Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
RECTIV vs ISORDIL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
RECTIV (nitroglycerin) is a nitric oxide (NO) donor that relaxes vascular smooth muscle via stimulation of intracellular cyclic guanosine monophosphate (c GMP) production, leading to vasodilation. In chronic anal fissures, it reduces internal anal sphincter pressure and improves blood flow to the anoderm.
Isosorbide dinitrate is converted to nitric oxide (NO) in vascular smooth muscle, activating guanylate cyclase, increasing c GMP, leading to vasodilation of veins (greater effect) and arteries. Reduces preload and afterload, decreasing myocardial oxygen demand.
FDA-approved: Treatment of moderate to severe pain associated with chronic anal fissures
Angina pectoris (prophylaxis and acute treatment),Heart failure (off-label: adjunctive treatment in acute myocardial infarction)
1 gram (0.5 mg nitroglycerin) applied intrarectally as an ointment 10-15 minutes before anticipated bowel movement, up to twice daily.
Isosorbide dinitrate: initial 5-20 mg orally 2-3 times daily, maintenance 10-40 mg orally 2-3 times daily. Sublingual: 2.5-5 mg every 15 minutes for up to 3 doses for acute angina. Extended-release: 40 mg orally once daily, increased to 80 mg once daily as tolerated.
Terminal elimination half-life is approximately 2-4 hours in healthy adults. In patients with severe hepatic impairment, half-life may be prolonged up to 8-10 hours, requiring dose adjustment.
Terminal half-life: 1–4 hours (isosorbide dinitrate); clinical context: short duration requires frequent dosing or sustained-release formulations.
Primarily hepatic metabolism via glutathione-organic nitrate reductase, with subsequent denitration and conjugation. Metabolites include inorganic nitrate and 1,2-glyceryl dinitrate. Also undergoes hydrolysis by esterases.
Primarily hepatic via glutathione-organic nitrate reductase; also undergoes denitration to active metabolites (isosorbide-2-mononitrate and isosorbide-5-mononitrate).
Primarily renal; approximately 60-70% of the parent drug and metabolites excreted in urine within 24 hours. Fecal elimination accounts for ~20-30% via biliary secretion. Less than 1% unchanged drug recovered in feces.
Renal: 80% as inactive metabolites; biliary/fecal: 20% as conjugates.
Approximately 60% bound to plasma proteins, primarily albumin. Binding is reversible and concentration-dependent.
~28% bound to albumin.
Volume of distribution is approximately 2-4 L/kg, indicating extensive tissue distribution. Clinical meaning: high Vd suggests significant uptake into vascular smooth muscle and other tissues.
2–4 L/kg, indicating extensive tissue distribution.
Sublingual: approximately 40-50% due to first-pass metabolism. Oral: <10% due to extensive hepatic first-pass effect. Topical (RECTIV): systemic bioavailability is negligible (<1%) when applied as directed to the anal mucosa.
Sublingual: ~40–60% (first-pass bypassed); oral: <30% due to extensive first-pass hepatic metabolism.
No dosage adjustment required for renal impairment. Use with caution in severe impairment due to potential for volume depletion.
No specific GFR-based dose adjustments are recommended; however, caution is advised in severe renal impairment due to potential accumulation of metabolites.
Child-Pugh A: no adjustment. Child-Pugh B: reduce dose to 1 gram (0.5 mg) once daily. Child-Pugh C: contraindicated.
In Child-Pugh class A: no adjustment. Child-Pugh class B and C: reduce dose by 50% and monitor for hypotension.
Safety and efficacy not established in pediatric patients under 18 years.
Isosorbide dinitrate: not recommended for use in children due to lack of safety and efficacy data; no established pediatric dosing guidelines.
Use with caution; start at lowest effective dose (1 gram) and monitor for hypotension. Consider decreased renal/hepatic function.
Elderly patients may have increased sensitivity to hypotension. Initiate with lowest doses (e.g., 5 mg orally twice daily) and titrate slowly. Monitor blood pressure and orthostatic changes.
No FDA boxed warning.
Do not use in patients with erectile dysfunction medications (PDE-5 inhibitors) due to risk of severe hypotension.
Hypotension and syncope: Use with caution in patients with hypotension, hypovolemia, or those taking antihypertensives.,Severe anemia or conditions where vasodilation is detrimental.,Concomitant use with phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil) is contraindicated due to risk of severe hypotension.,May cause headaches and local burning or itching at application site.
Hypotension (especially with volume depletion or alcohol),Tolerance with prolonged use (intermittent dosing recommended),Exacerbation of angina upon abrupt withdrawal,Use cautiously in hypertrophic cardiomyopathy
Concomitant use of PDE-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil),History of hypersensitivity to nitroglycerin or any component of the formulation,Severe anemia,Increased intracranial pressure (e.g., head trauma, cerebral hemorrhage),Circulatory failure (shock) or severe hypotension
Hypersensitivity to nitrates,Concurrent use with PDE-5 inhibitors (sildenafil, tadalafil, vardenafil),Severe anemia,Increased intracranial pressure (head trauma, cerebral hemorrhage),Acute circulatory failure (shock, vascular collapse)
No specific food restrictions. Avoid alcohol as it may worsen hypotension and headache. Grapefruit juice may increase nitroglycerin levels; avoid concurrent consumption.
Avoid excessive alcohol consumption. No specific food interactions; however, high-fat meals may delay absorption of oral formulations. Maintain consistent dietary habits to minimize variations in drug effects.
Pregnancy Category B. No evidence of teratogenicity in animal studies at doses up to 10 mg/kg/day (approximately 50 times the recommended human dose). No well-controlled studies in pregnant women; use only if clearly needed. Fetal risk cannot be ruled out.
Isosorbide dinitrate (ISORDIL) is an organic nitrate vasodilator. Animal studies have not demonstrated teratogenic effects, but adequate human studies in pregnant women are lacking. It should be used during pregnancy only if clearly needed. Potential fetal risks include hypotension and reduced uteroplacental perfusion, particularly in the first trimester. Second and third trimester risks are theoretical due to maternal hemodynamic changes. Avoid use near term due to risk of neonatal methemoglobinemia. FDA pregnancy category C.
Not recommended during breastfeeding. Drug is administered topically for hemorrhoids; systemic absorption is minimal, but no data on excretion in human milk. M/P ratio not determined.
Excretion in human milk is unknown. Due to potential for serious adverse reactions in nursing infants (e.g., methemoglobinemia), a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. M/P ratio not reported.
No dose adjustment required; pharmacokinetics not studied in pregnancy. Use the same dose as in non-pregnant patients, but with caution due to lack of safety data.
Pregnancy may alter pharmacokinetics due to increased plasma volume and renal clearance; however, no specific dose adjustments are established. Use lowest effective dose with careful titration to avoid hypotension. Initiate with 5-10 mg sublingual for acute episodes; for prophylaxis, 10-40 mg orally every 6 hours. Monitor for excessive hypotension.
RECTIV (nitroglycerin) 0.4% ointment is indicated for chronic anal fissure pain. Apply a 1-inch strip intra-anally every 12 hours for up to 8 weeks. May cause headache; monitor blood pressure. Contraindicated with PDE5 inhibitors (sildenafil, tadalafil, vardenafil) due to severe hypotension. Avoid in patients with hypotension (SBP <90 mm Hg) or hypovolemia. Do not use with strong CYP3A4 inhibitors (e.g., ritonavir, cobicistat).
Isordil (isosorbide dinitrate) is a nitrate vasodilator used for angina prophylaxis. Sublingual formulation provides rapid onset for acute attacks; oral sustained-release is for chronic prophylaxis. Tolerance develops with continuous exposure; use a daily nitrate-free interval of 10-12 hours. Avoid use with PDE-5 inhibitors (sildenafil, tadalafil, vardenafil) due to severe hypotension. Monitor for headache, hypotension, and reflex tachycardia.
Apply 1-inch strip of ointment inside the anus every 12 hours using the applicator.,Wash hands before and after application.,Do not use more than 8 weeks unless directed by your doctor.,Avoid sexual activity during treatment as partner may absorb medication.,Do not take erectile dysfunction drugs (Viagra, Cialis, Levitra) while using this medication.,Seek medical help if you experience severe headache, dizziness, or fainting.,Store at room temperature away from heat and direct light.,Do not use if you have low blood pressure or are dehydrated.
Take sublingual isordil at the first sign of an angina attack; sit down before using to avoid dizziness.,For chronic prophylaxis, take as prescribed; do not skip doses to maintain the nitrate-free interval.,Avoid alcohol as it can increase the risk of hypotension and dizziness.,Report any severe headaches, worsening chest pain, or fainting to your healthcare provider immediately.,Never take erectile dysfunction medications (e.g., Viagra, Cialis, Levitra) while on isordil.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about RECTIV vs ISORDIL, answered by our medical review team.
RECTIV is a Nitrate Vasodilator that works by RECTIV (nitroglycerin) is a nitric oxide (NO) donor that relaxes vascular smooth muscle via stimulation of intracellular cyclic guanosine monophosphate (c GMP) production, leading to vasodilation. In chronic anal fissures, it reduces internal anal sphincter pressure and improves blood flow to the anoderm.. ISORDIL is a Nitrate Vasodilator that works by Isosorbide dinitrate is converted to nitric oxide (NO) in vascular smooth muscle, activating guanylate cyclase, increasing c GMP, leading to vasodilation of veins (greater effect) and arteries. Reduces preload and afterload, decreasing myocardial oxygen demand.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between RECTIV and ISORDIL depend on the specific clinical indication. These are both Nitrate Vasodilator agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of RECTIV is: 1 gram (0.5 mg nitroglycerin) applied intrarectally as an ointment 10-15 minutes before anticipated bowel movement, up to twice daily.. The standard adult dose of ISORDIL is: Isosorbide dinitrate: initial 5-20 mg orally 2-3 times daily, maintenance 10-40 mg orally 2-3 times daily. Sublingual: 2.5-5 mg every 15 minutes for up to 3 doses for acute angina. Extended-release: 40 mg orally once daily, increased to 80 mg once daily as tolerated.. 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 RECTIV and ISORDIL 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. RECTIV is classified as Category C. Pregnancy Category B. No evidence of teratogenicity in animal studies at doses up to 10 mg/kg/day (approximately 50 times the recommended human dose). No well-controlled studies in. ISORDIL is classified as Category C. Isosorbide dinitrate (ISORDIL) is an organic nitrate vasodilator. Animal studies have not demonstrated teratogenic effects, but adequate human studies in pregnant women are lacking. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.