Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
Hydralazine vs REMODULIN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased peripheral vascular resistance and blood pressure. Its exact mechanism is unclear but may involve interference with calcium movement and increased c GMP levels.
Treprostinil is a synthetic prostacyclin analog that directly vasodilates pulmonary and systemic arterial beds, inhibits platelet aggregation, and suppresses smooth muscle proliferation.
Hypertension (adjunctive therapy),Off-label: Chronic heart failure (in combination with isosorbide dinitrate, especially in African American patients)
Pulmonary arterial hypertension (WHO Group I) to improve exercise capacity and reduce symptoms,Off-label: Severe Raynaud's phenomenon, digital ischemia, and salvage therapy for PAH in patients failing other prostacyclins
10-50 mg orally every 6 hours, titrate to maximum 300 mg/day; 10-20 mg intramuscularly or intravenously every 4-6 hours as needed.
Continuous subcutaneous infusion: Initially 1.25 ng/kg/min; increase by 1.25 ng/kg/min every week for first 4 weeks, then by 2.5 ng/kg/min every week as tolerated. Intravenous infusion: same dosing.
The terminal elimination half-life of hydralazine is approximately 2-4 hours in patients with normal renal function. However, the duration of antihypertensive effect may be longer (6-12 hours) due to tissue binding and slow release from vascular smooth muscle. In renal impairment, half-life may extend to 7-16 hours, necessitating dose adjustment.
Terminal elimination half-life is approximately 4 hours (range 2-7 hours) following continuous subcutaneous infusion; clinical context: requires continuous infusion due to short half-life.
Primarily hepatic via acetylation (N-acetyltransferase 2, NAT2). Metabolites include hydralazine pyruvic acid hydrazone and acetylhydralazine.
Hepatic metabolism via CYP2C8 and CYP2C9 (major), with minor contributions from CYP2C19 and CYP2D6; major metabolite is a glucuronide conjugate.
Hydralazine is primarily metabolized in the liver via N-acetylation and hydroxylation. Approximately 80-90% of the drug is eliminated in urine as metabolites, with less than 10% excreted unchanged. A small fraction appears in feces via biliary excretion.
Renal: 20-30% as unchanged drug; fecal: 70-80% as metabolites (via biliary elimination).
85-90% bound primarily to albumin and alpha-1-acid glycoprotein.
Approximately 58% bound to human plasma proteins, primarily to albumin.
1.5-2.0 L/kg. This high Vd indicates extensive tissue binding and accumulation in vascular smooth muscle.
Volume of distribution (Vd) is 1.3 L/kg (range 0.8-2.0 L/kg); clinical meaning: extensive distribution into tissues, exceeding total body water.
Oral: 10-30% due to extensive first-pass metabolism. Bioavailability is lower in fast acetylators. Bioavailability is 100% for intravenous administration.
Subcutaneous: approximately 100% bioavailable compared to intravenous; oral: negligible (not administered orally).
GFR 10-50 m L/min: administer every 8-12 hours; GFR <10 m L/min: administer every 12-24 hours.
No dosage adjustment required for renal impairment.
Child-Pugh A: caution, consider starting at 25% of normal dose; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated.
Mild to moderate hepatic impairment (Child-Pugh class A or B): no adjustment. Severe hepatic impairment (Child-Pugh class C): contraindicated.
0.75-1 mg/kg/day orally divided every 6-12 hours, maximum 7.5 mg/kg/day; intravenous: 0.1-0.2 mg/kg/dose every 4-6 hours as needed.
Not established; safety and efficacy in pediatric patients have not been studied.
Start at 10 mg orally twice daily, increase slowly; monitor for hypotension and reflex tachycardia; maximal dose 200 mg/day.
No specific dose adjustment recommended; use with caution due to age-related renal/hepatic decline.
Systemic lupus erythematosus-like syndrome (drug-induced lupus) with long-term use at high doses.
None. However, infusion site reactions (pain, erythema, induration) and risk of catheter-related bloodstream infections are significant concerns.
May cause drug-induced lupus erythematosus; discontinue if symptoms develop.,Peripheral neuritis (pyridoxine deficiency) with long-term use.,May precipitate angina or myocardial infarction in patients with coronary artery disease.,Tachycardia and palpitations may occur; use with beta-blockers if needed.,Blood dyscrasias (rare).
Sudden discontinuation may worsen PAH; taper if possible.,Infusion site reactions are common; avoid extravasation.,Risk of bleeding due to antiplatelet effects; use with caution in patients with peptic ulcer disease or on anticoagulants.,Hepatic impairment may increase exposure; dosage adjustment may be needed.,May cause systemic hypotension; monitor blood pressure.
Hypersensitivity to hydralazine,Coronary artery disease (angina pectoris, myocardial infarction),Mitral valve rheumatic heart disease,Aortic aneurysm (relative)
Known hypersensitivity to treprostinil or any excipient,Patients with severe hepatic impairment (Child-Pugh class C) due to lack of safety data
Take with food or milk to reduce stomach upset and slow absorption. Avoid high-tyramine foods (e.g., aged cheese, cured meats, fermented products) if taking a combination product containing hydralazine and hydrochlorothiazide–though hydralazine alone has no known significant food interactions. Limiting salt intake enhances antihypertensive effect.
There are no known food interactions with treprostinil. However, patients should maintain a balanced diet as part of overall PAH management. Grapefruit juice has not been reported to interact, but always consult with a healthcare provider.
FDA Pregnancy Category C. First trimester: No well-controlled studies; animal studies show no evidence of teratogenicity but embryotoxicity at high doses. Second/Third trimesters: Associated with maternal hypotension potentially reducing placental perfusion; no fetal malformations reported, but neonatal thrombocytopenia, lupus-like syndrome, and arrhythmias reported with chronic use near term.
Teriprostinil (REMODULIN) is contraindicated in pregnancy due to teratogenic effects in animal studies (increased cardiovascular and skeletal malformations). There are no adequate human data; however, based on animal findings, fetal risk cannot be excluded, particularly in the first trimester. In later trimesters, risks include potential fetal harm from maternal hypotension and hypoxia.
Excreted into breast milk in small amounts (M/P ratio estimated 1.0-1.4). No reported adverse effects in infants. American Academy of Pediatrics considers compatible with breastfeeding. Monitor infant for hypotensive effects or drug accumulation, especially in neonates or preterm infants.
It is unknown if teriprostinil is excreted in human milk. M/P ratio not established. Due to potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during treatment and for at least 48 hours after the last dose.
Increased volume of distribution and plasma clearance may require dose adjustments. Initial oral: 10 mg 4 times daily, titrate up to 300 mg/day. In severe hypertension, IV bolus (5-10 mg) may be used with caution. Monitor for reflex tachycardia and hypotension; dose titration based on maternal response.
Pregnancy is a contraindication; thus no dose adjustments are applicable. However, if used in exceptional circumstances, plasma volume expansion in pregnancy may alter drug distribution, but specific dose recommendations are lacking. Use is not recommended.
Hydralazine is a direct-acting vasodilator; first dose may cause profound hypotension—administer with food to减缓 absorption. Monitor for drug-induced lupus (especially in slow acetylators); baseline ANA recommended. Tachyphylaxis occurs; combine with beta-blocker and diuretic to counteract reflex tachycardia and fluid retention. Adjust dose in renal impairment (creatinine clearance < 10 m L/min).
REMODULIN (treprostinil) is a prostacyclin analog used for pulmonary arterial hypertension (PAH). Avoid abrupt discontinuation due to risk of rebound pulmonary hypertension. Monitor for infusion site reactions and bleeding risk due to antiplatelet effects. Dose titration should be guided by PAH symptoms and side effects. Use with caution in patients with hepatic impairment.
Take this medication exactly as prescribed, usually 3-4 times daily. Swallow tablets whole with a glass of water.,Do not stop taking this drug suddenly, as this may cause a rapid increase in blood pressure.,This medication may cause dizziness or lightheadedness, especially when getting up from a sitting or lying position. Rise slowly.,Report any unexplained fever, joint pain, rash, or sore throat to your healthcare provider immediately—these could be signs of a lupus-like reaction.,Avoid alcohol, as it can increase side effects like dizziness or drowsiness.,If you miss a dose, take it as soon as you remember unless it is almost time for the next dose. Do not double the dose.
Do not stop taking this medication suddenly; sudden cessation may cause worsening of symptoms.,Report any signs of bleeding (e.g., easy bruising, nosebleeds, blood in urine or stool) to your healthcare provider.,If using subcutaneous infusion, rotate injection sites to prevent site reactions and infection.,Store medication as directed; do not freeze or expose to excessive heat.,Avoid activities that increase bleeding risk, such as contact sports, until you discuss with your doctor.
"Oxaprozin, a nonsteroidal anti-inflammatory drug (NSAID), can reduce the antihypertensive efficacy of hydralazine, a direct-acting vasodilator. NSAIDs inhibit prostaglandin synthesis, which can lead to sodium and fluid retention and increased vascular resistance, thereby counteracting the vasodilatory effects of hydralazine. This interaction may result in diminished blood pressure control and require dosage adjustments or alternative therapies."
"Hydralazine, a direct-acting vasodilator, may reduce the antihypertensive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) like sulindac. NSAIDs inhibit cyclooxygenase-mediated prostaglandin synthesis, leading to sodium retention and increased vascular tone, which can antagonize the vasodilatory effects of hydralazine. This interaction may result in elevated blood pressure and diminished control of hypertension in patients receiving both agents."
"Hydralazine, a direct-acting vasodilator, may reduce the antihypertensive efficacy of Tolfenamic acid, a nonsteroidal anti-inflammatory drug (NSAID) that non-selectively inhibits cyclooxygenase (COX) enzymes. The interaction arises because Tolfenamic acid's inhibition of COX-2 reduces synthesis of vasodilatory prostaglandins (e.g., prostacyclin) in the vascular endothelium, which counteracts the vasodilation induced by Hydralazine. Clinically, this can lead to blunted blood pressure reduction, potentially requiring dose adjustments or alternative therapies to maintain adequate hypertension control."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about Hydralazine vs REMODULIN, answered by our medical review team.
Hydralazine is a Vasodilator that works by Hydralazine is a direct-acting vasodilator that relaxes arteriolar smooth muscle, leading to decreased peripheral vascular resistance and blood pressure. Its exact mechanism is unclear but may involve interference with calcium movement and increased c GMP levels.. REMODULIN is a Prostacyclin Vasodilator that works by Treprostinil is a synthetic prostacyclin analog that directly vasodilates pulmonary and systemic arterial beds, inhibits platelet aggregation, and suppresses smooth muscle proliferation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between Hydralazine and REMODULIN depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of Hydralazine is: 10-50 mg orally every 6 hours, titrate to maximum 300 mg/day; 10-20 mg intramuscularly or intravenously every 4-6 hours as needed.. The standard adult dose of REMODULIN is: Continuous subcutaneous infusion: Initially 1.25 ng/kg/min; increase by 1.25 ng/kg/min every week for first 4 weeks, then by 2.5 ng/kg/min every week as tolerated. Intravenous infusion: same dosing.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between Hydralazine and REMODULIN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. Hydralazine is classified as Category A/B. FDA Pregnancy Category C. First trimester: No well-controlled studies; animal studies show no evidence of teratogenicity but embryotoxicity at high doses. Second/Third trimesters: . REMODULIN is classified as Category C. Teriprostinil (REMODULIN) is contraindicated in pregnancy due to teratogenic effects in animal studies (increased cardiovascular and skeletal malformations). There are no adequate . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.