ABSTRACT
Insulin pen-cartridge devices have evolved in order to increase patient compliance and convenience of use in a portable, multiple dosage device. With the advent of a portable insulin containing device, stability considerations have evolved from standard chemical indicators to include the effects of temperature and agitation on physical characteristics. To address these issues, two automated physical stress tests were developed based on market research data and input from regulatory authorities to understand the effect of thermomechanical stress on the product. First, the temperature cycling and resuspension test (TCRT) includes temperature cycling (25-37 degreesC) combined with agitation. The high temperature and extreme agitation test (HTEAT) includes continuous high temperature (37 degreesC) exposure combined with 4 h daily agitation. The total stress exposure is a function of the temperature, agitation, and time. The tests range from moderate stress (TCRT) to considerable stress (HTEAT) determined from the number of cartridge inversions and average daily temperature. Physical stress testing of both insulin suspensions and solution formulations in cartridges were performed and interpreted with respect to multiple endpoints. For suspensions, prolonged exposure to extreme stress caused the protein to form agglomerates, either in the suspension or adhered to the cartridge walls. In contrast, protein solutions subjected to the same extreme stress conditions did not exhibit any visually detectable change. Visual changes in the product under physical stress conditions can increase dose-potency result variability as well as exhibit acid-insoluble aggregates.
Subject(s)
Hypoglycemic Agents/administration & dosage , Insulin/administration & dosage , Drug Stability , Hypoglycemic Agents/chemistry , Insulin/chemistry , Stress, Mechanical , Syringes , TemperatureABSTRACT
An infrared/attenuated total reflection (ATR) technique has been utilized to study the structural changes in proteins induced by nonaqueous solvents, without the need of dissolving the protein in the nonaqueous solvent. For the two proteins studied, methanol and ethylene glycol caused similar changes in albumin, i.e., an increase in helix secondary structure. However, the two solvents had dissimilar effects on immunoglobulin G (IgG). Changes in the pH of aqueous solutions of IgG produced a third effect. By dissolving some IgG in ethylene glycol and then adsorbing IgG from this solution onto an ATR crystal, the time behavior of the adsorption process could be studied and a mechanism for the structural changes proposed.
Subject(s)
Immunoglobulin G , Serum Albumin , Adsorption , Ethylene Glycols , Fourier Analysis , Humans , Hydrogen-Ion Concentration , Methanol , Protein Conformation , Solvents , Spectrophotometry, Infrared , gamma-GlobulinsABSTRACT
Fourier transform infrared transmission spectra have been obtained of the enzyme ribonuclease in both H2O and 2H2O. The resolution of the spectra have been enhanced by Fourier self-deconvolution procedures. The infrared spectrum of ribonuclease changes during exchange of the enzyme's amide hydrogens for deuterium and the exchange has been followed in the amide I and amide II spectral regions. The amide I band shifts towards lower wavenumbers during both the fast and slow phases of hydrogen exchange and the interpretation of these shifts has aided the band assignments. In particular these studies have allowed an assignment to be made for the high frequency component of the beta-strand absorption that differs from that proposed previously. This paper represents the first example of the use of deconvoluted Fourier transform infrared spectra in conjunction with hydrogen-deuterium exchange in order to aid in the assignment of a protein's infrared bands.