As of now, three placebo-controlled studies of rhGH, alone (46) or in combination with rhIGF-1 (48,57), have been performed. Each featured a similar study design and duration and included measurement of body composition by a state-of-the art technique, DEXA, in all or in sizable subgroups of patients. The increases in LBM achieved with combinations of rhIGF-1 and rhGH at the doses employed were either no greater (48) or actually less than (57) those achieved with treatment with a pharmacologic dose of rhGH alone during a comparable period (46). Taken together, these results provide little justification for using a combination of two recombinant drugs, requiring three or four subcutaneous injections daily, in preference to a single dose of rhGH alone. Interestingly, these results provide a suggestion of a dose-response relationship between rhGH and LBM. For example, the increase in LBM in patients who received rhGH at an average dose of 6 mg/d (46) was approximately three times greater than that seen in a smaller group of patients who received 1.4 mg/d (48). Similarly, in patients who received 10 mg/d of IGF-1, those who were treated concurrently with rhGH in a dose of 1.4 mg/d (48) experienced an approximately threefold greater increase in LBM those who received a total of 0.7 mg/d (57).
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