Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEMADEX vs RELISTOR
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Inhibits the Na-K-2Cl symporter in the thick ascending limb of the loop of Henle, reducing reabsorption of sodium, chloride, and potassium, leading to increased urine output.
Peripherally acting mu-opioid receptor antagonist that blocks opioid-induced constipation without affecting central analgesia.
Edema associated with heart failure, hepatic cirrhosis, and renal disease,Hypertension (off-label)
Treatment of opioid-induced constipation (OIC) in adult patients with chronic non-cancer pain,Treatment of OIC in adult patients with advanced illness who are receiving palliative care
Oral: 5-10 mg once daily; may increase to 20 mg once daily if needed. IV: 5-10 mg once daily; may increase to 20 mg once daily if needed. Maximum dose: 40 mg/day.
0.15 mg/kg subcutaneously once daily, maximum 16 mg per dose; for opioid-induced constipation, 8 mg subcutaneously once daily.
The terminal elimination half-life is approximately 4 hours (range 2-8 hours) in patients with normal renal function. In renal impairment (creatinine clearance <30 m L/min), half-life is prolonged to 10-12 hours due to reduced renal clearance. In hepatic cirrhosis, half-life may be extended to 8-9 hours due to decreased metabolism.
Terminal elimination half-life is approximately 8-10 hours in patients with normal renal function. In patients with end-stage renal disease, half-life is prolonged (~14-18 hours).
Primarily hepatic via CYP450 enzymes, with minimal renal clearance.
Primarily hepatic via CYP3A4 and CYP2D6 isoenzymes; also undergoes gut wall metabolism.
Approximately 50% of the absorbed dose is excreted unchanged in the urine via glomerular filtration and active tubular secretion. The remainder undergoes hepatic metabolism to glucuronide conjugates and minor oxidative metabolites, with biliary excretion of metabolites (about 30-40% of the dose) eliminated in feces. Renal clearance is the primary route for the parent drug.
Renal excretion of unchanged drug accounts for approximately 16% of the dose; biliary/fecal excretion is the major route (approximately 54% recovered in feces).
Torsemide (DEMADEX) is extensively bound to plasma proteins, primarily albumin, with a protein binding of >99%.
Approximately 11-15% bound to plasma proteins (primarily albumin).
The apparent volume of distribution (Vd) is approximately 0.16 L/kg (range 0.12–0.20 L/kg), indicating distribution primarily within extracellular fluid. Vd is increased in conditions with expanded extracellular volume (e.g., heart failure, cirrhosis, nephrotic syndrome).
Approximately 1.1 L/kg (central volume ~0.3 L/kg); indicates extensive extravascular distribution.
Oral bioavailability is approximately 80–90%, with minimal first-pass metabolism. Absorption is rapid and not significantly affected by food.
Subcutaneous: approximately 82-100% (mean ~97%); oral: approximately 6% (low due to first-pass metabolism).
GFR <20 m L/min/1.73 m²: Use with caution; may require dose reduction or discontinuation due to accumulation. GFR 20-50: No adjustment needed. GFR >50: No adjustment.
For creatinine clearance <30 m L/min: 0.075 mg/kg subcutaneously every other day, maximum 8 mg per dose; not recommended in patients with end-stage renal disease requiring dialysis.
Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose by 50% or extend interval. Child-Pugh C: Avoid use or reduce dose by 75%.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); not studied in severe impairment (Child-Pugh C).
Neonates and infants: 0.1-0.2 mg/kg/dose IV/IM once daily. Children: Oral: 0.5-1 mg/kg once daily; IV/IM: 0.1-0.2 mg/kg/dose once daily. Maximum: 5 mg/day.
Safety and efficacy not established in pediatric patients.
Start at lower end of dose range (2.5-5 mg orally once daily); titrate slowly due to increased sensitivity and renal impairment risk.
No specific dose adjustment recommended; use caution due to potential for renal impairment, monitor renal function.
None.
Gastrointestinal perforation: Cases of gastrointestinal perforation have been reported in patients with conditions that may result in impaired structural integrity of the gastrointestinal tract.
Hypotension and volume depletion,Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia),Ototoxicity (especially with rapid IV administration or high doses),Hyperuricemia,Sulfonamide allergy cross-reactivity
Risk of gastrointestinal perforation,Opioid withdrawal symptoms including diarrhea, nausea, vomiting, abdominal pain,Disruption of analgesic effect if used with opioids crossing the blood-brain barrier (theoretical),Not recommended in patients with known or suspected mechanical gastrointestinal obstruction
Anuria,Severe electrolyte depletion,Hypersensitivity to sulfonamides or bumetanide (Demadex is a sulfonamide derivative)
Known or suspected mechanical gastrointestinal obstruction,Known hypersensitivity to methylnaltrexone or any component of the formulation
Avoid excessive licorice intake (glycyrrhizin) as it can exacerbate hypokalemia. Limit sodium-rich foods (processed foods, canned soups) to enhance diuretic effect and control edema. Increase potassium-rich foods (bananas, oranges, potatoes) unless on a potassium-sparing medication. Avoid grapefruit juice as it may affect metabolism.
No specific food interactions reported with methylnaltrexone. No dietary restrictions necessary. However, to optimize bowel function, patients should maintain adequate fluid intake and dietary fiber as tolerated, unless contraindicated due to underlying illness.
DEMADEX (torsemide) is a loop diuretic. Human data are limited. In animal studies, high doses caused fetal resorptions and maternal toxicity. First trimester: insufficient human data; avoid unless benefit outweighs risk. Second/third trimester: risk of fetal oligohydramnios, renal impairment, and hypovolemia; use only if clearly needed.
Animal studies show no teratogenic effects at doses up to 300 mg/kg/day in rats and rabbits. No adequate human data; risk cannot be excluded in first trimester. Second and third trimester: limited data, potential for gastrointestinal effects in fetus if exposed transplacentally.
Torsemide is excreted in breast milk in small amounts; M/P ratio not reported. Due to potential for diuresis, electrolyte imbalance, and allergic reactions in the infant, caution is recommended. Alternative diuretics with more safety data are preferred.
Excreted in human milk at low concentrations; M/P ratio approximately 0.6. No reported adverse effects in breastfeeding infants. Caution advised due to potential for gastrointestinal effects.
Dosing may need adjustment due to increased plasma volume and GFR in pregnancy. Start at lowest effective dose. Monitor diuretic response and electrolyte balance; dose titration may be required. Postpartum, drug elimination may return to prepregnancy kinetics.
No pharmacokinetic studies in pregnancy; dose adjustments not recommended based on available data. Use only if clearly needed for severe opioid-induced constipation unresponsive to standard therapy.
DEMADEX (torsemide) is a loop diuretic with high bioavailability (80-100%) and a longer half-life (3-4 hours) than furosemide, allowing once-daily dosing. It is primarily metabolized by CYP2C9, so caution is needed with CYP2C9 inhibitors like amiodarone. Monitor for ototoxicity at high doses or rapid infusion. Hypokalemia risk persists; consider potassium supplementation or aldosterone antagonist. Use cautiously in sulfonamide allergy due to potential cross-sensitivity.
Relistor (methylnaltrexone) is a peripherally acting mu-opioid receptor antagonist (PAMORA) used for opioid-induced constipation (OIC) in patients with advanced illness or chronic pain. It does not cross the blood-brain barrier, thus does not reverse central opioid analgesia. Administer subcutaneously; onset typically within 1-4 hours. Contraindicated in patients with known or suspected mechanical gastrointestinal obstruction. Use with caution in renal impairment (Cr Cl <30 m L/min) as dose reduction recommended. Monitor for gastrointestinal perforation, especially in patients with underlying GI pathology. Coadministration with other opioid antagonists may precipitate opioid withdrawal.
Take DEMADEX exactly as prescribed, usually once daily in the morning to avoid nighttime urination.,Weigh yourself daily and report sudden weight gain or loss of more than 2-3 pounds in a day.,Avoid alcohol and beverages containing caffeine as they may increase dehydration.,Do not take DEMADEX with licorice (which can worsen hypokalemia) or with high-sodium antacids.,Report signs of hearing loss, ringing in the ears, dizziness, or muscle cramps immediately.,Stand up slowly to prevent dizziness from low blood pressure.,Monitor for signs of dehydration: dry mouth, thirst, infrequent urination.
Relistor is used to treat constipation caused by opioid pain medications without affecting pain relief.,Inject the medication exactly as prescribed; do not use more often than every other day.,You should have a bowel movement within a few hours of receiving the injection; if not, contact your doctor.,Common side effects include abdominal pain, nausea, diarrhea, and flatulence.,Stop Relistor and seek immediate medical attention if you experience severe abdominal pain, vomiting, or signs of intestinal obstruction (e.g., inability to pass gas).,Tell your doctor if you have kidney problems, as the dose may need adjustment.,Do not take other medicines for constipation without your doctor's approval.
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 DEMADEX vs RELISTOR, answered by our medical review team.
DEMADEX is a Loop Diuretic that works by Inhibits the Na-K-2Cl symporter in the thick ascending limb of the loop of Henle, reducing reabsorption of sodium, chloride, and potassium, leading to increased urine output.. RELISTOR is a Peripheral Opioid Antagonist that works by Peripherally acting mu-opioid receptor antagonist that blocks opioid-induced constipation without affecting central analgesia.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DEMADEX and RELISTOR 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 DEMADEX is: Oral: 5-10 mg once daily; may increase to 20 mg once daily if needed. IV: 5-10 mg once daily; may increase to 20 mg once daily if needed. Maximum dose: 40 mg/day.. The standard adult dose of RELISTOR is: 0.15 mg/kg subcutaneously once daily, maximum 16 mg per dose; for opioid-induced constipation, 8 mg subcutaneously once daily.. 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 DEMADEX and RELISTOR 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. DEMADEX is classified as Category C. DEMADEX (torsemide) is a loop diuretic. Human data are limited. In animal studies, high doses caused fetal resorptions and maternal toxicity. First trimester: insufficient human da. RELISTOR is classified as Category C. Animal studies show no teratogenic effects at doses up to 300 mg/kg/day in rats and rabbits. No adequate human data; risk cannot be excluded in first trimester. Second and third tr. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.