Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
During clinical trials, adverse events were classified as follows: (1) adverse events during dose initiation and escalation, (2) adverse events during chronic dosing, and (3) adverse events associated with the drug delivery system.
Adverse Events during Dose Initiation and Escalation
During early clinical trials, epoprostenol was increased in 2-ng/kg/min increments until the patients developed symptomatic intolerance. The most common adverse events and the adverse events that limited further increases in dose were generally related to vasodilation, the major pharmacologic effect of epoprostenol. The most common dose-limiting adverse events (occurring in >1% of patients) were nausea, vomiting, headache, hypotension, and flushing, but also include chest pain, anxiety, dizziness, bradycardia, dyspnea, abdominal pain, musculoskeletal pain, and tachycardia. Table 8 lists the adverse events reported during dose initiation and escalation in decreasing order of frequency.
Table 8: Adverse Events during Dose Initiation and Escalation
Adverse Events Occurring in ≥1% of Patients
| Epoprostenol (n = 391)
|
Flushing
| 58%
|
Headache
| 49%
|
Nausea/vomiting
| 32%
|
Hypotension
| 16%
|
Anxiety, nervousness, agitation
| 11%
|
Chest pain
| 11%
|
Dizziness
| 8%
|
Bradycardia
| 5%
|
Abdominal pain
| 5%
|
Musculoskeletal pain
| 3%
|
Dyspnea
| 2%
|
Back pain
| 2%
|
Sweating
| 1%
|
Dyspepsia
| 1%
|
Hypesthesia/paresthesia
| 1%
|
Tachycardia
| 1%
|
Adverse Events during Chronic Administration:
Interpretation of adverse events is complicated by the clinical features of PAH, which are similar to some of the pharmacologic effects of epoprostenol (e.g., dizziness, syncope). Adverse events which may be related to the underlying disease include dyspnea, fatigue, chest pain, edema, hypoxia, right ventricular failure, and pallor. Several adverse events, on the other hand, can clearly be attributed to epoprostenol. These include hypotension, bradycardia, tachycardia, pulmonary edema, bleeding at various sites, thrombocytopenia, headache, abdominal pain, pain (unspecified), sweating, rash, arthralgia, jaw pain, flushing, diarrhea, nausea and vomiting, flu-like symptoms, anxiety/nervousness, and agitation. In addition, chest pain, fatigue, and pallor have been reported during epoprostenol therapy, and a role for the drug in these events cannot be excluded.
Adverse Events during Chronic Administration for Idiopathic or Heritable PAH:
In an effort to separate the adverse effects of the drug from the adverse effects of the underlying disease, Table 9 lists adverse events that occurred at a rate at least 10% greater on epoprostenol than on conventional therapy in controlled trials for idiopathic or heritable PAH.
Table 9: Adverse Events Regardless of Attribution Occurring in Patients with Idiopathic or Heritable PAH with ≥10% Difference between Epoprostenol and Conventional Therapy Alone
Adverse Event
| Epoprostenol (n = 52)
| Conventional Therapy (n = 54)
|
Occurrence More Common With Epoprostenol
|
General
| | |
Chills/fever/sepsis/flu-like symptoms
| 25%
| 11%
|
Cardiovascular
| | |
Tachycardia
| 35%
| 24%
|
Flushing
| 42%
| 2%
|
Gastrointestinal
| | |
Diarrhea
| 37%
| 6%
|
Nausea/vomiting
| 67%
| 48%
|
Musculoskeletal
| | |
Jaw pain
| 54%
| 0%
|
Myalgia
| 44%
| 31%
|
Nonspecific musculoskeletal pain
| 35%
| 15%
|
Neurological
| | |
Anxiety/nervousness/tremor
| 21%
| 9%
|
Dizziness
| 83%
| 70%
|
Headache
| 83%
| 33%
|
Hypesthesia, hyperesthesia, paresthesia
| 12%
| 2%
|
Thrombocytopenia has been reported during uncontrolled clinical trials in patients receiving epoprostenol.
Adverse Events during Chronic Administration for PAH/SSD
In an effort to separate the adverse effects of the drug from the adverse effects of the underlying disease, Table 10 lists adverse events that occurred at a rate at least 10% greater on epoprostenol in the controlled trial.
Table 10: Adverse Events Regardless of Attribution Occurring in Patients with PAH/SSD With ≥10% Difference Between Epoprostenol and Conventional Therapy Alone
Adverse Event
| Epoprostenol (n = 56)
| Conventional Therapy (n = 55)
|
Cardiovascular
| | |
Flushing
| 23%
| 0%
|
Hypotension
| 13%
| 0%
|
Gastrointestinal
| | |
Anorexia
| 66%
| 47%
|
Nausea/vomiting
| 41%
| 16%
|
Diarrhea
| 50%
| 5%
|
Musculoskeletal
| | |
Jaw pain
| 75%
| 0%
|
Pain/neck pain/arthralgia
| 84%
| 65%
|
Neurological
| | |
Headache
| 46%
| 5%
|
Skin and Appendages
| | |
Skin ulcer
| 39%
| 24%
|
Eczema/rash/urticaria
| 25%
| 4%
|
Although the relationship to epoprostenol administration has not been established, pulmonary embolism has been reported in several patients taking epoprostenol and there have been reports of hepatic failure.
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. This rate was higher than reported in patients using chronic indwelling central venous catheters to administer parenteral nutrition, but lower than reported in oncology patients using these catheters. Malfunctions in the delivery system resulting in an inadvertent bolus of or a reduction in epoprostenol were associated with symptoms related to excess or insufficient epoprostenol, respectively.