Related Experiment Video
Updated: Jul 30, 2026
10:33
Generation of Alginate Microspheres for Biomedical Applications
Published on: August 12, 2012
Porcine insulin biodegradable polyester microspheres: stability and in vitro release characteristics
1Warner-Lambert Research Division, Morris Plains, New Jersey 07950, USA.
Pharmaceutical Development and Technology
|February 12, 2000
Summary
Porcine insulin rapidly degrades in biodegradable microspheres, with less than 50% remaining after 4 weeks. This instability is linked to decreasing pH within the polymer matrix due to acid production.
Area of Science:
- Biomaterials Science
- Pharmaceutical Technology
- Drug Delivery Systems
Background:
- Biodegradable polymers like poly(DL-lactide-co-glycolide) (DL-PLGA) and poly(L-lactide) (L-PLA) are used for drug encapsulation.
- Insulin stability within these matrices is crucial for effective therapeutic delivery.
- Understanding degradation pathways is essential for optimizing formulation and storage.
Purpose of the Study:
- To investigate the stability of porcine insulin encapsulated in DL-PLGA and L-PLA microspheres.
- To characterize insulin degradation products under accelerated stability conditions.
- To elucidate the mechanisms underlying insulin degradation within these biodegradable systems.
Main Methods:
- Microspheres fabricated using double-emulsion-solvent evaporation and emulsion-solvent evaporation techniques.
- Accelerated stability studies conducted at 40°C and 75% relative humidity.
- In vitro release studies performed in phosphate-buffered saline at 37°C.
- Analysis of degradation products using chromatographic and spectroscopic methods.
- pH monitoring within microspheres using an acid-base indicator.
Main Results:
- Porcine insulin exhibited significant degradation (<50% intact) within 4 weeks in all formulations.
- Major degradation products identified as A-21 desamido insulin and covalent insulin dimer.
- In vitro release was slow and incomplete (<30% in 30 days).
- Significant insulin degradation occurred even within unreleased microspheres.
- pH within 50:50 DL-PLGA microspheres decreased to ~3.8 within 3 weeks.
Conclusions:
- Porcine insulin is unstable in both DL-PLGA and L-PLA biodegradable microspheres.
- Acid-catalyzed hydrolysis, driven by polymer degradation products (lactic and glycolic acids), is the primary cause of insulin instability.
- The acidic microenvironment within the microspheres significantly impacts insulin integrity and release kinetics.
- Formulation strategies must address the acidic nature of these biodegradable polymers to ensure therapeutic efficacy.
More Related Videos
09:31Sustained Administration of β-cell Mitogens to Intact Mouse Islets Ex Vivo Using Biodegradable Poly(lactic-co-glycolic acid) Microspheres
Published on: November 5, 2016
09:39Injectable Supramolecular Polymer-Nanoparticle Hydrogels for Cell and Drug Delivery Applications
Published on: February 7, 2021
Related Concept Videos
01:25Insulin: Biosynthesis, Chemistry, and Preparation
The endoplasmic reticulum (ER) of pancreatic β-cells synthesizes preproinsulin, which consists of a signal peptide, A and B chains, and a C-peptide. Preproinsulin is then cleaved and folded into proinsulin, which translocates to the Golgi apparatus for sorting and packaging into secretory granules. In these granules, enzymatic clipping generates insulin and C-peptide.
Damage or functional impairment of β-cells inhibits insulin production, leading to diabetes. Diabetes treatment primarily uses...
Damage or functional impairment of β-cells inhibits insulin production, leading to diabetes. Diabetes treatment primarily uses...
01:30Production of Pharmaceuticals
Industrial insulin production uses genetically engineered E. coli expressing a proinsulin gene controlled by a tryptophan promoter and containing a methionine linker for later cleavage. The cells also carry ampicillin resistance for selective growth. Seed cultures are stored at −80 °C and production begins by thawing a small amount to inoculate starter cultures, which are progressively scaled to a 50,000-L bioreactor. In the bioreactor, E. coli grow in nutrient-rich media under sterile, tightly...
01:27Bioplastics
Bioplastics derived from microbial processes present a sustainable alternative to conventional petroleum-based plastics. Among these, polyhydroxyalkanoates (PHAs), particularly polyhydroxybutyrates (PHBs), have emerged as prominent candidates due to their biodegradability and biocompatibility. These polymers are synthesized by a variety of bacteria, such as Cupriavidus necator and Pseudomonas putida, which naturally accumulate PHAs as intracellular carbon and energy reserves, especially under...