Testosterone and gonadotrophin profiles in patients on daily or monthly LHRH analogue ICI 118630 (Zoladex) compared with orchiectomy.

Diurnal profiles of circulating gonadotrophins and testosterone have been measured in patients with prostatic carcinoma on long-term treatment with the LHRH agonist analogue ICI 118630, which was administered either by subcutaneous daily injection or monthly injection of the depot preparation. These have been compared with profiles in patients who had undergone orchiectomy. Daily injection of the analogue induced a significant rise in the level of LH but this was not associated with a significant rise in circulating testosterone. There was no diurnal variation of LH or testosterone concentration in patients receiving the depot preparation and this did not differ in patients who were "mid-cycle" compared with those who were "end-cycle". The depot preparation did, however, induce significantly lower circulating levels of testosterone than did daily injection of the analogue and the levels were comparable with those achieved after orchiectomy.