Introduction: Triptorelin, the synthetic analog of gonadotrophin-releasing hormone, is used
for the treatment of sex hormone dependent diseases via parenteral administration. The aim of the present
study was to investigate the possibility of triptorelin pulmonary delivery and preparation of a pulmonary
nanocarrier delivery system for it.
Methods: Triptorelin was loaded in Pluronic-F127 grafted poly (methyl vinyl ether-alt-maleic acid)
nanomicelles by direct dissolution method. Effects of the processing variables including: drug/polymer
ratio, temperature, stirring rate and time on the physicochemical properties of nanomicelles including
zeta potential, particle size, drug entrapment efficiency and release profiles of triptorelin loaded
nanomicelles were evaluated. For animal studies 24 Wistar rats were separated into four groups of six.
Group 1 received blank nanomicelles, groups 2, 3 and 4 were treated with a single dose of 250 µg.kg-1
of triptorelin solution subcutaneously (sc), pulmonary spraying of triptorelin solution (250 µg.kg-1) and
pulmonary spraying of triptorelin nanomicelles (250 µg.kg-1), respectively by microsprayer.
Results: The optimized micelles had particle size of 87.35 nm, zeta potential of -12.8 mV, entrapment
efficiency of 84.36% and release efficiency of 65%. The area under the blood testosterone levels increment
differed significantly (p<0.05) between pulmonary triptorelin nanomicelles and drug solution.
The pharmacological activity of the simple solution was 59.38%, while it was 80.18% for the nanomicelles
relative to sc route of administration with prolonged residence time.
Conclusion: The results of this study show that not only triptorelin is absorbable from the lungs but
also nanomicelles can significantly enhance its pulmonary absorption compared to its simple solution.