In vivo study on the pharmacological interactions between a chinese herbal formula ELP and antiresorptive drugs to counteract osteoporosis

Chun-Hay Ko, Institute of Chinese Medicine, Chinese University of Hong Kong
Wing-Sum Siu, Institute of Chinese Medicine, Chinese University of Hong Kong
Hing-Lok Wong, Jockey Club Centre for Osteoporosis Care and Control, Chinese University of Hong Kong
Si Gao, Institute of Chinese Medicine, Chinese University of Hong Kong
Wai-Ting Shum, Institute of Chinese Medicine, Chinese University of Hong Kong
Ching-Po Lau, Institute of Chinese Medicine, Chinese University of Hong Kong
Sau-Wan Cheng, Institute of Chinese Medicine, Chinese University of Hong Kong
Jacqueline Chor-Wing Tam, Institute of Chinese Medicine, Chinese University of Hong Kong
Leung-Kim Hung, Department of Orthopaedics and Traumatology, Chinese University of Hong Kong
Kwok-Pui Fung, Institute of Chinese Medicine, Chinese University of Hong Kong
Clara Bik-San Lau, Institute of Chinese Medicine, Chinese University of Hong Kong
Quan-Bin Han, Institute of Chinese Medicine, Chinese University of Hong Kong
Ping-Chung Leung, Institute of Chinese Medicine, Chinese University of Hong Kong

Abstract

Antiresorptive drugs, alendronate and raloxifene, are effective in lowering bone mineral density (BMD) loss in postmenopausal women. However, long-term treatment may be associated with serious side effects. Our research group has recently discovered that a Chinese herbal formula, ELP, could significantly reduce BMD loss in animal and human studies. Therefore, the present study aimed to investigate the potential synergistic bone-protective effects of different herb-drug combinations using ovariectomized rats. To assess the efficacy of different combinations, the total BMD was monitored biweekly in the 8-week course of daily oral treatment. Bone microarchitecture, bone strength, and deoxypyridinoline level were also determined after 8 weeks. From our results, coadministration of ELP and raloxifene increased the total tibial BMD by 5.26 (2.5 mg/kg/day of raloxifene; P = 0.014) and 5.94 (0.25 mg/kg/day of raloxifene; P = 0.026) when compared with the respective dosage groups with raloxifene alone. Similar synergistic effects were also observed in BMD increase at distal femur (0.25 mg/kg/day; P = 0.001) and reduction in urinary deoxypyridinoline crosslink excretion (2.5 and 0.25 mg/kg/day; both P = 0.02). However, such interactions could not be observed in all alendronate-treated groups. Our data provide first evidence that ELP could synergistically enhance the therapeutic effects of raloxifene, so that the clinical dosage of raloxifene could be reduced. © 2012 Chun-Hay Ko et al.