Clinical use of extended-release oral treprostinil in the treatment of pulmonary arterial hypertension

Pharmacotherapy for Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia: Past, Present, and Future

Approximately 8-42% of premature infants with chronic lung disease of prematurity, bronchopulmonary dysplasia (BPD), develop pulmonary hypertension (PH). Infants with BPD-PH carry alarmingly high mortality rates of up to 47%. Effective PH-targeted pharmacotherapies are desperately needed for these infants. Although many PH-targeted pharmacotherapies are commonly used to treat BPD-PH, all current use is off-label. Moreover, all current recommendations for the use of any PH-targeted therapy in infants with BPD-PH are based on expert opinion and consensus statements. Randomized Control Trials (RCTs) are needed to determine the efficacy of PH-targeted treatments in premature infants with or at risk of BPD-PH. Prior to performing efficacy RCTs, studies need to be conducted to obtain pharmacokinetic, pharmacodynamic, and safety data for any pharmacotherapy used in this understudied and fragile patient population. This review will discuss current and needed treatment strategies, identify knowledge deficits, and delineate both challenges to be overcome and approaches to be taken to develop effective PH-targeted pharmacotherapies that will improve outcomes for premature infants with or at risk of developing BPD-PH.

Comparative effectiveness of oral prostacyclin pathway drugs on hospitalization in patients with pulmonary hypertension in the United States: a retrospective database analysis

Two oral medications targeting the prostacyclin pathway are available to treat pulmonary arterial hypertension in the United States: oral treprostinil and selexipag. We compared real-world hospitalization in patients receiving these medications. A retrospective administrative claims study was conducted using the Optum® Clinformatics® Data Mart database. Patients with pulmonary hypertension were identified using diagnostic codes. Cohort inclusion required age ≥ 18 years, first oral treprostinil or selexipag prescription between 1 January 2015 and 30 September 2017 (index date), and continuous enrollment in the prior ≥6 months. Patients who switched index drug were excluded. Follow-up was from index date until the first of end of index drug exposure, end of continuous enrollment, death, or 31 December 2017. Multivariable Cox proportional hazard and Poisson regression were used to compare risk and rate, respectively, of hospitalization associated with oral treprostinil vs. selexipag, adjusting for potential confounders. The study cohort included 99 patients receiving oral treprostinil and 123 receiving selexipag. Mean age was 61 years, and most patients were females (71%). Compared with oral treprostinil, selexipag was associated with a 46% lower risk of all-cause hospitalization (hazard ratio 0.54, 95% confidence interval 0.31, 0.92; P = 0.02), a 47% lower risk of pulmonary hypertension-related hospitalization (hazard ratio 0.53, 95% confidence interval 0.31, 0.93; P = 0.03), a 42% lower all-cause hospitalization rate (rate ratio 0.58, 95% confidence interval 0.39, 0.87; P = 0.01), and a 46% lower pulmonary hypertension-related hospitalization rate (rate ratio 0.54, 95% confidence interval 0.35, 0.82; P = 0.004). This study suggests that selexipag is associated with lower hospitalization risk and rate than oral treprostinil.

Transitions between infused and oral prostacyclin pathway agents in pulmonary arterial hypertension: key considerations

Prostacyclin pathway agents are a critical treatment for patients with pulmonary arterial hypertension. Seven prostacyclin pathway agents are available, including agents administered by parenteral infusion, by inhalation, and orally. Pulmonary arterial hypertension patients are now transitioned from one prostacyclin pathway agent to another with increasing frequency. Such transitions require careful downtitration and uptitration to avoid decompensation from rapid withdrawal and to achieve a patient's optimal dose based on efficacy and tolerability. Clinical guidance is especially lacking for transitions involving the newer, oral prostacyclin pathway agents; specifically, selexipag and oral treprostinil. We present three case reports of patients with pulmonary arterial hypertension who underwent one or more transition between parenteral and oral prostacyclin pathway agents, including some transitions that were successful and some that were not. These cases illustrate key considerations, such as titration protocols, patient selection, side effect management, and pharmacokinetics.

Transition from selexipag to oral treprostinil in a patient with pulmonary arterial hypertension

Prostacyclins are the mainstay treatment for patients with severe pulmonary arterial hypertension. This case highlights the transition from selexipag to oral treprostinil. Our patient improved both subjectively and objectively. Cardiac output and index, as measured by the echocardiogram, improved 12% and 7.7%, respectively. Invasive hemodynamic data revealed greater improvements: cardiac output improved by 25% and cardiac index by 28%. Mixed venous oxygen saturation improved from 65% to 71%. A possible explanation is that selexipag has a maximal dose, whereas there is no recommended maximum dose of oral treprostinil. Another theory is oral treprostinil has higher affinity to the IP receptor, though selexipag has a higher specificity. However, there are no bio-equivalency data, and data comparing pharmacodynamics of both drugs are lacking. Furthermore, no head-to-head trials comparing these agents exist.

An implantable pump Lenus pro® in the treatment of pulmonary arterial hypertension with intravenous treprostinil

Background

Subcutaneous treprostinil is a prostacyclin analogue used to treat pulmonary arterial hypertension (PAH). Due to local pain it can cause a deterioration of heart related quality of life (HRQoL) or even abandonment of treatment. The aim of this paper was to assess the feasibility of treatment with intravenous treprostinil administered by means of the Lenus Pro® implantable pump.

Methods

This was a retrospective, multi-center study involving 12 patients (8 females) with PAH treated with a subcutaneous infusion of treprostinil with intolerable pain at the infusion site. Clinical evaluation, including HRQoL assessment with SF-36 questionnaire was performed, before pump implantation and 2–9 months after. The median time of follow-up time was 14 months (4–29 months).

Results

After implantation of the Lenus Pro® pump, no statistically significant changes were observed in the 6-min walking distance and NT-proBNP. After implantation 50% of patients were in II WHO functional class (33% before, p = 0,59). There was a significant improvement in HRQoL within the Physical Component Score (28 ± 7 vs 38 ± 8 pts., p < 0,001) and in specific domains of SF-36 form: physical role (31 ± 7 pts. vs. 41 ± 12 pts., p = 0,03), bodily pain (31 ± 12 vs. 50 ± 14 pts., p = 0,02), and vitality (37 ± 8 pts. vs. 50 ± 14 pts., p = 0,03). During the periprocedural period, one patient developed a recurrent haematoma at the implantation site. During follow-up in one patient, the drug delivering cannula slipped out of the subclavian vein, what required repositioning repeated twice, and in another patient an unexpected increase in the drug administration rate was observed.

Conclusions

In patients with PAH who do not tolerate subcutaneous infusion of treprostinil, the use of the Lenus Pro® implantable pump results in significant subjective improvement of vitality and physical aspect of the HRQoL with acceptable safety profile.

Effect of gemfibrozil and rifampicin on the pharmacokinetics of selexipag and its active metabolite in healthy subjects

AIMS

Based on in vitro data, there is evidence to suggest that cytochrome P450 (CYP) 2C8 is involved in the metabolism of selexipag and its active metabolite, ACT-333679. The present study evaluated the possible pharmacokinetic interactions of selexipag with gemfibrozil, a strong CYP2C8 inhibitor, and rifampicin, an inducer of CYP2C8.

METHODS

The study consisted of two independent parts, each conducted according to an open-label, randomized, crossover design. The pharmacokinetics and safety of selexipag and ACT-333679 were studied following single-dose administration either alone or in the presence of multiple-dose gemfibrozil (part I) or rifampicin (part II) in healthy male subjects.

RESULTS

Gemfibrozil had comparatively small effects on selexipag (less than 2-fold difference in any pharmacokinetic variable) but, with respect to ACT-333679, increased the maximum plasma concentration (C_max ) 3.6-fold [90% confidence interval (CI) 3.1, 4.3] and the area under the plasma concentration-time curve from zero to infinity (AUC_0-∞ ) 11.1-fold (90% CI 9.2, 13.4). The marked increased exposure to ACT-333679, which mediates the majority of the pharmacological activity of selexipag, was accompanied by significantly more adverse events such as headache, nausea and vomiting. Coadministration of rifampicin increased the C_max of selexipag 1.8-fold (90% CI 1.4, 2.2) and its AUC0_-∞ 1.3-fold (90% CI 1.1, 1.4); its effects on ACT-333679 were to increase its C_max 1.3-fold (90% CI 1.1, 1.6), shorten its half-life by 63% and reduce its AUC0_-∞ by half (90% CI 0.45, 0.59).

CONCLUSION

Concomitant administration of selexipag and strong inhibitors of CYP2C8 must be avoided, whereas when coadministered with inducers of CYP2C8, dose adjustments of selexipag should be envisaged.