Three-monthly GnRH agonist (buserelin) for prostatic cancer.

A new slow release formulation of buserelin given as a 3-monthly depot injection has been evaluated in 4 patients with advanced prostatic cancer previously maintained on shorter acting depots. Treatment was maintained for a mean period of 21 months. Steady state urinary buserelin concentrations were reached by the beginning of the third treatment week and maintained until the end of the third treatment month. Serum testosterone remained suppressed in the castrate range for the duration of the study. Seven previously untreated patients were entered into treatment. Serum testosterone was suppressed into the castrate range between the seventh and fourteenth days after implantation. This preparation offers an advantage for the patient and clinician over existing methods of GnRH analogue administration and will now enter further clinical trial.