Aspartame effect in sickle cell anemia

Objective To examine the in vitro and in vivo attributes of aspartame and to determine its efficacy for treating sickle cell anemia. Rationale Aspartame ( L ‐aspartyl‐ L ‐phenylalanine methyl ester) binds with 2 human Bence Jones proteins. The proteins (Mcg and Sea) showed phenylalanine penetrating into hydrophobic binding sites. This aspartame property suggested a potential to interfere with sickle hemoglobin fibril formation. Methods For the in vitro studies, blood from 20 subjects monitored for sickle cell anemia was collected in heparinized tubes. Specimens were divided in thirds and aspartame was added to 2 tubes to yield a 1 mg/mL or 2 mg/mL concentration. Sickled cells that were present after a drop from each aliquot was added to a fresh 2% metabisulfite solution were counted 3 times. For the in vivo studies, 23 subjects from the Sickle Cell Clinic (University of Oklahoma Health Sciences Center, Oklahoma City, Okla) consented to participate in a randomized single‐dose administration of 1.5, 3.0, or 6 mg/kg aspartame. Heparinized blood was obtained at 0, 30, 60, 120, 240, 480, and 1440 minutes after aspartame administration. Specimens were counted in a blinded manner by means of the technique used for the in vitro method, but a photomicrograph of 1 field from each triplicate count was made. The pictures were marked and were computer counted. Results For the in vitro studies, sickled cells decreased from 28% to <14% when 1 mg/mL aspartame was added and decreased further with 2 mg/mL. For the in vivo studies, a decreased number of sickled cells in homozygous blood (HbSS) were observed after oral administration of aspartame. Sickling was inhibited by 6 mg/kg aspartame for at least 6 hours in 15 subjects with HbSS anemia. Conclusions Further evaluations of the efficacy of aspartame for sickle crisis and crisis prevention appears to be warranted. Clinical Pharmacology & Therapeutics (2001) 69 , 346–355; doi: 10.1067/mcp.2001.115141