The effect of add-back treatment with tibolone (Livial) on patients treated with the gonadotropin-releasing hormone agonist triptorelin (Decapeptyl).

To assess whether tibolone can prevent the bone loss and symptomatic side effects normally associated with GnRH agonist (GnRH-a) use and whether tibolone modifies the effect of GnRH-a on endometriosis. Prospective, double-blind, placebo-controlled, group comparative study. Gynecological research unit in a London teaching hospital. Twenty-nine patients with endometriosis and two with fibroids. Six months of treatment with 3.75 mg/mo IM triptorelin combined with daily tablets of either placebo or 2.5 mg tibolone. Daily symptom diary for hot flushes and bleeding episodes, laparoscopic scoring of endometriosis, endocrine and biochemical changes, and bone mineral density scans. Lumbar spine bone mineral density decreased significantly from baseline in the placebo group (-5.1%) but not in the tibolone group (-1.1%). The frequency of hot flushes and sweating episodes was reduced significantly by tibolone. There was no difference between the two treatment groups with regard to the endometriosis scores. The addition of tibolone to GnRH-a treatment reduces the bone loss and vasomotor symptoms that normally occur with GnRH-a, thus making long-term treatment with GnRH-a safer and more acceptable. It does not negate the therapeutic effect of GnRH-a on endometriosis.