Use of the energy waveform electrocardiogram to detect subclinical left ventricular dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

Recent guidelines propose N-terminal pro-B-type natriuretic peptide (NT-proBNP) for recognition of asymptomatic left ventricular (LV) dysfunction (Stage B Heart Failure, SBHF) in type 2 diabetes mellitus (T2DM). Wavelet Transform based signal-processing transforms electrocardiogram (ECG) waveforms into an energy distribution waveform (ew)ECG, providing frequency and energy features that machine learning can use as additional inputs to improve the identification of SBHF. Accordingly, we sought whether machine learning model based on ewECG features was superior to NT-proBNP, as well as a conventional screening tool-the Atherosclerosis Risk in Communities (ARIC) HF risk score, in SBHF screening among patients with T2DM.

METHODS

Participants in two clinical trials of SBHF (defined as diastolic dysfunction [DD], reduced global longitudinal strain [GLS ≤ 18%] or LV hypertrophy [LVH]) in T2DM underwent 12-lead ECG with additional ewECG feature and echocardiography. Supervised machine learning was adopted to identify the optimal combination of ewECG extracted features for SBHF screening in 178 participants in one trial and tested in 97 participants in the other trial. The accuracy of the ewECG model in SBHF screening was compared with NT-proBNP and ARIC HF.

RESULTS

SBHF was identified in 128 (72%) participants in the training dataset (median 72 years, 41% female) and 64 (66%) in the validation dataset (median 70 years, 43% female). Fifteen ewECG features showed an area under the curve (AUC) of 0.81 (95% CI 0.787-0.794) in identifying SBHF, significantly better than both NT-proBNP (AUC 0.56, 95% CI 0.44-0.68, p < 0.001) and ARIC HF (AUC 0.67, 95%CI 0.56-0.79, p = 0.002). ewECG features were also led to robust models screening for DD (AUC 0.74, 95% CI 0.73-0.74), reduced GLS (AUC 0.76, 95% CI 0.73-0.74) and LVH (AUC 0.90, 95% CI 0.88-0.89).

CONCLUSIONS

Machine learning based modelling using additional ewECG extracted features are superior to NT-proBNP and ARIC HF in SBHF screening among patients with T2DM, providing an alternative HF screening strategy for asymptomatic patients and potentially act as a guidance tool to determine those who required echocardiogram to confirm diagnosis. Trial registration LEAVE-DM, ACTRN 12619001393145 and Vic-ELF, ACTRN 12617000116325.

Association of biomarkers and risk scores with subclinical left ventricular dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

Subclinical LV dysfunction (LVD) identifies heart failure (HF) risk in type 2 diabetes mellitus (T2DM). We sought the extent to which clinical scores (ARIC-HF, WATCH-DM), natriuretic peptides (NTpBNP) and troponin (hs-TnT) were associated with subclinical LV dysfunction (LVD). These associations could inform the ability of these tests to identify which patients should undergo echocardiography.

METHODS

Participants with T2DM were prospectively recruited from three community-based populations. ARIC-HF risk at 4 years and WATCH-DM scores were calculated from clinical data. NTpBNP and hs-TnT were measured using an electro-chemiluminescence assay. All underwent a comprehensive echocardiogram. We calculated the sensitivity and specificity of clinical scores and biomarkers to identify abnormal global longitudinal strain (GLS ≥ -16%)), diastolic function (E/e' ≥ 14 or e' < 8 cm/s), left atrial volume index (LAV > 34 ml/m²) and LV hypertrophy (LV mass index > 88 g/m² (F) > 102 g/m²(M)).

RESULTS

Of 804 participants (median age 69 years [inter-quartile range (IQR) 65-73], 36% female), clinical scores suggested significant HF risk (median ARIC-HF 8% [IQR 4-12]; WATCH-DM 10 points [IQR 8-12]), and the median NTpBNP was 50 pg/mL [IQR 25-101] and hs-TnT 9.6 pg/mL [IQR 6.8-13.6]. Abnormal GLS was present in 126 (17%), elevated E/e' in 114 (15%), impaired e' in 629 (78%), increased LAV in 351 (44%) and LV hypertrophy in 113 (14%). After adjustments for age, body-mass index, and renal function, each standard deviation increase in NTpBNP was associated with a GLS increase of 0.32 (p < 0.001) and hs-TnT increase by 0.26 (p < 0.001). Similar trends were observed with ARIC-HF (standardised β = 0.22, p < 0.001) and WATCH-DM (standardised β = 0.22, p < 0.001) in univariable analyses. However, none of the risk assessment tools provided satisfactory discrimination for abnormal GLS (AUC 63%), diastolic indices (e' AUC 54-61%) or LV mass (AUC 59-67%). At a sensitivity of 90%, there was an unacceptably low (< 50%) specificity.

CONCLUSION

Although risk assessment based on clinical scores or biomarkers would be desirable to stratify HF risk in people with T2DM, they show a weak relationship with subclinical LVD.

Implementation of more sensitive cardiac troponin T assay in a state-wide health service

AIMS

Explore the impact of deploying high-sensitivity (hs) cardiac troponin T (cTnT) assay across a state-wide health service.

METHODS AND RESULTS

Presentations to emergency departments of six tertiary hospitals between January 2008 and August 2019 were included; standard cTnT assay was superseded by hs-cTnT in June 2011 without changing the reference range (≥30 ng/L reported as elevated), despite cTnT level of 30 ng/L being equivalent to ∼44 ng/L with hs-cTnT. Clinical outcomes were captured using state-wide linked health records. Interrupted time series analyses were used adjusted for seasonality and multiple co-morbidities using propensity score matching allowing for correlation within hospitals. In total, 614,847 presentations had ≥1 troponin measurement. Clinical ordering of troponin decreased throughout the study with no increase in elevated measurements amongst those tested with hs-cTnT. Small but statistically significant changes in index myocardial infarction (MI) diagnosis (-0.36%/year, 95%CI [confidence interval]:-0.48, -0.24,p < 0.001) and invasive coronary angiography (0.12%/year,95%CI:0, 0.24,p = 0.02) were seen, with no impact on death/MI at 30 days or 3-year survival in episodes of care (EOCs) with elevated cTnT after hs-cTnT implementation. Length of stay (LOS) was shorter among those with an elevated hs-cTnT (-4.44 h/year, 95%CI:-5.27, -3.60, p < 0.001). Non-elevated cTnT EOCs demonstrated shorter total LOS and improved 3-year survival (adjusted hazard ratio:0.90, 95%CI:0.83, 0.97,p = 0.008) although death/MI at 30 days was unchanged using hs-cTnT.

CONCLUSION

Widespread implementation of hs-cTnT without altering clinical thresholds reported to clinicians provided significantly shorter LOS without a clinically significant impact on clinical outcomes. A safer cohort with non-elevated cTnT was identified by hs-cTnT compared to the standard cTnT assay.

Use of novel non-invasive techniques and biomarkers to guide outpatient management of fluid overload and reduce hospital readmission: systematic review and meta-analysis

Aims

Fluid congestion is a leading cause of hospital admission, readmission, and mortality in heart failure (HF). We performed a systematic review and meta‐analysis to determine the effectiveness of an advanced fluid management programme (AFMP). The AFMP was defined as an intervention providing tailored diuretic therapy guided by intravascular volume assessment, in hospitalized patients or after discharge. The AFMP group was compared with patients who received standard care treatment. The aim of this systematic review and meta‐analysis was to determine the effectiveness of an AFMP in improving patient outcomes.

Methods and results

A systematic review of randomized controlled trials, case–control studies, and crossover studies using the terms ‘heart failure’, ‘fluid management’, and ‘readmission’ was conducted in PubMed, CINAHL, and Scopus up until November 2020. Studies reporting the association of an AFMP on readmission and/or mortality were included in our meta‐analyses. Risk of bias was assessed in non‐randomized studies using the Newcastle–Ottawa Scale. From 232 retrieved studies, 12 were included in the data synthesis. The 6040 patients in the included studies had a mean age of 72 ± 4 years and mean left ventricular ejection fraction of 39 ± 8%, there were slightly more men (n = 3022) than women, and the follow‐up period was a mean of 4.8 ± 3.1 months. Readmission data were available in 5362 patients; of these, 1629 were readmitted. Mortality data were available in 5787 patients; of these, 584 died. HF patients who had an AFMP in hospital and/or after discharge had lower odds of all‐cause readmission (odds ratio—OR 0.64 [95% confidence interval—CI 0.44, 0.92], P = 0.02) with moderate heterogeneity (I² = 46.5) and lower odds of all‐cause mortality (OR 0.82 [95% CI 0.69, 0.98], P = 0.03) with low heterogeneity (I² = 0). The use of an AFMP was equally effective in reducing readmission and mortality regardless of age and follow‐up duration. Effective pre‐discharge diuresis was associated with significantly lower readmission odds (OR 0.43 [95% CI 0.26, 0.71], P = 0.001) compared with a fluid management plan as part of post‐discharge follow‐up.

Conclusions

An effective AFMP is associated with improving readmission and mortality in HF. Our results encourage attainment of optimal volume status at discharge and prescription of optimal diuretic dose. Ongoing support to maintain euvolaemia and effective collaboration between healthcare teams, along with effective patient education and engagement, may help to reduce adverse outcomes in HF patients.

Role of microvascular dysfunction in left ventricular dysfunction in type 2 diabetes mellitus

BACKGROUND

Although microvascular disease (mVD) has been linked to poor cardiovascular outcomes in diabetes mellitus, the contribution of mVD to diabetic cardiomyopathy (DC) is unexplored. We investigated whether LV systolic and diastolic dysfunction is associated with mVD in T2DM.

METHODS

We recruited 32 asymptomatic patients with T2DM (age 71 ± 4 years, 31% females) from a community-based population. All underwent a comprehensive echocardiogram at baseline including assessment of global longitudinal strain (GLS) and diastolic function. Adenosine stress perfusion on cardiac magnetic resonance imaging (CMR) was performed in all patients. Coronary sinus flow (CSF) was measured offline at rest and peak stress with coronary flow reserve (CFR) calculated as the ratio of global stress and rest CSF.

RESULTS

Resting CSF was reduced in 15 (47%) compared to 4 (13%) with adenosine-stress (p = 0.023). Overall, CFR was observed to be reduced in the cohort (2.38 [IQR 2.20]). Abnormal CFR was not associated with diabetes duration of ≥10 years or poor glycaemic control. CFR was not associated with abnormal GLS (OR 1.04 [95% CI 0.49, 2.20], p = 0.93). However, a modest negative correlation was observed with e' and CFR (r = -0.49, p = 0.004).

CONCLUSION

This pilot study did not show correlation between subclinical systolic dysfunction and a novel MRI biomarker of microvascular disease. However, there was a weak correlation with myocardial relaxation. Confirmation of these findings in larger studies is indicated.

Evolution of Myocardial Dysfunction in Asymptomatic Patients at Risk of Heart Failure

OBJECTIVES

The determinants of changes in systolic and diastolic parameters in patients age >65 years, at risk of heart failure (HF), and with and without asymptomatic type 2 diabetes mellitus (T2DM) was assessed by echocardiography. The association between metformin and myocardial function was also assessed.

BACKGROUND

The increasing prevalence of T2DM will likely further fuel the epidemic of HF. Understanding the development or progression of left ventricular (LV) dysfunction may inform effective measures for HF prevention.

METHODS

A total of 982 patients with at least one HF risk factor (hypertension, obesity, or T2DM) were recruited from 2 community-based populations and divided into 2 groups: T2DM (n = 431, age 71 ± 4 years) and non-T2DM (n = 551, age 71 ± 5 years). Associations of metformin therapy were evaluated in the T2DM group. All underwent a comprehensive echocardiogram, including global longitudinal strain (GLS) and diastolic function (transmitral flow [E], annular velocity [e']) at baseline and follow-up (median 19 months [interquartile range: 17 to 26 months]). Comparisons were facilitated by propensity matching.

RESULTS

A reduction in GLS was observed in the T2DM group (baseline -17.8 ± 2.6% vs. follow-up -17.4 ± 2.8%; p = 0.003), but not in the non-T2DM group (-18.7 ± 2.7% vs. -18.6 ± 3.0%; p = 0.41). Estimated LV filling pressures increased in both the T2DM group (p = 0.001) and the non-T2DM group (p = 0.04). Metformin-treated patients with T2DM did not increase estimated LV filling pressure (E/e' baseline 8.9 ± 2.7 vs. follow-up 9.1 ± 2.7; p = 0.485) or change e' (7.6 ± 1.5 cm/s vs. 7.6 ± 1.8 cm/s; p = 0.88). After propensity matching, metformin was associated with a smaller change in e' (β = 0.58 [95% CI: 0.13 to 1.03]; p = 0.013) and E/e' (β = -0.96 [95% CI: -1.66 to -0.26]; p = 0.007) but was not associated with a change in GLS (p = 0.46).

CONCLUSIONS

Over 2 years, there is a worsening of GLS and LV filling pressures in asymptomatic diabetic patients with HF risk factors. Metformin use is associated with less deterioration of LV filling pressures and myocardial relaxation but had no association with systolic function.

Metformin treatment in heart failure with preserved ejection fraction: a systematic review and meta-regression analysis

Background

Observational series suggest a mortality benefit from metformin in the heart failure (HF) population. However, the benefit of metformin in HF with preserved ejection fraction (HFpEF) has yet to be explored. We performed a systematic review and meta-analysis to identify whether variation in EF impacts mortality outcomes in HF patients treated with metformin.

Methods

MEDLINE and EMBASE were searched up to October 2019. Observational studies and randomised trials reporting mortality in HF patients and the proportion of patients with an EF > 50% at baseline were included. Other baseline variables were used to assess for heterogeneity in treatment outcomes between groups. Regression models were used to determine the interaction between metformin and subgroups on mortality.

Results

Four studies reported the proportion of patients with a preserved EF and were analysed. Metformin reduced mortality in both preserved or reduced EF after adjustment with HF therapies such as angiotensin converting enzyme inhibitors (ACEi) and beta-blockers (β = − 0.2 [95% CI − 0.3 to − 0.1], p = 0.02). Significantly greater protective effects were seen with EF > 50% (p = 0.003). Metformin treatment with insulin, ACEi and beta-blocker therapy were also shown to have a reduction in mortality (insulin p = 0.002; ACEi p < 0.001; beta-blocker p = 0.017), whereas female gender was associated with worse outcomes (p < 0.001).

Conclusions

Metformin treatment is associated with a reduction in mortality in patients with HFpEF.

Invasive management of acute coronary syndrome: Interaction with competing risks

BACKGROUND

The aim of this study was to characterise the interaction between ACS- and non-ACS-risk on the benefits of invasive management in patients presenting with acute coronary syndrome (ACS).

METHODS

Consecutive patients admitted to a tertiary hospital's Cardiac Care Unit in the months of July-December, 2003-2011 with troponin elevation (>30 ng/L) were included. "ACS-specific-risk" was estimated using the GRACE score and "non-ACS-risk" was estimated using the Charlson-Comorbidity-Index (CCI). Inverse-probability-of-treatment weighting was used to adjust for baseline differences between patients who did or did not receive invasive management. A multivariable flexible parametric model was used to characterise the time-varying hazard.

RESULTS

In total, 3057 patients were included with a median follow-up of 9.0 years. Based on CCI, 1783 patients were classified as 'low-non-ACS risk' (CCI ≤ 1; invasive management 81%; 12-month mortality 5%), 820 as 'medium-non-ACS risk' (CCI 2-3; invasive management 68%; 12-month mortality 13%), and 468 as 'high-non-ACS risk' (CCI ≥ 4; invasive management 47%; 12-month mortality 29%). After adjustment, invasive management was associated with a significant reduction in one-year overall-mortality in the 'low-risk' and 'medium-risk' groups (HR = 0.38, 95%CI:0.26-0.56; HR = 0.46, 95%CI:0.32-0.67); but not in the 'high-risk' group (HR = 1.02, 95%CI:0.67-1.56). The absolute benefit of invasive management was greatest with higher baseline ACS-risk, with a non-linear interaction between ACS- and non-ACS-risk.

CONCLUSIONS

There is a complex interaction between ACS- and non-ACS-risk on the benefit of invasive management. These results highlight the need to develop robust methods to objectively quantify risk attributable to non-ACS comorbidities in order to make informed decisions regarding the use of invasive management in individuals with numerous comorbidities.

Rational clinical evaluation of suspected acute coronary syndromes: The value of more information

OBJECTIVE

Many meta-analyses have provided synthesised likelihood ratio data to aid clinical decision-making. However, much less has been published on how to safely combine clinical information in practice. We aimed to explore the benefits and risks of pooling clinical information during the ED assessment of suspected acute coronary syndrome.

METHODS

Clinical information on 1776 patients was collected within a randomised trial conducted across five South Australian EDs between July 2011 and March 2013. Bayes theorem was used to calculate patient-specific post-test probabilities using age- and gender-specific pre-test probabilities and likelihood ratios corresponding to the presence or absence of 18 clinical factors. Model performance was assessed as the presence of adverse cardiac outcomes among patients theoretically discharged at a post-test probability less than 1%.

RESULTS

Bayes theorem-based models containing high-sensitivity troponin T (hs-troponin) outperformed models excluding hs-troponin, as well as models utilising TIMI and GRACE scores. In models containing hs-troponin, a plateau in improving discharge safety was observed after the inclusion of four clinical factors. Models with fewer clinical factors better approximated the true event rate, tended to be safer and resulted in a smaller standard deviation in post-test probability estimates.

CONCLUSIONS

We showed that there is a definable point where additional information becomes uninformative and may actually lead to less certainty. This evidence supports the concept that clinical decision-making in the assessment of suspected acute coronary syndrome should be focused on obtaining the least amount of information that provides the highest benefit for informing the decisions of admission or discharge.

Has invasive management for acute coronary syndromes become more 'risk-appropriate': pooled results of five Australian registries

Background

Despite being recommended in acute coronary syndrome (ACS) guidelines, the use of invasive management within specific risk groups continues to be debated. This study examines the change in the use of invasive management in ACS by patient risk and the associated change in mortality within Australia over the last 17 years.

Methods

Pooled cohorts derived from five ACS registries (ACACIA, CONCORDANCE, GRACE, Snapshot-ACS, and Predict) spanned from 1999 to 2015. After excluding patients without a final diagnosis of ACS (n = 4460), enrolled outside Australia (n = 1477) and without an enrolling year (n = 4), 15 912 patients were analysed. Data was stratified across three time periods (1999-2004, 2005-2009, and 2010-2015) using clinical risk characteristics (age, ACS diagnosis, biomarker elevation, and GRACE score) to monitor change in practice.

Results

Over the 17-year period, the use of invasive management increased (4073/6863 (59.3%) cases [1999-2009] vs. 6670/8706 (76.6%) cases [2010-2015]). Invasive management accounted for improvements in mortality in intermediate- and high-risk groups (intermediate risk: 14% (95% CI 1-66%) [1999-2009] vs. 49% (95% CI 2-59%) [2010-2015]; high risk: 24% (95% CI 6-42%) [1999-2009] vs. 48% (95% CI 19-76%) [2010-2015]). Patients receiving no angiography compared with interventional management had worse outcomes (1999-2004 1.55 HR [95% CI 1.36-1.80], P < 0.0001 vs. 2010-2015 1.90 HR [95% CI 1.45-2.51], P < 0.0001).

Conclusions

Clinical practice in ACS has changed over the last 17 years with positive outcomes seen with invasive management among high-risk patients. Unfortunately, a considerable burden of mortality remains in patients managed medically, highlighting a need for more focused strategies that improve care and outcomes in this group.

Induction of tumor necrosis factor α and interleukin-1β in subcutaneously implanted chamber by lipopolysaccharide

Lipopolysaccharide (LPS) is the major component of the outermost membrane of Gram-negative bacteria and is considered to be one of the major virulence factors of these bacteria. While the effect of systemic injection of LPS is well characterized, the characterization of cytokine secretion in response to local injection of LPS is lacking. The present study was designed to determine the local production of tumor necrosis factor α (TNFα) and interleukin-1β (IL-1β) over a 4 day period following injection of LPS into subcutaneous implanted chambers in mice. Mice were challenged by a single or repeated injection of Salmonella typhosa LPS into the chambers. Chamber fluids were aspirated at different time intervals and were used for assessment of leukocyte and cytokine levels. A single injection of LPS was found to induce cell influx into the chamber which peaked after 4 h. TNFα and IL-1β levels increased rapidly, reaching their maximum levels within 4 h. After 24 h, TNFα levels declined markedly and were undetectable at 48 and 96 h. TNFα mRNA levels in the sedimented cells followed a similar pattern. In contrast, IL-1β showed a more gradual decrease with levels significantly different from baseline still being present 96 h post-LPS challenge. Four consecutive daily injections of LPS into the chambers resulted in undetectable levels of TNFα in the chamber fluid, while significant levels of IL-1β were detected. These levels were significantly higher than the levels of IL-1β in the chamber fluid 96 h after a single injection and approximately 60% of the levels measured 24 h after a single intra-chamber injection of LPS. The results emphasize the difference between single and repeated exposure to LPS in vivo, and suggest a role for TNFα in the initial phase of the local inflammatory response and for IL-1β in the later phase.

The effect of mild and moderate renal impairment on the pharmacokinetics of pridopidine, a new drug for Huntington's disease

Aim

Pridopidine, a new oral drug for treatment of patients with motor symptoms associated with Huntington's Disease (HD) is currently under development. In steady‐state conditions, pridopidine elimination is mediated primarily through renal excretion. This study evaluated single dose and steady‐state pharmacokinetics (PK) of a daily dose of pridopidine in subjects with mild and moderate renal impairment and matched healthy subjects.

Methods

Subjects with mild renal impairment (n = 12), moderate impairment (n = 12), or their matched healthy controls (n = 25) participated in this study. Subjects received a single dose of pridopidine (45 mg) on day 1 and a multiple dose cycle of 45 mg once daily on days 5–18. Blood and urine samples were collected on days 1 and 18 for PK analysis.

Results

Mild renal impairment did not affect the PK of pridopidine whilst an increase in exposure was seen in subjects with moderate renal impairment. Subjects with moderate impairment showed reduced plasma clearance (by 44%) and had 68% higher AUC (90% CI 1.22, 2.30) and 26% higher C_max (90% CI 1.02, 1.56) values than those with normal renal function at steady‐state. Pridopidine was safe and well tolerated in healthy subjects and in subjects with mild and moderate renal impairment.

Conclusions

Mild renal impairment has no impact on exposure to pridopidine while moderately impaired renal function resulted in higher pridopidine concentrations.

Pharmacokinetics, pharmacodynamics and safety of empagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in subjects with renal impairment

AIMS

Empagliflozin is a selective sodium glucose cotransporter 2 (SGLT2) inhibitor that inhibits renal glucose reabsorption and is being investigated for the treatment of type 2 diabetes mellitus (T2DM).

METHODS

In this open-label study, the effect of renal impairment on the pharmacokinetics, pharmacodynamics and safety of a 50 mg dose of empagliflozin was investigated in 40 subjects, grouped according to estimated glomerular filtration rate (eGFR).

RESULTS

Maximum empagliflozin plasma concentrations were similar in subjects with normal renal function and renal impairment. Area under the empagliflozin concentration-time curve (AUC0 -∞ ) values increased by approximately 18, 20, 66 and 48% in subjects with mild, moderate, severe renal impairment and renal failure/end stage renal disease (ESRD), respectively, in comparison to healthy subjects. This was attributed to decreased renal clearance (CLR ). Urinary glucose excretion (UGE) decreased with increasing renal impairment and correlated with decreased eGFR and CLR . Empagliflozin was well tolerated, with no increase in adverse events associated with renal impairment.

CONCLUSIONS

Renal insufficiency resulted in decreased CLR of empagliflozin, moderately increased systemic exposure and decreased UGE. A single 50 mg dose of empagliflozin was well tolerated in subjects with normal renal function and any degree of renal impairment. The pharmacokinetic results of this study indicate that no dose adjustment of empagliflozin is required in patients with renal impairment.

Multiple-dose tolerability, pharmacokinetics, and pharmacodynamics of ponesimod, an S1P1 receptor modulator: favorable impact of dose up-titration

This multiple-ascending-dose study investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of ponesimod, an S1P1 receptor modulator and a potential new treatment for autoimmune diseases. In part A, 10 healthy male and female subjects received once daily oral doses of ponesimod (5, 10, or 20 mg) or placebo for 7 days. Sinus bradycardia and, in some subjects, atrioventricular (AV) block occurred primarily on the first day of dosing, as desensitization developed to ponesimod-induced heart rate (HR) reduction and PR-prolongation. This elicited the design of an up-titration schedule in 17 subjects to a dose of 40 mg in part B. The up-titration regimen reduced HR and PQ/PR effects. Reported adverse events were mainly related to the cardiac and respiratory systems. Respiratory effects increased with higher doses. Ponesimod multiple-dose pharmacokinetics were slightly more than dose-proportional and characterized by a time to maximum concentration and an elimination half-life varying from 2.5 to 4.0 hours and 30.9 to 33.5 hours, respectively, and an accumulation of about 2.3-fold. Ponesimod caused a dose-dependent sustained decrease in total lymphocyte count, reversible within 7 days of discontinuation. A pharmacokinetic-pharmacodynamic model enabled comparing day 1 and steady-state conditions. These results warrant further investigation of ponesimod in patients.

Effect of renal impairment on the pharmacokinetics of the dipeptidyl peptidase-4 inhibitor linagliptin(*)

AIM

This study assessed the influence of various degrees of renal impairment on the exposure of linagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor with a primarily non-renal route of excretion, in subjects with type 2 diabetes mellitus (T2DM).

METHODS

Linagliptin pharmacokinetics was studied under single-dose and steady-state conditions in subjects with mild, moderate and severe renal impairment (with and without T2DM) and end-stage renal disease and compared with the pharmacokinetics in subjects with normal renal function (with and without T2DM).

RESULTS

Renal excretion of unchanged linagliptin was <7% in all groups. Under single-dose conditions, the degree of renal impairment did not affect mean plasma linagliptin concentration-time profiles. These showed a similar decline and almost identical plasma concentrations 24 h postdosing in subjects with mild, moderate or severe renal impairment and in subjects with T2DM with and without renal impairment. Although there was a tendency towards slightly higher (20-60%) exposure in renally impaired subjects (with and without T2DM) compared with subjects with normal renal function, the steady-state AUC and C(max) values showed a large overlap and were not affected by the degree of renal impairment. The accumulation half-life of linagliptin ranged from 14-15 h in subjects with normal renal function to 18 h in severe renal impairment. Only a weak correlation (r(2) = 0.18) was seen between creatinine clearance and steady-state exposure.

CONCLUSIONS

Renal impairment has only a minor effect on linagliptin pharmacokinetics. Consequently, there will be no need for adjusting the linagliptin dose in renally impaired patients with T2DM.

IL-10 gene transfer attenuates P. gingivalis-induced inflammation

IL-10 is an anti-inflammatory cytokine secreted by stimulated Th2 lymphocytes that can down-regulate inflammatory responses to bacterial challenge. We hypothesized that local delivery of IL-10 using gene-transfer will down-regulate inflammatory responses. We examined the effect of IL-10 plasmid injection on the local cytokine response. Two weeks after the implantation of chambers, either IL-10 plasmid or vector was injected into the mice. Four days later, they were challenged with an intra-chamber injection of P. gingivalis. The intra-chamber levels of IL-10, IFNgamma, TNFalpha, and IL-1beta were evaluated after 2 and 24 hrs. The results showed that local IL-10 gene delivery elevated the levels of IL-10 at both time periods. It attenuated the levels of IFNgamma (656 +/- 154 to 218 +/- 144 pg/mL) and TNFalpha (23 +/- 2.0 to 12.5 +/- 2.9 ng/mL) at 2 hrs, and of IL-1beta (21.5 +/- 5.7 to 12.4 +/- 3.0 ng/mL) at 24 hrs. The results suggest the possibility of modulating the local inflammatory response to P. gingivalis by direct IL-10 gene transfer.

Pharmacokinetic interaction between bosentan and the oral contraceptives norethisterone and ethinyl estradiol

OBJECTIVE

Bosentan has been shown in vitro and in vivo to induce the cytochrome P450 enzymes CYP2C9 and CYP3A4. The present study was conducted to investigate the effect of bosentan on the pharmacokinetics of a combined oral contraceptive.

SUBJECTS AND METHODS

In a randomized, 2-way crossover study, 20 healthy female subjects received Treatments A and B. Treatment A consisted of a single dose of OrthoNovum containing 1 mg norethisterone (norethindrone) and 35 microg ethinyl estradiol. Treatment B consisted of bosentan, 125 mg b.i.d. for 7 days plus concomitant norethisterone and ethinyl estradiol on Day 7. Plasma concentrations of norethisterone and ethinyl estradiol were measured on days of oral contraceptive administration.

RESULTS

In the absence of bosentan, the pharmacokinetics of norethisterone and ethinyl estradiol were characterized by Cmax and AUC0-infinity values (95% CI) of 9.8 (8.1, 11.9) ng/ml and 72.9 (57.0, 93.1) ng x h/ml, and 53.0 (47.0, 59.9) pg/ml and 758 (655, 878) pg x h/ml, respectively. Concomitant bosentan did not affect the Cmax but significantly decreased the AUC of norethisterone and ethinyl estradiol by 13.7% (-23.5, -2.6) and 31.0% (-40.5,-20.2), respectively. The maximum decrease in AUC of norethisterone and ethinyl estradiol in an individual subject was 56% and 66%, respectively.

CONCLUSIONS

Bosentan decreases the AUC of norethisterone and ethinyl estradiol in healthy female subjects. In patients treated with bosentan, reduced efficacy of hormonal contraceptives should be considered.

Pharmacokinetics of moxifloxacin, a novel 8-methoxy-quinolone, in patients with renal dysfunction

AIMS

To evaluate the influence of impaired renal function on the plasma and urinary pharmacokinetics of moxifloxacin, a novel 8-methoxy-quinolone antibacterial drug.

METHODS

Twenty male and 12 female subjects (8 healthy subjects, 24 patients with impaired renal function), 18--75 years of age were investigated in parallel fashion with four groups stratified according to creatinine clearance (CLCR; n=8 for each group). The pharmacokinetics of moxifloxacin and the metabolites M1 (sulphonate metabolite) and M2 (glucuronide) in plasma and urine were determined repeatedly up to 96 h after single oral doses of 400 mg. Patients were monitored intensively with regard to clinical and laboratory safety and tolerability.

RESULTS

Single doses of 400 mg moxifloxacin were safe and well tolerated. The urinary excretion of moxifloxacin (Aeur, P: 0.0002) and renal clearance (CLR, P<0.0001) were reduced with decreasing CLCR, mean Cmax was slightly reduced (Cmax-ratio 85.0%, 90% CI 67.9, 106.4% severe renal impairment vs healthy subjects) but the AUC was unchanged even in severe renal impairment (AUC-ratio 101.3%, 90% CI 79.7, 128.6%). The mean AUC of the N-sulphonate M1 was slightly increased (by about 53% for the most severe disease) by impaired renal function, but there was no significant correlation between individual AUC and CLCR, whilst Aeur and CLR were significantly correlated with CLCR. In contrast, for the acylglucuronide M2, Aeur (P: 0.0026), CLR (P<0.0001) and AUC (P: 0.0011) were directly correlated with CLCR.

CONCLUSIONS

Renal dysfunction had little effect on the plasma pharmacokinetics of either moxifloxacin or metabolite M1, although their renal clearance and urinary excretion were reduced. In contrast renal dysfunction did result in changes in the plasma pharmacokinetics of metabolite M2, causing greater and longer exposure. However the extent of these changes is unlikely to be of clinical relevance.

Experimental stress suppresses recruitment of macrophages but enhanced their P. gingivalis LPS-stimulated secretion of nitric oxide

BACKGROUND

Epidemiological studies have suggested that stress can alter the onset and progression of periodontal disease. However, the mechanisms involved are not clear. The present study was designed to examine whether the functional response of mouse macrophages stimulated by Porphyromonas gingivalis lipopolysaccharide (LPS) is affected by experimental stress, and to investigate the role of corticosterone (CS) in the stress-related effects.

METHODS

Two models of stress were used: emotional (isolation) and physical (cold). We measured thioglycollate-induced macrophage recruitment in vivo, and LPS-induced nitric oxide (NO) secretion by the macrophages in vitro. Two groups of mice were exposed to the stress conditions: isolation or cold. A third group was injected daily with CS, and a fourth group was used as a control (no stress). After 3 days of stress conditions, thioglycollate was injected into the peritoneal cavity. Four days later, peritoneal macrophages were isolated, counted, and cultured. The secretion of NO by the cultured cells was evaluated with and without P. gingivalis LPS stimulation.

RESULTS

The number of cells in the peritoneal lavage of stressed mice was significantly reduced in comparison to macrophages isolated from non-stressed animals. The number of macrophages from CS-treated mice did not differ from controls. NO secretion from unstimulated macrophages did not differ between the stressed and control groups. Stimulation of the macrophages with P. gingivalis LPS significantly enhanced NO secretion by macrophages from the control and stressed animals, but not by the CS-treated group. NO levels secreted by P. gingivalis-stimulated cells from the two stressed groups were significantly higher than the levels secreted by controls, and the isolation group released significantly higher levels than the cold group. Stimulation of the macrophages with P. gingivalis LPS and interferon (IFN)-gamma resulted in enhanced NO secretion in the 4 groups compared to LPS alone, with no significant differences between the groups.

CONCLUSIONS

The results suggest that experimental stress modulates the response of macrophages to inflammatory stimulants, and that CS is not the sole mediator involved. The presence of IFN-gamma in the culture may mask the functional differences induced by stress. The stress-induced upregulation of NO secretion might be involved in the accelerated periodontal destruction in stressed subjects.

Repeat bacterial challenge in a subcutaneous chamber model results in augmented tumour necrosis factor-alpha and interferon-gamma response, and suppression of interleukin-10

The present study compared the effect of a single or a repeat challenge with the Gram-negative pathogen Porphyromonas gingivalis on the local inflammatory response within subcutaneous chamber model in mice. Subcutaneous chambers were implanted 2 weeks prior to the final challenge. The repeat-challenge (REP) group received two intrachamber bacterial injections 14 days apart, while the single-injection group (SIN) received only a single bacterial challenge. Injection of saline was used as the control. The cellular contents of the chamber exudates were used for differential cell counts, and the supernatants were analysed for tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and interleukin (IL)-10 levels. Immunoglobulin G1 (IgG1) and IgG2a levels to P. gingivalis in the exudates were also determined. The results showed that the leucocyte counts increased significantly post-challenge, and the REP group showed the highest number of lymphocytes and neutrophils. Both P. gingivalis-challenged groups exhibited significant increase in TNF-alpha and IL-10 levels at day 1 post-challenge. TNF-alpha levels in the chamber exudate were threefold higher in the REP group compared with the SIN group on day 1 post-challenge (P < 0.05). In contrast, IL-10 levels were significantly lower in the REP group 1 day post-challenge compared with the SIN group. The REP group had significantly higher levels of IFN-gamma at baseline, and this difference remained significant 1 day post-challenge. Analysis of antibody levels to P. gingivalis showed that while the control and the SIN groups had no anti-P. gingivalis IgG in the chamber exudate during the 7-day study period, the REP group showed high anti-P. gingivalis IgG levels. In addition, the titres of IgG2a were fivefold higher than the IgG1 titres. The results showed that a repeat local challenge with P. gingivalis augmented the proinflammatory cytokines TNF-alpha and IFN-gamma, while inhibiting the accumulation of the anti-inflammatory cytokine IL-10. This shift towards a T helper 1 (Th1)-dominant response was reflected in the relatively high anti-P. gingivalis IgG2a titres in the local inflammatory environment 7 days post-challenge.

Pharmacokinetics and pharmacodynamics of the acetylcholinesterase inhibitor metrifonate in patients with renal impairment

The aim of this study was to assess the influence of renal function on the pharmacokinetics, pharmacodynamics, safety, and tolerability of the acetylcholinesterase inhibitor metrifonate. Four groups of six age- and gender-matched subjects with varying degrees of renal function (creatinine clearances more than 90, 60-90, 30-60, and less than 30 mL/min/ 1.73 m2, respectively) were administered a single 50-mg oral dose of metrifonate. Blood and urine samples were collected for 24 hours and concentrations of metrifonate and its metabolites dichlorvos, dichloroacetic acid, and M3 were determined. Inhibition of acetylcholinesterase activity in erythrocytes and butyrylcholinesterase in plasma were also measured. Metrifonate was well tolerated in all treatment groups. The urinary excretion of metrifonate and dichlorvos decreased with decreasing renal function but accounted for less than 2% of the elimination. There were no statistically significant differences in primary pharmacokinetic parameters--Cmax, t(max), area under the concentration-time curve (AUC), and t1/2--of metrifonate and dichlorvos among the different groups. The excretion of dichloroacetic acid and M3 was not influenced by renal impairment. Acetylcholinesterase was not inhibited, whereas butyrylcholinesterase was inhibited markedly but independently of renal function. No metrifonate dose adjustments are needed when treating subjects with renal impairment.

Activation of murine macrophages by lipoprotein and lipooligosaccharide of Treponema denticola

We have recently demonstrated that the periodontopathogenic oral spirochete Treponema denticola possesses membrane-associated lipoproteins in addition to lipooligosaccharide (LOS). The aim of the present study was to test the potential of these oral spirochetal components to induce the production of inflammatory mediators by human macrophages, which in turn may stimulate tissue breakdown as observed in periodontal diseases. An enriched lipoprotein fraction (dLPP) from T. denticola ATCC 35404 obtained upon extraction of the treponemes with Triton X-114 was found to stimulate the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), and interleukin-1 (IL-1) by mouse macrophages in a dose-dependent manner. Induction of NO by dLPP was at 25% of the levels obtained by Salmonella typhosa lipopolysaccharide (LPS) at similar concentrations, while IL-1 was produced at similar levels by both inducers. dLPP-mediated macrophage activation was unaffected by amounts of polymyxin B that neutralized the induction produced by S. typhosa LPS. dLPP also induced NO and TNF-alpha secretion from macrophages isolated from endotoxin-unresponsive C3H/HeJ mice to an extent similar to the stimulation produced in endotoxin-responsive mice. Purified T. denticola LOS also produced a concentration-dependent activation of NO and TNF-alpha in LPS-responsive and -nonresponsive mouse macrophages. However, macrophage activation by LOS was inhibited by polymyxin B. These results suggest that T. denticola lipoproteins and LOS may play a role in the inflammatory processes that characterize periodontal diseases.

The Effect of Stress on the Inflammatory Response toPorphyromonas gingivalisin a Mouse Subcutaneous Chamber Model

BACKGROUND

The impact of emotional stress on the outcome of infectious diseases was studied in animal models and humans, but data related to the effect of stress on periodontal infection are limited. Using the subcutaneous chamber model in mice, the present study was carried out to investigate the effect of stress on the host response to Porphyromonas gingivalis.

METHODS

Mice with subcutaneous chambers (2 per animal) were divided into 4 treatment groups: cold-stress; isolation-stress; corticosterone (CS)-injected; and controls. On the third day of stress conditions, heat-killed P. gingivalis were injected into the chambers. The chambers were sampled 1 and 5 days later and analyzed for leukocyte number, tumor necrosis factor (TNF)-alpha levels, and interferon (IFN)-gamma levels.

RESULTS

Injection of P. gingivalis induced the migration of leukocytes into the chambers and increased the intrachamber levels of IFN-gamma and TNF-alpha. There were no significant differences in cell number and IFN-gamma levels between the different treatment groups, but the levels of TNF-alpha were significantly lower in the isolation-stress and cold-stress groups compared to control animals. CS-injected animals were not different from controls. In addition, the levels of TNF-alpha in the stressed animals were lower on the fifth day post-injection than on the first day, but not in the CS and control group.

CONCLUSIONS

The results suggest that the levels of TNF-alpha induced by P. gingivalis in the infection site are downregulated in stressed animals, and CS is not the sole mediator responsible. The stress-induced reduction in TNF-alpha levels might have an impact on the pathogenesis of periodontal disease in humans experiencing emotional stress.

Effects of tetracyclines on the pathologic activity of endotoxin: in vitro and in vivo studies

Lipopolysaccharide (LPS) is considered to be one of the major virulence factors of Gram-negative bacteria. Recently, tetracyclines (TTCs) were found to prevent the patho-physiological changes associated with LPS in vivo and the secretion of inflammatory mediators in vitro. However, the mechanism by which TTCs prevents LPS-induced pathology in vivo is still unclear. In order to shed light on that problem, we carried out in vitro and in vivo experiments. TTC inhibited the secretion of nitric oxide (NO) and TNF alpha from LPS-stimulated macrophages and inhibited macrophage-induced thymocyte proliferation. However, TTC inhibited NO secretion with use of concentrations five-fold lower than those that inhibited TNF alpha secretion and thymocyte proliferation. The secretion of NO was inhibited by the addition of TTC to the cultures up to 6 hrs post-LPS stimulation. TTC inhibition of LPS-induced NO secretion was not reversed by the addition of recombinant TNF alpha, and TTC inhibition of LPS-induced TNF alpha secretion was not reversed by the addition of NO donor. These results suggest that the inhibition of TNF alpha by TTC is not the result of the inhibition of LPS-induced NO secretion or vice versa. In vivo experiments had shown that TTC prevented mortality in LPS-treated mice, but not in mice pre-sensitized with galactosamine prior to the LPS challenge. These results suggest that TTC activity in vivo is due not to the suppression of synthesis of inflammatory mediators but rather to the induction of acute phase-like response, which antagonizes the LPS-induced activity.

Anti-D immunoglobulin in Rh(D) negative volunteers: clearance of Rh(D) positive red cells and kinetics of serum anti-D levels

Properties of a new anti-D immunoglobulin were assessed in Rh(D) negative healthy male adults. Six volunteers received intravenous, and five volunteers intramuscular injections of 200 micrograms anti-D, 48 hours after pre-treatment with 5 mL of Rh(D) positive erythrocytes. Immediately after intravenous administration of anti-D, a rapid decrease of the Rh(D) positive erythroyctes was noted. After intramuscular injection of anti-D, there was a lag phase of 6 hours until the erythrocytes decreased, and the elimination rate was slower. Twenty-four hours after injection of anti-D, the Rh(D) positive erythrocytes were at the detection limit or no longer detectable in all volunteers. After intravenous administration, anti-D serum levels decreased from 45 ng/mL at 2 hours to 29 ng/mL at 24 hours, whereas after intramuscular administration, anti-D became detectable at 4 hours and increased to 11 ng/mL at 24 hours. During subsequent months, anti-D serum levels decreased at similar rates in both groups. After six months, anti-D was not detectable in any of the volunteers. Thus, the new anti-D immunoglobulin induced elimination of the Rh(D) positive erythrocytes and suggested that Rh(D) immunization of the volunteers was prevented.

Bacterial lipopolysaccharide induces early and late activation of protein kinase C in inflammatory macrophages by selective activation of PKC-epsilon

Experiments from our and other laboratories have shown that specific inhibitors of protein kinase C (PKC) inhibited the secretion of nitric oxide, TNF alpha, and IL-1 beta from lipopolysaccharide (LPS)-stimulated macrophages, suggesting an important role for PKC in the inflammatory response. The present study was designed to investigate the mechanism whereby LPS stimulates PKC activity in inflammatory macrophages. Mouse macrophages were stimulated with 0-1 microgram/ml LPS for 0-18 hours, and PKC activity was detected in cell lysates. PKC isoform specificity was determined by blocking PKC activity with isoform-specific antibodies. Treatment of macrophages with 1 microgram/ml LPS induced a two-fold increase in PKC activity within 15 minutes and an additional more significant peak of PKC activity appeared 3 hours post-LPS stimulation. A lower dose of LPS (10 ng/ml) induced the later peak only. The enhancement in PKC activity induced by LPS occurred in both the cytosol and membrane fractions, but the enhancement in the membrane fraction was significantly greater than in the cytosol. The increase in PKC activity in both peaks was abolished only by the addition of anti-PKC-epsilon antibody. The present experiments suggest that PKC activation is an important pathway in the LPS-induced secretory response of macrophages and that PKC-epsilon is the major isoform involved.

Tetracycline inhibits Porphyromonas gingivalis lipopolysaccharide-induced lesions in vivo and TNF alpha processing in vitro

Lipopolysaccharides (LPS) are considered one of the more important virulence factors related to the pathogenesis of periodontal diseases. Based on tetracycline (TTC) ability to bind divalent metal ions, the present study was designed to examine the effect of TTC on P. gingivalis LPS-induced lesions in vivo and on LPS-induced TNF alpha production in vitro. Subcutaneous injection of 50-100 micrograms of P. gingivalis LPS into BALB/C mice induced a visible lesion within 24 h with evident tissue necrosis. Daily systemic administration of TTC for the first 4 d following LPS challenge reduced the size of the lesion, and total inhibition of lesion formation was observed in 75-100% of the treated mice. A non-related broad spectrum antibiotic, ampicillin, or the IL-1 inhibitor ML-20, had no effect on the lesion size. In order to explore some aspects of the mechanism involved, we tested the effect of TTC on LPS-induced TNF alpha secretion by human monocytes in vitro. TTC (1 mM) was found to block LPS-stimulated TNF alpha secretion. Western blotting of monocyte cytoplasmic membranes for membrane-bound TNF alpha show that TTC causes the retention of membrane-associated TNF alpha on monocyte membranes, thereby preventing the release of TNF alpha into the culture media. The results suggest the TTC is an effective in vivo therapy for preventing P. gingivalis LPS-induced subcutaneous lesion formation in the murine model. The mechanism of TTC treatment probably involves blocking the activity of metalloproteinases, including TNF alpha processing enzyme, thereby preventing LPS-induced tissue destruction.

Human monocyte response to cementum extracts from periodontally diseased teeth: effect of conditioning with tetracycline

Monocyte inflammatory cytokines, such as TNF alpha and IL-1 beta, have been implicated in the pathogenesis of periodontal destruction. The present study was designed to test the ability of extracts of cementum from periodontally diseased teeth to induce the secretion of these mediators by monocytes, to evaluate the role of adsorbed endotoxin in this process, and to test the effect of cementum conditioning with tetracycline on the monocyte response. Human monocytes were incubated with varying concentrations of cementum extracts, and TNF alpha and IL-1 beta levels in the media were measured. The results showed that while extracts of healthy cementum had no effect on monocyte secretion, concentration as low as 0.5 mg/ml of cementum from diseased sites raised the levels of TNF alpha and IL-1 beta secretion 10-fold. This response was dose-dependent. Diseased cementum were found to contain 1.5 ng/mg endotoxin, while endotoxin was not detectable in the extracts of the healthy cementum. However, neutralization of the endotoxin by polymyxin B only partially reduced the monocyte secretory response by 50 to 70%, suggesting that other factors in the extracts are also involved in monocyte stimulation. To simulate the effect of root conditioning, cementum was first agitated in a tetracycline or control solution prior to its extraction in media. Pretreatment of diseased cementum with tetracycline (50 mg/ml) was found to block the secretion of TNF alpha from cementum-stimulated monocytes. Pretreatment of the diseased cementum with 10 mg/ml tetracycline was not more effective than saline and HCI controls, with all treatments reducing cytokine secretion by approximately 80%. The direct addition of tetracycline to cementum-stimulated monocyte culture was found to block TNF alpha secretion in a dose dependent manner. The results suggest that extracts from diseased cementum are potent stimulators of monocyte secretion, and that endotoxin as well as other factor(s) appear to be involved. These factors are partially extracted by washing and a 10 mg/ml tetracycline solution is not more effective than saline in achieving this goal. In addition, tetracycline was found to be a potent inhibitor of TNF alpha secretion by cementum-stimulated monocytes, suggesting a novel mechanism for this drug in periodontal therapy.

Protection against endotoxic shock and lipopolysaccharide-induced local inflammation by tetracycline: correlation with inhibition of cytokine secretion

Septic shock results from excessive stimulation of host immune cells, particularly monocytes and macrophages, by lipopolysaccharide (LPS) released from gram-negative bacteria. Macrophage-derived cytokines, such as tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1 beta), have been identified as central mediators in the pathogenesis of septic shock and the resultant mortality. Therefore, these cytokines were targets for experimental therapy for septic shock. Because of tetracycline's ability to intervene in cellular mechanisms involved in cytokine secretion, we tested the effect of tetracycline on LPS-induced septic shock and inflammatory lesions in mice. Tetracycline was found to protect mice against LPS-induced lethality and to abolish clinical signs of LPS-induced inflammatory lesions. This protection correlates with tetracycline's ability to reduce LPS-induced TNF-alpha levels in serum. Furthermore, tetracycline was found to inhibit LPS-induced TNF-alpha and IL-1 beta secretion, but not cytokine mRNA accumulation, in human monocytes in vitro. The results presented here suggest that tetracycline is a potent drug for LPS-induced pathology and that its mechanism of action involves blockage of posttranscriptional events of cytokine production.

Clinical aspects of cardiovascular effects of H2-receptor antagonists

In vitro studies and animal experiments as well as clinical observations in humans concerning cardiovascular effects of H2-receptor antagonists have been published shortly after the development. Thus, clinical studies were performed to investigate these effects. The following review summarizes the results from in vitro studies up to the clinical investigations performed.

Changes in the effects of nizatidine and famotidine on cardiac performance after pretreatment with ranitidine

This was an open, randomized study of the cardiovascular effects of the histamine H2 receptor antagonists ranitidine, famotidine, and nizatidine after single oral doses alone or in combination in healthy volunteers. When compared with placebo ranitidine (450 mg) did not have any haemodynamic effects. Nizatidine (300 mg) caused significant falls in heart rate and cardiac output. Famotidine (40 mg) caused significant falls in stroke volume and cardiac output and an increase in pre-ejection period. Pretreatment with ranitidine abolished the haemodynamic effects of nizatidine and caused a time-shift of 2 h in the onset of the cardiovascular effects of famotidine. The difference in the results for nizatidine and famotidine can be explained by the longer half-life of famotidine. Vascular effects are assumed to be responsible for impairment of cardiac performance by famotidine.

Bunazosin in patients with impaired hepatic or renal function

Following a single oral dose of 6 mg bunazosin, a novel alpha 1-adrenoceptor antagonist, the pharmacokinetics and blood pressure behaviour of 37 patients were studied. 12 subjects had normal renal and hepatic function (mean creatinine clearance (GFR) 107 +/- 240 ml/min, antipyrine clearance (AP Cl) 47 +/- 10.2 ml/min; x +/- SD), 13 subjects had impaired renal function (mean GFR 38 +/- 11.5 ml/min, AP Cl 39 +/- 4.0 ml/min), and 12 patients had liver cirrhosis which was confirmed by liver biopsy (mean AP Cl 18 +/- 9.2 ml/min, GFR 92 +/- 8.1 ml/min). The groups studied were matched for age and body weight. The area under the plasma level time curve (AUC0-infinity) of bunazosin increased from 96.6 +/- 48.7 micrograms.ml-1.h in the normals to 157.0 +/- 101.0 micrograms.ml-1.h in the liver patients and to 298.2 +/- 199.4 micrograms.ml-1.h in patients with impaired renal function (P < 0.05). As there was a close correlation between plasma levels and antihypertensive activity of bunazosin in the present study, dosage adjustment of the alpha 1-receptor blocker in patients with impaired liver and kidney function appears to be mandatory.