RESUMO
Liquid protein formulations are prone to form aggregates. The effect of nonionic surfactants such as Polysorbate 20 [PS 20] and n-Dodecyl beta-D-maltoside [DDM] on the prevention of aggregation and conformational changes of recombinant human IFNbeta-1b [rhIFN beta_1b] was explored. Polysorbate has been used in formulations of protein pharmaceuticals. There have been concerns about using PS 20 due to its residual peroxide content which may negatively affect protein efficacy. n-Dodecyl beta-D-maltoside has been of interest and shown to be highly effective in prevention of aggregation. Fresh bulk of rhIFN beta_1b was formulated using DDM or different concentrations of PS 20. Formulations were exposed to light stress condition according to the ICH guideline of Q1b. The overall conformational integrity of individual samples was characterized by a combination of Circular dichroism [CD], Fluorescence spectroscopy and RP_HPLC techniques. The CD spectrum depicting the conformational integrity of rhIFN beta_1b showed 31.9% and 31.2% decreases in alpha-helix content of protein samples with 0.2% or 0.02% of PS20 compared to only18.2% of that containing 0.2% DDM. The RP-HPLC analysis also showed that the oxidized impurity in formulation containing DDM is less than those contain PS 20. Complementary analysis of the liquid formulations using IFR and UV methods also was in compliance with the data obtained by CD. Compared to PS 20, the sample of rhIFN beta_1b formulation with DDM was more resistant to the destruction effect of light. Results were in accordance with previous studies and could suggest DDM as a reliable anti-aggregation surfactant in biopharmaceutical formulations
RESUMO
The urea breath test [UBT] which is carried out with [13]C or [14]C labeled urea is one of the most important non invasive methods for detection of Helicobacter pylori infection. Application of [13]C-UBT is becoming increasingly popular because of its non radioactive nature which makes it suitable for diagnostic purposes in children and women of child bearing ages. While isotope ratio mass spectrometer [IRMS] is generally used to detect [13]C in expired breath, this instrument is expensive and recently non dispersive isotope selective infrared [NDIR] spectroscopy which is a lower cost technique has been employed as a reliable counterpart for IRMS in small clinics. The aim of this study was to assess the validity of NDIR spectroscopy technique in Iranian population in comparison with histological examination, rapid urease test and [14]C-urea breath test as gold standard. Seventy six patients with dyspepsia were underwent [13]CUBT for diagnosis of Helicobacter pylori infection. Good agreements were found between the [13]C-UBT and gold standard methods. The [13]C-UBT showed 100% sensitivity, 97.3% specificity, 97.56% positive predictive value, 100% negative predictive value and 98.65% accuracy. On the basis of these results it could be concluded that [13]C-UBT performed with NDIR spectroscopy is a reliable, accurate and non invasive diagnostic tool for detection of Helicobacter pylori infection in the Iranian population