Dimethyl Sulfoxide

INDICATIONS AND USAGE RIMSO-50 ® (dimethyl sulfoxide) is indicated for the symptomatic relief of patients with interstitial cystitis. RIMSO-50 ® has not been approved as being safe and effective for any other indication. There is no clinical evidence of effectiveness of dimethyl sulfoxide in the treatment of bacterial infections of the urinary tract.

CLINICAL PHARMACOLOGY Dimethyl sulfoxide is metabolised in man by oxidation to dimethyl sulfone or by reduction to dimethyl sulfide. Dimethyl sulfoxide and dimethyl sulfone are excreted in the urine and feces. Dimethyl sulfide is eliminated through the breath and skin and is responsible for the characteristic odor from patients on dimethyl sulfoxide medication. Dimethyl sulfone can persist in serum for longer than two weeks after a single intravesical instillation. No residual accumulation of dimethyl sulfoxide has occurred in man or lower animals who have received treatment for protracted periods of time. Following topical application, dimethyl sulfoxide is absorbed and generally distributed in the tissues and body fluids.

DOSAGE AND ADMINISTRATION Instillation of 50 mL of RIMSO-50 ® (dimethyl sulfoxide) directly into the bladder may be accomplished by catheter or asepto syringe and allow to remain for 15 minutes. Application of an analgesic lubricant gel such as lidocaine jelly to the urethra is suggested prior to insertion of the catheter to avoid spasm. The medication is expelled by spontaneous voiding. It is recommended that the treatment be repeated every two weeks until maximum symptomatic relief is obtained. Thereafter, time intervals between therapy may be increased appropriately. Administration of oral analgesic medication or suppositories containing belladonna and opium prior to the instillation of RIMSO-50 ® can reduce bladder spasm. In patients with severe interstitial cystitis with very sensitive bladders, the initial treatment, and possibly the second and third (depending on patient response) should be done under anesthesia. (Saddle block has been suggested).

ADVERSE REACTIONS A garlic-like taste may be noted by the patient within a few minutes after instillation of RIMSO-50 ® (dimethyl sulfoxide). This taste may last several hours and because of the presence of metabolites, an odor on the breath and skin may remain for 72 hours. Transient chemical cystitis has been noted following instillation of dimethyl sulfoxide. The patient may experience moderately severe discomfort on administration. Usually this becomes less prominent with repeated administration.

WARNINGS Dimethyl sulfoxide can initiate the liberation of histamine and there has been occasional hypersensitivity reaction with topical administration of dimethyl sulfoxide. This hypersensitivity has been reported in one patients receiving intravesical RIMSO-50 ® . The physician should be cognizant of this possibility in prescribing RIMSO-50 ® . If anaphylactoid symptoms develop, appropriate therapy should be instituted.

CONTRAINDICATIONS None known.

OVERDOSAGE The oral LD 50 of dimethyl sulfoxide in the dog is greater than 10 gm/kg. It is improbable that this dosage level could be obtained with intravesical instillation of RIMSO-50 ® in the patient. In case of accidental oral ingestion, specific measures should be taken to induce emesis. Additional measures which may be considered are gastric lavage, activated charcoal and force diuresis.