Treatment of prostatic carcinoma with D‐Trp‐6‐LH‐RH: Plasma hormone levels after daily subcutaneous injections and periodic administration of delayed‐release preparations

The hormonal effects of a delayed‐release intramuscular (IM) preparation of D‐Trp‐6‐LH‐RH (Decapeptyl microcapsules) were investigated in men aged 65–75 years. Six men with a prostatic adenoma (group A) received subcutaneously (SC) 500 μg Decapeptyl/day for seven days. Seven men with a prostatic carcinoma (group B) were given the same SC treatment, but in addition received on days 8, 28, and 56 an IM injection of Decapeptyl microcapsules. During SC treatment, plasma Decapeptyl levels rose to 2–4 ng/ml. Plasma LH, FSH, and 17‐hydroxy‐progesterone peaked on day 2, and estradiol‐17β on day 3, whereas high testosterone levels were maintained from day 2 to day 4, and then fell abruptly on day 6. In group A, hormone levels were minimal on day 12 or 14 but returned to basal on day 23. After IM injection of microcapsules on day 8, two out of seven subjects from group B exhibited the same hormonal pattern as for group A, but testosterone secretion was completely suppressed after the second IM injection. In both subjects, plasma Decapeptyl was undetectable in most samples from day 10 to day 28, but became detectable after the second injection. In five subjects from group B, plasma Decapeptyl was detectable in all plasma samples from day 10 to day 49. Testosterone levels were in the castrate range after day 24 (0.25 ± 0.03 ng/ml). Mean LH level (± SEM) decreased progressively from day 14 (65 ± 6 ng LER 907/ml) to day 56 (36 ± 2 ng/ml). These data provide evidence for the efficacy of periodic administration of Decapeptyl microcapsules for suppressing testicular secretion.