Molecular formula. C6H14O6S2
Relative molecular mass. 246.3
Chemical name. 1,4-Butanediol dimethanesulfonate; tetramethylene dimethanesulfonate; CAS Reg. No. 55-98-1.
Other name. Myelosanum.
Description. A white, crystalline powder.
Solubility. Very slightly soluble in water; sparingly soluble in acetone R; slightly soluble in ethanol (~750 g/l) TS.
Category. Cytotoxic drug.
Storage. Busulfan should be kept in a well-closed container, protected from light.
Additional information. CAUTION: Busulfan must be handled with care, avoiding contact with the skin and inhalation of airborne particles.
Definition. Busulfan contains not less than 98.5% and not more than 100.5% of C6H14O6S2, calculated with reference to the dried substance.
A. Heat 0.1 g with 10 ml of water and 5 ml of sodium hydroxide (1 mol/l) VS until a clear solution is obtained; an intense odour of methanesulfonic acid is perceptible. Cool the solution and divide it into two equal portions for test B.
B. To one portion of the solution prepared in test A add 0.05 ml of potassium permanganate (10 g/l) TS; the purple colour changes to violet, then to blue, and finally to emerald-green. Acidify the second portion of the solution prepared in test A with 2 ml of sulfuric acid (~100 g/l) TS, add 0.05 ml of potassium permanganate (10 g/l) TS and shake; the colour of the permanganate is slowly discharged.
C. To a test-tube transfer 0.10 g of the test substance, suspend it in 1.0 ml of copper edetate TS and 0.5 ml of ammonia (~260 g/l) TS, then add 0.5 ml of hydrogen peroxide (~60 g/l) TS; this constitutes solution 1. Similarly, prepare a blank without the test substance; this constitutes solution 2. Place both tubes in a water-bath for 5 minutes, cool and add 1.0 ml of hydrochloric acid (~70 g/l) TS and 4.0 ml of barium chloride (50 g/l) TS; solution 2 remains clear and an opalescence is produced in solution 1, which changes to a white precipitate after a few minutes.
Melting range. 115 - 118 °C.
Sulfated ash. Not more than 1.0 mg/g.
Loss on drying. Dry to constant weight at 60 °C under reduced pressure (not exceeding 0.6 kPa or about 5 mm of mercury); it loses not more than 20 mg/g.
Assay. To about 0.25 g, accurately weighed, add 25 ml of water and boil gently under reflux for 30 minutes. Wash the condenser with a small quantity of water, cool, and titrate with carbonate-free sodium hydroxide (0.1 mol/l) VS, using phenolphthalein/ethanol TS as indicator. Repeat the operation without the substance being examined and make any necessary corrections. Each ml of carbonate-free sodium hydroxide (0.1 mol/l) VS is equivalent to 12.32 mg of C6H14O6S2.