Sterile Diluent

Each vial is for single dose only; discard any unused diluent or unused reconstituted solution.

Select a concentration for the solution of epoprostenol sodium for injection that is compatible with the infusion pump being used with respect to minimum and maximum flow rates, reservoir capacity, and the infusion pump criteria listed below [see Dosage and Administration (2.4)].

Using aseptic technique, reconstitute epoprostenol sodium for injection only with STERILE DILUENT for epoprostenol sodium for injection. Table 1 gives directions for preparing several different concentrations of epoprostenol sodium for injection. See Table 2 for storage and administration time limits for the reconstituted epoprostenol sodium for injection.

Initiate intravenous infusions of epoprostenol sodium for injection at 2 ng/kg/min. Alter the infusion by 1- to 2-ng/kg/min increments at intervals sufficient to allow assessment of clinical response. These intervals should be at least 15 minutes.

During dose initiation, asymptomatic increases in pulmonary artery pressure coincident with increases in cardiac output may occur. In such cases, consider dose reduction, but such an increase does not imply that chronic treatment is contraindicated.

Base changes in the chronic infusion rate on persistence, recurrence, or worsening of the patient's symptoms of pulmonary hypertension and the occurrence of adverse vasodilatory reactions. In general, expect progressive increases in dose.

If dose-related adverse reactions occur, make dose decreases gradually in 2-ng/kg/min decrements every 15 minutes or longer until the dose-limiting effects resolve [see Adverse Reactions ( 6.1, 6.2)]. Avoid abrupt withdrawal of epoprostenol sodium for injection or sudden large reductions in infusion rates [see Warnings and Precautions ( 5.2)].

Following establishment of a new chronic infusion rate, measure standing and supine blood pressure for several hours.

Taper doses of epoprostenol sodium for injection after initiation of cardiopulmonary bypass in patients receiving lung transplants.

Initiate epoprostenol in a setting with adequate personnel and equipment for physiologic monitoring and emergency care.

Inspect parenteral drug products for particulate matter and discoloration prior to administration whenever solution and container permit. If either particulate matter or discoloration is noted, do not use.

Administer continuous chronic infusion of epoprostenol sodium for injection through a central venous catheter. Temporary peripheral intravenous infusion may be used until central access is established. Do not administer bolus injections of epoprostenol sodium for injection.

The ambulatory infusion pump used to administer epoprostenol sodium for injection should: (1) be small and lightweight, (2) be able to adjust infusion rates in 2-ng/kg/min increments, (3) have occlusion, end-of-infusion, and low-battery alarms, (4) be accurate to ± 6% of the programmed rate, and (5) be positive-pressure-driven (continuous or pulsatile) with intervals between pulses not exceeding 3 minutes at infusion rates used to deliver epoprostenol sodium for injection. The reservoir should be made of polyvinyl chloride, polypropylene, or glass. Use a 60-inch microbore non-di-(2-ethylhexyl)phthalate (DEHP) extension set with proximal antisyphon valve, low-priming volume (0.9 mL), and in-line 0.22-micron filter.

To avoid interruptions in drug delivery, the patient should have access to a backup infusion pump and intravenous infusion sets.

Do not administer or dilute reconstituted solutions of epoprostenol sodium for injection with other parenteral solutions or medications. Consider a multi-lumen catheter if other intravenous therapies are routinely administered.

Select a concentration for the solution of epoprostenol sodium for injection that is compatible with the infusion pump being used with respect to minimum and maximum flow rates, reservoir capacity, and the infusion pump criteria listed above. When administered chronically, prepare epoprostenol sodium for injection in a drug delivery reservoir appropriate for the infusion pump with a total reservoir volume of at least 100 mL, using 2 vials of STERILE DILUENT for epoprostenol sodium for injection.

Generally, 3,000 ng/mL and 10,000 ng/mL are satisfactory concentrations to deliver between 2 to 16 ng/kg/min in adults. Higher infusion rates, and therefore, more concentrated solutions, may be necessary with long-term administration of epoprostenol sodium for injection.

Infusion rates may be calculated using the following formula:

Example calculations for infusion rates are as follows:

Example 1: for a 60-kg person at the recommended initial dose of 2 ng/kg/min using a 3,000-ng/mL concentration, the infusion rate would be as follows:

Example 2: for a 70-kg person at a dose of 16 ng/kg/min using a 15,000-ng/mL concentration, the infusion rate would be as follows:

If the patient develops pulmonary edema during initiation with epoprostenol, discontinue therapy and do not readminister. Consider the possibility of associated pulmonary veno-occlusive disease in such patients.

Avoid abrupt withdrawal (including interruptions in drug delivery) or sudden large reductions in dosage of epoprostenol because symptoms associated with rebound pulmonary hypertension (e.g., dyspnea, dizziness, and asthenia) may occur. In clinical trials, one Class III patient's death was judged attributable to the interruption of epoprostenol.

Epoprostenol is a potent pulmonary and systemic vasodilator and can cause hypotension and other reactions such as flushing, nausea, vomiting, dizziness, and headache. Monitor blood pressure and symptoms regularly during initiation and after dose change [see Dosage and Administration ( 2.2)].

Epoprostenol is a potent inhibitor of platelet aggregation. Therefore, expect an increased risk for hemorrhagic complications, particularly for patients with other risk factors for bleeding [see Clinical Pharmacology ( 12.3)].

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Adverse reactions are shown in Table 3 and are generally related to vasodilatory effects.

Adverse Events Attributable to the Drug Delivery System

Chronic infusions of epoprostenol are delivered using a small, portable infusion pump through an indwelling central venous catheter. During controlled PAH trials of up to 12 weeks’ duration, the local infection rate was about 18% and the rate for pain was about 11%. During long-term follow-up, sepsis was reported at a rate of 0.3 infections/patient per year in patients treated with epoprostenol.

The following events have been identified during postapproval use of epoprostenol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate reliably their frequency or establish a causal relationship to drug exposure.

Blood and Lymphatic

Anemia, hypersplenism, pancytopenia, splenomegaly, thrombocytopenia.

Cardiac

High output cardiac failure.

Endocrine and Metabolic

Hyperthyroidism.

Gastrointestinal

Hepatic failure.

Respiratory, Thoracic, and Mediastinal

Pulmonary embolism.

Risk Summary

Limited published data from case series and case reports have not established an association with epoprostenol and major birth defects, miscarriage or adverse maternal or fetal outcomes when epoprostenol is used during pregnancy. There are risks to the mother and fetus from untreated pulmonary arterial hypertension (see Clinical Considerations). In animal reproduction studies, pregnant rats and rabbits received epoprostenol sodium during organogenesis at exposures of 2.5 and 4.8 times the maximum recommended human dose (MRHD), respectively, and there was no effect on the fetus (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Clinical Considerations

Disease-Associated Maternal and/or Embryo/Fetal Risk: Pregnant women with untreated pulmonary arterial hypertension are at risk for heart failure, stroke, preterm delivery, and maternal and fetal death.

Data

Animal Data: Embryo-fetal development studies have been performed in rats and rabbits during organogenesis. Epoprostenol sodium doses up to 100 mcg/kg/day, a dose that was maternally toxic in rabbits but not in rats, (600 mcg/m²/day in rats, 2.5 times the MRHD, and 1,180 mcg/m²/day in rabbits, 4.8 times the MRHD based on body surface area), had no effect on the fetus.

In a postnatal development study, epoprostenol sodium was administered subcutaneously to female rats for 2 weeks prior to mating through weaning and to male rats for 60 days prior to and through mating at a male and female toxic dose of up to 100 mcg/kg/day (600 mcg/m²/day, 2.5 times the MRHD based on body surface area). There was no effect on growth and development of the offspring.

Risk Summary

There are no data on the presence of epoprostenol in either human or animal milk, the effects on the breastfed infant, or the effect on milk production.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for epoprostenol and any potential adverse effects on the breastfed child from epoprostenol or from the underlying maternal condition.

Safety and effectiveness in pediatric patients have not been established.

Clinical trials of epoprostenol in pulmonary hypertension did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.

Epoprostenol has 2 major pharmacological actions: (1) direct vasodilation of pulmonary and systemic arterial vascular beds and (2) inhibition of platelet aggregation.

Acute Hemodynamic Effects

Acute intravenous infusions of epoprostenol for up to 15 minutes in patients with idiopathic or heritable PAH or PAH/SSD produce dose-related increases in cardiac index (CI) and stroke volume (SV) and dose-related decreases in pulmonary vascular resistance (PVR), total pulmonary resistance (TPR), and mean systemic arterial pressure (SAPm). The effects of epoprostenol on mean pulmonary artery pressure (PAPm) were variable and minor.

In humans, hemodynamic changes due to epoprostenol (e.g., increased heart rate, facial flushing) returned to baseline within 10 minutes of termination of 60-minute infusions of 1 to 16 ng/kg/min. This pharmacodynamic behavior is consistent with a short in vivo half-life and rapid clearance in humans, as suggested by the results of animal and in vitro studies.

In animals, the vasodilatory effects reduce right- and left-ventricular afterload and increase cardiac output and stroke volume. The effect of epoprostenol on heart rate in animals varies with dose. At low doses, there is vagally-mediated bradycardia, but at higher doses, epoprostenol causes reflex tachycardia in response to direct vasodilation and hypotension. No major effects on cardiac conduction have been observed. Additional pharmacologic effects of epoprostenol in animals include bronchodilation, inhibition of gastric acid secretion, and decreased gastric emptying.

Drug Interaction Studies

Additional reductions in blood pressure may occur when epoprostenol is administered with diuretics, antihypertensive agents, or other vasodilators.

When other antiplatelet agents or anticoagulants are used concomitantly, there is a potential for epoprostenol to increase the risk of bleeding. However, patients receiving infusions of epoprostenol in clinical trials were maintained on anticoagulants without evidence of increased bleeding.

Absorption/Distribution

Epoprostenol is rapidly hydrolyzed at neutral pH in blood and is also subject to enzymatic degradation. No available chemical assay is sufficiently sensitive and specific to assess the in vivo human pharmacokinetics of epoprostenol. Animal studies using tritium-labeled epoprostenol have indicated a high clearance (93 mL/kg/min), small volume of distribution (357 mL/kg), and a short half-life (2.7 minutes). During infusions in animals, steady-state plasma concentrations of tritium-labeled epoprostenol were reached within 15 minutes and were proportional to infusion rates.

Metabolism

Tritium-labeled epoprostenol has been administered to humans in order to identify the metabolic products of epoprostenol. Epoprostenol is metabolized to 2 primary metabolites: 6-keto-PGF_1α (formed by spontaneous degradation) and 6,15-diketo-13,14-dihydro-PGF_1α (enzymatically formed), both of which have pharmacological activity orders of magnitude less than epoprostenol in animal test systems. The recovery of radioactivity in urine and feces over a 1-week period was 82% and 4% of the administered dose, respectively. Fourteen additional minor metabolites have been isolated from urine, indicating that epoprostenol is extensively metabolized in humans.

Elimination

The in vitro half-life of epoprostenol in human blood at 37°C and pH 7.4 is approximately 6 minutes; therefore, the in vivo half-life of epoprostenol in humans is expected to be no greater than 6 minutes.

Drug Interaction Studies

In a pharmacokinetic substudy in patients with congestive heart failure receiving furosemide in whom therapy with epoprostenol was initiated, apparent oral clearance values for furosemide (n = 23) were decreased by 13% on the second day of therapy and returned to baseline values by Day 87. The change in furosemide clearance value is not likely to be clinically significant.

In a pharmacokinetic substudy in patients with congestive heart failure receiving digoxin in whom therapy with epoprostenol was initiated, apparent oral clearance values for digoxin (n = 30) were decreased by 15% on the second day of therapy and returned to baseline values by Day 87. Clinical significance of this interaction is not known.

Long-term studies in animals have not been performed to evaluate carcinogenic potential. A micronucleus test in rats revealed no evidence of mutagenicity. The Ames test and DNA elution tests were also negative, although the instability of epoprostenol makes the significance of these tests uncertain.

In a fertility/postnatal development study, epoprostenol sodium was administered subcutaneously to female rats for 2 weeks prior to mating through weaning and to male rats for 60 days prior to and through mating at an adult toxic dose of up to 100 mcg/kg/day (600 mcg/m²/day, 2.5 times the MRHD based on body surface area). There was no effect on fertility in female or male rats.

Hemodynamic Effects

Chronic continuous infusions of epoprostenol in patients with idiopathic or heritable PAH were studied in 2 prospective, open, randomized trials of 8 and 12 weeks’ duration comparing epoprostenol plus conventional therapy with conventional therapy alone. Dosage of epoprostenol was determined as described in Dosage and Administration ( 2) and averaged 9.2 ng/kg/min at trials’ end. Conventional therapy varied among patients and included some or all of the following: anticoagulants in essentially all patients; oral vasodilators, diuretics, and digoxin in one-half to two-thirds of patients; and supplemental oxygen in about half the patients. Except for 2 NYHA Functional Class II patients, all patients were either functional Class III or Class IV. As results were similar in the 2 trials, the pooled results are described.

Chronic hemodynamic effects were generally similar to acute effects. Increases in CI, SV, and arterial oxygen saturation and decreases in PAPm, mean right atrial pressure (RAPm), TPR, and systemic vascular resistance (SVR) were observed in patients who received epoprostenol chronically compared with those who did not. Table 4 illustrates the treatment-related hemodynamic changes in these patients after 8 or 12 weeks of treatment.

These hemodynamic improvements appeared to persist when epoprostenol was administered for at least 36 months in an open, nonrandomized trial.

The acute hemodynamic response to epoprostenol did not correlate well with improvement in exercise tolerance or survival during chronic use of epoprostenol.

Clinical Effects

A statistically significant improvement was observed in exercise capacity, as measured by the 6-minute walk test in patients receiving continuous intravenous epoprostenol plus conventional therapy (n = 52) for 8 or 12 weeks compared with those receiving conventional therapy alone (n = 54). Improvements were apparent as early as the first week of therapy. Increases in exercise capacity were accompanied by statistically significant improvement in dyspnea and fatigue, as measured by the Chronic Heart Failure Questionnaire and the Dyspnea Fatigue Index, respectively.

Survival was improved in NYHA Functional Class III and Class IV patients with idiopathic or heritable PAH treated with epoprostenol for 12 weeks in a multicenter, open, randomized, parallel trial. At the end of the treatment period, 8 of 40 (20%) patients receiving conventional therapy alone died, whereas none of the 41 patients receiving epoprostenol died (P = 0.003).

Hemodynamic Effects

Chronic continuous infusions of epoprostenol in patients with PAH/SSD were studied in a prospective, open, randomized trial of 12 weeks’ duration comparing epoprostenol plus conventional therapy (n = 56) with conventional therapy alone (n = 55). Except for 5 NYHA Functional Class II patients, all patients were either functional Class III or Class IV. In the controlled 12-week trial in PAH/SSD, for example, the dose increased from a mean starting dose of 2.2 ng/kg/min. During the first 7 days of treatment, the dose was increased daily to a mean dose of 4.1 ng/kg/min on Day 7 of treatment. At the end of Week 12, the mean dose was 11.2 ng/kg/min. The mean incremental increase was 2 to 3 ng/kg/min every 3 weeks.

Conventional therapy varied among patients and included some or all of the following: anticoagulants in essentially all patients, supplemental oxygen and diuretics in two-thirds of the patients, oral vasodilators in 40% of the patients, and digoxin in a third of the patients. A statistically significant increase in CI and statistically significant decreases in PAPm, RAPm, PVR, and SAPm after 12 weeks of treatment were observed in patients who received epoprostenol chronically compared with those who did not. Table 5 illustrates the treatment-related hemodynamic changes in these patients after 12 weeks of treatment.

Clinical Effects

Statistically significant improvement was observed in exercise capacity, as measured by the 6-minute walk, in patients receiving continuous intravenous epoprostenol plus conventional therapy for 12 weeks compared with those receiving conventional therapy alone. Improvements were apparent in some patients at the end of the first week of therapy. Increases in exercise capacity were accompanied by statistically significant improvements in dyspnea and fatigue, as measured by the Borg Dyspnea Index and Dyspnea Fatigue Index. At Week 12, NYHA functional class improved in 21 of 51 (41%) patients treated with epoprostenol compared with none of the 48 patients treated with conventional therapy alone. However, more patients in both treatment groups (28/51 [55%] with epoprostenol and 35/48 [73%] with conventional therapy alone) showed no change in functional class, and 2/51 (4%) with epoprostenol and 13/48 (27%) with conventional therapy alone worsened.

No statistical difference in survival over 12 weeks was observed in patients with PAH/SSD treated with epoprostenol as compared with those receiving conventional therapy alone. At the end of the treatment period, 4 of 56 (7%) patients receiving epoprostenol died, whereas 5 of 55 (9%) patients receiving conventional therapy alone died.

A large trial evaluating the effect of epoprostenol on survival in NYHA Class III and IV patients with congestive heart failure due to severe left ventricular systolic dysfunction was terminated after an interim analysis of 471 patients revealed a higher mortality in patients receiving epoprostenol plus conventional therapy than in those receiving conventional therapy alone. The chronic use of epoprostenol in patients with heart failure due to severe left ventricular systolic dysfunction is therefore contraindicated.

Epoprostenol Sodium for Injection is supplied as a sterile freeze-dried powder in 10 mL flint glass vials with gray butyl rubber closures, individually packaged in a carton.

The STERILE DILUENT for Epoprostenol Sodium for Injection is supplied in flint glass vials containing 50 mL diluent with butyl rubber closures.

Proper storage and handling are essential to maintain the potency of epoprostenol sodium for injection.

Unopened vials of epoprostenol sodium for injection powder are stable until the date indicated on the package when stored at room temperature, 20°C to 25°C (68°F to 77°F) [see USP Controlled Room Temperature] and protected from light in the carton.

Unopened vial of STERILE DILUENT for epoprostenol sodium for injection is stable until the date indicated on the package when stored at room temperature, 20°C to 25°C (68°F to 77°F) [see USP Controlled Room Temperature]. DO NOT FREEZE.