Project description:Pulmonary arterial hypertension is a chronic and life-threatening disease that if left untreated is fatal. Current therapies include stimulating the nitric oxide-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate axis, improving the prostacyclin pathway and inhibiting the endothelin pathway. Phosphodiesterase type 5 inhibitors, such as sildenafil, and the sGC stimulator riociguat are currently used in the treatment of pulmonary arterial hypertension. This article discusses the similarities and differences between phosphodiesterase type 5 inhibitors and sGC stimulator based on pharmacological action and clinical trials, and considers which is better for the treatment of pulmonary arterial hypertension.
Project description:A proportion of pulmonary arterial hypertension (PAH) patients do not reach treatment goals with phosphodiesterase-5 inhibitors (PDE5i). RESPITE investigated the safety, feasibility and benefit of switching from PDE5i to riociguat in these patients.RESPITE was a 24-week, open-label, multicentre, uncontrolled study. Patients in World Health Organization (WHO) functional class (FC) III, with 6-min walking distance (6MWD) 165-440 m, cardiac index <3.0 L·min-1·m-2 and pulmonary vascular resistance >400 dyn·s·cm-5 underwent a 1-3 day PDE5i treatment-free period before receiving riociguat adjusted up to 2.5 mg maximum t.i.d Exploratory end-points included change in 6MWD, WHO FC, N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and safety.Of 61 patients enrolled, 51 (84%) completed RESPITE. 50 (82%) were receiving concomitant endothelin receptor antagonists. At week 24, mean±sd 6MWD had increased by 31±63 m, NT-proBNP decreased by 347±1235 pg·mL-1 and WHO FC improved in 28 patients (54%). 32 patients (52%) experienced study drug-related adverse events and 10 (16%) experienced serious adverse events (2 (3%) study drug-related, none during the PDE5i treatment-free period). Six patients (10%) experienced clinical worsening, including death in two (not study drug-related).In conclusion, selected patients with PAH may benefit from switching from PDE5i to riociguat, but this strategy needs to be further studied.
Project description:Chronic exposure to cold caused pulmonary arterial hypertension (cold-induced pulmonary hypertension [CIPH]) and increased phosphodiesterase-1C (PDE-1C) expression in pulmonary arteries (PAs) in rats. The purpose of this study is to investigate a hypothesis that inhibition of PDE-1 would decrease inflammatory infiltrates and superoxide production leading to attenuation of CIPH. Three groups of male rats were exposed to moderate cold (5±1°C) continuously, whereas 3 groups were maintained at room temperature (23.5±1°C, warm; 6 rats/group). After 8-week exposure to cold, 3 groups in each temperature condition received continuous intravenous infusion of 8-isobutyl-methylxanthine (8-IBMX) (PDE-1 inhibitor), apocynin (NADPH oxidase inhibitor) or vehicle, respectively, for 1 week. Cold exposure significantly increased right-ventricular systolic pressure compared with warm groups (33.8±3.2 versus 18.6±0.3 mm Hg), indicating that animals developed CIPH. Notably, treatment with 8-IBMX significantly attenuated the cold-induced increase in right ventricular pressure (23.5±1.8 mm Hg). Cold exposure also caused right-ventricular hypertrophy, whereas 8-IBMX reversed cold-induced right ventricular hypertrophy. Cold exposure increased PDE-1C protein expression, macrophage infiltration, NADPH oxidase activity, and superoxide production in PAs and resulted in PA remodeling. 8-IBMX abolished cold-induced upregulation of PDE-1C in PAs. Interestingly, inhibition of PDE-1 eliminated cold-induced macrophage infiltration, NADPH oxidase activation, and superoxide production in PAs and reversed PA remodeling. Inhibition of NADPH oxidase by apocynin abolished cold-induced superoxide production and attenuated CIPH and PA remodeling. In conclusion, inhibition of PDE-1 attenuated CIPH and reversed cold-induced PA remodeling by suppressing macrophage infiltration and superoxide production, suggesting that upregulation of PDE-1C expression may be involved in the pathogenesis of CIPH.
Project description:Pulmonary Hypertension due to left heart disease is the most common type of Pulmonary Hypertension. Morbidity and mortality significantly increase once Pulmonary Hypertension is present. Treatment is aimed toward optimizing the underlying condition. Targeted therapy has been evaluated in small studies with mixed results. The goal of this systematic review is to identify the possible benefit and safety of Phosphodiesterase 5 inhibitors in Pulmonary Hypertension due to left heart disease with elevated pulmonary vascular resistance, diagnosed by right heart catheterization. Electronic searches using MEDLINE/PREMEDLINE, EMBASE, and The Cochrane Library were searched on 21 October 2018. Randomized clinical trials comparing Phosphodiesterase 5 inhibitors versus placebo in patients with proven Pulmonary Hypertension by right heart catheterization secondary to left heart disease (both heart failure with reduced ejection fraction and with preserved ejection fraction) and reported pulmonary vascular resistance were included. We identified 436 potentially relevant studies. After reviewing the titles and abstracts to exclude irrelevant articles, five randomized clinical trials were considered for the study. Sildenafil was well tolerated among all studies. Sildenafil was found to improve hemodynamics, exercise capacity, and quality of life in patients with elevated pulmonary vascular resistance. Phosphodiesterase 5 inhibitors therapy in patients with proven Pulmonary Hypertension due to left heart disease and elevated pulmonary vascular resistance by right heart catheterization may improve the quality of life, exercise capacity, and pulmonary hemodynamics. Further prospective randomized controlled studies are needed to confirm.
Project description:Purpose: One of the promising chemical groups for the development of new antihypertensive medicines, the action of which is associated with the inhibition of phosphodiesterase III (PDE3) activity, are phosphorylated oxazole derivatives (OVPs). This study aimed to prove experimentally the presence of the OVPs antihypertensive effect associated with decreasing of PDE activity and to justify its molecular mechanism. Methods: An experimental study of the effect of OVPs on phosphodiesterase activity was performed on Wistar rats. Determination of PDE activity was performed by fluorimetric method using umbelliferon in blood serum and organs. The docking method was used to investigate the potential molecular mechanisms of the antihypertensive action of OVPs with PDE3. Results: The introduction of OVP-1 50 mg/kg, as a leader compound, led to the restoration of PDE activity in the aorta, heart and serum of rats with hypertension to the values observed in the intact group. This may indicate the possibility of the development of vasodilating action of OVPs by the influence of the latter on the increase in cGMP synthesis due to inhibition of PDE activity. The calculated results of molecular docking of ligands OVPs to the active site of PDE3 showed that all test compounds have a common type of complexation due to phosphonate groups, piperidine rings, side and terminal phenyl and methylphenyl groups. Conclusion: The analysis of the obtained results both in vivo and in silico showed that phosphorylated oxazole derivatives represent a new platform for further studies as phosphodiesterase III inhibitors with antihypertensive activity.
Project description:Pulmonary hypertension (PH) is a life-threatening disorder characterized by increased pulmonary artery pressure, remodeling of the pulmonary vasculature, and right ventricular failure. Loss of endothelium-derived nitric oxide (NO) and prostacyclin contributes to PH pathogenesis, and current therapies are targeted to restore these pathways. Phosphodiesterases (PDEs) are a family of enzymes that break down cGMP and cAMP, which underpin the bioactivity of NO and prostacyclin. PDE5 inhibitors (eg, sildenafil) are licensed for PH, but a role for PDE2 in lung physiology and disease has yet to be established. Herein, we investigated whether PDE2 inhibition modulates pulmonary cyclic nucleotide signaling and ameliorates experimental PH.The selective PDE2 inhibitor BAY 60-7550 augmented atrial natriuretic peptide- and treprostinil-evoked pulmonary vascular relaxation in isolated arteries from chronically hypoxic rats. BAY 60-7550 prevented the onset of both hypoxia- and bleomycin-induced PH and produced a significantly greater reduction in disease severity when given in combination with a neutral endopeptidase inhibitor (enhances endogenous natriuretic peptides), trepostinil, inorganic nitrate (NO donor), or a PDE5 inhibitor. Proliferation of pulmonary artery smooth muscle cells from patients with pulmonary arterial hypertension was reduced by BAY 60-7550, an effect further enhanced in the presence of atrial natriuretic peptide, NO, and treprostinil.PDE2 inhibition elicits pulmonary dilation, prevents pulmonary vascular remodeling, and reduces the right ventricular hypertrophy characteristic of PH. This favorable pharmacodynamic profile is dependent on natriuretic peptide bioactivity and is additive with prostacyclin analogues, PDE5 inhibitor, and NO. PDE2 inhibition represents a viable, orally active therapy for PH.
Project description:Optimization efforts were devoted to discover novel PDE10A inhibitors in order to improve solubility and pharmacokinetics properties for a long-term therapy against pulmonary arterial hypertension (PAH) starting from the previously synthesized inhibitor A. As a result, a potent and highly selective PDE10A inhibitor, 14·3HCl (half maximal inhibitory concentration, IC50 = 2.8 nmol/L and >3500-fold selectivity) exhibiting desirable solubility and metabolic stability with a remarkable bioavailability of 50% was identified with the aid of efficient methods of binding free energy predictions. Animal PAH studies showed that the improvement offered by 14·3HCl [2.5 mg/kg, oral administration (p.o.)] was comparable to tadalafil (5.0 mg/kg, p.o.), verifying the feasibility of PDE10A inhibitors for the anti-PAH treatment. The crystal structure of the PDE10A-14 complex illustrates their binding pattern, which provided a guideline for rational design of highly selective PDE10A inhibitors.