High inter-individual variability of vardenafil pharmacokinetics in patients with pulmonary hypertension

Peripheral Vascular Ageing in Pulmonary Arterial Hypertension as Assessed by Common Carotid Artery Intima Thickness and Intima/Media Thickness Ratio: An Investigation Using Non-Invasive High-Resolution Ultrasound

BACKGROUND

Pulmonary arterial hypertension (PAH; World Heath Organization [WHO] Group 1) is associated with increased pulmonary arterial pressure and resistance, with pulmonary vascular remodelling. The vascular anatomy of the systemic arteries has been less well studied.

METHOD

Nineteen (19) patients with PAH, confirmed by right heart catheterisation (RHC), 14 patients with left ventricular heart failure with reduced ejection fraction (LVrEF), and 30 healthy subjects were enrolled. Common carotid artery (CCA) intima thickness, intima/media (I/M) thickness ratio, and intima-media thickness (IMT) were assessed using non-invasive ultrasound (22 MHz centre frequency).

RESULTS

The CCA intima thickness was correlated with several RHC variables (all p<0.05). The intima was 56% thicker (+0.05 mm; 95% CI 0.03, 0.06; p<0.0001) and the I/M thickness ratio was 128% greater (+0.21; 95% CI 0.13, 0.28; p<0.0001) in patients with PAH than healthy subjects. These values were also significantly higher than in patients with LVrEF. In ROC curve analysis, the c-values for CCA intima thickness (0.92) and I/M ratio (0.87), but not for IMT, correctly indicated which individuals belonged to the PAH or healthy control groups. The CCA IMT showed no corresponding significant group differences or associations and was of no use according to receiver operating curve analysis.

CONCLUSIONS

Patients with PAH displayed signs of peripheral vascular remodelling, challenging the common opinion that vascular changes in PAH are restricted to the lung vasculature. Correlations with cardiopulmonary variables from RHC support peripheral vascular coupling and the association with vascular ageing. Results from this pilot study warrant further confirmation.

Treatment of Cardiovascular Dysfunction With PDE5-Inhibitors - Temperature Dependent Effects on Transport and Metabolism of cAMP and cGMP

Introduction

Cardiovascular dysfunction is a potentially lethal complication of hypothermia. Due to a knowledge gap, pharmacological interventions are not recommended at core temperatures below 30°C. Yet, further cooling is induced in surgical procedures and survival of accidental hypothermia is reported after rewarming from below 15°C, advocating a need for evidence-based treatment guidelines. In vivo studies have proposed vasodilation and afterload reduction through arteriole smooth muscle cGMP-elevation as a favorable strategy to prevent cardiovascular dysfunction in hypothermia. Further development of treatment guidelines demand information about temperature-dependent changes in pharmacological effects of clinically relevant vasodilators.

Materials and Methods

Human phosphodiesterase-enzymes and inverted erythrocytes were utilized to evaluate how vasodilators sildenafil and vardenafil affected cellular efflux and enzymatic breakdown of cAMP and cGMP, at 37°C, 34°C, 32°C, 28°C, 24°C, and 20°C. The ability of both drugs to reach their cytosolic site of action was assessed at the same temperatures. IC₅₀- and K_i-values were calculated from dose–response curves at all temperatures, to evaluate temperature-dependent effects of both drugs.

Results

Both drugs were able to reach the intracellular space at all hypothermic temperatures, with no reduction compared to normothermia. Sildenafil IC₅₀ and K_i-values increased during hypothermia for enzymatic breakdown of both cAMP (IC₅₀: 122 ± 18.9 μM at 37°C vs. 269 ± 14.7 μM at 20°C, p < 0.05) and cGMP (IC₅₀: 0.009 ± 0.000 μM at 37°C vs. 0.024 ± 0.004 μM at 32°C, p < 0.05), while no significant changes were detected for vardenafil. Neither of the drugs showed significant hypothermia-induced changes in IC₅₀ and K_i–values for inhibition of cellular cAMP and cGMP efflux.

Conclusion

Sildenafil and particularly vardenafil were ableto inhibit elimination of cGMP down to 20°C. As the cellular effects of these drugs can cause afterload reduction, they show potential in treating cardiovascular dysfunction during hypothermia. As in normothermia, both drugs showed higher selectivity for inhibition of cGMP-elimination than cAMP-elimination at low core temperatures, indicating that risk for cardiotoxic side effects is not increased by hypothermia.

Evaluation of the combination of endothelin receptor antagonists (ERA) and phosphodiesterase-5 inhibitors for the treatment of pulmonary arterial hypertension (PAH) in pathologic human pulmonary arteries in an ex-vivo organ bath model

PURPOSE

Medical combination therapy of pulmonary arterial hypertension (PAH) may alleviate the drawbacks of monotherapy by avoiding drug tolerance and by increasing effectiveness, as shown by the combination of ambrisentan and tadalafil (AMBITION trial). The present ex-vivo study evaluated the combination of the endothelin receptor antagonists (ERA) macitentan and bosentan with the phosphodiesterase-5 (PDE-5) inhibitor vardenafil in pulmonary arteries from patients suffering from terminal lung disease as a model of PAH.

METHODS

Segments of the pulmonary vessels were excised from resected lungs of patients requiring lung transplantation (LTX). Contraction of pulmonary arteries (PA) was elicited by consecutive dose-response curves of endothelin-1 (ET-1) followed by norepinephrine (NE) to allow inhibition by different pathways. Forces were measured isometrically in an organ bath in the presence and absence of ERA and PDE-5 inhibitors and their combination.

RESULTS

PA of 38 patients were examined between October 2016 and November 2019. Bosentan (1E-7 M) and macitentan (1E-8 M, 3E-8 M, 1E-7 M) inhibited ET-1 induced contractions, whereas vardenafil (1E-6 M, 3E-6 M, 1E-5 M) inhibited only the NE induced part of the contractions. Vardenafil enhanced bosentan-induced inhibition of vasoconstriction in a dose-dependent fashion. Combination effects exceeded single bosentan at 3E-6 M and 1E-5 M vardenafil, and they exceeded single vardenafil at the lower vardenafil concentrations. Macitentan showed a more pronounced inhibition than bosentan regardless of the lower concentrations. Accordingly, combination effects with vardenafil resembled those of macitentan alone.

CONCLUSIONS

Macitentan and bosentan were potent antagonists of vasoconstriction in PA of LTX patients. The benefit of drug combinations was demonstrated at selected concentrations only owing to a narrow therapeutic range of vardenafil in this ex-vivo model. These results suggest the utility of drug combinations other than the established pair of ambrisentan and tadalafil in PAH treatment but also make a case for a further assessment of vasodilator properties of drugs complementing ERA.

Mycophenolate mofetil for systemic sclerosis: drug exposure exhibits considerable inter-individual variation-a prospective, observational study

Objective

Mycophenolate mofetil (MMF) is an established therapy for systemic sclerosis (SSc), but its pharmacokinetics in this disease remains unexplored. We have investigated drug exposure in MMF-treated patients with SSc in relation to clinical features of the disease and common concomitant drugs.

Methods

This study was predefined to include 35 MMF-treated SSc patients who were using MMF at a fixed dose of 0.5, 1.0 or 1.5 g twice daily since at least 3 months. The 12-h drug exposure of the active MMF metabolite mycophenolic acid (MPA) was estimated by repeated analysis of plasma MPA over a 6-h period. This 12-h drug exposure was dose normalised to a daily intake of 3 g MMF (MPA_AUC_3g) in order to compare subjects using MMF at different doses. Drug exposure was analysed in reference to the clinical characteristics including body weight, renal function, autoantibodies, intestinal dysbiosis, intestinal inflammation assessed by faecal (F)-calprotectin, intestinal symptoms assessed by the University of California Los Angeles Scleroderma Trial Consortium Gastrointestinal Tract Instrument 2.0 and concomitant drug usage including proton-pump inhibitors (PPI).

Results

Thirty-four out of 35 study participants completed the study. The mean daily MMF dose was 2.1 g. Drug exposure expressed as MPA_AUC_3g varied up to 8-fold between patients (median 115, range 27–226 mg h/L).

MPA_AUC_3g was inversely related to body weight (r_s = − 0.58, p < 0.001) and renal function (r_s = − 0.34, p = 0.054). Anti-topoisomerase-1 antibodies and male sex were associated with lower MPA_AUC_3g (87 vs 123 and 71 vs 141; p = 0.008 and p = 0.015, respectively). MPA_AUC_3g was inversely related to the intestinal abundance of lactobacilli and to F-calprotectin (r_s = − 0.54, p = 0.004; r_s = − 0.36, p = 0.034), but not to gastrointestinal symptoms. MPA_AUC_3g was inversely related to PPI usage (r_s = − 0.45, p = 0.007). We found no association between MPA_AUC_3g and disease subtype, disease duration or disease activity.

Conclusion

MMF-treated SSc patients exhibit considerable inter-individual variation in drug exposure, and lower MPA levels were primarily found in PPI users with poor prognostic factors. Body weight, renal function, sex, serology, gastrointestinal manifestations and/or measuring individual MPA exposure should be considered when using MMF for SSc.

Acute vasodilator response to vardenafil and clinical outcome in patients with pulmonary hypertension

PURPOSE

Acute vasodilator testing is recommended in patients with pulmonary arterial hypertension to identify individuals who may benefit from long-term treatment with oral calcium channel blockers. The aim of this study was to investigate the use of vardenafil in acute vasoreactivity testing compared to adenosine.

METHODS

A total of 20 patients eligible for right heart catheterisation were enrolled. Acute vasoreactivity testing was carried out with intravenous (iv) adenosine (n = 18) followed by oral vardenafil (n = 20). Haemodynamic responses were recorded at baseline and after 60 min (vardenafil). Responders were defined according to consensus guideline criteria.

RESULTS

Both vardenafil and adenosine significantly decreased mean pulmonary arterial pressure (mPAP, p < 0.001 and p = 0.026, respectively) and pulmonary vascular resistance (p < 0.001 and p > 0.001, respectively), and significantly increased cardiac output (p = 0.001 and p = 0.005, respectively). Vardenafil reduced mPAP more than adenosine (p = 0.044), while adenosine resulted in higher responses of cardiac index (p = 0.009) and pulmonary arterial oxygen saturation (p = 0.042). Acute adverse reactions were common with adenosine, while no side effects were observed after a single oral dose vardenafil. Vardenafil identified five responders (out of 20), while adenosine identified three responders (out of 18). During a 7-year follow-up, vardenafil responders had significantly lower NT-proBNP levels compared to non-responders.

CONCLUSIONS

Vardenafil may be safely used for acute vasoreactivity testing in patients with PH. A single oral dose of vardenafil is better tolerated than iv adenosine and may identify additional responders who could benefit from long-term vasodilator treatment.

Changes in plasma levels of asymmetric dimethylarginine, symmetric dimethylarginine, and arginine after a single dose of vardenafil in patients with pulmonary hypertension

OBJECTIVE

We investigated whether vardenafil, a phosphodiesterase-5 inhibitor, alters plasma levels of asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and arginine.

PATIENTS AND METHODS

ADMA, SDMA, and arginine were measured (0-540 min) in 12 patients with pulmonary hypertension after a single oral dose of vardenafil. Invasive hemodynamic data were collected at baseline and after 60 min.

RESULTS

A reduction in ADMA was observed at 30 and 45 min with a median change of -11.1% (P=0.021) and -12.5% (P=0.002). SDMA decreased with a median -5.3% change (P=0.032) at 45 min. An increase in arginine, median 40.3% (P=0.002), 45.0% (P=0.010), and 77.1% (P=0.008) was observed at 120, 300, and 540 min respectively. An increase in the arginine/ADMA ratio, median 11.7% (P=0.012), 32.5% (P=0.003), 26.5% (P=0.021), 33% (P=0.007), 48.5% (P=0.007), and 63.1% (P=0.008) was observed at 15, 45, 60, 120, 300, and 540 min respectively. There was a positive correlation between vardenafil exposure and the percent change in the arginine/ADMA ratio from baseline to 540 min (r=0.80; P=0.01). A correlation between baseline mean right atrial pressure (mRAP) and baseline ADMA (r=0.65; P=0.023), and baseline SDMA (r=0.61; P=0.035) was observed. A correlation between the baseline arginine/ADMA ratio and baseline cardiac output (CO) (r=0.59; P=0.045) and baseline cardiac index (CI) (r=0.61; P=0.036) was observed. Baseline arginine/ADMA ratio correlated with baseline mRAP (r=-0.79; P=0.002). A correlation between change (0-60 min) in CI and change in arginine (r=0.77; P=0.003) as well as change in the arginine/ADMA ratio (r=0.61; P=0.037) was observed.

CONCLUSIONS

Vardenafil induced changes in ADMA, SDMA, arginine, and the arginine/ADMA ratio in patients with PH. An increase in arginine and the arginine/ADMA ratio was associated with improvement in CI.