A novel approach has been developed for the quantitative determination of circulating drug concentrations in clinical studies using dried blood spots (DBS) on paper, rather than conventional plasma samples. A quantitative bioanalytical HPLC-MS/MS assay requiring small blood volumes (15 microL) has been validated using acetaminophen as a tool compound (range 25 to 5000 ng/mL human blood). The assay employed simple solvent extraction of a punch taken from the DBS sample, followed by reversed phase HPLC separation, combined with selected reaction monitoring mass spectrometric detection. In addition to performing routine experiments to establish the validity of the assay to internationally accepted criteria (precision, accuracy, linearity, sensitivity, selectivity), a number of experiments were performed to specifically demonstrate the quality of the quantitative data generated using this novel sample format, namely, stability of the analyte and metabolites in whole human blood and in DBS samples; effect of the volume of blood spotted, the device used to spot the blood, or the temperature of blood spotted. The validated DBS approach was successfully applied to a clinical study (single oral dose of 500 mg or 1 g acetaminophen).

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In this article we discuss various shipping containers for these samples, illustrate the environmental extremes encountered during the shipping process, demonstrate a cost-effective method of monitoring both temperature and humidity, and discuss validation steps that may be implemented to minimize the impact of these variables on your study design.

This work demonstrates that quantitative analysis of a drug extracted from dried blood spots can provide high-quality data while minimizing the volume of blood withdrawn from volunteers.

Reducing the required frequence of drug dosing can improve the adherence of patients to chronic treatments. Hence, drugs with longer in vivo half-lives are highly desirable. One of the most promising approaches to extend the in vivo half-life of drugs is conjugation to human serum albumin (HSA). In this work, we describe the use of AlbuBinder 1, a small-molecule noncovalent HSA binder, to extend the in vivo half-life and pharmacology of small-molecule BMP1/TLL inhibitors in humanized mice (HSA KI/KI). A series of conjugates of AlbuBinder 1 with BMP1/TLL inhibitors were prepared. In particular, conjugate c showed good solubility and a half-life extension of >20-fold versus the parent molecule in the HSA KI/KI mice, reaching half-lives of >48 h with maintained maximal inhibition of plasma BMP1/TLL. The same conjugate showed a half-life of only 3 h in the wild-type mice, suggesting that the half-life extension was principally due to specific interactions with HSA. It is envisioned that conjugation to AlbuBinder 1 should be applicable to a wide range of small molecule or peptide drugs with short half-lives. In this context, AlbuBinders represent a viable alternative to existing half-life extension technologies.