Drug Interactions between diethylstilbestrol and Nutropin

MONITOR: Coadministration of oral estrogen replacement therapy may diminish the therapeutic effects of human growth hormone. Some of the pharmacodynamic effects of human growth hormone are primarily mediated by insulin-like growth factor 1 (IGF-1), and orally administered estrogen can suppress growth hormone (GH)-dependent IGF-1 production in the liver. Gender differences have been shown in responsiveness to GH, with women requiring higher doses than men to achieve a similar response. The results of one study demonstrated that women taking oral estrogen required higher doses of GH to achieve an adequate response compared with men or women using transdermal estrogen. In addition, the study showed that GH requirements were also higher for GH-deficient women receiving primarily oral estrogen replacement therapy than for eugonadal GH-deficient women. This interaction does not appear to apply to non-orally administered estrogens.

MANAGEMENT: Patients receiving human growth hormone with oral estrogen replacement therapy should be monitored for potentially diminished GH efficacy. A higher dosage of growth hormone may be required to maintain serum IGF-1 levels within the normal age-appropriate range in order to achieve the defined treatment goal. Please consult individual product labeling for the appropriate initial dosage of growth hormone recommended. Dosage adjustments as well as clinical and laboratory monitoring should be considered following the addition or discontinuation of oral estrogen replacement therapy during use of growth hormone.