Quantification of Hydrochlorothiazide and Ramipril/Ramiprilate in Blood Serum and Cerebrospinal Fluid: A Pharmacokinetic Assessment of Central Nervous System Adverse Effects.

BACKGROUND: A drug must reach the central nervous system (CNS) in order to directly cause CNS adverse effects (AEs). Our current study addressed the pharmacokinetic (PK) background of the assumption that CNS concentrations of hydrochlorothiazide (HCT) and ramiprilate may directly cause CNS AEs such as headache and drowsiness. METHODS: In neurological patients, paired serum and cerebrospinal fluid (CSF) samples were withdrawn simultaneously. Some of them were treated with HCT (n = 15, daily chronic doses 7.5-25 mg) or ramipril (n = 9, 2.5-10 mg). Total concentrations of HCT and ramiprilate were quantified in these samples. To this end, sensitive liquid chromatography/tandem mass spectrometry methods were developed. RESULTS: CSF reached 4.1% (interquartile ranges 2.5-5%) of total serum concentrations for HCT and 2.3% (1.7-5.7%) for ramiprilate, corresponding to about 11.3% and 5.5% of respective unbound serum concentrations. CONCLUSION: The PK/Pharmacodynamic characteristics of HCT and ramiprilate in the CNS are unknown. However, since the CSF levels of these agents, both free and bound, were much lower than the corresponding concentrations in serum, it is unlikely that the observed CNS AEs are mediated primarily via direct effects in the brain.

Challenges in Simultaneous Determination of Hydrochlorothiazide and Ramipril in Human Plasma: Application to a Bioequivalence Study.

An isotope dilution selective and sensitive high-performance liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) method has been developed for the simultaneous determination of hydrochlorothiazide (HCTZ) and ramipril in human plasma through a new concept of periodical polarity switching. Extraction of HCTZ, ramipril and their deuterated analogs as internal standards (ISs) was carried out from 150 µL of human plasma by solid-phase extraction method. Chromatographic separation of analytes was performed on Hypurity C18 (150 mm × 4.6 mm, 5 µ) column under gradient conditions with methanol:0.2% (v/v) formic acid in water as the mobile phase. The method was validated over a concentration range of 0.750-300 ng/mL for HCTZ and 0.125-80.0 ng/mL for ramipril. The mean extraction recovery for analytes and ISs were >(86.0%), consistent across all four QC levels. The challenges to evaluate matrix effect and continuous reproducibility of method during long analytical run was studied and resolved. Processed samples, freeze-thaw, long-term and whole blood stability were evaluated for both the analytes. The method was applied to support a bioequivalence study of 25 mg of HCTZ and 5 mg of ramipril tablet formulation in nine healthy Indian subjects. Assay reproducibility was demonstrated by reanalysis of 42 incurred samples.

Hansen solubility parameters for assay method optimization of simvastatin, ramipril, atenolol, hydrochlorothiazide and aspirin in human plasma using liquid chromatography with tandem mass spectrometry.

A simple, specific, sensitive, validated method was developed using liquid chromatography with tandem mass spectrometry with electrospray ionization of human plasma for the simultaneous estimation of drugs (simvastatin, ramipril, atenolol, hydrochlorothiazide, and aspirin) of PolycapTM capsule used in cardiovascular therapy. The interaction of these actives including internal standards between the stationary and mobile phase were investigated using Hansen solubility parameters. Chromatographic separation was performed on Phenomenex Synergi Polar-RP (30 × 2 mm, 4 µm) column with a gradient mobile phase composition of acetonitrile and 5 mM ammonium formate for positive mode and 0.1% formic acid in both water and acetonitrile for negative mode. The flow rate and runtime were 1.0 mL/min and 3.5 min, respectively. Sample extraction was done by protein precipitation using acetonitrile, enabling a fast analysis. The calibration ranges from 0.1 to 100, 0.1 to 100, and 1 to 1000 ng/mL for simvastatin, ramipril, and atenolol using internal standard carbamazepine in positive mode, respectively, whereas it was 0.3-300 and 2-2000 ng/mL for hydrochlorothiazide and aspirin using internal standard 7-hydroxy coumarin in negative mode, respectively. Hansen solubility parameters can be used as a high-throughput optimizing tool for column and mobile phase selection in bioanalysis. This validated bioanalytical method has the potential for future fixed dose combination based preclinical and clinical studies that can save analysis time.

Angiotensin Converting Enzyme Inhibitor Dialyzability and Outcomes in Older Patients Receiving Hemodialysis.

BACKGROUND/AIMS: Some angiotensin converting enzyme (ACE) inhibitors are efficiently removed from circulation by hemodialysis ('high dialyzability'), whereas others are not ('low dialyzability'). In patients receiving hemodialysis, this may influence the effectiveness of ACE inhibitors. METHODS: Using linked healthcare databases we identified older patients receiving chronic hemodialysis who filled new ACE inhibitor prescriptions. The low dialyzability group (n = 3,369) included fosinopril and ramipril. The high dialyzability group (n = 5,974) included enalapril, lisinopril, and perindopril. The primary outcome was all-cause mortality within 180 days of first ACE inhibitor prescription. RESULTS: There were 361 deaths among 5,974 patients (6.0%) prescribed with low dialyzability ACE inhibitors and 179 deaths among 3,369 patients (5.3%) prescribed with high dialyzability ACE inhibitors (relative risk 1.1, 95% CI 0.9-1.3, p = 0.6). CONCLUSION: In this study of older patients receiving hemodialysis, the dialyzability of ACE inhibitors was not associated with mortality or cardiovascular outcomes.

Paediatric drug development of ramipril: reformulation, in vitro and in vivo evaluation.

Ramipril is used mainly for the treatment of hypertension and to reduce incidence of fatality following heart attacks in patients who develop indications of congestive heart failure. In the paediatric population, it is used most commonly for the treatment of heart failure, hypertension in type 1 diabetes and diabetic nephropathy. Due to the lack of a suitable liquid formulation, the current study evaluates the development of a range of oral liquid formulations of ramipril along with their in vitro and in vivo absorption studies. Three different formulation development approaches were studied: solubilisation using acetic acid as a co-solvent, complexation with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and suspension development using xanthan gum. Systematic optimisation of formulation parameters for the different strategies resulted in the development of products stable for 12 months at long-term stability conditions. In vivo evaluation showed C(max) of 10.48 µg/ml for co-solvent, 13.04 µg/ml for the suspension and 29.58 µg/ml for the cyclodextrin-based ramipril solution. Interestingly, both ramipril solution (co-solvent) and the suspension showed a T(max) of 2.5 h, however, cyclodextrin-based ramipril produced T(max) at 0.75 h following administration. The results presented in this study provide translatable products for oral liquid ramipril which offer preferential paediatric use over existing alternatives.

Development and validation of bioanalytical method for simultaneous estimation of ramipril and hydrochlorothiazide in human plasma using liquid chromatography-tandem mass spectrometry.

The present study describes a novel liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for the simultaneous estimation of ramipril (RAM) and hydrochlorothiazide (HCTZ) in human plasma using liquid-liquid extraction technique. This method made use of electrospray ionization in positive mode for RAM and in negative mode for HCTZ using triple quadrupole mass spectrometry where carbamazepine was used as an internal standard (IS). Analytes were recovered by methyl tertiary butyl ether:dichloromethane (85:15) subsequently separated on an Enable C18 G column (150 mm × 4.6 mm, 5 µm) using methanol:0.1% formic acid in water (85:15) as a mobile phase, at a flow rate of 0.5 mL/min. Quantification of RAM, HCTZ and IS was performed using multi-reaction monitoring mode (MRM) where transition of m/z 417.2→234.1 (RAM) and 237.0→194.0 (IS) in positive mode and 296.1→205.0 for HCTZ in negative mode. The calibration curve was linear (r(2)>0.99) over the concentration range of 2-170 ng/mL for RAM and 8-680 ng/mL for HCTZ. The intra-day and inter-day precisions were <15% and the accuracy was all within ±15% (at LLOQ level ±20%). Additionally, the LC-MS/MS method was fully validated for all the other parameters such as selectivity, matrix effect, recovery and stability as well. In conclusion, the findings of the present study revealed the selectivity and sensitivity of this method for the simultaneous estimation of RAM and HCTZ in human plasma.

Liquid chromatography-tandem mass spectrometry method for simultaneous quantification of bisoprolol, ramiprilat, propranolol and midazolam in rat dried blood spots.

Dried blood spot (DBS) sampling represents a suitable method for pharmacokinetic studies in rats, particularly if serial sampling is needed. To study the pharmacokinetics of drugs in a rat heart failure (HF) model, we developed and validated a method for the simultaneous determination of bisoprolol, ramiprilat, propranolol and midazolam in DBS samples. Bisoprolol and ramipril are widely used in the treatment of HF, and midazolam and propranolol are markers of hepatic metabolism, which can be altered in HF. A 20µL sample of rat blood was pipetted onto Whatman 903 Protein Saver Card and allowed to dry. The whole spot was excised and 300µL of solvent (methanol with 10% ultrapure water and 0.1% formic acid) was added. After mixing and incubating the sample in an ultrasonic bath, a mixture of isotopically labeled internal standards was added. After centrifugation, the extracts were cleaned on an Ostro™ plate and analyzed using liquid chromatography-tandem mass spectroscopy. The method was successfully validated. No significant interference was observed in the retention times of analytes or internal standards. The intraday and interday accuracy and precision were within a ±15% interval. The method was linear in the range 5-250µg/L and the lower limit of quantification was 5µg/L for all four analytes. The absolute matrix effect ranged from 98.7% for midazolam to 121% for ramiprilat. The recovery was lowest for ramiprilat and highest for propranolol. Samples were stable at all tested temperatures. The method has been used successfully in a real-time pharmacokinetic study in rats.

Lack of clinically relevant drug-drug interaction between empagliflozin, a sodium glucose cotransporter 2 inhibitor, and verapamil, ramipril, or digoxin in healthy volunteers.

BACKGROUND: Empagliflozin is a sodium glucose cotransporter 2 inhibitor in clinical development as a treatment for type 2 diabetes mellitus. OBJECTIVE: The goal of this study was to investigate potential drug-drug interactions between empagliflozin and verapamil, ramipril, and digoxin in healthy volunteers. METHODS: The potential drug-drug interactions were evaluated in 3 separate trials. In the first study, 16 subjects were randomized to receive single-dose empagliflozin 25 mg alone or single-dose empagliflozin 25 mg with single-dose verapamil 120 mg. In the second study, 23 subjects were randomized to receive empagliflozin 25 mg once daily (QD) for 5 days, ramipril (2.5 mg on day 1 then 5 mg QD on days 2-5) for 5 days or empagliflozin 25 mg with ramipril (2.5 mg on day 1 then 5 mg QD on days 2-5) for 5 days. In the third study, 20 subjects were randomized to receive single-dose digoxin 0.5 mg alone or empagliflozin 25 mg QD for 8 days with single-dose digoxin 0.5 mg on day 5. RESULTS: Exposure of empagliflozin was not affected by coadministration with verapamil (AUC0-∞: geometric mean ratio [GMR], 102.95%; 90% CI, 98.87-107.20; Cmax: GMR, 92.39%; 90% CI, 85.38-99.97) or ramipril (AUC over a uniform dosing interval τ at steady state [AUCτ,ss]: GMR, 96.55%; 90% CI, 93.05-100.18; Cmax at steady state [Cmax,ss]: GMR, 104.47%; 90% CI 97.65-111.77). Empagliflozin had no clinically relevant effect on exposure of ramipril (AUCτ,ss: GMR, 108.14%; 90% CI 100.51-116.35; Cmax,ss: GMR, 103.61%; 90% CI, 89.73-119.64) or its active metabolite ramiprilat (AUCτ,ss: GMR, 98.67%; 90% CI, 96.00-101.42; Cmax,ss: GMR, 98.29%; 90% CI, 92.67-104.25). Coadministration of empagliflozin had no clinically meaningful effect on digoxin AUC0-∞ (GMR, 106.11%; 90% CI, 96.71-116.41); however, a slight increase in Cmax was observed that was not considered clinically relevant (GMR, 113.94%; 90% CI, 99.33-130.70). All treatments were well tolerated. There were no serious adverse events or adverse events leading to discontinuation in any of the studies. CONCLUSIONS: No dose adjustment of empagliflozin is required when coadministered with ramipril or verapamil, and no dose adjustment of digoxin or ramipril is required when coadministered with empagliflozin. ClinicalTrials.gov identifiers: NCT01306175 (digoxin), NCT01276301 (verapamil), and NCT01284621 (ramipril).

Bioequivalence study of 10 mg ramipril tablets in healthy Thai volunteers.

OBJECTIVE: To determine the bioequivalence of 10 mg dose of ramipril tablets between the test product (Ramtace 10 mg, Unison Laboratories, Thailand) and the reference product (Tritace 10 mg, Aventis Pharma SPA, Italy). MATERIAL AND METHOD: The present study was carried out with a single dose, 2-treatment, 2-period, 2-sequence randomized crossover design under fasting condition with a minimum of 14 days washout period in 24 healthy Thai male and female volunteers. Plasma samples for determination of ramipril and ramiprilat were obtained pre-dose and at frequent intervals for up to 72 h post dose. Ramipril and ramiprilat plasma concentrations were quantified by a validated method employing high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All ofthe pharmacokinetic parameters were investigated using non-compartmental analysis. RESULTS: The result demonstrated the 90% confidence interval (90%CI) of the geometric mean ratio (test/reference) of C max, AUC(0-72) and AUC(0-infinity) of ramipril were 97.26% (84.50%-111.93%), 100.70% (89.47%-113.34%) and 100.29% (88.90% 113.15%), respectively. For ramiprilat, the 90% CI for C max, AUC(0-72), and AUC(0-infinity) were 108.87% (103.00%-115.07%), 104.93% (100.50%-109.55%) and 103.30% (98.03%-108.85%), respectively. CONCLUSION: the 90% confidence intervals for log-transformed geometric mean test/reference formulation ratios of primary parameters were entirely within 80.00%-125.00%. Thus, it can be concluded that the test formulation was bioequivalent to the reference formulation.

Impact of methylation of acyl glucuronide metabolites on incurred sample reanalysis evaluation: ramiprilat case study.

BACKGROUND: Reanalysis of incurred samples showed that the bioanalytical method for the quantification of ramipril and ramiprilat was generating irreproducible results for ramiprilat. RESULTS: An additional peak interfering with ramiprilat was observed in the incurred samples but not in the calibrant and quality control samples. A similar interference was detected for ramipril, but it was chromatographically separated. Interferences were produced during sample preparation, which involves strong cation exchanger cartridges. The interfering products corresponded to the methylation of ramipril and ramiprilat glucuronide. CONCLUSION: Following this discovery, a reproducible method was developed and successfully validated for ramipril and ramiprilat. Additional stability tests were performed in the presence of glucuronide and diketopiperazine metabolites of ramipril and ramiprilat to demonstrate the method specificity.

Development and validation of UPLC tandem mass spectrometry assay for separation of a phase II metabolite of ramipril using actual study samples and its application to a bioequivalence study.

In this paper, we present a validated UPLC-MS/MS assay for determination of ramipril and ramiprilat from human plasma samples. The assay is capable of isolating phase II metabolites (acylglucornides) of ramipril from in vivo study samples which is otherwise not possible using conventional HPLC conditions. Both analytes were extracted from human plasma using solid-phase extraction technique. Chromatographic separation of analytes and their respective internal standards was carried out using an Acquity UPLC BEH C(18) (2.1 × 100 mm), 1.7 µm column followed by mass spectrometric detection using an Waters Quattro Premier XE. The method was validated over the range 0.35-70.0 ng/mL for ramipril and 1.0-40.0 ng/mL for ramiprilat.

Simultaneous determination of ramipril, ramiprilat and telmisartan in human plasma using liquid chromatography tandem mass spectrometry.

A rapid and sensitive liquid chromatography tandem mass spectrometry method has been developed and validated for the simultaneous determination of ramipril, ramiprilat and telmisartan in human plasma. The solid-phase extraction technique was used for the extraction of ramipril, ramiprilat and telmisartan from human plasma. Trandolaprilat and hydrochlorothiazide were used as the internal standards (ISs). Chromatography was performed on a Hypurity C18, 5 µm, 50 mm × 4.6mm column, with the mobile phase consisting of ammonium acetate and acetonitrile (in a 20:80 ratio), followed by detection using mass spectrometry. The method involves a simple reversed isocratic chromatography condition and mass spectrometry detection, which enables detection at sub-nanogram levels. The method was validated and the lower limit of quantification for ramipril, ramiprilat and telmisartan was found to be 0.1 ng mL(-1), 0.1 ng mL(-1) and 2 ng mL(-1), respectively. The mean recovery for ramipril, ramiprilat and telmisartan ranged from 90.1 to 104.1%. This method increased the sensitivity and selectivity; resulting in high-throughput analysis of ramipril, ramiprilat and telmisartan using two different ISs in a single experiment for bioequivalence studies, with a chromatographic run time of 1.5 min only.

Simultaneous determination of atorvastatin, amlodipine, ramipril and benazepril in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A rapid, simple, sensitive and specific LC-MS/MS method has been developed and validated for the simultaneous estimation of atorvastatin (ATO), amlodipine (AML), ramipril (RAM) and benazepril (BEN) using nevirapine as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Analytes and IS were extracted from plasma by simple liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on C(18) column by pumping 0.1% formic acid-acetonitrile (15:85, v/v) at a flow rate of 1 mL/min. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 0.26-210 ng/mL for ATO; 0.05-20.5 ng/mL for AML; 0.25-208 ng/mL for RAM and 0.74-607 ng/mL for BEN with mean correlation coefficient of ≥0.99 for each analyte. The intra-day and inter-day precision and accuracy results were well with in the acceptable limits. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers.

Sensitivity enhancement and matrix effect evaluation during summation of multiple transition pairs-case studies of clopidogrel and ramiprilat.

Sensitivity enhancement via summation of multiple MRM transition pairs is gaining popularity in tandem mass spectrometric assays. Numerous validation experiments describing the assays for two model substrates, clopidogrel and ramiprilat, were performed. The quantitation of clopidogrel was achieved by the summation of transition pairs m/z 322.2 to m/z 212.0 and m/z 322.2 to m/z 184.0, while that of ramiprilat was achieved by the summation of transition pairs m/z 389.2 to m/z 206.1 and m/z 389.2 to m/z156.1. The use of summation approach achieved sensitivities of >2 fold for both compounds as compared with the reported single MRM transition pair assays. The validation experiments addressed some important assay development issues, such as: (a) lack of impact of matrix effect; (b) unequivocal verification of the percentage contribution of each MRM transition pair towards sensitivity; (c) sensitivity enhancement factor achieved by summation approach of MRM transition pairs; and (d) accurate prediction of quality control samples using summation approach vs a single MRM transition pair. In summary, the appropriateness of using two MRM transition pairs for quantitation was demonstrated for both clopidogrel and ramiprilat. Additionally, pharmacokinetic application of the MRM transition pair assays using a summation approach was established for the two compounds.

Bioanalytical method development and validation using incurred samples--simultaneous quantitation of ramipril and ramiprilat in human EDTA plasma by LC-MS/MS.

A new method development and validation approach is proposed in order to develop a reliable method for the simultaneous quantitation of ramipril and ramiprilat in the presence of numerous labile metabolites. This new approach involves the usage of a synthesized labile acyl glucuronide of ramipril as well as individual and pooled incurred (study) samples in the development and validation process. Following the method validation and prior to its application to a large clinical study, a mini pilot study was performed to evaluate the performance of the method. When the samples from the mini pilot study were analyzed by two different scientists, 100% of the results from incurred sample reanalysis (ISR) matched within 8% of difference and the mean differences were 0.21% and 1.40% for ramipril and ramiprilat, respectively. The validated concentration range reported in this article is 0.2-80 ng/mL for both analytes. Various stabilities, such as bench-top, autosampler, freeze/thaw, and long-term, were also successfully evaluated. The key to the success were low sample processing temperature (4 degrees C), proper choice of sample extraction procedure, and adequate chromatographic conditions to obtain good peak shape without the need of derivatization and baseline separation between the analytes and their glucuronide metabolites.

Pharmacokinetics and pharmacodynamics of ramipril and ramiprilat in healthy cats.

The pharmacokinetics of ramipril and its active metabolite, ramiprilat, was determined in cats following single and repeated oral doses of ramipril (Vasotop tablets) (once daily for 9 days) at dose rates of 0.125, 0.25, 0.5 and 1.0 mg/kg. The pharmacodynamic effects were assessed by measuring plasma angiotensin-converting enzyme (ACE) activity. Maximum ramipril concentrations were attained within 30 min following a single dose and declined rapidly (concentrations were below the limit of quantification 4 h after treatment). Peak ramiprilat concentrations were detected at approximately 1.5 h. The apparent terminal half-life (t((1/2)beta)) was > or =20 h irrespective of the dose. Ramiprilat accumulated in plasma (ratio of accumulation 1.3 to 1.9 depending on the dose rate) following repeated administration. Steady-state conditions were attained after the second dose. Excretion was predominant in faeces (87%) and to a lesser extent in urine (11%). The rate and extent of absorption of ramipril as well as its conversion to ramiprilat were not significantly influenced by the presence of food in the gastrointestinal tract. Plasma-ACE activity was almost completely abolished 0.5-2.0 h after treatment, irrespective of the dose rate. Significant inhibition of ACE activity of 54.7 to 82.6% (depending on the dosage) was still present 24 h after treatment. Treatment was well-tolerated in all cats. Ramipril at a dose rate of 0.125 mg/kg once daily produces significant and long-lasting inhibition of ACE activity in healthy cats. The appropriateness of this dosage regime needs to be confirmed in diseased cats.

Liquid chromatography tandem mass spectrometry method for simultaneous determination of metoprolol tartrate and ramipril in human plasma.

A simple, rapid, sensitive and specific liquid chromatography-tandem mass spectrometry method was developed and validated for quantification of metoprolol tartrate (MT) and ramipril, in human plasma. Both the drugs were extracted by liquid-liquid extraction with diethyl ether-dichloromethane (70:30, v/v). The chromatographic separation was performed on a reversed-phase C8 column with a mobile phase of 10 mM ammonium formate-methanol (3:97, v/v). The protonated analyte was quantitated in positive ionization by multiple reaction monitoring with a mass spectrometer. The method was validated over the concentration range of 5-500 ng/ml for metoprolol and ramipril in human plasma. The precursor to product ion transitions of m/z 268.0-103.10 and m/z 417.20-117.20 were used to measure metoprolol and ramipril, respectively.

Development and bioavailability assessment of ramipril nanoemulsion formulation.

The objective of our investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of Ramipril, with minimum surfactant concentration that could improve its solubility, stability and oral bioavailability. Formulations were taken from the o/w nanoemulsion region of phase diagrams, which were subjected to thermodynamic stability and dispersibility tests. The composition of optimized formulation was Sefsol 218 (20% w/w), Tween 80 (18% w/w), Carbitol (18% w/w) and standard buffer solution pH 5 (44% w/w) as oil, surfactant, cosurfactant and aqueous phase, respectively, containing 5 mg of ramipril showing drug release (95%), droplet size (80.9 nm), polydispersity (0.271), viscosity (10.68 cP), and infinite dilution capability. In vitro drug release of the nanoemulsion formulations was highly significant (p<0.01) as compared to marketed capsule formulation and drug suspension. The relative bioavailability of ramipril nanoemulsion to that of conventional capsule form was found to be 229.62% whereas to that of drug suspension was 539.49%. The present study revealed that ramipril nanoemulsion could be used as a liquid formulation for pediatric and geriatric patients and can be formulated as self-nanoemulsifying drug delivery system (SNEDDS) as a unit dosage form.

Effect of short-term ACE inhibitor treatment on peripheral insulin sensitivity in obese insulin-resistant subjects.

AIMS/HYPOTHESIS: This study was designed to investigate the effect of short-term ACE inhibitor treatment on insulin sensitivity and to examine possible underlying metabolic and haemodynamic effects in obese insulin-resistant subjects. METHODS: A randomised, double-blind placebo-controlled trial was performed in 18 obese insulin-resistant men (age, 53 +/- 2 years; BMI, 32.6 +/- 0.8 kg/m(2); homeostasis model assessment of insulin resistance, 5.6 +/- 0.5; systolic blood pressure [SBP], 140.8 +/- 3.2; diastolic blood pressure [DBP], 88.8 +/- 1.6 mmHg), who were free of any medication. The aim was to examine the effects of 2 weeks of ACE inhibitor treatment (ramipril, 5 mg/day) on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and intramuscular triacylglycerol (IMTG) content. RESULTS: Ramipril treatment decreased ACE activity compared with placebo (-22.0 +/- 1.7 vs 0.2 +/- 1.1 U/l, respectively, p < 0.001), resulting in a significantly reduced blood pressure (SBP, -10.8 +/- 2.1 vs -2.7 +/- 2.0 mmHg, respectively, p = 0.01; DBP, -10.1 +/- 1.3 vs -4.2 +/- 2.1 mmHg, respectively, p = 0.03). Ramipril treatment had no effect on whole-body insulin-mediated glucose disposal (before: 17.9 +/- 2.0, after: 19.1 +/- 2.4 micromol kg body weight(-1) min(-1), p = 0.44), insulin-mediated glucose uptake across the forearm (before: 1.82 +/- 0.39, after: 1.92 +/- 0.29 micromol 100 ml forearm tissue(-1) min(-1), p = 0.81) and IMTG content (before: 45.4 +/- 18.8, after: 48.8 +/- 27.5 micromol/mg dry muscle, p = 0.92). Furthermore, the increase in carbohydrate oxidation (p < 0.001) and forearm blood flow (p < 0.01), and the decrease in fat oxidation (p < 0.001) during insulin stimulation were not significantly different between treatments. CONCLUSIONS/INTERPRETATION: Short-term ramipril treatment adequately reduced ACE activity and blood pressure, but had no significant effects on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and IMTG content in obese insulin-resistant subjects.

Pharmacokinetic and pharmacodynamic parameters of ramipril and ramiprilat in healthy dogs and dogs with reduced glomerular filtration rate.

Ramipril, an angiotensin-converting enzyme (ACE) inhibitor for use in dogs, is converted in vivo to its active form, ramiprilat, which is eliminated in the bile and urine in the dog. The objective of this study was to assess the effect of renal impairment on the pharmacokinetics (PKs) and pharmacodynamics (PDs) of ramipril and ramiprilat. Ten adult Beagle dogs were used. PK/PD studies were performed before and after the induction of subclinical renal impairment. Ramiprilat was given at 0.25 mg/kg by a single IV bolus. After a 2-week washout period, ramipril was administered PO at 0.25 mg/kg once daily for 8 days. Ramipril and ramiprilat PKs were studied by using a physiologically based model. The relationship between free plasma ramiprilat concentration and ACE activity was described by using the fractional Hill model. Glomerular filtration rate was decreased by 58%. No biologically relevant changes in usual plasma variables were observed between the 1st and the 8th day of oral treatment with ramipril under either condition. After an IV bolus of ramiprilat, the only changes in renal-impaired dogs were a 14 and 49% decrease in clearance of the free fraction of ramiprilat (P < .01) and free plasma concentration required to produce 50% of the maximal effect (P < .05), respectively. After repeated PO administration of ramipril, there were no alterations in any of the PK and PD parameters in healthy or renal-impaired dogs. No adjustment of the recommended PO dosage of ramipril is needed in dogs with moderate renal impairment.