Relative incidence and predictors of pulmonary arterial hypertension complicating type 2 diabetes: The Fremantle Diabetes Study Phase I

Differential inhibition of sildenafil and macitentan on saxagliptin metabolism

The development of diabetes mellitus (DM) is generally accompanied by erectile dysfunction (ED) and pulmonary arterial hypertension (PAH), which increases the use of combination drug therapy and the risk of drug-drug interactions. Saxagliptin for the treatment of DM, sildenafil for the treatment of ED and PAH, and macitentan for the treatment of PAH are all substrates of CYP3A4, which indicates their potential involvement in drug-drug interactions. Therefore, we investigated potential pharmacokinetic interactions between saxagliptin and sildenafil/macitentan. We investigated this speculation both in vitro and in vivo, and explored the underlying mechanism using in vitro hepatic metabolic models and molecular docking assays. The results showed that sildenafil substantially inhibited the metabolism of saxagliptin by occupying the catalytic site of CYP3A4 in a competitive manner, leading to the alterations in the pharmacokinetic properties of saxagliptin in terms of increased maximum plasma concentration (Cmax), area under the plasma concentration-time curve from time 0 to 24 h (AUC(0-t)), area under the plasma concentration-time curve from time 0 extrapolated to infinite time (AUC(0-∞)), decreased clearance rate (CLz/F), and prolonged terminal half-life (t1/2). In contrast, a slight inhibition was observed in saxagliptin metabolism when concomitantly used with macitentan, as no pharmacokinetic parameters were altered, except for CLz/F. Thus, dosage adjustment of saxagliptin may be required in combination with sildenafil to achieve safe therapeutic plasma concentrations and reduce the risk of potential toxicity, but it is not necessary for co-administration with macitentan.

Prevalence, Incidence and Associates of Pulmonary Hypertension Complicating Type 2 Diabetes: Insights from the Fremantle Diabetes Study Phase 2 and National Echocardiographic Database of Australia

There is a paucity of epidemiologic data examining the relationship between pulmonary hypertension (PH) and diabetes. The aim of this study was to determine prevalence, incidence and associates of PH complicating type 2 diabetes. Data from 1430 participants (mean age 65.5 years, 51.5% males) in the Fremantle Diabetes Study Phase 2 (FDS2) were linked with the National Echocardiographic Database of Australia (NEDA) to ascertain the prevalence and incidence of PH (estimated right ventricular systolic pressure (eRVSP) >30 mmHg as a new suggested threshold or the conventional >40 mmHg) over a 12-year period. PH prevalence in FDS2 was compared with that in NEDA overall and a geographically close sub-population. Multivariable analyses identified associates of prevalent/incident PH in the FDS2 cohort. Of 275 FDS2 patients (19.2%) with pre-entry echocardiography, 90 had eRVSP >30 mmHg and 35 had eRVSP >40 mmHg (prevalences 32.7% (95% CI 27.3–38.7%) and 12.7% (9.1–17.4%), respectively), rates that are 35–50% greater than national/local NEDA general population estimates. Moreover, 70 (5.0%) and 123 (9.2%) FDS2 participants were identified with incident PH at the respective eRVSP thresholds (incidence (95% CI) 7.6 (6.0–9.7) and 14.2 (11.8–17.0)/1000 person-years), paralleling data from recognised high-risk conditions such as systemic sclerosis. The baseline plasma N-terminal pro-brain natriuretic peptide concentration was the strongest independent associate of prevalent/incident PH. Approximately 1 in 8 people with type 2 diabetes have PH using the eRVSP >40 mmHg threshold. Its presence should be considered as part of regular clinical assessment of individuals with type 2 diabetes.