[Basics for the Use of Andexanet]. / Grundlagen zur Anwendung von Andexanet.

BACKGROUND: For life-threatening or uncontrollable bleeding in association with the thrombin inhibitor dabigatran, the monoclonal antibody fragment idarucizumab is available, and for bleeding in association with the direct factor Xa inhibitors rivaroxaban or apixaban, the modified recombinant FXa protein andexanet is available for reversal. These antidotes represent emergency drugs that are typically used only after performing guideline-compliant multimodal measures. METHODS: An interdisciplinary group of experienced experts in the fields of angiology, hematology, internal medicine, clinical pharmacology, laboratory medicine, transfusion medicine, anesthesiology, intensive care, and hemostaseology developed recommendations relevant to daily clinical practice based on the current scientific evidence. RESULTS: Reversal of oral anticoagulants should be considered for severe bleeding in the following situations: (1) life-threatening bleeding or refractory hemorrhagic shock, (2) intracerebral bleeding, or (3) endoscopically unstoppable gastrointestinal bleeding. After successful hemostasis, anticoagulation (e.g., direct oral anticoagulant, vitamin K antagonist, and heparin) should be resumed promptly, taking into account individual bleeding and thromboembolic risk. DISCUSSION: This article aims to facilitate the management of patients with andexanet by all medical disciplines involved, thereby ensuring optimal care of patients during bleeding episodes.

[Clinical pharmacology of current antiplatelet drugs]. / Klinische Pharmakologie der aktuellen antithrombozytären Substanzen.

Dual antiplatelet therapy with low-dose acetylsalicylic acid (ASA) and an inhibitor of the P2Y12 adenosine diphosphate (ADP) receptor is the standard treatment for patients presenting with acute coronary syndrome (ACS) or undergoing elective coronary interventions according to the current guidelines published by the European Society of Cardiology (ESC). New generation P2Y12 inhibitors, such as prasugrel and ticagrelor exert stronger and more consistent inhibition of the P2Y12 receptor. In clinical studies enrolling patients with ACS these drugs decreased the incidence of ischemic events compared to the standard therapy with clopidogrel and ASA; however, this beneficial effect was associated with an increase in bleeding events. Alternative therapeutic approaches via addition of drugs with different modes of action showed an overall reduction of ischemic events but also failed to uncouple this beneficial effect from an increased bleeding risk.

Clinical implications of drug-drug interactions with P2Y12 receptor inhibitors.

Polypharmacy in patients undergoing coronary artery stenting or in those presenting with an acute coronary syndrome is common. Nevertheless, the risk of drug-drug interactions in patients treated simultaneously with P2Y12 receptor inhibitors is less well considered in routine clinical practice. Whereas the irreversible P2Y12 receptor inhibitors clopidogrel and prasugrel are prodrugs requiring cytochrome P450 (CYP) enzymes for metabolic activation, such activation is not necessary for the direct-acting reversible P2Y12 receptor inhibitor ticagrelor. Several drugs frequently used in cardiology have been shown to interact with the metabolism of P2Y12 receptor inhibitors in pharmacodynamic studies. Whereas several drug-drug interactions have been described for clopidogrel and ticagrelor, prasugrel seems to have a low potential for drug-drug interactions. The clinical implications of these interactions have raised concern. In general, concomitant administration of P2Y12 receptor antagonists and strong inhibitors or inducers of CYP3A/CYP2C19 should be performed with caution in patients treated with clopidogrel/ticagrelor. Under most circumstances, clinicians have the option of prescribing alternative drugs with less risk of drug-drug interactions when used concomitantly with P2Y12 receptor inhibitors.

High on-treatment platelet reactivity and P2Y12 antagonists in clinical trials.

Dual antiplatelet therapy with aspirin and clopidogrel in patients undergoing percutaneous coronary intervention (PCI) and in patients with acute coronary syndromes (ACS) has substantially decreased the rate of cardiovascular events. Within the past decade, the variability in pharmacodynamic response as well as the moderate antiplatelet efficacy of clopidogrel has raised major concerns, since high on-clopidogrel platelet reactivity has consistently been associated with increased risk for ischaemic events in PCI patients. The variability in response could be linked to genetic polymorphisms impacting on activity of cytochrome P450 enzymes as well as clinical and demographic variables, but, taken together, factors identified so far can explain only up to approximately 12% of this variability in adenosine diphosphate-induced platelet aggregation on clopidogrel. Regulatory agencies as well as major cardiac societies suggest the use of other anti-platelet medications or alternative dosing strategies for clopidogrel in patients with reduced effectiveness of clopidogrel. This review will focus on the current status of alternate strategies for more sufficient suppression of high platelet reactivity.

Personalizing antiplatelet therapy with clopidogrel.

Dual antiplatelet therapy with aspirin and clopidogrel is the accepted standard for prevention of ischemic complications after percutaneous coronary intervention and has been shown to reduce cardiovascular events in patients with acute coronary syndromes (ACSs). There is substantial interindividual variability in antiplatelet response to clopidogrel. Various clinical studies have demonstrated that patients with high on-clopidogrel platelet reactivity incur an increased risk for ischemic events. In recent years, several clinical and demographic variables as well as multiple genetic factors contributing to the variability in antiplatelet response to clopidogrel have been identified. We discuss strategies based on platelet function testing or genotyping for improvement of antiplatelet effects of clopidogrel and thereby clinical outcome.

Micro-array profiling exhibits remarkable intra-individual stability of human platelet micro-RNA.

Platelets play an important role in haemostasis and thrombus formation. Latest research identified platelets harbouring so called microRNAs (miRNA). MiRNAs are short single-stranded RNAs modulating gene expression by targeting mRNAs. Limited data exist on inter-individual variability of platelet miRNA profile while no data are available on intra-individual variability. We assessed platelet miRNA profile in five volunteers at five time points over a time course of 10 days; 24 hours prior to the last blood sampling, subjects took 500 mg acetylsalicylic acid (ASA). Platelet miRNA was isolated from leucocyte-depleted platelet-rich plasma, and miRNA array-analysis was performed. Temporal patterns and ASA effect were explored by a linear mixed effects model for each miRNA. For the 20 most abundantly expressed platelet miRNAs, target gene search was performed and an annotation network was created. MiRNA expression profiling of 1,281 human miRNAs revealed relevant expression of 221 miRNAs consistently expressed in all samples at all time points. Correlation of platelet miRNA ranks was highly significant to other studies. Global distribution of miRNA expression was relatively similar in all subjects. No miRNA exhibited a significant effect of time at level 0.05. After 24 hours, no significant effect of ASA was found. Concerning functional implications of the 20 most abundantly expressed miRNAs, we found six functional themes. In conclusion, platelet miRNA profile is remarkably stable over the time period studied. Single-point analysis of platelet miRNA profile is reasonable when inter-individual differences are studied. The functional annotation network points toward extra-platelet effects of platelet miRNAs.

Use of B-type natriuretic peptide to predict blood pressure improvement after percutaneous revascularisation for renal artery stenosis.

OBJECTIVES: The purpose of this study was to evaluate the utility of B-type natriuretic peptide (BNP) to predict blood pressure (BP) response in patients with renal artery stenosis (RAS) after renal angioplasty and stenting (PTRA). METHODS: In 120 patients with RAS and hypertension referred for PTRA, 24-h ambulatory BP recordings were obtained before and 6 months after intervention. BNP was measured before, 1 day and 6 months after PTRA. RESULTS: BP improved in 54% of patients. Median BNP levels pre-intervention were 97 pg ml(-1) (interquartile range (IQR) 35-250) and decreased significantly within 1 day of PTRA to 62 pg ml(-1) (IQR 24-182) (p < 0.001), remaining at 75 pg ml(-1) (IQR 31-190) at 6 months. The area under the receiver operating curve for pre-intervention BNP to predict BP improvement was 0.57 (95% confidence interval (CI) 0.46-0.67). Pre-intervention BNP >50 pg ml(-1) was seen in 79% of patients with BP improvement compared with 56% in patients without improvement (p = 0.01). In a multivariate logistic regression analysis, BNP >50 pg ml(-1) was significantly associated with BP improvement (odds ratio (OR) 4.0, 95% CI 1.2-13.2). CONCLUSIONS: BNP levels are elevated in patients with RAS and decrease after revascularisation. Although BNP does not seem useful as a continuous variable, pre-interventional BNP >50 pg ml(-1) may be helpful to identify patients in whom PTRA will improve BP.

Proton pump inhibitors for prevention of bleeding episodes in cardiac patients with dual antiplatelet therapy - between Scylla and Charybdis?

Guidelines from national and international cardiac societies recommend dual antiplatelet therapy with aspirin and thienopyridines (clopidogrel, ticlopidine) in patients with acute coronary syndrome and patients undergoing percutaneous coronary intervention. The most-feared complication of antiplatelet therapy is hemorrhage. Long-term treatment with aspirin increased bleeding rates compared to placebo and similar bleeding rates were observed on clopidogrel. Dual antiplatelet therapy increased hemorrhage with the dose of aspirin administered impacting on increased bleeding rates. Concomitant treatment with a proton pump inhibitor (PPI) decreased bleeding rates in patients on antiplatelet therapy. An analysis of medical and pharmacy databases indicated a more than 3-fold increase in the incidence of myocardial infarction within 12 months after starting treatment with clopidogrel in patients on concomitant treatment with a PPI. This might be attributed to a drug-drug interaction between PPIs and clopidogrel because recent clinical studies showed that treatment with the PPI omeprazole attenuated the antiplatelet effect of clopidogrel most likely by inhibiting the formation of the active metabolite which carries the antiplatelet activity of the drug. Therefore, sufficiently powered prospective clinical studies in cardiac patients on dual antiplatelet therapy investigating the potential drug interaction between PPIs and the antiplatelet effect of clopidogrel are awaited eagerly.

A clinical trial on absorption and N-acetylation of oral and rectal mesalazine.

BACKGROUND: Mesalazine (5-ASA) is a standard treatment for ulcerative colitis. Extent of absorption and N-acetylation determine systemic exposure to 5-ASA, and are thereby relevant for the safety of the treatment. The aim of the study was to compare absorption and N-acetylation of 5-ASA following rectal or oral drug administration. Healthy subjects were compared to patients with ulcerative colitis to evaluate the impact of chronic inflammation of colorectal mucosa on disposition of 5-ASA. MATERIALS AND METHODS: First, 12 healthy adults were randomized to receive 2 g of 5-ASA by each of four different formulations: oral delayed release granules, 30 mL enema, 60 mL rectal foam, and 120 mL rectal foam. Second, 12 patients with active ulcerative colitis received 60 mL rectal foam. Pharmacokinetic analysis was performed by determination of 5-ASA and its acetylated, pharmacologically inactive metabolite (Ac-5-ASA) in plasma and urine. RESULTS: First, systemic exposure to 5-ASA was markedly lower after rectal drug administration as compared to oral dosing (P < 0.001; e.g. median relative bioavailability of 60 mL rectal foam: 36%). Second, N-acetylation of rectal 5-ASA was lower in patients than in healthy subjects [area under the curve (AUC) ratio Ac-5-ASA/5-ASA: 1.6 +/- 0.5 vs. 2.3 +/- 0.4, mean +/- SD, P < 0.01]. High peak plasma concentrations of 5-ASA were correlated with high microscopic disease activity (r = 0.67, P < 0.05). CONCLUSIONS: Rectal delivery of 5-ASA results in low systemic drug exposure with potentially reduced toxicity in comparison with oral drug administration. Chronic inflammation of colorectal mucosa might be a relevant source of variability in pharmacokinetics of 5-ASA.

Systemic bioavailability of nasally applied chlorphenamine maleate (0.4% nasal spray) relative to tablets administered perorally.

AIM: This study investigated the bioavailability of single doses of 1.12 and 2.24 mg chlorphenamine maleate applied intranasally (0.4% nasal spray) relative to a single peroral dose of 8 mg chlorphenamine maleate (tablets). METHODS: Twenty-four (24) subjects were treated with single nasal doses of 1.12 mg and 2.24 mg chlorphenamine maleate (0.4% nasal spray) and two 4 mg chlorphenamine maleate tablets (Piriton) on 3 separate study days according to a 3-way cross-over design with a 7-day wash-out between periods. Blood was sampled before and at 0.25, 0.50, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 12, 16 and 24 hours after drug administration. Additional blood samples were obtained 36, 48 and 72 hours after peroral administration only. All subjects were included in the pharmacokinetic analysis. RESULTS: Nasally applied chlorphenamine maleate was readily absorbed, reaching peak plasma levels after 0.25 to 3.0 hours. The dose-normalized estimated mean Cmax values were 1.24, 1.43 and 1.21 ng/ml for the peroral tablet and the 1.12 mg and 2.24 mg nasal dose, respectively. The dose-normalized estimated mean AUC(0-infinity) values were 25.91, 26.44 and 25.56 ng x h/ml for the tablet and the 1.12 and 2.24 mg nasal dose, respectively. The estimated treatment ratios (nasal dose to tablet) of the dose-normalized values for the 1.12 mg nasal dose were 1.15 (900 CI: 1.0-1.32) and 1.02 (90% CI: 0.88-1.18) for Cmax and AUC(0-infinity), respectively, for the 2.24 mg nasal dose they were 0.98 (90% CI: 0.85-1.13) and 0.99 (90% CI: 0.85-1.13) for Cmax and AUC(0-infinity), respectively. The other pharmacokinetic characteristics (tmax, t(1/2), lambda(z), AUC(0-tf), MRTtot, CL/f and Vz/f) were comparable across all treatments. These data indicate that the disposition of chlorphenamine maleate was independent of the route and dose of administration. CONCLUSIONS: Chlorphenamine maleate is readily absorbed after nasal application using a 0.4% nasal spray. The nasal administration showed that the systemic bioavailability at the two dose levels used was comparable to that for the tablet. Maximum concentrations on the low dose, however, were higher and those on the high dose were comparable to those for the tablet. The nasal application of chlorphenamine maleate does not alter the overall systemic exposure compared to the oral route.

Pharmacokinetics of tilidine in terminal renal failure.

The aim of the present study was to investigate the pharmacokinetics of tilidine and its metabolites during the dialysis procedure and in the dialysis-free interval. Tilidine is a prodrug that is metabolized presystemically into the active metabolite nortilidine. Nortilidine is degraded thereafter to bisnortilidine and several polar metabolites. Nine patients with a creatinine clearance < 5 ml/min were treated in a crossover design with single oral doses of 1.5 mg/kg on the day of dialysis (dialysis performed from 3 to 6 hours after drug administration) and on a day in the dialysis-free interval. Blood samples were taken frequently and analyzed for tilidine, nortilidine, and bisnortilidine. Drug and metabolite concentrations were also measured in aliquots of dialysate collected during dialysis. Only negligible amounts of tilidine, nortilidine, and bisnortilidine (about 0.9% of the dose) were recovered from the dialysate. The pharmacokinetics of nortilidine and its inactive metabolite bisnortilidine was not affected by dialysis. The presystemic apparent clearance of the prodrug tilidine was decreased significantly during the dialysis-free interval. A significant decrease of the rate of elimination and an increase of the AUC of bisnortilidine were observed if these parameters were compared with data obtained from healthy volunteers. The plasma concentrations of nortilidine were comparable in patients and normal volunteers. Thus, a reduction of the dose of tilidine in patients with severely impaired kidney function seems not to be required. Tilidine and its metabolites cannot be removed from the body by dialysis.

Effect of lysine clonixinate on the pharmacokinetics and anticoagulant activity of phenprocoumon.

The effect of the non-steroidal anti-inflammatory drug lysine clonixinate ([2-(3-chloro-o-toluidino)nicotinic acid]-L-lysinate, CAS 55837-30-4) on the pharmacokinetics and anticoagulant activity of phenprocoumon (4-hydroxy-3-(1-phenylpropyl)-coumarin, CAS 435-97-2) was investigated in an open, randomised, two-fold, cross-over study in 12 healthy male volunteers. These subjects received a single dose of 18 mg phenprocoumon without or with concomitant treatment with lysine clonixinate (125 mg five times a day for 3 days before and 13 days after ingestion of a single dose of phenprocoumon). Pharmacokinetic parameters of phenprocoumon following oral administration were: CL/f: 0.779 +/- 0.157 ml/min, half-life of elimination: 147.2 +/- 19.9 h; free fraction in serum: 0.51 +/- 0.20%. These parameters were not significantly altered by concomitant treatment with lysine clonixinate. Prothrombin time increased from 13.3 +/- 1.3 s (at time 0) to 17.7 +/- 2.7 s following phenprocoumon and from 13.3 +/- 1.2 s to 18.0 +/- 2.2 s following combined administration. Prothrombin time returned to the pretreatment values 240 h after administration of phenprocoumon. The integrated effect (AUEC0-288 h) was identical following both treatments (4.303 +/- 461 and 4.303 +/- 312 s x h for phenprocoumon alone and phenprocoumon with lysine clonixinate, respectively). Thus, lysine clonixinate administered in therapeutic doses does not affect the pharmacokinetics and anticoagulant activity of phenproxoumon.

Comparison of the initial hemodynamic effects of immediate-release versus sustained-release isosorbide-5-mononitrate following single oral doses.

In this double-blind, randomized, placebo-controlled cross-over study, the authors investigated the initial time course of effects of isosorbide-5-mononitrate (IS-5-MN) on hemodynamic parameters in 15 healthy male volunteers after administering a single oral dose of either an immediate-release formulation (IS-5-MN 20 mg) or of a sustained-release formulation (IS-5-MN 50 mg). The latter formulation released 15 mg IS-5-MN immediately, while 35 mg of the dose was sustained release. The onset of effect on the a/b-ratio of the finger pulse curve (20 minutes after administration) and on heart rate following orthostatic challenge (30 minutes) was not different following ingestion of either the immediate-release or the sustained-release formulation. Only the systolic blood pressure following orthostatic challenge was affected earlier after ingestion of the immediate-release form of IS-5-MN (10 vs. 30 minutes). There was no statistically significant difference in the maximum effect on the measured hemodynamic parameters between the two formulations. There was no significant difference with respect to the effect per dose between both of the active treatments (i.e., IS-5-MN 20 mg immediate release and IS-5-MN 50 mg sustained release) within 6 hours after administration. The hemodynamic findings were consistent with the observed rates of the increase of plasma concentrations of IS-5-MN following both formulations. Thus, the administration of the sustained-release formulation of IS-5-MN 50 mg caused similar maximum effects when compared with an immediate-release formulation (20 mg). While the onset of effect of IS-5-MN on the a/b-ratio of the finger pulse curve and on heart rate following orthostasis was similar after administration of either the immediate- or the sustained-release formulation, the onset of effect of the sustained-release formulation on systolic blood pressure orthostasis was determined slightly later. However, the latter difference seems to be of minor clinical relevance.

Age-dependent differences in the anticoagulant effect of phenprocoumon in patients after heart valve surgery.

OBJECTIVE: An enhanced response to warfarin and an increased risk of major bleeding has been observed in older patients. The reason for this increase in sensitivity remains unknown. It could be due to pharmacodynamic reasons, pharmacokinetic reasons, or both. METHODS: We therefore followed an anticoagulant regimen with phenprocoumon in 19 older (76 years) and 19 younger patients (50 years) following heart valve replacement. INR values were determined frequently. At the 4th and around the 24th day after starting treatment with phenprocoumon, we also measured the total and unbound plasma concentration of phenprocoumon. RESULTS: The dose requirement to obtain the desired anticoagulant effect was significantly lower in the older patients than in the younger patients (26.3 vs. 37.3 micrograms.kg-1.day-1). The total plasma concentration (2.19 vs. 2.43 micrograms.ml-1), the percentage unbound drug in the plasma (0.61 vs. 0.64%) and the unbound plasma concentration (13.8 vs. 15.1 ng.ml-1) did not differ significantly between older and younger patients. The dose-adjusted INR (INR/dose) was higher in the older patients (110 vs. 67) but the INR adjusted for the unbound plasma concentration (INR/Cuss) which reflects the intrinsic sensitivity to the drug, was not significantly different (192 vs. 173). However, the older patients had an about 30% significantly lower metabolic clearance based on unbound drug (84 vs. 115 ml.kg-1.h-1). CONCLUSIONS: Older patients (> 70 years) require a dose approximately 30% lower than younger patients (< 160 years). Pharmacokinetic reasons (reduced metabolic clearance) are mainly responsible for the lower dose requirement of the older patients after heart valve surgery.

Short-term hemodynamic, anti-ischemic, and antianginal effects of pirsidomine, a new sydnonimine.

Pirsidomine is a new sydnonimine compound in clinical development. As a prodrug, it is transformed into a nitric oxide-releasing metabolite in vivo. In animal tests there were no signs of tolerance with repeated administration. The short-term effects of 10, 20, and 40 mg of the drug on pulmonary hemodynamics and ischemic parameters were examined at rest and during exercise in a double-blind, randomized, placebo-controlled study. The study included 48 patients with documented coronary artery disease and exercise-induced ST-segment depression. Compared with the baseline test, there was a reduction of diastolic pulmonary artery pressure with pirsidomine at rest (placebo: -0.4 +/- 0.5 mm Hg; 10 mg: - 1.5 +/- 2.4 mm Hg; 20 mg: - 1.4 +/- 1.1 mm Hg; 40 mg: - 2.3 +/- 1.3 mm Hg [p < 0.05 ]) and at the highest comparable workload (placebo: -2.8 +/- 1.9 mm Hg; 10 mg: -7.3 +/- 6.8 mm Hg; 20 mg: -8.4 +/- 7.9 mm Hg [p <0.05]; 40 mg: -13.8 +/- 7.1 mm Hg [p <0.05]). ST-segment depression decreased at the highest comparable workload (placebo: -0.33 +/- 0.49 mm; 10 mg: -1.33 +/- 1.37 mm [p <0.05]; 20 mg: -1.33 +/- 0.83 mm [p <0.05]; 40 mg: -1.96 +/- 0.86 mm [p <0.05]) and total exercise time increased (placebo: 15 +/- 48 s; 10 mg: 98 +/- 126 s; 20 mg: 165 +/- 251 s [p <0.05]; 40 mg: 155 +/- 174 s [p <0.05]). Of 40 patients who complained of angina pectoris symptoms in the baseline test, 15 became free of angina pectoris with pirsidomine. Compared with placebo, blood pressure, heart rate during exercise, and cardiac output during exercise showed no significant change. Plasma concentration response relations of the metabolite revealed concentrations that caused a half-maximum effect of 6 ng/ml, 13 ng/ml, 20 ng/ml, and 28 ng/ml in reduction of ST-segment depression, reduction of diastolic pulmonary artery pressure, relief of angina pectoris symptoms, and an increase in exercise duration, respectively. Thus, pirsidomine is an effective anti-ischemic and antianginal agent. A significant preload reduction was obtained with plasma metabolite concentrations lower than those necessary to achieve a satisfactory antianginal effect.

A pharmacodynamic and pharmacokinetic comparison of intravenous quinaprilat and oral quinapril.

Quinaprilat is the active metabolite of quinapril, an orally active angiotensin-converting enzyme (ACE) inhibitor. The dose-response and duration-of-effect after single intravenous doses of quinaprilat and placebo (part A) and after administration of oral quinapril solution and intravenous quinaprilat (part B) were assessed in a randomized, crossover study of two groups of 12 healthy volunteers. Pharmacodynamic effects of quinaprilat and oral quinapril were assessed by measurement of blood pressure changes after an infusion of angiotensin I (A-I) at a dose previously determined to produce an increase in diastolic blood pressure of 25 mmHg under standardized conditions (A-I pressor response). A clear dose-response relationship was demonstrated for quinaprilat in this pharmacodynamic model, with 0.5 mg as the lowest effective dose. Doses of 1.0 mg and higher partially suppressed A-I pressor response for at least 6 hours. Onset of action was observed within 15 minutes of intravenous administration of quinaprilat and was independent of dose, whereas peak effect and duration of action appeared to be dose related. Quinaprilat doses of 2.5 mg and 10 mg achieved approximately 50% and > 80% inhibition of the A-I pressor response, respectively. In part B, these doses of intravenous quinaprilat were compared with oral doses of quinapril previously found to produce 50% (2.5 mg) and 90% (10 mg) inhibition of the A-I pressor response. The magnitude of effect was similar after administration of 20 mg quinapril orally and 10 mg quinaprilat intravenously. Duration of action was longer, however, after administration of intravenous quinaprilat (10 mg) than after oral quinapril (20 mg), due to the higher maximum plasma concentration (Cmax) of quinaprilat. Mean area under the plasma concentration-time curve extrapolated to infinity (AUC0-infinity) of quinaprilat was similar after the 10-mg dose of intravenous quinaprilat and the 20-mg dose of oral quinapril. Based on the concentrations of quinaprilat observed in this study, the absolute bioavailability of quinapril was approximately 50%; intravenous quinaprilat should therefore produce a pharmacodynamic response similar to that obtained with oral quinapril at approximately half the dose.

Digital pulse plethysmography as a non-invasive method for predicting drug-induced changes in left ventricular preload.

OBJECTIVE: Changes in the contour of the plethysmographically recorded digital pulse curve after nitrate ingestion are well known, but it has not been fully established whether these changes reflect nitrate action on left ventricular (LV) preload or afterload. Therefore, we compared the pulse wave contour after administration of equieffective doses of nitroglycerin and nifedipine. METHODS: In 20 patients with coronary artery disease we measured aortic blood pressure curve in the aorta ascendens, digital volume pulse curve with a photoelectric pulse pickup, Riva Rocci blood pressure and heart rate after administration of either 0.8 mg nitroglycerin or 10 mg nifedipine. RESULTS: Peak plasma concentrations of nitroglycerin and nifedipine were achieved 5 min and 20 min after ingestion of the drugs. Systolic aortic blood pressure decreased after both nitroglycerin and nifedipine to 19.4 mmHg, but diastolic blood pressure decreased only after nifedipine by 10.5 mmHg (P < 0.05). Riva Rocci blood pressures showed a similar time course. Heart rate increased from 67.4 to 70.9 beats.min-1 after nitroglycerin and from 58.9 to 69.4 beats.min-1 after nifedipine. The calculated a/b ratio of the aortic pressure curve increased after both medications (nitroglycerin, from 1.66 to 1.99; nifedipine, from 1.66 to 1.93) and its time course mimicked that of the systolic blood pressure. The a/b ratio of the digital pulse curve did not change after nifedipine, but showed a pronounced rise after nitroglycerin from 1.29 to 1.84. With regard to pharmacological actions, nitroglycerin causes a reduction in LV preload and afterload, whereas nifedipine has only LV-afterload-reducing activity. CONCLUSION: We conclude, that the reduction in afterload did not cause the typical changes in wave contour of the peripheral pulse curve which occur with organic nitrates. Most likely changes in the a/b ratio reflect changes in LV preload.

Prolongation of the PQ interval as a measure of therapeutic inequivalence between two formulations of diltiazem.

We studied the use of atrioventricular (AV) conduction time to assess the therapeutic equivalence of two diltiazem formulations in 20 volunteers in a double-blind, cross-over trial. ECG recording was carried out before and at several intervals after drug administration, and prolongation of the PQ interval (delta PQ) was taken as a pharmacodynamic response. In addition, diltiazem plasma concentrations were determined in 8 subjects. The effect of diltiazem increased proportionally with the plasma concentration and could be detected up to 10 h after administration. The area under the effect-time curve (AUEC(0-10)), the peak effect (Emax), and the effect mean residence time (MRTE) showed significant differences. In contrast to the pharmacodynamics, the pharmacokinetic profiles of diltiazem do not vary to the same extent. We conclude that the formulations are therapeutically different. Furthermore, at the administered dose, delta PQ appears to be a sensitive measure for assessing the electrophysiological properties of diltiazem.

Low-dose almitrine bismesylate in the treatment of hypoxemia due to chronic obstructive pulmonary disease.

STUDY OBJECTIVE: Assessment of acute and chronic effects of low-dose almitrine bismesylate (AB) in stable chronic obstructive pulmonary disease (COPD). STUDY DESIGN: Oral administration of AB, 25 mg three times a day, for 6 months in all patients. Pulmonary function, blood gases, and peripheral nerve conduction velocity were measured at baseline and after long-term administration of AB. In addition, oral pharmacokinetics and effects on pulmonary circulation at rest were studied in half of the patients. Intravenous pharmacokinetics were measured after a single intravenous dose of 60 mg of AB 3 months before the start of oral AB treatment in the other seven patients. SETTING: Outpatient clinic of a community hospital in a coal mining district in southwest Germany. PATIENTS: Fourteen patients with clinically stable COPD and hypoxemia. RESULTS: Acute effects of AB were as follows: a significant increase in arterial oxygen tension (PaO2) from 61 +/- 7 mm Hg to 74 +/- 8 mm Hg (p < 0.001), a decrease in arterial carbon dioxide tension (PaCO2) from 41 +/- 8 mm Hg to 38 +/- 7 mm Hg (p < 0.01), a rise of pH from 7.45 +/- 0.04 to 7.48 +/- 0.04 (p < 0.01), and a transient increase in mean pulmonary artery pressure from 26 +/- 7 to 29 +/- 6 mm Hg (not significant). After long-term treatment, once tissues were saturated with almitrine, improvement in gas exchange persisted with a PaO2 of 70 +/- 10 mm Hg (p < 0.001) and a PaCO2 of 39 +/- 6 mm Hg (not significant) without elevation of pH (7.45 +/- 0.04) or of pulmonary artery pressure (26 +/- 8 mm Hg). The terminal half-life of AB was 56 +/- 45 days after a single intravenous administration, and 55 +/- 16 days after long-term oral dosing. None of the patients developed clinically manifest peripheral neuropathy. Impaired asymptomatic peripheral motor nerve function was prevalent in 4 (29 percent) of the patients and remained unchanged during long-term AB administration. However, asymptomatic impairment of motor nerve conduction velocity developed in two patients with inadequate high AB plasma levels despite low-dose therapy. Both patients were known to have additional conditions predisposing for neuropathy. CONCLUSIONS: Low-dose AB therapy, 75 mg daily, resulted in sustained elevation of arterial oxygen tension in hypoxemic patients with COPD. Although pulmonary artery pressure increased transiently after the first dose, it remained unchanged with long-term treatment despite persistent improvement of pulmonary gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of the anti-ischemic activity of nebivolol in comparison with atenolol.

The anti-ischemic effect of 5 mg nebivolol o.i.d., a newly developed beta 1-selective adrenoceptor blocking drug with vasodilating properties, was compared with that of atenolol (100 mg o.i.d.) following a treatment period of 6 days. The study was performed in 24 patients with documented coronary artery disease and stable angina pectoris according to a double-blind randomized study, designed using conventional symptom-limited exercise testing. Exercise testing 3 h after the first dose showed a more marked ST-segment reduction by atenolol than by nebivolol (59% vs. 18%). ST-segment depression measured 24 h after administration of the penultimate dose was statistically significantly reduced by nebivolol (from 0.19 +/- 0.07 to 0.13 +/- 0.07 mV; P = 0.0059) but not by atenolol (from 0.17 +/- 0.06 to 0.14 +/- 0.10 mV; P = 0.0703). Approximately 3 h after the last dose, the reduction was comparable (45% and 38% by nebivolol and atenolol, respectively). Exercise duration, exercise time necessary to produce ST-segment depression by 0.1 mV and exercise time to the onset of angina were also prolonged following administration of both drugs. Thus, at steady-state single daily doses of 100 mg atenolol and 5 mg nebivolol were about equieffective when measured at time of maximal effect (i.e. 3 h after drug administration). However, duration of action with respect to the ST-segment depression seems to be slightly longer for nebivolol.