Treprostinil, sold under the brand names Remodulin for infusion, Orenitram for oral, and Tyvaso for inhalation, is a vasodilator that is used for the treatment of  pulmonary arterial hypertension. Treprostinil is a synthetic analog of prostacyclin (PGI2). Treprostinil was approved for use in the United States in May 2002.The drug can be given in various forms: IV, subcutaneous injection, oral inhalation, as well as oral extended-release tablets. The subcutaneous administration tends to be very painful. Medical uses
Treprostinil is indicated for the treatment of pulmonary arterial hypertension in people with NYHA Class II-IV symptoms to diminish symptoms associated with exercise. It may be administered as a continuous subcutaneous infusion or continuous intravenous infusion; however, because of the risks associated with chronic indwelling central venous catheters, including serious blood stream infections, continuous intravenous infusion should be reserved for patients who are intolerant of the subcutaneous route, or in whom these risks are considered warranted. This medication is also available in inhaled and tablet forms. In people with pulmonary arterial hypertension requiring transition from epoprostenol sodium (Flolan), treprostinil is indicated to diminish the rate of clinical deterioration. The risks and benefits of each drug should be carefully considered prior to transition. Treprostinil therapy may be effective in treating Degos disease. Adverse effects
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.
Dosage and administration
For infusion
Treprostinil may be administered as a continuous subcutaneous infusion or continuous intravenous infusion via a small infusion pump that the patient must wear at all times. Treprostinil can be given subcutaneously by continuous infusion using an infusion set connected to an infusion pump, but also may be given intravenously via a central venous catheter if the patient is unable to tolerate subcutaneous administration because of severe site pain or reaction. Remodulin is supplied in 20 mL vials, containing treprostinil 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 treprostinil should be increased no more than 1.25 ng/kg/min per week for the first month, then 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 (headache, nausea, emesis, restlessness, anxiety and infusion site pain or reaction). Dosage adjustments may be undertaken more often if tolerated. There is little experience with doses >40 ng/kg/min. Abrupt cessation of infusion should be avoided. Restarting a Remodulin infusion within a few hours after an interruption can be done using the same dose rate.