Stability of insulin mixtures in disposable plastic insulin syringes

FDA perspective on peptide formulation and stability issues

Traditionally, peptide drugs are prepared as sterile solutions and administered to patients by daily injection. However, this form of drug delivery causes pain and inconvenience to patients and thus has been poorly accepted. In addition to improving patient compliance, many novel delivery systems have been developed to address the need for prolonged, localized (targeted), or pulsatile drug action. Examples include, but are not limited to oral, nasal, or long-acting controlled release injectable dosage forms; a number of them have been approved by FDA recently. The unique characteristics and the relevant regulatory issues with respect to each type of delivery system are presented.

Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces

The stability of protein-based pharmaceuticals (e.g., insulin) is important for their production, storage, and delivery. To gain an understanding of insulin's aggregation mechanism in aqueous solutions, the effects of agitation rate, interfacial interactions, and insulin concentration on the overall aggregation rate were examined. Ultraviolet absorption spectroscopy, high-performance liquid chromatography, and quasielastic light scattering analyses were used to monitor the aggregation reaction and identify intermediate species. The reaction proceeded in two stages; insulin stability was enhanced at higher concentration. Mathematical modeling of proposed kinetic schemes was employed to identify possible reaction pathways and to explain greater stability at higher insulin concentration.