Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
BUMEX vs RELISTOR
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Bumetanide inhibits the Na-K-2Cl symporter (NKCC2) in the thick ascending limb of the loop of Henle, reducing reabsorption of sodium, chloride, and potassium, leading to increased diuresis.
Peripherally acting mu-opioid receptor antagonist that blocks opioid-induced constipation without affecting central analgesia.
Edema associated with congestive heart failure,Edema associated with hepatic cirrhosis,Edema associated with renal disease including nephrotic syndrome
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
0.5-2 mg orally once daily; if inadequate response, may increase to 2-4 mg once daily or twice daily. Maximum 10 mg/day. IV: 0.5-1 mg IV over 1-2 minutes; may repeat every 2-3 hours up to 10 mg/day.
0.15 mg/kg subcutaneously once daily, maximum 16 mg per dose; for opioid-induced constipation, 8 mg subcutaneously once daily.
Terminal elimination half-life: 1.5–2 hours in normal renal function; prolonged to 2.5–4 hours in severe renal impairment (Cr Cl <20 m L/min).
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 metabolized by the liver via cytochrome P450 enzymes, including CYP2C9 and CYP3A4.
Primarily hepatic via CYP3A4 and CYP2D6 isoenzymes; also undergoes gut wall metabolism.
Renal: 80% as unchanged drug; biliary/fecal: 15% as metabolites; total renal elimination accounts for ~85% of clearance.
Renal excretion of unchanged drug accounts for approximately 16% of the dose; biliary/fecal excretion is the major route (approximately 54% recovered in feces).
Bumetanide is 94–96% bound to plasma proteins (primarily albumin).
Approximately 11-15% bound to plasma proteins (primarily albumin).
0.15–0.22 L/kg; indicates primarily extracellular distribution.
Approximately 1.1 L/kg (central volume ~0.3 L/kg); indicates extensive extravascular distribution.
Oral bioavailability: 80–100% (mean ~95%).
Subcutaneous: approximately 82-100% (mean ~97%); oral: approximately 6% (low due to first-pass metabolism).
e GFR <20 m L/min/1.73 m²: Avoid loop diuretics; consider alternative. No adjustment for mild to moderate renal impairment, but monitor response. In severe renal failure, may require higher doses due to reduced tubular secretion.
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 Class B or C: Reduce initial dose by 50% due to impaired metabolism and increased risk of volume depletion. Titrate cautiously.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); not studied in severe impairment (Child-Pugh C).
Infants/Children: Oral: 0.015-0.1 mg/kg/dose once daily; maximum 10 mg/day. IV/IM: 0.015-0.1 mg/kg/dose every 12-24 hours; maximum 0.5 mg/kg/dose. Neonates: 0.01-0.05 mg/kg/dose every 24-48 hours.
Safety and efficacy not established in pediatric patients.
Start at 0.5 mg orally once daily; increase cautiously due to enhanced pharmacodynamic effects and higher risk of electrolyte disturbances, volume depletion, and ototoxicity. Monitor renal function and electrolytes closely.
No specific dose adjustment recommended; use caution due to potential for renal impairment, monitor renal function.
Bumetanide is a potent diuretic; if given in excessive amounts, can lead to profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required, and dose and dosage schedule must be adjusted to individual patient's needs.
Gastrointestinal perforation: Cases of gastrointestinal perforation have been reported in patients with conditions that may result in impaired structural integrity of the gastrointestinal tract.
Electrolyte depletion (hypokalemia, hyponatremia, hypochloremia),Dehydration and hypovolemia,Ototoxicity (especially with rapid injection or in renal impairment),Excessive diuresis causing hypotension and thromboembolic events,May increase serum uric acid levels and precipitate gout,Risk of hypokalemia in patients with cirrhosis and ascites
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,Hepatic coma or severe electrolyte depletion until condition is corrected,Hypersensitivity to bumetanide or sulfonamides (cross-sensitivity possible)
Known or suspected mechanical gastrointestinal obstruction,Known hypersensitivity to methylnaltrexone or any component of the formulation
Avoid excessive salt intake; no specific food interactions reported. Avoid licorice as it may worsen hypokalemia. Grapefruit juice may increase bumetanide levels; use caution.
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.
Bumetanide (BUMEX) is a loop diuretic classified as FDA Pregnancy Category C. Animal studies have shown embryocidal effects and delayed ossification at high doses. Human data are limited; no well-controlled studies exist. First trimester: theoretical risk based on animal data; avoid unless essential. Second/third trimesters: may cause maternal hypovolemia, decreased placental perfusion, and fetal oliguria; use only if clearly needed and monitor amniotic fluid volume. Neonatal risks include electrolyte imbalances and ototoxicity if used close to delivery.
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.
Bumetanide is excreted into human milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.05-0.10. Based on limited data, amounts ingested by breastfed infants are unlikely to cause adverse effects. However, due to potential risk of hypersensitivity, electrolyte disturbances, or diuresis in the infant, caution is advised, especially in premature or renal-impaired infants. Alternative diuretics with more safety data may be 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.
Pregnancy may alter bumetanide pharmacokinetics due to increased plasma volume, renal blood flow, and glomerular filtration rate. Higher doses may be required to achieve the same diuretic effect. However, no standard dose adjustment guidelines exist; use the lowest effective dose and titrate based on clinical response, monitoring for electrolyte disturbances and volume depletion. In severe preeclampsia or renal impairment, dose may need reduction. Close therapeutic drug monitoring is not routinely available; clinical monitoring of diuresis and electrolytes guides dosing.
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.
Bumetanide is a loop diuretic approximately 40 times more potent than furosemide; onset of diuresis within 30-60 minutes after oral administration. Monitor for ototoxicity, especially with rapid IV administration or concurrent use of other ototoxic drugs. Hypokalemia is a common adverse effect; consider potassium supplementation or concurrent use of potassium-sparing diuretics. Contraindicated in anuria, hepatic coma, and severe electrolyte depletion. May cause hyperuricemia and precipitate gout attacks.
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 this medication exactly as prescribed, typically once daily in the morning to avoid nighttime urination.,Avoid sudden position changes to prevent dizziness from low blood pressure.,Do not consume grapefruit juice or alcohol while taking this drug.,Monitor for signs of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat, or confusion.,Weigh yourself daily and report rapid weight gain or loss to your healthcare provider.
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 BUMEX vs RELISTOR, answered by our medical review team.
BUMEX is a Loop Diuretic that works by Bumetanide inhibits the Na-K-2Cl symporter (NKCC2) in the thick ascending limb of the loop of Henle, reducing reabsorption of sodium, chloride, and potassium, leading to increased diuresis.. 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 BUMEX 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 BUMEX is: 0.5-2 mg orally once daily; if inadequate response, may increase to 2-4 mg once daily or twice daily. Maximum 10 mg/day. IV: 0.5-1 mg IV over 1-2 minutes; may repeat every 2-3 hours up to 10 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 BUMEX 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. BUMEX is classified as Category C. Bumetanide (BUMEX) is a loop diuretic classified as FDA Pregnancy Category C. Animal studies have shown embryocidal effects and delayed ossification at high doses. Human data are l. 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.