Defense Date


Document Type


Degree Name

Doctor of Philosophy


Pharmaceutical Sciences

First Advisor

Matthew S. Halquist

Second Advisor

H. Thomas Karnes

Third Advisor

Jurgen Venitz

Fourth Advisor

Sarah Rutan

Fifth Advisor

Parthasarathy Madurantakam


Biorelevant in vitro release/dissolution tests are designed to predict the in vivo behavior of a drug and are crucial in understanding its in vivo performance. Currently, there is no standardized compendial in vitro release testing methods or regulatory guidance’s for release/dissolution testing of implants due to their complex physiological locations.Furthermore, existing compendial methods do not capture the local release profile of ‘novel’ parenterals in physiological low fluid volume surrounding areas.

Long acting and in situ forming implants with orthobiologic proteins and peptides have increased over the past few decades due to a better understanding of genetic engineering. One of these products, INFUSE® Bone Graft (Medtronics, MN, USA), is an implant which helps in bone regeneration at the trauma site and is comprised of a) an absorbable collagen sponge (ACS) and b) recombinant human bone morphogenetic protein-2 (rhBMP-2). INFUSE® Bone Graft is an FDA approved product for acute, open shaft tibial fractures, lumbar spinal fusions and sinus or ridge augmentations in the jaws. The evaluation of implant products such as INFUSE® Bone Graft requires a good understanding of local and systemic release in vivo in order to ensure safe, effective, and predictable product performance.

The primary goal of this study is to develop a predictive ‘biorelevant’ release model, which factors in clinically relevant physiological parameters suitable for studying and effectively predicting extended release of implants, using INFUSE Bone Graft® as our model implant. A novel biorelevant in vitro model was designed and tested. The model was observed to be discriminatory between two different carrier formulations of rhBMP-2 using a model independent approach - similarity factor (f2). Additionally, a high throughput assay to quantify rhBMP-2 release using high performance liquid chromatography with UV/VIS detection was also developed and validated. Successful completion of this study facilitated an in vitro release study design that incorporated the complex biorelevant parameters of implant dosage forms, the model will offer crucial insights into biological performance, and aid in developing methods to characterize release of other similar dosage forms.


© Deblina Biswas

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VCU Theses and Dissertations

Date of Submission


Available for download on Wednesday, July 27, 2022