Significantly longer time to deterioration of quality of life due to CANKADO PRO-React eHealth support in HR+ HER2- metastatic breast cancer patients receiving palbociclib and endocrine therapy: primary outcome analysis of the multicenter randomized AGO-B WSG PreCycle trial.

BACKGROUND: The multicenter, randomized, phase IV, intergroup AGO-B WSG PreCycle trial (NCT03220178) evaluated the impact of CANKADO-based electronic patient-reported outcome (ePRO) assessment on quality of life (QoL) in hormone receptor-positive, human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer (MBC) patients receiving palbociclib and an aromatase inhibitor or palbociclib + fulvestrant. CANKADO PRO-React, a European Union-registered medical device, is an interactive autonomous application reacting to patient self-reported observations. PATIENTS AND METHODS: Between 2017 and 2021, 499 patients (median age 59 years) from 71 centers were randomized (2 : 1, stratified by therapy line) between an active version of CANKADO PRO-React (CANKADO-active arm) and a version with limited functionality (CANKADO-inform arm). A total of 412 patients (271 CANKADO-active; 141 CANKADO-inform) were available for analysis of the primary endpoint, time to deterioration (TTD) of QoL [10-point drop on the Functional Assessment of Cancer Therapy-General (FACT-G) score], using an Aalen-Johansen estimator for cumulative incidence function of TTD DQoL (QoL deterioration) with 95% pointwise confidence intervals (CIs). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and DQoL. RESULTS: In all patients [intention-to-treat (ITT)-ePRO], cumulative incidence of DQoL was significantly more favorable (lower) in the CANKADO-active arm (hazard ratio 0.698, 95% CI 0.506-0.963). Among first-line patients (n = 295), the corresponding hazard ratio was 0.716 (0.484-1.060; P = 0.09), and in second-line patients (n = 117) it was 0.661 (0.374-1.168; P = 0.2). Absolute patient numbers declined in later visits; FACT-G completion rates were 80% and higher until about visit 30. Mean FACT-G scores showed a steady decline from baseline and an offset in favor of CANKADO-active. No significant differences in clinical outcome were observed between arms: median PFS (ITT population) was 21.4 (95% CI 19.4-23.7) (CANKADO-active) and 18.7 (15.1-23.5) months (CANKADO-inform); median OS was not reached (CANKADO-active) and 42.6 months (CANKADO-inform). CONCLUSIONS: PreCycle is the first multicenter randomized eHealth trial demonstrating a significant benefit for MBC patients receiving oral tumor therapy when using an interactive autonomous patient empowerment application.

Comparison of prognostic and predictive impact of genomic or central grade and immunohistochemical subtypes or IHC4 in HR+/HER2- early breast cancer: WSG-AGO EC-Doc Trial.

INTRODUCTION: Potential prognostic and predictive markers in early, intermediate-risk breast cancer (BC) include histological grade, Ki-67, genomic signatures, e.g. genomic grade index (GGI), and intrinsic subtypes. Their prognostic/predictive impact in hormone receptor (HR: ER and/or PR) positive/HER2- BC is controversial. WSG-AGO EC-Doc demonstrated superior event-free survival (EFS) in patients with 1-3 positive lymph node receiving epirubicin/cyclophosphamide-docetaxel (EC-Doc) versus 5-fluoruracil/epirubicin/cyclophosphamide (FEC). METHODS: In a representative trial subset, we quantify concordance among factors used for clinical chemotherapy indication. We investigate the impact of central histology (n = 772), immunohistochemistry for intrinsic subtyping and IHC4, and dichotomous (GG) or continuous (GGI) genomic grade (n = 472) on patient outcome and benefit from taxane chemotherapy, focusing on HR+/HER2- patients (n = 459). RESULTS: Concordance of local grade (LG) with central (CG) or genomic grade was modest. In HR+/HER2- patients, low (GG-1: 16%), equivocal (GG-EQ: 17%), and high (GG-3: 67%) GG were associated with respective 5-year EFS of 100%, 93%, and 85%. GGI was prognostic for EFS within all LG subgroups and within CG3, whereas IHC4 was prognostic only in CG3 tumors.In unselected and HR+/HER2- patients, CG3 and luminal-A-like subtype entered the multivariate EFS model, but not IHC4 or GG. In the whole population, continuous GGI entered the model [hazard ratio (H.R.) of 75th versus 25th = 2.79; P = 0.01], displacing luminal-A-like subtype; within HR+/HER2- (H.R. = 5.36; P < 0.001), GGI was the only remaining prognostic factor.In multivariate interaction analysis (including central and genomic grade), luminal-B-like subtype [HR+ and (Ki-67 ≥20% or HER2+)] was predictive for benefit of EC-Doc versus FEC in unselected but not in HR+/HER2- patients. CONCLUSION: In the WSG-AGO EC-Doc trial for intermediate-risk BC, CG, intrinsic subtype (by IHC), and GG provide prognostic information. Continuous GGI (but not IHC4) adds prognostic information even when IHC subtype and CG are available. Finally, the high interobserver variability for histological grade and the still missing validation of Ki-67 preclude indicating or omitting adjuvant chemotherapy based on these single factors alone. TRIAL REGISTRATION: The WSG-AGO/EC-Doc is registered at ClinicalTrials.gov, NCT02115204.

The West German Study Group Breast Cancer Intrinsic Subtype study: a prospective multicenter decision impact study utilizing the Prosigna assay for adjuvant treatment decision-making in estrogen-receptor-positive, HER2-negative early-stage breast cancer.

PURPOSE: The West German Study Group (WSG) Breast Cancer Intrinsic Subtype (BCIST) study was designed to assess the influence of Prosigna gene signature assay results on physicians' adjuvant treatment recommendations by determining the extent of change in pre-test treatment recommendations following assay results. Secondary objectives were to assess the influence of Prosigna results on physicians' confidence in their therapeutic recommendations and on patients' decisional conflict status, anxiety levels, and functional status. METHODS: This prospective, observational, decision impact study enrolled consecutive postmenopausal patients with estrogen-receptor (ER)-positive, HER2-negative, lymph-node-negative early-stage breast cancer in 11 centers in Germany. Physicians based their pre-test adjuvant treatment recommendations on standard clinico-pathological parameters. Tumor specimens were assayed using the Prosigna test in a WSG central pathology laboratory following manufacturer's guidelines. An independent pathology laboratory performed subsequent Prosigna assays on tumor sections to assess assay result concordance with the central laboratory. Physicians completed treatment confidence questionnaires prior to and after receiving Prosigna test results. Patients completed standardized questionnaires on decisional conflict, anxiety, and health status both before and after Prosigna testing. RESULTS: The present study population consisted predominantly of low-to-intermediate risk patients (N = 198). Prosigna had 29.3% discordance in intrinsic subtyping with local immunohistochemistry test results. After Prosigna test results, a change in the adjuvant therapy recommendation occurred in 36 (18.2%) patients; 22 (11.1%) patients switched from no chemotherapy to chemotherapy. After Prosigna test results, physicians expressed increased confidence in their prognostic assessment in 87.9% of patients, and increased confidence in their treatment recommendation in 89.4%. Patients reported improved anxiety and emotional/functional well-being after receiving Prosigna test results. CONCLUSIONS: Use of the Prosigna assay led to a change in 18.2% of adjuvant treatment decisions. Prosigna testing was associated with increased patient and physician confidence in treatment decisions, and with decreased patient anxiety and improved well-being. Any comparison of the therapeutic decision-making impacts of different genomic assays must account for potential confounding factors.

Final analysis of the prospective WSG-AGO EC-Doc versus FEC phase III trial in intermediate-risk (pN1) early breast cancer: efficacy and predictive value of Ki67 expression.

BACKGROUND: Taxane-based adjuvant chemotherapy is standard in node-positive (N+) early breast cancer (BC). The magnitude of benefit in intermediate-risk N+ early BC is still unclear. WSG-AGO epiribicine and cyclophosphamide (EC)-Doc is a large trial evaluating modern taxane-based chemotherapy in patients with 1-3 positive lymph nodes (LNs) only. PATIENTS AND METHODS: A total of 2011 BC patients (18-65 years, pN1) were entered into a randomized phase III trial comparing 4 × E90C600 q3w followed by 4 × docetaxel 100 q3w (n = 1008) with the current standard: 6 × F500E100C500 q3w (n = 828) or C600M40F600 d1, 8× q4w (n = 175). Primary end point was event-free survival (EFS); secondary end points were overall survival (OS), toxicity, translational research, and quality of life. Central tumor bank samples were evaluable in a representative collective (n = 772; 40%). Ki-67 was assessed centrally in hormone receptor-positive disease as a surrogate marker for the distinction of luminal A/B-like tumors. RESULTS: Baseline characteristics were well balanced between study arms in both main study and central tumor bank subset. At 59-month median follow-up, superior efficacy of EC-Doc [versus FEC (a combination of 5-fluorouracil, epirubicin, and cyclophosphamide)] was seen in EFS and OS: 5-year EFS: 89.8% versus 87.3% (P = 0.038); 5-year OS: 94.5% versus 92.8% (P = 0.034); both tests one-tailed. EC-Doc caused more toxicity. In hormone receptor-positive (HR)+ disease, only high-Ki-67 tumors (≥ 20%) derived significant benefit from taxane-based therapy: hazard ratio = 0.39 (95% CI 0.18-0.82) for EC-Doc versus FEC (test for interaction; P = 0.01). CONCLUSION: EC-Doc significantly improved EFS and OS versus FEC in intermediate-risk BC (1-3 LNs) within all subgroups as defined by local pathology. In HR+ disease, patients with luminal A-like tumors may be potentially over-treated by taxane-based chemotherapy. CLINICAL TRIAL NUMBER: ClinicalTrials.gov, NCT02115204.

Final results from the prospective phase III WSG-ARA trial: impact of adjuvant darbepoetin alfa on event-free survival in early breast cancer.

BACKGROUND: WSG-ARA plus trial evaluated the effect of adjuvant darbepoetin alfa (DA) on outcome in node positive primary breast cancer (BC). PATIENTS AND METHODS: One thousand two hundred thirty-four patients were randomized to chemotherapy either with DA (DA+; n = 615) or without DA (DA-; n = 619). DA (500 µg q3w) was started at hemoglobin (Hb) levels <13.0 g/dl (<12 g/dl after DA label amendment) and stopped at Hb levels ≥14.0 g/dl (12 g/dl after label amendment). Primary efficacy end point was event-free survival (EFS); secondary end points were toxicity, quality of life (QoL) and overall survival (OS). RESULTS: Venous thrombosis (DA+: 3.0%, DA-: 1.0%; P = 0.013) was significantly higher for DA+, but not pulmonary embolism (0.3% in both arms). Median Hb levels were stable in DA+ (12.6 g/dl) and decreased in DA- (11.7 g/dl). Hb levels >15 g/dl were reported in 0.8% of cycles. QoL parameters did not significantly differ between arms. At 39 months, DA had no significant impact on EFS (DA+: 89.3%, DA-: 87.5%; Plog-rank = 0.55) or OS (DA+: 95.5%, DA-: 95.4%; Plog-rank = 0.77). CONCLUSIONS: DA treatment did not impact EFS or OS in routine adjuvant BC treatment.

Prognostic impact of proteolytic factors (urokinase-type plasminogen activator, plasminogen activator inhibitor 1, and cathepsins B, D, and L) in primary breast cancer reflects effects of adjuvant systemic therapy.

PURPOSE: Prognostic and predictive impact of five proteolytic factors associated with tumor invasion and metastasis in primary breast cancer were evaluated after long-term follow-up. EXPERIMENTAL DESIGN: Antigen levels of urokinase-type plasminogen activator, plasminogen activator inhibitor-1 (PAI-1), Cathepsins B, D, and L were determined using immunochemical assays in primary tumor tissue of 276 patients. RESULTS: During follow-up (median 109 months), 119 (43%) patients relapsed, and 117 (42%) died. In the whole collective, lymph node status (P < 0.001; RR 3.8), Cathepsin L (P < 0.001; RR 2.6), and PAI-1 (P = 0.027; RR 1.7) were the only independent significant factors in multivariate analysis for disease-free survival (DFS). For overall survival (OS), lymph node status (P < 0.001; RR 2.9), Cathepsin L (P = 0.017; RR 1.9), PAI-1 (P = 0.01; RR 1.9), and grading (P = 0.026; RR 1.7) were significant. In the node-negative subgroup, PAI-1 was the only significant factor for DFS (P = 0.004; RR 3.7) and the strongest factor (P = 0.004; RR 3.7) for OS next to grading (P = 0.017; RR 3.1). In node-positive patients, Cathepsin L was the only significant factor for both DFS (P < 0.001; RR 3.2) and OS (P = 0.003; RR 2.5). For all proteolytic factors but Cathepsin L, the univariate prognostic impact on DFS was substantial in patients without adjuvant systemic therapy but was diminished if adjuvant therapy had been administered. Cathepsin L maintained its strong prognostic impact on DFS even in patients with adjuvant endocrine therapy (P = 0.01; RR 2.8). CONCLUSIONS: The observed effect of adjuvant systemic therapy on their prognostic strength suggests that the assessed proteolytic factors supply predictive information on therapy response.

Clinical relevance of the plasminogen activator inhibitor type 1--a multifaceted proteolytic factor.

The plasminogen activator inhibitor type-1 (PAI-1) is a multifaceted proteolytic factor. It not only functions as an inhibitor of the protease uPA (urokinase-type plasminogen activator), but also plays an important role in signal transduction, cell adherence, and cell migration. Thus--an apparent paradox considering its name--although it inhibits uPA during blood coagulation, it actually promotes invasion and metastasis. In the early 1990s, clinical evidence associated elevated PAI-1 levels in tumor tissue with poor clinical outcome in primary breast cancer. These clinical data have since been supported by experimental evidence that the concerted action of uPA, its cell surface receptor uPA-R, and PAI-1 facilitates invasion and metastasis. The strong prognostic impact of PAI-1 in primary breast cancer has been validated by international research groups assessing fresh tumor tissue extracts by ELISA. There is clinical evidence that high-risk patients with elevated PAI-1 in their tumor benefit from adjuvant systemic therapy. uPA also has a strong prognostic impact in primary breast cancer. In node-negative breast cancer, risk-group selection for adjuvant systemic therapy based on tumor levels of both PAI-1 and uPA is close to routine clinical use. Also in other malignancies such as ovarian, esophageal, gastric, colorectal or hepatocellular cancer, elevated PAI-1 is associated with tumor aggressiveness and poor patient outcome. This abundant clinical evidence implicating PAI-1 as a key factor for tumor invasion and metastasis renders it a promising target for tumor therapy. Novel therapeutic approaches targeting the PAI-1/uPA interaction are already in pre-clinical testing.

Evidence of a source of HIV type 1 within the central nervous system by ultraintensive sampling of cerebrospinal fluid and plasma.

Defining the source of HIV-1 RNA in cerebrospinal fluid (CSF) will facilitate studies of treatment efficacy in the brain. Four antiretroviral drug-naive adults underwent two 48-hr ultraintensive CSF sampling procedures, once at baseline and again beginning on day 4 after initiating three-drug therapy with stavudine, lamivudine, and nelfinavir. At baseline, constant CSF HIV-1 RNA concentrations were maintained by daily entry of at least 10(4) to 10(6) HIV-1 RNA copies into CSF. Change from baseline to day 5 ranged from -0.38 to -1.18 log(10) HIV-1 RNA copies/ml in CSF, and from -0.80 to -1.33 log(10) HIV-1 RNA copies/ml in plasma, with no correlation between CSF and plasma changes. There was no evidence of genotypic or phenotypic viral resistance in either CSF or plasma. With regard to pharmacokinetics, mean CSF-to-plasma area-under-the-curve (AUC) ratios were 38.9% for stavudine and 15.3% for lamivudine. Nelfinavir and its active M8 metabolite could not be accurately quantified in CSF, although plasma M8 peak level and AUC(0-8hr) correlated with CSF HIV-1 RNA decline. This study supports the utility of ultraintensive CSF sampling for studying HIV-1 pathogenesis and therapy in the CNS, and provides strong evidence that HIV-1 RNA in CSF arises, at least in part, from a source other than plasma.

Invasion marker PAI-1 remains a strong prognostic factor after long-term follow-up both for primary breast cancer and following first relapse.

In 1991, our group was the first to report the prognostic strength of plasminogen activator inhibitor type 1 (PAI-1) in primary breast cancer. The prognostic impact of invasion markers PAI-1 and urokinase-type plasminogen activator (uPA) on disease-free survival (DFS) and overall survival (OS) in breast cancer has since been independently confirmed. We now report on the prognostic impact of PAI-1 and uPA after long-term median follow-up of 77 months for our cohort (n = 316). Levels of uPA, PAI-1, and cathepsin D were determined in tumor tissue extracts by immunoenzymatic methods. S-phase fraction (SPF) was measured flowcytometrically in paraffin sections. Using log-rank statistics, optimized cutoffs were found for PAI-1 (14 ng/mg), uPA (3 ng/mg), cathepsin D (41 pmol/mg), and SPF (6%). In all patients, various factors (PAI-1, uPA, nodal status, SPF, cathepsin D, grading, tumor size, hormone receptor status) showed significant univariate impact on DFS. In Cox analysis, only nodal status (p < 0.001, RR: 3.1) and PAI-1 (p < 0.001, RR: 2.7) remained significant. In node-negative patients (n = 147), PAI-1, uPA, and SPF had significant univariate impact on DFS, whereas in Cox analysis, only PAI-1 was significant. PAI-1 was also significant for DFS within subgroups defined by established factors. In CART analysis, uPA enhanced the prognostic value of PAT-1 and nodal status for determination of a very-low-risk subgroup. For OS, only lymph node status and PAI-1 were significant in multivariate analysis. PAI-1 levels in the primary tumor were also a significant prognostic marker for survival after first relapse in both univariate and multivariate analysis.

Effect of high-dose oral ganciclovir on didanosine disposition in human immunodeficiency virus (HIV)-positive patients.

This study was designed to investigate the interaction between high-dose oral ganciclovir (6,000 mg/day) and didanosine at steady state in patients who were seropositive for human immunodeficiency virus (HIV) and cytomegalovirus (CMV) infection. The study was conducted as an open-label, randomized, three-period crossover study. Patients received (in random order) multiple oral doses of didanosine 200 mg every 12 hours alone, ganciclovir 2,000 mg every 8 hours alone, and ganciclovir 2,000 mg every 8 hours in combination with didanosine 200 mg every 12 hours. Blood and urine samples for determinations of drug concentrations were obtained on day 3 of each dose regimen. When ganciclovir was administered either before or 2 hours after didanosine, the mean increases in maximum concentration (Cmax), area under the concentration-time curve (AUC0-12), and percent excreted in urine of didanosine were 58.6% and 87.3%, 87.3% and 124%, and 100% and 153%, respectively. There were no statistically significant effects of didanosine on the steady-state pharmacokinetics of ganciclovir in the presence of didanosine, irrespective of sequence of administration. There were no significant changes in renal clearance of didanosine, suggesting that the mechanism for the interaction does not involve competition for active renal tubular secretion. The mechanism responsible for increased didanosine concentrations and percent excreted in urine during concurrent ganciclovir therapy may be a result of increased bioavailability of didanosine. However, the mechanism appears to be saturated at oral ganciclovir doses of 3 g/day.

Clinical pharmacology of intravenous enoximone: pharmacodynamics and pharmacokinetics in patients with heart failure.

Twenty-one patients with heart failure (New York Heart Association [NYHA] class II to IV) received a 24-hour infusion of enoximone followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I to III received an 0.5 mg/kg bolus, followed by a maintenance infusion of 2.5, 5.0, or 10.0 micrograms/kg/min. Group IV patients received a maintenance infusion of 5.0 micrograms/kg/min without a loading dose. Serial assessment of hemodynamics, plasma levels of enoximone and enoximone sulfoxide, and ventricular ectopy were performed. Enoximone produced a clinically significant increase in cardiac index, and a decrease in mean pulmonary artery wedge pressure and systemic vascular resistance in all groups. Enoximone mildly increased heart rate, and had a minimal effect on mean arterial pressure. There was no statistically significant change in ventricular ectopy during the infusion. Significant hemodynamic improvement was noted at even the lowest infusion rate, and did not increase in linear fashion at higher infusion rates. In patients who did not receive an initial loading bolus of 0.5 mg/kg, the increase in cardiac index was delayed by approximately 1 hour. Plasma concentrations of both enoximone and its major metabolite continued to rise throughout the 24-hour infusion in group III (10.0 micrograms/kg/min), rather than reaching steady state as predicted by the terminal exponential half-lives of these compounds. This is suggestive of nonlinear pharmacokinetics and indicates a potential for excessive accumulation of enoximone and its metabolite during prolonged infusion. These findings may have important implications in guiding the intravenous administration of enoximone.(ABSTRACT TRUNCATED AT 250 WORDS)

Disposition kinetics of orally administered enoximone in patients with moderate to severe heart failure.

Enoximone is a phosphodiesterase inhibitor, which has been studied extensively for use in the management of patients with moderate-to-severe heart failure. The authors have studied the absorption and disposition kinetics of enoximone and its primary metabolite, enoximone sulfoxide, after both single oral doses of enoximone and at steady-state after short-term chronic oral therapy. A total of ten patients (two female, eight male) with moderate-to-severe heart failure (NYHA class II-IV) were enrolled into the study after giving written informed consent. The plasma levels of enoximone sulfoxide were greater than those of enoximone at all sampling times. The peak enoximone sulfoxide plasma concentrations ranged from 3.5 to 17.3 times the peak enoximone plasma levels for individual patients. The average steady-state plasma concentrations for enoximone were 115 +/- 40 ng/mL and 190 +/- 78 ng/mL for 50 mg every 8 hours and 100 mg every 8 hours dosage regimens, respectively. The absorption and disposition kinetics of enoximone were found to be significantly variable between patients. The authors also evaluated the relationship between dose administered and steady-state plasma levels as well as the relationship between the observed and predicted steady-state plasma levels. The authors found a linear relationship between the dose that was administered and the accrued plasma levels, as well as a good correlation between the predicted and observed steady-state levels. Although these data confirm previous reports that the sulfide metabolite of enoximone accumulates extensively in the plasma during oral therapy, reaching levels much higher than those of enoximone, these data do not support previous suggestions that the disposition of enoximone is nonlinear.

Opioids potentiate contractile response of rabbit myocardium to the beta adrenergic agonist isoproterenol.

Opioid agonists and antagonists have both been reported to augment myocardial contractile force in vitro. We reported that the strong opioid agonists morphine and levorphanol, the weak agonist dextrorphan (an optical isomer of levorphanol), and the opioid antagonist naloxone all potentiate the stimulatory effects of the beta-adrenergic agonist isoproterenol on isometric tension generated by isolated rabbit right ventricular myocardium. The EC50 of isoproterenol was found to be shifted leftward 2.7-, 5.4-, 5.3-, and 3.4-fold respectively (p less than 0.05 when compared with controls), when the opioids were added at a final concentration of 1 x 10(5) M. Lower concentrations of opioid or antagonist did not potentiate the effects of isoproterenol. The rank order potency for potentiation thus differs markedly from that of opioid analgesia. The observed potentiation is therefore not agonist specific and not stereospecific. Furthermore, the drugs alone at a range of concentration from 10(-8) to 10(-5) M had no effect on isometric tension generated. We conclude that opioid agonists and antagonists potentiate the response of ventricular myocardium to the effects of beta-adrenergic stimulation by a novel mechanism unrelated to the binding of these drugs to opioid receptors. The paradoxical augmentation of myocardial contractility by either class of agent under a variety of clinical and experimental conditions is thus explained by these findings. Either agent may interact with myocardial tissue to cause increased sensitivity to stimulation by circulating catecholamines.

Pharmacodynamics of enoximone during intravenous infusion.

Twenty-one patients with heart failure (NYHA class II-IV) received a 24-hour infusion of enoximone, followed by a 12-hour washout period. Patients were randomly assigned to one of four treatment groups. Groups I-III received a 0.5 mg/kg bolus, followed by a maintenance infusion of 2.5, 5.0 or 10.0 micrograms/kg/minute. Group IV patients received a maintenance infusion of 5.0 micrograms/kg/minute without the bolus. Serial assessments of haemodynamics, plasma levels of enoximone and enoximone sulphoxide, and ventricular ectopy were performed. Enoximone produced a significant increase in cardiac index (28.1-46.7%) and a decrease in mean pulmonary artery wedge pressure (6.4-35.7%) and systemic vascular resistance (34.7-78.9%). Enoximone had minimal effect on heart rate and blood pressure. In patients who did not receive an initial bolus of 0.5 mg/kg, haemodynamic changes were delayed by approximately 1 hour. Significant haemodynamic improvement was noted at even the lowest infusion rate and did not increase in linear fashion at higher infusion rates. During infusion of enoximone at 10.0 micrograms/kg/minute, both enoximone and its sulphoxide accumulated non-linearly and did not achieve a steady state. No significant adverse effects were noted in these patients. Enoximone infusion at rates greater than 5.0 micrograms/kg/minute may confer minimal additional haemodynamic benefit, while resulting in significant accumulation of enoximone and enoximone sulphoxide. Ventricular ectopy did not increase significantly in most patients.

Rate-related electrophysiologic effects of long-term administration of amiodarone on canine ventricular myocardium in vivo.

The electrophysiologic effects of amiodarone were examined in 13 dogs that received 30 g amiodarone orally during 3 weeks and compared with 13 control dogs that did not receive amiodarone. Longitudinal and transverse epicardial conduction velocities were estimated with a square array of 64 closely spaced electrodes and a computer-assisted acquisition and analysis system. Amiodarone caused a rate-dependent decrease in conduction velocity with a slightly greater effect in the longitudinal direction of propagation. Rate-related depression of conduction velocity developed rapidly after abrupt shortening of the pacing cycle length; 67% of the change occurred between the first two beats of the rapid train, and little change occurred after the 10th beat. Recovery from use-dependent depression of conduction velocity was exponential with a mean time constant of 447 +/- 172 msec in the longitudinal direction and 452 +/- 265 msec in the transverse direction. Repolarization intervals, defined as the interval between the activation time and the repolarization time in the unipolar electrograms, correlated highly with refractory period determinations in the absence and presence of amiodarone at each cycle length tested. The increase in repolarization intervals and refractory periods resulting from amiodarone treatment did not vary with cycle length. Amiodarone treatment also resulted in a significant rate-related reduction in systolic blood pressure. The systolic blood pressure in the group that received amiodarone decreased by a mean of 50 +/- 23% between steady-state pacing cycle lengths of 1,000 and 200 msec, whereas the corresponding decrease in the control group was 21 +/- 32% (p less than 0.05). Plasma and myocardial amiodarone and desethylamiodarone levels were comparable to those observed clinically. We conclude that long-term amiodarone administration causes rate-dependent reductions in conduction velocity and blood pressure and causes rate-independent increases in repolarization intervals.

Update: cardiac antiarrhythmic drugs.

The last ten years have been a period of extensive research and development of new agents for the treatment of cardiac rhythm abnormalities. Several new subclass Ic agents have been developed, and more recently the class III agents have become the focus of attention. These new agents are all remarkable for their potency and potential for producing side effects. While none of these agents offers the perfect cure for the treatment or prevention of cardiac arrhythmias, they all offer advantages and options that are valuable for clinical management of patients.

In vivo evaluation of the effects of altered cyclosporine metabolism on its immunosuppressive potency.

The dose-response and plasma concentration-response relationships of cyclosporine after both inducing and inhibiting its metabolism were studied in a mouse heart transplant model. The metabolism of cyclosporine was altered by coadministering phenobarbital and cimetidine as metabolism inducing and inhibiting agents, respectively. We found that phenobarbital depressed the immunosuppressive potency of cyclosporine by enhancing its metabolism resulting in lower cyclosporine blood levels. On the other hand, when cimetidine was administered concurrently with cyclosporine, the immunosuppressive effect was enhanced due to inhibition of the metabolism of cyclosporine which produced higher cyclosporine blood levels. When graft survival was evaluated relative to blood cyclosporine concentrations, however, it appeared that cimetidine had a direct negative effect on the survival of transplanted organs independent and contrary to its effect on the accumulation of cyclosporine. The immunosuppression produced by cyclosporine at these elevated blood levels was less than expected. The accrued data support the conclusion that cyclosporine and not its metabolites are primarily responsible for its immunosuppressive activity in the mouse.

Effect of albumin on the electrophysiologic stability of isolated perfused rabbit hearts.

The electrophysiologic stability of isolated perfused rabbit hearts was evaluated over a period of 5 h. Hearts perfused with protein-free buffer deteriorated over time, with significant shortening of the ventricular effective refractory period (ERP) and development of ventricular fibrillation. When serum albumin (6.01 x 10(-4) mM) was added to the perfusate, hearts were more stable, the ventricular ERPs remained relatively constant throughout the 5-h perfusion period, and hearts did not fibrillate. When a fatty acid-free protein source was used, the hearts demonstrated similar stability to those perfused with protein containing fatty acids. Despite marked changes in the refractory periods of hearts perfused with protein-free buffer, the QRS interval did not change over time, indicating that this is a very insensitive parameter for monitoring the electrophysiologic stability of isolated perfused hearts. In studies utilizing isolated hearts to evaluate antiarrhythmic drug effects, it is preferable to use a protein-containing buffer.

Pharmacodynamics of procainamide in patients with ventricular tachyarrhythmias.

The onset and offset of the electropharmacologic effect of procainamide was studied in nine patients with ventricular arrhythmias. Procainamide was given at a constant infusion rate of 0.27 +/- 0.05 mg/kg/min for 50 to 60 minutes to an average total dose of 15.5 +/- 4.4 mg/kg. The QRS interval (used as an index of electropharmacologic effect) at a paced cycle length of 500 ms, and the plasma procainamide concentration were measured simultaneously every 5 minutes during infusion and at frequent intervals for up to 4 hours during a washout period. The average peak plasma concentration was 15.8 +/- 9.6 micrograms/ml and the average maximum QRS interval prolongation was 23.9 +/- 6.8% from baseline. The temporal and static plasma concentration-effect relationships were evaluated by pharmacodynamic modeling and linear regression. For six patients, there was a minimal (less than 2 minutes) delay in the plasma concentration-effect relationship, and the data fit a linear relationship with an average slope of 3.2 +/- 1.1 msec/microgram/ml. For the other three patients, there was a significant delay (3, 10, and 18 minutes respectively) in the plasma concentration-effect relationship. In most patients, the electropharmacologic effect of procainamide is rapid and proportional to plasma concentration; but in a minority of patients, significant delay occurs and could influence the results and interpretation of electropharmacologic studies.