Daily subcutaneous injection of human growth hormone has been used for the treatment of growth hormone deficiency and growth failure but has led to poor patient compliance and renal toxicity. Thus, it is crucial to develop favorable growth hormone delivery systems to improve patient compliance. In the present study, to increase the oral bioavailability of growth hormone and improve patient compliance, enteric-coated capsules filled with monomethoxyl poly(ethylene glycol)-b-poly(L-lactide-co-glycolide) nanoparticles were prepared to facilitate oral growth hormone delivery. The nanoparticles were less than 100 nm in size, exhibited narrow polydispersity indices < 0.3, and showed a zeta potential of -4.87 mV. The highest efficiency of growth hormone encapsulation achieved in this study was nearly 70%. An in vitro release experiment showed that adequate amounts of growth hormone were retained under simulated gastric conditions and significant amounts of growth hormone were released under simulated intestinal conditions. The bioavailability of encapsulated growth hormone relative to subcutaneously injected growth hormone in Sprague-Dawley rats was 11.06%. Thus, the use of poly(ethylene glycol)-b-poly(L-lactide-co-glycolide) nanoparticles yielded promising results, and these agents should be investigated further regarding their potential as an oral growth hormone delivery system in the future.
Keywords: Human growth hormone; PEG-PLA; bioavailability; nanoparticles; release.