Plasma gonadotropin response to D-Ala6-LH-RH propylamide.

A long-acting analog of LH-RH, D-Ala6-desGly10-LH-RH propylamide (D-Ala6-LH-RH PA) was administered intramuscularly in a dose of 250 micrograms to 11 women with amenorrhea in whom the determinations of urinary steroid secretion, progesterone challenge, clomiphene, HMG, and LH-RH tests had been performed previously. Blood samples were taken twice before the injection and at 0.5, 1, 2, 4, 8, 12, 24, 26, 28, 30, and 32 h. No visible side effects were observed. Plasma levels of LH and FSH were determined by radioimmunoassays and expressed in mIU/2nd-IRP HMG/ml. The analog caused a great elevation in plasma LH and FSH levels. The maximal absolute increment for LH was between 3.93 and 115.89 mIU/ml, and the maximal increment in percentage was between 220 and 4,300. The time of the LH peak varied between 0.5 and 12 h. For FSH, the maximal absolute increment was between 6.45 and 50.92 mIU/ml and the maximal increment in percentage was between 63 and 1,442. The peak of FSH occurred in most cases at 4 to 8 h.