Treprostinil

Overview
Treprostinil is a synthetic analogue of prostacyclin, used to treat pulmonary hypertension. Treprostinil is marketed as Remodulin®.

Clinical pharmacology
As an analogue of prostacyclin PGI2, treprostinil effects vasodilation, which in turn lowers the blood pressure. Treprostinil also inhibits platelet aggregation, though the role this phenomenon may play in relation to pulmonary hypertension has yet to be determined.

Dosage and administration
Treprostinil is administered via a small infusion pump that the patient must wear at all times. Treprostinil is preferentially given subcutaneously using an infusion set, but may be given intravenously via a central venous catheter if the patient is unable to tolerate the potential pain and discomfort of subcutaneous administration.

Treprostinil, under the trademark Remodulin&reg;, is supplied in 20 mL vials, ranging in concentrations of 1 mg/mL, 2.5 mg/mL, 5 mg/mL, and 10 mg/mL. Treprostinil can be administered subcutaneously as supplied. It must be diluted for intravenous infusion with either sterile water or a 0.9% sodium chloride solution prior to administration.

The infusion rate is normally initiated at 1.25 ng/kg/min for new patients, but may be reduced to 0.625 ng/kg/min if the normal rate provokes unwanted side effects in the patient. The infusion rate of trepostinil should be increased no more than 1.25 ng/kg/min per week for the first month, then no more than 2.5 ng/kg/min per week for the remaining duration of infusion. The infusion rate should ideally be high enough to improve symptoms of pulmonary hypertension, while minimizing unpleasant side effects.

Oral and inhaled forms of treprostinil are currently undergoing clinical trials.

Important safety information
Precautions:


 * Since treprostinil is a vasodilator, its antihypertensive effect may be compounded by other medications that affect the blood pressure, including calcium channel blockers, diuretics, and other vasodilating agents.


 * Because of treprostinil's inhibiting effect on platelet aggregation, there is an increased risk of bleeding, especially among patients who are also taking anticoagulants.


 * It is not known whether treprostinil is excreted in breast milk. Caution is advised when administering this medication to nursing women.


 * Caution is advised when administering treprostinil to patients who have impaired kidney or liver function.

Common side effects:


 * 85% of patients report pain or other reaction at the infusion site. Other side effects may include headache, diarrhea, nausea, rash, jaw pain, vasodilatation, dizziness, edema (swelling), pruritus (itching), and hypotension.

Warnings:


 * Abrupt interruption of the treprostinil infusion can lead to worsening of pulmonary hypertension symptoms, and should be avoided.

Treprostinil