitors differ. Captopril has rapid onset with relatively short duration of action, whereas enalapril and lisinopril have slower onset and relatively long duration of action. Captopril is an active ACE inhibitor in its orally absorbable parent form. In contrast, enalapril must be deesterified in the liver to the metabolite enalaprilat in order to inhibit the converting enzyme; this accounts for its delayed onset of action. Lisinopril does not require metabolic activation to be effective; however, a slow and incomplete absorption pattern explains the delay in onset of activity. Captopril and its disulfide metabolites are primarily excreted in the urine with minor elimination in the feces. Approximately two-thirds of an administered enalapril dose is excreted in the urine as both the parent drug and the metabolite enalaprilat; the remainder of these two substances are excreted in the feces. Lisinopril does not undergo measurable metabolism and approximately one-third is excreted unchanged in the urine with the remaining parent drug being excreted in the feces. The ACE inhibitors lower systemic vascular resistance with a resultant decrease in blood pressure. Their efficacy is comparable to diuretics and beta-blockers in treating patients with mild, moderate, or severe essential and renovascular hypertension. In those patients with severe congestive heart failure (CHF) the ACE inhibitors produce a reduction in systemic vascular resistance, blood pressure, pulmonary capillary wedge pressure, and pulmonary artery pressure. These drugs may produce improvement in cardiac output and stroke volume and, with chronic administration, may promote regression of left ventricular hypertrophy. The antihypertensive effects of the ACE inhibitors are enhanced when these agents are combined with a diuretic. Captopril and enalapril have been shown to be of particular benefits as adjunctive therapy in patients with congestive heart failure, both in terms of subjective improvement of patient symptoms, and in improving overall hemodynamic status.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics of lisinopril (IV/PO) in healthy volunteers

When three intravenous doses of lisinopril were administered to healthy volunteers, area under the curve (to infinity) vs dose was linear with a positive intercept. Subtracting area under the extrapolated terminal phase of the serum profile from zero to infinity retained the linear relationship, but shifted the regression line to a zero intercept. It is postulated that the terminal phase reflects binding of drug to angiotensin-converting enzyme (ACE). The half-life for the terminal phase (approximately 40 h) was not predictive of steady-state parameters when ten daily doses (q24h) of lisinopril were administered orally to healthy volunteers. The mean effective half-life for accumulation was 12.6 h. The mean accumulation ratio was 1.38. Steady state was attained after the second daily dose. The observations in these studies with lisinopril are similar to those reported for enalaprilat, the active metabolite of the ACE inhibitor, enalapril maleate.

Lisinopril: a new angiotensin-converting enzyme inhibitor

Lisinopril is a synthetic, nonsulfhydryl, angiotensin-converting enzyme inhibitor. Its bioavailability is approximately 25% and is not affected by food. Hepatic metabolism is not required for pharmacologic effect, which occurs 1 hour after administration. Peak serum concentration and effect are delayed, occurring 6-8 hours after a single dose and lasting for at least 24 hours. The drug is eliminated primarily by the kidneys. The elimination half-life is 12.6 hours and is prolonged in renal impairment. Lisinopril 10-80 mg once a day is effective in lowering blood pressure in all grades of essential and renovascular hypertension. It is as effective as hydrochlorothiazide, atenolol, metoprolol, and nifedipine. Combining lisinopril with hydrochlorothiazide produces a greater degree of blood pressure reduction. Patients with congestive heart failure have demonstrated immediate and prolonged beneficial hemodynamic effects and increased exercise tolerance. Lisinopril is well tolerated. Clinically significant drug interactions have not been reported, but caution should be used when lisinopril is administered with diuretics, nifedipine, or agents that may increase concentrations of potassium. The usual initial oral dosage of lisinopril is 10 mg once a day (range 20-40 mg/day). Lower dosages may be necessary in patients with renal impairment or congestive heart failure, elderly persons, and those receiving diuretics.

The clinical pharmacokinetics of quinapril

Quinapril (Q) and quinaprilat (QT) pharmacokinetics are dose proportional following single oral 2.5- to 80-mg Q doses. Q absorption and hydrolysis to QT is rapid with peak Q and QT concentrations occurring one and two hours postdose, respectively. Peak plasma QT concentrations were approximately fourfold higher than those of Q (923 vs 207 ng/mL following 40-mg Q). Dose-proportional QT area under the curve and dose-independent percent of dose excreted in urine as QT demonstrate that the extent of Q conversion to QT is constant over the dose range studied. Q and QT were eliminated from plasma with apparent half-lives of 0.8 and 1.9 hours and apparent plasma clearances of 1,850 and 220 mL/min, respectively, over the 2.5- to 80-mg dose range. Following oral 14C-Q, 61% and 37% of radiolabel was recovered in urine and feces, respectively. Q plus QT accounted for 46% of radioactivity circulating in plasma and 56% of that excreted in urine. Metabolism to compounds other than QT is not extensive. Two diketopiperazine metabolites of Q have been identified in plasma and urine, with approximately 6% of an administered dose excreted in urine as each of these metabolites. Peak plasma concentrations of these metabolites are similar to that of Q, and each is eliminated rapidly with a half-life of approximately one hour. Urinary excretion profiles indicate the presence of other minor metabolites. In summary, the absorption of Q and conversion to QT is rapid and dose-proportional, subsequent clearance of both Q and QT is independent of dose, and metabolism to compounds other than QT is not extensive.

The influence of food on the pharmacokinetics and ACE inhibition of cilazapril

1. The influence of food on the pharmacokinetics and angiotensin-converting enzyme (ACE) inhibitory effects of oral 5 mg doses of cilazapril was investigated in a two-way crossover study in 16 volunteers. 2. Plasma and urine concentrations of cilazaprilat, the active diacid metabolite of cilazapril, and plasma ACE activity were determined by a radio-enzymatic method. 3. Cmax decreased by 30% (P less than 0.05) with a delay in (t)max of 1 h (P less than 0.05) and area under curve (AUC) was decreased by 14% (P less than 0.05). The elimination rate was unaltered. 4. Onset of ACE inhibition was delayed by approximately 30 min but degree and duration were unaffected. 5. The effect of food on the bioavailability of cilazapril at this dose would not be expected to be clinically significant.

A study of the potential pharmacokinetic interaction of lisinopril and digoxin in normal volunteers

1. The pharmacokinetics of single oral doses of 20 mg lisinopril and 0.25 mg digoxin, given alone and together, have been studied in 12 normal young male volunteers. 2. Peak serum conc of lisinopril occurred at 6 to 8 h and were slightly higher during combined treatment. Subsequent elimination proceeded moderately rapidly in both cases, concn declining to approx. 25% of peak values in 24 h. The AUC of lisinopril was similarly slightly higher during combined treatment. 3. After lisinopril alone, urinary elimination of unchanged lisinopril was 13% dose in 72 h, and after combined therapy was 17% dose. 4. Although there were no statistically significant differences in lisinopril pharmacokinetics during single or combined treatment, serum and urinary parameters suggest that bioavailability may be enhanced slightly during combined treatment. 5. Plasma concentrations of digoxin were slightly lower and urinary excretion slightly higher during combined treatment, the mean renal clearance being 20% higher.

Pharmacokinetics of lisinopril

The angiotensin-converting enzyme inhibitor, lisinopril, has an oral bioavailability of 25 percent +/- 4 percent, which is unaffected by food. The accumulation half-life averages 12.6 hours despite a terminal serum half-life of approximately 40 hours. Steady state is attained after two daily doses (every 24 hours) in healthy volunteers. The drug is not metabolized but is eliminated via the kidneys. Lisinopril probably undergoes glomerular filtration, tubular secretion, and tubular reabsorption. There is no pharmacokinetic interaction between lisinopril and furosemide.

Effects of food on the bioavailability of CGS 16617, an angiotensin-converting enzyme inhibitor, in healthy subjects

CGS 16617, a direct-acting angiotensin-converting-enzyme inhibitor, was administered as a single dose of 20 mg in aqueous solution to 12 healthy male volunteers on two occasions in a randomized, cross-over design study. On one occasion, the dose was administered after an overnight fast; on the other occasion, it was administered after subjects ate a standard breakfast. Administration of CGS 16617 after food was associated with statistically significant decreases in peak plasma concentrations (58%) and areas under the plasma concentration-time curves (23%) compared with drug administration in the fasted state. Also, the time to peak plasma concentration was increased (57%) in a statistically significant manner when CGS 16617 was administered after food. Thus, the ingestion of food decreased both the rate and extent of absorption of this drug, but the mechanism of the interaction is unknown at present.

Lisinopril. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension and congestive heart failure

Lisinopril is an orally active angiotensin-converting enzyme (ACE) inhibitor which at dosages of 20 to 80 mg once daily is effective in lowering blood pressure in all grades of essential hypertension. It is at least as effective as usual therapeutic dosages of hydrochlorothiazide, atenolol, metoprolol and nifedipine while direct comparisons with other ACE inhibitors have not been reported. Many patients achieve an adequate blood pressure reduction with lisinopril alone, and in those who do not, most will with the addition of hydrochlorothiazide; lisinopril also attenuates hypokalaemia induced by thiazide diuretics. In patients with congestive heart failure resistant to conventional therapy, lisinopril 2.5 to 20 mg once daily improved indices of cardiac function and appeared to produce greater benefit than captopril in one controlled study. Lisinopril is well tolerated, with few serious adverse effects being reported. Thus, lisinopril is a suitable treatment for essential hypertension and shows promise in the treatment of congestive heart failure. If additional studies confirm these preliminary findings, then lisinopril will have a similar profile of indications to other ACE inhibitors, and like some other drugs in this class it offers the convenience of once daily administration.

Lisinopril: a new angiotensin-converting enzyme inhibitor

Lisinopril is a new, nonsulfhydryl angiotensin-converting enzyme inhibitor approved for the treatment of hypertension. After oral administration, 25-29 percent of the dose is absorbed intact; biotransformation is not required for pharmacological activity. Onset of action occurs one to two hours after administration, with effects still present 24 hours later. The major route of elimination is through renal excretion and an elimination half-life of 12.6 hours has been reported in normotensive individuals. In patients with impaired renal function (creatinine clearance less than or equal to 30 ml/min) a longer half-life and accumulation have been observed. Lisinopril 20-80 mg/d has been shown to be as effective as hydrochlorothiazide, nifedipine, and beta-blocking agents in the treatment of essential hypertension. Its efficacy in renovascular hypertension has also been demonstrated. In congestive heart failure (CHF) doses of 2.5-20 mg/d appear to provide hemodynamic effects comparable to those of captopril. Dizziness and cough have been the most frequently reported side effects; rash and proteinuria have also been reported in a small number of patients. Interactions with diuretics, potassium supplements, and possibly with nonsteroidal antiinflammatory agents may occur. Lisinopril appears to be similar in efficacy to other antihypertensive agents in the treatment of essential hypertension and to captopril in the treatment of CHF. Whether lisinopril is safer or more effective than captopril or enalapril in the treatment of hypertension or CHF requires further investigation. Prolonged duration of action of lisinopril allows once daily dosing, unlike captopril for which dosing is required every 8-12 hours or enalapril which may necessitate twice daily dosing.

Pharmacokinetics of lisinopril in hypertensive patients with normal and impaired renal function

The pharmacokinetics of lisinopril was studied after administration of single and multiple doses of 5 mg to hypertensive patients with normal and impaired renal function. In patients with severe renal failure the peak concentrations were higher, the decline in serum concentration was slower and the time to peak concentration was extended. Accumulation of lisinopril was highly correlated with the creatinine clearance. The effective half-life was doubled and tripled in patients with mild and severe renal impairment, respectively, as compared to patients with a normal renal function. Lisinopril lowered blood pressure in all three groups over 24 h. It is suggested that smaller doses of lisinopril should be administered to patients with severe renal failure.

An optimized fluoroenzymatic assay for the determination of angiotensin converting enzyme inhibitors in biological fluids

An easy, analytically sound fluoroenzymatic assay for angiotensin converting enzyme (ACE) inhibitors is described. Drug samples and standards are extracted with methanol and evaporated to dryness. Drug residues are then incubated with the substrate N-benzyloxycarbonyl-phenyllanyl-l-histidyl-leucine and human plasma ACE at 37 degrees C, pH 7.65, for 1 h. Fluorescence of the o-phthaldialdehyde derivatized product is measured at wavelengths of 365 nm (excitation) and 490 nm (emission). A computer program converts fluorescence to percent of ACE activity inhibited and correlates this percent inhibition with drug concentration. The ester prodrug enalapril (MK-421) was measurable at levels of a 1 ng ml(-1) in serum after base hydrolysis to enalaprilat. Lowest reliable detection limits for enalaprilat (MK-422) and lisinopril (MK-521) in serum were 0.7 ng ml(-1). This method is easily adapted to most other ACE inhibitors, is well suited to automation and avoids the use of radioactivity.

Influence of food on the pharmacokinetics of quinapril and its active diacid metabolite, CI-928

A randomized two-way crossover study was conducted in 12 healthy volunteers to assess the effect of food on the pharmacokinetics of quinapril (CI-906) and its active metabolite, CI-928, after quinapril dosing. Forty-milligram oral quinapril doses were administered in a fasted or a fed state with a one-week washout period between treatments. No significant treatment differences were observed in quinapril and CI-928 values for maximum plasma concentration, area under the plasma concentration-time curve, or percentage of dose excreted in the urine. Small but significant increases of less than 0.5 hour in quinapril and CI-928 tmax values were observed after consumption of food. The pharmacokinetic profiles of quinapril and CI-928 were not significantly altered by the administration of food.