A comparison of tibolone and conjugated equine estrogens effects on coronary artery atherosclerosis and bone density of postmenopausal monkeys

This study compared the effects of tibolone, a tissue-specific compound for the treatment of climacteric symptoms and the prevention of osteoporosis, with those of conjugated equine estrogens (CEE) with and without medroxypro gesterone (MPA) on bone mineral density and coronary atherosclerosis (CAA) of postmenopausal cynomolgus monkeys. The groups were tibolone [two doses w ere used, 0.05 mg/kg (LoTib) and 0.2 mg/kg (HiTib)], CEE (0.042 mg/kg), CEE (0.042 mg/kg) plus WA (0.167 mg/kg given continuously), and a control grou p given no treatment for 2 yr. Compared with no treatment, bone mineral den sity was higher by 6.3% (P = 0.0004) in the LoTib group and by 9.5% (P = 0. 02) in the HiTib group compared with 4.3% (P = 0.12) for CEE and 4.5% (P = 0.10) for CEE+MPA. Plasma high density lipoprotein cholesterol was reduced by 49% with HiTib and by 34% with LoTib. There were no differences in CAA b etween control and HiTib (P = 0.60) or LoTib (P = 0.58). CEE and CEE+MPA bo th reduced CAA by about 62% (CEE vs. control, P = 0.02; CEE+MPA vs. control , P = 0.01). Despite adverse effects of tibolone on plasma lipoprotein conc entrations, there was no increase in CAA, suggesting that tibolone is a car diovascular-safe treatment for climacteric symptoms and the prevention of o steoporosis.