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BioMed Research International
Volume 2013, Article ID 273498, 8 pages
Research Article

The Steady-State Serum Concentration of Genistein Aglycone Is Affected by Formulation: A Bioequivalence Study of Bone Products

1Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, 98125 Messina, Italy
2Department of Medical Education and Scientific Affairs, Primus Pharmaceuticals, Inc., Scottsdale, AZ, USA
3Section of Physiology and Human Nutrition, Department of Biochemical, Physiological and Nutritional Sciences, University of Messina, Messina, Italy
4Department of Obstetrical and Gynecological Sciences, University of Messina, Messina, Italy
5Department of Clinical Affairs, Primus Pharmaceuticals, Inc., Scottsdale, AZ, USA

Received 30 July 2012; Revised 19 November 2012; Accepted 21 November 2012

Academic Editor: Fátima Regina Mena Barreto Silva

Copyright © 2013 Alessandra Bitto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An FDA-regulated, prescription medical food (Fosteum; 27 mg natural genistein, 200 IU cholecalciferol, 20 mg citrated zinc bisglycinate (4 mg elemental zinc) per capsule) and an over-the-counter (OTC) supplement (Citracal Plus Bone Density Builder; 27 mg synthetic genistein, 600 mg elemental calcium (calcium citrate), 400 IU vitamin D3, 50 mg magnesium, 7.5 mg zinc, 1 mg copper, 75 μg molybdenum, 250 μg boron per two tablets) were compared to a clinically proven bone formulation (27 mg natural genistein, 400 IU cholecalciferol, 500 mg elemental calcium (calcium carbonate) per tablet; the Squadrito formulation) in an 8-day steady-state pharmacokinetic (PK) study of healthy postmenopausal women ( ) randomized to receive 54 mg of genistein per day. Trough serum samples were obtained before the final dose on the morning of the ninth day followed by sampling at 1, 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, and 96 hrs. Total serum genistein, after β-glucuronidase/sulfatase digestion, was measured by time-resolved fluorometric assay. Maximal time ( ), concentration ( ), half-life ( ), and area under the curve (AUC) were determined for genistein in each formulation. Fosteum and the Squadrito study formulation were equivalent for genistein (2 hrs), (0.7  M), (  versus   hrs), and AUC (  versus   ng·hr/mL). The OTC supplement’s synthetically derived genistein, however, showed altered (6 hrs), (0.57 μM), (  hrs), and AUC (  ng·hr/mL). Differences in uptake may be due to multiple ingredients in the OTC supplement which interfere with genistein absorption.