Accelerator mass spectrometry offers new opportunities for microdosing of peptide and protein pharmaceuticals

Abstract

Accelerator Mass Spectrometry (AMS) is an ultra-sensitive analytical method which has been instrumental in developing microdosing as a strategic tool in early drug development. Considerable data is available for AMS microdosing using typical pharmaceutical drugs with a molecular weight of a few hundred Daltons. The so-called biopharmaceuticals such as proteins offer interesting possibilities as drug candidates; however, experimental data for protein microdosing and AMS is scarce. The analysis of proteins in conjunction with early drug development and microdosing is overviewed and three case studies are presented on the topic. In the first case study AMS experimental data is presented, for the measured concentration of orally administered recombinant insulin in the blood stream of laboratory rabbits. Case study 2 concerns minimum sample size requirements. AMS samples normally require about 1 mg of carbon (10 microL of blood) which makes AMS analysis unsuitable in some applications due to the limited availability of samples such as human biopsies or DNA from specific cells. Experimental results are presented where the sample size requirements have been reduced by about two orders of magnitude. The third case study concerns low concentration studies. It is generally accepted that protein pharmaceuticals may be potentially more hazardous than smaller molecules because of immunological reactions. Therefore, future first-in-man microdosing studies might require even lower exposure concentrations than is feasible today, in order to increase the safety margin. This issue is discussed based on the current available analytical capabilities.

Accelerator mass spectrometry of ultra-small samples with applications in the biosciences

“…Accelerator mass spectrometry (AMS) activities at Uppsala University have been ongoing since the early 1980's, applying the method to a variety of pure and applied fields using 14 C, 10 Be, 36 Cl and 129 I within multidisciplinary fields spanning from geology to environmental sciences. However, it was not until 2007 when the biomedical applications were initiated.…”

Microdosing studies using accelerated mass spectrometry as exploratory investigational new drug trials

“…For 14 C quantification assays, samples should be subjected to a highly purified graphitization process in which the human bodily fluid is combusted. Various pretreatment protocols are required before AMS analysis, depending on the necessity of sample drying or reduction (Kim et al, 2008(Kim et al, , 2010Arjomand, 2010;Salehpour et al, 2010). These processes involve unique manipulations that have been developed according to the pretreatment technology available at a given institution.…”

“…In recent years, biologics, including specific types of therapeutic proteins (antibodies), have been actively developed as new drug candidates. Because it is also important to obtain pharmacokinetic data for these biologics as early as possible, AMS-based microdosing studies have been applied (Salehpour et al, 2010).…”

Application of accelerator mass spectrometry to macromolecules: preclinical pharmacokinetic studies on a polybisphosphonate

“…The sample preparation was performed as described previously. [9][10][11] Briefly, the samples collected from the animal study were lyophilized (Scanvac Modulespin 40, Scanlaf A/S, Denmark) for 2 h at 2000 rpm at 10 -3 mbar vacuum and were subsequently placed in quartz tubes C for 3 h to produce CO 2 gas. The gas was cryogenically transferred in vacuum to vials containing 80 mg zinc powder as reducing agent + 2 mg iron powder as catalyst.…”

“…AMS analysis of macromolecules is still uncommon with only a few reported studies. [8,9] EXPERIMENTAL Preparation of 14 …”