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Macimorelin (AEZS-130)-stimulated growth hormone (GH) test: validation of a novel oral stimulation test for the diagnosis of adult GH deficiency.

The Journal of clinical endocrinology and metabolism (2013-04-06)
J M Garcia, R Swerdloff, C Wang, M Kyle, M Kipnes, B M K Biller, D Cook, K C J Yuen, V Bonert, A Dobs, M E Molitch, G R Merriam
ABSTRACT

In the absence of panhypopituitarism and low serum IGF-I levels, the diagnosis of adult GH deficiency (AGHD) requires confirmation with a GH stimulation test. Macimorelin is a novel, orally active ghrelin mimetic that stimulates GH secretion. The objective of the study was to determine the diagnostic efficacy and safety of macimorelin in AGHD. This was a multicenter open-label study comparing the diagnostic accuracy of oral macimorelin with that of arginine+GHRH in AGHD patients and healthy, matched controls. After 43 AGHD patients and 10 controls were tested, the GHRH analog Geref Diagnostic [GHRH(1-29)NH2] became unavailable in the United States. The study was completed by testing 10 additional AGHD patients and 38 controls with macimorelin alone. Peak GH area under the receiver operating characteristic curve after macimorelin was measured. Fifty AGHD subjects and 48 controls were evaluated. Peak GH levels in AGHD patients and controls after macimorelin were 2.36 ± 5.69 and 17.71 ± 19.11 ng/mL, respectively (P < .0001). With macimorelin, the receiver operating characteristic analysis yielded an optimal GH cut point of 2.7 ng/mL, with 82% sensitivity, 92% specificity, and 13% misclassification rate. For subjects receiving both tests, macimorelin showed discrimination comparable with arginine+GHRH (area under the receiver operating characteristic curve 0.99 vs 0.94, respectively, P = .29). Obesity (body mass index > 30 kg/m(2)) was present in 58% of subjects, and peak GH levels were inversely associated with body mass index in controls (r = -0.37, P = .01). Using the separate cut points of 6.8 ng/mL for nonobese and 2.7 for obese subjects reduced the misclassification rate to 11%. Only 1 drug-related serious adverse event, an asymptomatic QT interval prolongation on the electrocardiogram, was reported. Oral macimorelin is safe, convenient, and effective in diagnosing AGHD with accuracy comparable with the arginine+GHRH test.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
L-Tryptophan, reagent grade, ≥98% (HPLC)
Sigma-Aldrich
L-Tryptophan, from non-animal source, meets EP, JP, USP testing specifications, suitable for cell culture, 99.0-101.0%
Sigma-Aldrich
L-Tryptophan, BioUltra, ≥99.5% (NT)
Supelco
Tryptophan, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
L-Tryptophan, certified reference material, TraceCERT®