Pharmacokinetics and distribution of [35S]methylsulfonylmethane following oral administration to rats

Methylsulfonylmethane (MSM) is a sulfur-containing compound found in a wide range of human foods including fruits, vegetables, grains, and beverages. More recently, it has been marketed as a dietary supplement worldwide. The objective of this study was to evaluate the pharmacokinetic profile and distribution of radiolabeled MSM in rats. Male Sprague-Dawley rats were administered a single oral dose of [S-35]MSM (500 mg/kg), and blood levels of radioactivity were determined at different time points for up to 48 h. Tissue levels of radioactivity at 48 and 120 h and urine and fecal radioactivity levels were measured at different time points for up to 120 h following [S-35]MSM administration to rats. Oral [S-35]MSM was rapidly and efficiently absorbed with a mean t(max) of 2.1 h, C-max of 622 mu g equiv/mL, and AUC(0-inf) of 15124 h center dot mu g equiv/mL. The t(1/2) was 12.2 h. Soft tissue distribution of radioactivity indicated a fairly homogeneous distribution throughout the body with relatively lower concentrations in skin and bone. Approximately 85.8% of the dose was recovered in the urine after 120 h, whereas only 3% was found in the feces. No quantifiable levels of radioactivity were found in any tissues after 120 h, indicating complete elimination of [S-35]MSM. The results of this study suggest that [S-35]MSM is rapidly absorbed, well distributed, and completely excreted from the body.