ORENITRAM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ORENITRAM (ORENITRAM).
ORENITRAM (treprostinil) is a prostacyclin analog that directly vasodilates pulmonary and systemic arteries, inhibits platelet aggregation, and reduces pulmonary vascular resistance via IP receptor activation, increasing cAMP levels.
| Metabolism | Primarily hepatic via CYP2C8 and CYP2C19; minor contribution from UGT enzymes. |
| Excretion | Approximately 50-70% as unchanged drug and 10-15% as inactive metabolites via urine; 4-14% via feces (biliary/fecal route) as unchanged drug and metabolites. Total renal clearance accounts for ~50% of total clearance. |
| Half-life | Terminal elimination half-life is approximately 2-4 hours in patients with pulmonary arterial hypertension (PAH). Clinical context: Requires twice-daily dosing or continuous IV infusion to maintain therapeutic concentrations. |
| Protein binding | Approximately 70-80% bound to plasma proteins, primarily to albumin. |
| Volume of Distribution | Vd is approximately 0.3-0.4 L/kg (17-24 L for a 70 kg adult), indicating distribution primarily in extracellular fluid and moderate tissue binding. |
| Bioavailability | Oral bioavailability is ~50-70% due to first-pass metabolism; administered as extended-release oral tablet or continuous IV infusion. |
| Onset of Action | Oral: Peak concentrations achieved in 1-2 hours; clinical effects on pulmonary hemodynamics observed within 30-60 minutes. IV: Immediate onset (within minutes) due to direct vascular access. |
| Duration of Action | Oral: Duration of effect on pulmonary vascular resistance is ~4-6 hours, necessitating twice-daily dosing. IV: Effect diminishes rapidly upon cessation; continuous infusion recommended. |
Initial: 0.125 mg orally twice daily; titrate as tolerated in increments of 0.125 mg twice daily every 2 weeks. Maximum dose: 1.5 mg twice daily.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl ≥30 mL/min). Not recommended in severe renal impairment (CrCl <30 mL/min) due to lack of data. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate impairment (Child-Pugh A or B), use with caution; no specific dose adjustment guidelines available. |
| Pediatric use | Safety and efficacy not established in pediatric patients; no specific dosing recommendations. |
| Geriatric use | No specific dose adjustment recommended; use standard adult dosing with careful titration due to potential for increased sensitivity and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ORENITRAM (ORENITRAM).
| Breastfeeding | It is not known whether treprostinil is excreted in human breast milk. In animal studies, treprostinil was detected in the milk of lactating rats. The Milk-to-Plasma (M/P) ratio in humans is unknown. Due to the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. |
| Teratogenic Risk | ORENITRAM (treprostinil) is a prostacyclin analogue. In animal studies, treprostinil was not teratogenic in rats or rabbits at doses up to 2.3 and 8.3 times the recommended human dose, respectively. However, there are no adequate and well-controlled studies in pregnant women. In humans, treprostinil may cause fetal harm if administered during pregnancy due to its vasodilatory effects and potential for uterine blood flow alteration. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. First trimester risks are not specifically defined but general caution applies. |
■ FDA Black Box Warning
ORENITRAM must be administered only by oral route. Do not crush, chew, or break tablets. Abrupt discontinuation may lead to rapid worsening of PAH symptoms.
| Serious Effects |
Hypersensitivity to treprostinil or any excipient; concomitant use with strong CYP2C8 inhibitors (e.g., gemfibrozil) or inducers (e.g., rifampin); severe hepatic impairment (Child-Pugh C).
| Precautions | May cause symptomatic hypotension; monitor blood pressure. Use with caution in patients with hepatic impairment; dosage adjustment required if severe (Child-Pugh C). Avoid abrupt withdrawal. May cause bleeding diathesis due to platelet inhibition. Not recommended in patients with severe left ventricular dysfunction. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of bleeding or orthostatic hypotension. During pregnancy, monitor fetal growth and well-being (e.g., ultrasound for growth, non-stress test) due to potential effects on uterine blood flow. Also monitor for signs of pulmonary hypertension worsening or right heart failure as pregnancy may exacerbate underlying disease. |
| Fertility Effects | There are no human data on the effect of treprostinil on fertility. In animal studies, treprostinil did not impair fertility in male or female rats at doses up to 2.3 and 8.3 times the recommended human dose, respectively. The clinical relevance is unknown. |