RIMSO-50
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RIMSO-50 (RIMSO-50).
RIMSO-50 (dimethyl sulfoxide) is a solvent that, when instilled intravesically, penetrates the bladder wall and acts as a scavenger of hydroxyl radicals, thereby reducing inflammation and pain in interstitial cystitis. It also promotes collagen degradation and modulates nerve conduction.
| Metabolism | Metabolized by oxidation to dimethyl sulfone and reduction to dimethyl sulfide. Cytochrome P450 enzymes (CYP) are not primarily involved; metabolism is largely non-enzymatic or mediated by other oxidoreductases. |
| Excretion | Renal: 80% as unchanged drug; fecal: 15% as dimethyl sulfone metabolite; biliary: 5%. |
| Half-life | 11-14 hours; prolonged in renal impairment. |
| Protein binding | 2-5%; primarily to albumin. |
| Volume of Distribution | 0.6-0.8 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Intravesical: 15-25% (systemic absorption); oral: 70-90%. |
| Onset of Action | Intravesical: 15-30 minutes. |
| Duration of Action | Intravesical: 4-6 hours; systemic effects may persist longer due to metabolite accumulation. |
50 mL (50% solution) intravesically instilled via urethral catheter and retained for 4-6 hours, repeated every 1-2 weeks as tolerated.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for intravesical administration as systemic absorption is minimal. |
| Liver impairment | No dose adjustment required for intravesical administration as systemic absorption is minimal. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been studied. |
| Geriatric use | No specific dose adjustment required; same dosing as adults with careful monitoring due to potential age-related comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RIMSO-50 (RIMSO-50).
| Breastfeeding | Excretion into human milk is unknown. Due to the potential for serious adverse reactions (e.g., hemolysis, renal toxicity) in nursing infants, breastfeeding is not recommended during therapy and for at least 48 hours after the last dose. M/P ratio not established. |
| Teratogenic Risk | FDA Pregnancy Category C. Dimethyl sulfoxide (DMSO) is known to cause teratogenic effects in animal models (e.g., rats, mice) at high doses, including skeletal and visceral anomalies. First trimester: risk cannot be excluded; use only if clearly needed. Second and third trimesters: limited data; potential for fetal harm based on animal studies and possible systemic absorption. Avoid intravesical administration during pregnancy unless potential benefit outweighs risk. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to dimethyl sulfoxide or any component of the formulation.","Pregnancy (Category C; avoid unless potential benefit justifies risk).","Lactation (not recommended)."]
| Precautions | ["Administer only intravesically; not for subcutaneous, intramuscular, or intravenous use.","May cause exacerbation of symptoms in some patients during initial instillation.","Monitor for hypersensitivity reactions including anaphylaxis.","Contraindicated in patients with known hypersensitivity to DMSO or related compounds."] |
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| Fetal Monitoring | Monitor maternal renal function (serum creatinine, BUN) and liver enzymes periodically. Assess for signs of hemolysis (e.g., hemoglobin, haptoglobin, LDH) due to DMSO-induced hemolytic anemia. Fetal monitoring: consider fetal heart rate monitoring during instillation if late pregnancy; ultrasound for fetal growth and anatomy if exposure occurs in first trimester. |
| Fertility Effects | Animal studies suggest DMSO may impair fertility via effects on spermatogenesis (males) and ovarian function (females). In humans, no specific fertility studies; theoretical risk due to cellular cytotoxicity and potential systemic effects. Use with caution in patients planning conception. |