What is the recommended DMSO (Dimethyl Sulfoxide) concentration for treating interstitial cystitis?

DMSO Concentration for Interstitial Cystitis Treatment

The recommended DMSO concentration for treating interstitial cystitis is 50% w/w aqueous solution, which is the FDA-approved formulation for intravesical instillation. 1

Evidence-Based Rationale

The American Urological Association (AUA) guidelines specifically list DMSO as a second-line treatment option for interstitial cystitis/bladder pain syndrome (IC/BPS). According to these guidelines, intravesical DMSO is recommended alongside other second-line treatments such as heparin and lidocaine 2.

The FDA-approved formulation of DMSO for IC treatment is RIMSO-50®, which contains 50% w/w dimethyl sulfoxide in an aqueous solution (0.54 gm dimethyl sulfoxide per mL) 1. This concentration has been established as the standard for intravesical administration.

Clinical Application

Administration Protocol

• DMSO is administered via intravesical instillation directly into the bladder
• The solution is typically retained in the bladder for approximately 15 minutes 3
• Treatment is often given in a series of weekly instillations

Efficacy and Response Rates

• Clinical studies show response rates of approximately 61-65% in patients with IC 4, 5
• Patients typically experience significant decreases in symptom scores, frequency of urination, and pain levels 5

Predictors of Treatment Response

Several factors may affect treatment outcomes:

• Patients with advanced cystoscopic glomerulations, microscopic hematuria, and detrusor underactivity may have poorer responses 4
• An anesthetic bladder capacity <675 mL has been identified as an independent predictor of treatment failure 5

Safety Considerations

• Systemic absorption of DMSO from the bladder is relatively low (approximately 16.3%) 3
• The most common side effect is a garlic-like breath odor, reported in about 66.7% of patients 3
• Approximately 6.7% of patients may discontinue treatment due to intolerable bladder irritation 4
• DMSO has an excellent overall safety profile with acceptable morbidity 6

DMSO Cocktail Approach

Many clinicians use a "DMSO cocktail" approach, combining DMSO with other agents:

• A typical cocktail may include 50% DMSO (50 mL), hydrocortisone (100 mg), heparin sulfate (10,000 U), and bupivacaine (0.5%, 10 mL) 5
• This combination approach may optimize treatment outcomes for some patients

Treatment Algorithm

1. Initial Assessment: Confirm IC/BPS diagnosis and rule out other conditions (infection, malignancy)
2. First-line Treatments: Begin with conservative therapies (behavioral modifications, oral medications)
3. DMSO Initiation: If first-line treatments fail, proceed to 50% DMSO intravesical instillation
4. Treatment Schedule: Weekly instillations for 6-12 weeks
5. Response Evaluation: Assess symptom improvement at 3-week intervals during treatment
6. Maintenance: For responders, consider monthly maintenance instillations
7. Alternative Approaches: For non-responders after 6 weeks, consider DMSO cocktail or alternative therapies

Conclusion

The 50% w/w DMSO aqueous solution is the standard concentration for treating interstitial cystitis through intravesical instillation. This concentration provides the optimal balance between efficacy and tolerability, with approximately 61-65% of patients experiencing significant symptom improvement.