Pharmacology
Dimethyl sulfoxide is metabolized in man by oxidation to dimethyl sulfone or by the 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 2 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.
Indications
Rimso-50 (dimethyl sulfoxide 50%) 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.
Precautions
It is not known whether dimethyl sulfoxide is excreted in human milk. Because many drugs are excreted in human milk, mothers receiving dimethyl sulfoxide should refrain from nursing.
The safety of dimethyl sulfoxide for the human fetus has not been established, hence it should be given to pregnant women only when the potential benefits to the mother have been weighed against possible hazards to the child.
Dimethyl sulfoxide caused teratogenic responses in hamsters, rats and mice when administered intraperitoneally at high doses (2.5-12 g/kg). Oral or topical doses of dimethyl sulfoxide did not cause problems of reproduction in rats, mice or hamsters. Topical doses (5 g/kg – first two days, then 2.5 g/kg – last eight days) produced terata in rabbits, but in another study, topical doses of 1.1 g/kg days three through sixteen of gestation failed to produce any abnormalities.
The safety and effectiveness of Rimso-50 in children have not been established.
Supplied
Each bottle contains: 50 mL (54 g) of sterile and non-pyrogenic 50% w/w dimethyl sulfoxide aqueous solution. Store at room temperature (15 to 30°C). Protect from light.
Contraindications
None.
Warnings
Dimethyl sulfoxide can initiate the liberation of histamine and there has been an occasional hypersensitivity reaction with topical administration of dimethyl sulfoxide. This hypersensitivity has been reported in some patients receiving intravesical Rimso-50 (dimethyl sulfoxide 50%); The physician should be cognizant of this possibility in prescribing Rimso-50. If anaphylactoid symptoms develop, appropriate therapy should be instituted.
Adverse Effects
A garlic like taste may be noted by the patient within a few minutes after instillation of Rimso-50 (dimethyl sulfoxide 50%). 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 100% dimethyl sulfoxide.
The patient may experience moderately severe discomfort on administration. Usually this becomes less prominent with repeated administration.
Overdose
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.
Dosage
Instillation of 50 mL of Rimso-50 (dimethyl sulfoxide 50%) directly into the bladder may be accomplished by catheter or aseptic syringe and allowed to remain for 15 minutes. Application of an analgesic lubricant gel such as lidocaine jelly to the urethra is suggested prior to the insertion of the catheter to avoid spasm. The medication is expelled by spontaneous voiding. It is recommended that treatment be repeated every two weeks until maximum symptomatic relief is obtained. Thereafter, time intervals between therapy may be increased appropriately.
In selected cases where symptomatic relief is not complete, the bladder may be gently distended by gravity instillation with up to 500 mL of a solution prepared immediately prior to instillation in a glass vial, with one part Rimso-50 and one part sterile water prior to the instillation of the standard dose of Rimso-50. After retention of Rimso-50 for 15 minutes the medication is again expelled by spontaneous voiding.
Administration of oral analgesic medication or suppositories containing belladonna and opium prior to the instillation of Rimso-50 can reduce bladder spasm in particularly sensitive patients.
In patients with severe interstitial cystitis and very sensitive bladders, the initial treatment, and possibly the second and third (depending on patient response) should be done under anesthesia (preferably saddle block type).
Rimso-50 is recommended for bladder instillation only.
