Klinger B, Silbergeld A, Deghenghi R, Frenkel J, Laron Z. Desensitization from long-term intranasal treatment with hexarelin does not interfere with the biological effects of this growth hormonereleasing peptide in short children. Eur J Endocrinol 1996;134:716–9. ISSN 0804–4643
A clinical, prospective experiment was carried out to determine whether long-term intranasal administration of the growth hormone-releasing peptide hexarelin (His-d-2-methyl-Trp-Ala-Trp-d-Phe-Lys-NH2) affects pituitary growth hormone secretion. Hexarelin (60 μg/kg t.i.d.) was administered to seven prepubertal constitutionally short children (mean age ±sd = 7.6 ± 2.4 years). Serum human growth hormone (hGH) response to an intranasal (20 μg/kg) and intravenous (1 μg/kg) bolus of hexarelin before, during and after 6–10 months of treatment was measured. The mean (±sd) peak rise of hGH to the intranasal bolus before treatment was 70.6 ± mU/I. After 7 days of hexarelin treatment, mean peak values dropped to 34.1 ±15.7 mU/l (p < 0.002) and thereafter remained constant for 6 months of treatment at 37.5 10.3 ±mU/l (p < 0.03). The pretreatment peak to the iv hexarelin bolus was 84.8 52.5 ±mU/l, and at the end of the treatment period it was 19.8 10.9 ±mU/l (p < 0.05). Three months after stopping treatment the mean (±sd) hGH response rose to 42.1 ±4.7 mU/l (p < 0.005). Growth velocity increased from 5.3±0.9 cm/year (before treatment) to 7.4 1.6 cm/year at ±6–10 months of treatment (p < 0.005). In conclusion, the partial suppression of pituitary hGH responsiveness to long-term intranasal hexarelin treatment, probably due to desensitization, does not affect the observed increase in growth velocity.
Z Laron, Pediatric Endocrinology, 11 El Al Street, Ramat Efal, 52960, Israel