DiscoveryProbe™ FDA-approved Drug Library: High-Throughput Screening for Drug Repositioning and Target Identification

Executive Summary: The DiscoveryProbe™ FDA-approved Drug Library (L1021) comprises 2,320 pre-dissolved, clinically approved compounds suitable for high-throughput and high-content screening (Andi et al., 2022). The library includes drugs approved by major agencies (FDA, EMA, HMA, CFDA, PMDA) or listed in pharmacopeias, enabling rapid drug repositioning and pharmacological target identification. Compounds are delivered in 10 mM DMSO solutions, with 12–24 month stability at -20°C or -80°C, respectively. Representative compounds include doxorubicin, metformin, and atorvastatin, each with well-defined mechanisms of action. The library's standardized format minimizes workflow variability and enhances reproducibility in diverse biomedical research applications (internal reference).

Biological Rationale

Drug discovery faces significant attrition, with only 10–14% of candidates reaching approval in late-phase trials (Andi et al., 2022). Repurposing already-approved drugs can bypass early-stage safety hurdles, as these compounds have established pharmacokinetics and toxicity profiles. The SARS-CoV-2 pandemic highlighted the value of repurposing, exemplified by remdesivir—originally developed for HCV and Ebola, later repurposed as an RNA polymerase inhibitor against COVID-19 (Andi et al., 2022). Systematic screening of FDA-approved libraries, such as DiscoveryProbe™, expedites the identification of novel inhibitors for targets like viral proteases, kinases, or signaling regulators. This approach is equally applicable to cancer, neurodegenerative diseases, and rare disease models.

Mechanism of Action of DiscoveryProbe™ FDA-approved Drug Library

The DiscoveryProbe™ FDA-approved Drug Library encompasses a diverse range of mechanisms of action, including:

• Receptor agonists and antagonists: Target GPCRs, nuclear receptors, and cytokine receptors.
• Enzyme inhibitors: Modulate kinases, proteases (e.g., NS3/4A, Mpro), phosphatases, and metabolic enzymes.
• Ion channel modulators: Affect calcium, potassium, sodium, and chloride channels.
• Signal pathway regulators: Influence pathways such as PI3K/Akt, MAPK, and JAK/STAT.

Each compound is annotated with mechanism, regulatory status, and molecular identity. For example, doxorubicin acts as a topoisomerase II inhibitor; metformin modulates AMP-activated protein kinase; atorvastatin inhibits HMG-CoA reductase. The inclusion of drugs with covalent binding potential—such as α-ketoamide protease inhibitors—enables studies of irreversible target engagement (Andi et al., 2022).

Evidence & Benchmarks

• High-throughput screening (HTS) of FDA-approved libraries enabled the identification of HCV NS3/4A protease inhibitors as covalent binders of the SARS-CoV-2 main protease (Mpro) (Andi et al., 2022).
• Remdesivir, present in such libraries, was repurposed to inhibit the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2, showing efficacy in vitro and in clinical settings (Andi et al., 2022).
• The DiscoveryProbe™ FDA-approved Drug Library’s 2,320 compounds are each provided as 10 mM DMSO solutions, stable for up to 24 months at -80°C, ensuring consistent screening conditions (product page).
• HTS using this library identified drugs with combinatorial or synergistic activity in cancer and neurodegenerative disease models (internal reference).
• Compounds are selected for regulatory approval status, minimizing off-target liabilities and supporting translational research (internal reference).

Applications, Limits & Misconceptions

The DiscoveryProbe™ FDA-approved Drug Library is validated for the following applications:

• High-throughput and high-content screening of signaling pathways, enzymatic activity, or cell phenotypes.
• Drug repositioning and combinatorial therapy discovery in oncology, virology, and neurodegeneration.
• Pharmacological target identification, supported by integrated annotation and regulatory status.

Compared to traditional discovery, this library reduces lead time and enhances clinical translatability (internal reference). For a broader discussion of advanced screening strategies and mechanistic insight, see our companion article, which this piece extends by detailing evidence and workflow integration.

Common Pitfalls or Misconceptions

• The library is not suitable for discovery of entirely novel chemical scaffolds not present in approved drugs.
• Some compounds, though approved, may not be active in all model organisms or in vitro systems due to metabolism or transport differences.
• Predissolved DMSO formats are not compatible with assays requiring aqueous-only solutions.
• Regulatory approval does not guarantee efficacy in new indications; confirmatory studies are required.
• Stability claims are contingent on strict adherence to temperature and storage guidelines (12 months at -20°C, 24 months at -80°C).

Workflow Integration & Parameters

The DiscoveryProbe™ FDA-approved Drug Library is provided in standardized formats: 96-well plates, deep-well plates, and 2D-barcoded screw-top tubes. Each well contains a 10 mM DMSO solution, compatible with robotic liquid handlers and HTS/HCS platforms. Shipping is performed on blue ice for evaluation samples, and at room temperature or blue ice for other sizes as requested. Compounds are stable for 12 months at -20°C and up to 24 months at -80°C (product documentation).

Researchers can directly integrate the library into existing assay workflows. For signal pathway or enzyme inhibitor screens, dilute compounds to assay concentrations (commonly 1–10 µM final) in the appropriate buffer. Barcoded tube formats support traceability for hit validation or reordering. For expanded guidance on integrating the library with structural biology or advanced pathway analysis, see this article, which this overview updates by providing new evidence and product specifications.

Conclusion & Outlook

The DiscoveryProbe™ FDA-approved Drug Library accelerates drug repositioning, target identification, and mechanistic screening across diverse biomedical research areas. Its rigorously curated compounds, standardized formats, and regulatory vetting streamline high-throughput studies and support translational efforts. Ongoing peer-reviewed evidence, such as the identification of Mpro inhibitors for SARS-CoV-2, underscores the library’s impact (Andi et al., 2022). For researchers aiming to leap beyond traditional discovery, the DiscoveryProbe™ FDA-approved Drug Library represents a validated and versatile resource.