Phenytoin Infatabs and Treprostinil Sodium

• Generic Name: phenytoin
• Dosage Forms: tablet, chewable
• Other Brand Names: Dilantin, Phenytek, Dilantin Infatabs, Phenytoin Sodium, Prompt

Phenytoin is an anti-epileptic drug, also called an anticonvulsant. Phenytoin works by slowing down impulses in the brain that cause seizures.

Phenytoin is used to control seizures. It does not treat all types of seizures, and your doctor will determine if it is the right medicine for you.

• Generic Name: treprostinil
• Dosage Forms: n.a.
• Other Brand Names: Orenitram, Remodulin, Tyvaso, Tyvaso Refill Kit, Tyvaso Starter Kit

Treprostinil is used parenterally (as a continuous sub-Q or IV infusion) for treatment of pulmonary arterial hypertension (PAH; WHO group 1) to reduce symptoms associated with exercise; efficacy established in patients with NYHA functional class II–IV (predominantly class III) PAH (idiopathic, heritable, or associated with connective tissue disease or congenital systemic-to-pulmonary shunts). Also used parenterally to reduce rate of clinical deterioration in patients who require conversion from epoprostenol therapy; carefully consider risks and benefits of each drug prior to transition.

Treprostinil is used by oral inhalation to improve exercise ability in patients with PAH; efficacy established principally in patients with NYHA functional class III PAH (idiopathic, heritable, or associated with connective tissue disease). Controlled clinical experience with orally inhaled treprostinil is based primarily on short-term trials in patients receiving the drug as add-on therapy to bosentan or sildenafil.

Treprostinil diolamine is used orally (as extended-release tablets) to improve exercise capacity in patients with PAH; efficacy established principally in patients with WHO functional class II–III PAH (idiopathic, heritable, or associated with connective tissue disease). Oral treprostinil may be more convenient than inhaled or parenteral formulations; however, studies have shown only modest benefits of oral treprostinil on exercise capacity. When the drug is used as the sole vasodilator in patients with PAH, the effect on exercise capacity is approximately 10% of the deficit, and the effect, if any, in combination with other vasodilators is probably even less.

Parenteral or inhaled treprostinil is recommended as one of several treatment options for initial management of PAH in patients with NYHA/WHO functional class III or IV symptoms who are not candidates for calcium-channel blocker therapy or in whom such therapy failed. While oral treprostinil may be a potential initial treatment option for patients with less severe PAH, additional studies are needed.

Individualize choice of therapy; consider factors such as disease severity, route of administration, potential adverse effects and costs of treatment, clinician experience, and patient preference.

Combination therapy with drugs that target different pathophysiologic pathways of the disease should be considered since such therapy may provide additive and/or synergistic benefits. Results of studies evaluating combination therapy with treprostinil have been variable; some studies (inhaled treprostinil in combination with an endothelin-receptor antagonist or a PDE type 5 inhibitor) demonstrated improvements in 6-minute walking distance, while other studies (oral treprostinil with an endothelin-receptor antagonist and/or a PDE type 5 inhibitor) have not shown benefit.

Treprostinil and treprostinil diolamine have been designated orphan drugs by FDA for treatment of PAH.