Sustained in-vivo release of triptorelin acetate from a biodegradable silica depot: Comparison to Pamorelin® LA

Ari-Pekka Forsback, Panu Noppari*, Jesse Viljanen, Jari Mikkola, Mika Jokinen, Lasse Leino, Simon Bjerregaard, Camilla Borglin, Janet Halliday

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)
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Triptorelin acetate was encapsulated into silica microparticles by spray-drying a mixture of colloidal silica sol and triptorelin acetate solution. The resulting microparticles were then combined with another silica sol containing silica nanoparticles, which together formed an injectable silica-triptorelin acetate depot. The particle size and surface morphology of the silica-triptorelin acetate microparticles were characterized together with the in vitro release of triptorelin, injectability and rheology of the final injectable silica-triptorelin acetate depot. In vivo pharmacokinetics and pharmacodynamics of the silica-triptorelin acetate depot and Pamorelin® were evaluated and compared in Sprague-Dawley male rats after subcutaneous administration. Serum samples up to 91 days were collected and the plasma concentrations of triptorelin and testosterone were analyzed with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). In vivo pharmacokinetics showed that injections of the silica-triptorelin acetate depot gave 5-fold lower Cmax values than the corresponding Pamorelin® injections. The depot also showed a comparable sustained triptorelin release and equivalent pharmacodynamic effect as the Pamorelin® injections. Detectable triptorelin plasma concentrations were seen with the depot after the 91-day study period and testosterone plasma concentrations remained below the human castration limit for the same period.

Original languageEnglish
Article number1578
Number of pages14
Issue number6
Publication statusPublished - 16 Jun 2021
MoE publication typeA1 Journal article-refereed


  • Controlled release
  • Silica hydrogel
  • Silica microparticles
  • Silica nanoparticles
  • Triptorelin


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