Formulation of 99mTechnetium-labeled leuprolide loaded liposomes and its biodistribution study in New Zealand white female rabbits for assessment of its uterine targeting efficiency

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99mTc-labeled leuprolide-loaded liposomes administered vaginally showed preferential uterine uptake and retention in rabbits, suggesting improved uterine targeting compared to the plain drug.

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The paper studied formulation and characterization of vaginally administered leuprolide acetate–loaded liposomes labeled with 99mTechnetium to assess uterine targeting efficiency. Using a thin-film hydration method with DSPC:cholesterol lipids, the authors measured vesicle size (~189 nm), zeta potential, drug entrapment/loading (74.36% entrapment; 9.29% w/w loading), radiolabeling efficiency/stability, and release over 5 days, and evaluated labeling stability via DTPA challenge and biodistribution by gamma scintigraphy in New Zealand white female rabbits. The liposomes showed sustained release, high 99mTc labeling efficiency and stability in saline/serum, low transchelation, and preferential uterine uptake with longer retention than plain drug. Limitations include that the biodistribution and targeting were assessed only in rabbits and not in human disease models of uterine pathology. This paper is centrally about endometriosis — it investigates uterine targeting of leuprolide acetate, a drug of choice for endometriosis, using an intravaginal delivery strategy aimed at the uterus.

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Abstract

Leuprolide acetate (LPA), a GnRH analogue, is drug of choice for treatment of uterine fibroids and endometriosis. The current marketed formulations of LPA show severe systemic side effects. This project aims to formulate LPA loaded liposomes to be administered by vaginal route for uterine targeting. Liposomes were prepared by thin film hydration method using 1:1 M ratio of DSPC: Cholesterol and characterized for vesicle size, zeta potential, entrapment efficiency, and loading. Radiolabeling of LPA was performed by direct labeling with reduced technetium-99m. Binding affinity of 99mTc-labeled complexes was assessed by diethylenetriaminepentaacetic acid (DTPA) challenge test. Biodistribution study was done in New Zealand white female rabbits by administering the formulation via vaginal route. Spherical and discrete vesicles of size 189 nm were seen in TEM results with entrapment efficiency and loading of 74.36% and 9.29%w/w, respectively. Liposomes were able to sustain the drug release for 5 days. 99mTc-labeled complexes showed high labeling efficiency and stability both in saline and serum. DTPA challenge test confirmed low transchelation of 99mTc-labeled complexes. Biodistribution study by gamma scintigraphy revealed the preferential uptake of the formulation by uterus when administered vaginally. Compared to plain drug, liposomes concentrated and were retained within the uterus for a longer period of time. Uterine targeting of liposomal LPA indicates its potential to overcome the limitations of presently available formulations. Hence, this seems to be a promising approach for targeting the drugs, whose site of action is uterus.
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Abstract

Leuprolide acetate (LPA), a GnRH analogue, is drug of choice for treatment of uterine fibroids and endometriosis. The current marketed formulations of LPA show severe systemic side effects. This project aims to formulate LPA loaded liposomes to be administered by vaginal route for uterine targeting. Liposomes were prepared by thin film hydration method using 1:1 M ratio of DSPC: Cholesterol and characterized for vesicle size, zeta potential, entrapment efficiency, and loading. Radiolabeling of LPA was performed by direct labeling with reduced technetium-99m. Binding affinity of 99mTc-labeled complexes was assessed by diethylenetriaminepentaacetic acid (DTPA) challenge test. Biodistribution study was done in New Zealand white female rabbits by administering the formulation via vaginal route. Spherical and discrete vesicles of size 189 nm were seen in TEM results with entrapment efficiency and loading of 74.36% and 9.29%w/w, respectively. Liposomes were able to sustain the drug release for 5 days. 99mTc-labeled complexes showed high labeling efficiency and stability both in saline and serum. DTPA challenge test confirmed low transchelation of 99mTc-labeled complexes. Biodistribution study by gamma scintigraphy revealed the preferential uptake of the formulation by uterus when administered vaginally. Compared to plain drug, liposomes concentrated and were retained within the uterus for a longer period of time. Uterine targeting of liposomal LPA indicates its potential to overcome the limitations of presently available formulations. Hence, this seems to be a promising approach for targeting the drugs, whose site of action is uterus. Similar content being viewed by others

References

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Liposomes: a nanoscale drug carrying system to prevent indomethacin passage to the fetus in a pregnant mouse model. Am J Obstet Gynecol. 2015;212:508–10. Author information Authors and Affiliations Corresponding author Ethics declarations Ethics approval All institutional and national guidelines for the care and use of laboratory animals were followed. Conflict of interest The authors declare that they have no conflicts of interest. Rights and permissions About this article Cite this article Patel, A., Tyagi, A., Sharma, R.K. et al. Formulation of 99mTechnetium-labeled leuprolide loaded liposomes and its biodistribution study in New Zealand white female rabbits for assessment of its uterine targeting efficiency. Drug Deliv. and Transl. Res. 8, 43–53 (2018). https://doi.org/10.1007/s13346-017-0432-1 Published: Issue date: DOI: https://doi.org/10.1007/s13346-017-0432-1

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Leuprolide Technetium Uterus Animals Drug Liberation Female Leuprolide Leuprolide Liposomes Rabbits Technetium Technetium Tissue Distribution Uterus

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