Acute and repeat-dose toxicity evaluations form the cornerstone of preclinical safety assessment, establishing the dose-toxicity relationship and identifying target organ effects that inform first-in-human trial design. Protheragen provides comprehensive GLP-compliant acute and repeat-dose toxicity testing tailored specifically for radiopharmaceutical candidates, bridging the gap between biodistribution data and regulatory approval.
Acute toxicity studies evaluate the adverse effects of a single administration of a test substance, typically conducted across escalating dose levels to determine lethal dose ranges and identify clinical signs of toxicity within a short observation period. For pharmaceuticals, these studies traditionally involve at least two mammalian species—a rodent and a non-rodent—and assess parameters including mortality, body weight changes, clinical observations, and gross pathology. In the context of radiopharmaceuticals, acute toxicity assessments must account for both the pharmacological effects of the carrier molecule and the radiological burden of the attached radionuclide, requiring specialized endpoints such as hematology, clinical chemistry, and early histopathological screening to capture radiation-induced organ damage.
Fig 1. Qualitative reproducibility of organ-level effect observations in repeat dose studies of adult animals. (Friedman, Katie Paul, et al., 2023)
Repeat-dose toxicity studies extend these evaluations over longer durations, designed to mirror the intended clinical treatment regimen. According to ICH M3(R2) guidelines, the duration of repeat-dose studies must equal or exceed the proposed clinical trial duration, ranging from short-term subacute studies (2–4 weeks) to subchronic programs extending up to 6 months in rodents and 9 months in non-rodents. These investigations are pivotal for establishing the no-observed-adverse-effect level (NOAEL), identifying cumulative toxicities, and characterizing target organ pathology—particularly bone marrow suppression, nephrotoxicity, and salivary gland dysfunction—which are frequently dose-limiting in targeted radionuclide therapy. The resulting data directly inform the calculation of the maximum recommended starting dose (MRSD) for human trials and define the safety monitoring parameters essential for clinical protocols.
Protheragen offers integrated acute and repeat-dose toxicity assessment services specifically engineered for the radiopharmaceutical sector. Leveraging GLP-certified facilities, species-appropriate models, and multidisciplinary expertise spanning toxicology, pathology, and radiation dosimetry, we deliver IND-enabling safety packages that satisfy FDA, EMA, and IAEA expectations—ensuring your therapeutic or diagnostic radiopharmaceutical advances to clinical trials with a robust, defensible safety profile.
Dose-range finding and expanded acute toxicity evaluations in rodent and non-rodent species with full clinical pathology, necropsy, and histopathology endpoints to establish initial safety margins and LD50 ranges.
GLP-compliant 2-week to 9-month repeat-dose programs designed to support Phase I through Phase III clinical trials, with toxicokinetic sampling, antibody analysis (for biologics), and comprehensive organ toxicity assessment.
Dual-track evaluation using cold ligand for vector toxicity and dosimetry-based modeling for radiation-induced toxicity, including hematopoietic, renal, and salivary gland monitoring.
Cardiovascular (hERG/telemetry), central nervous system (Irwin/FOB), and respiratory safety assessments conducted in compliance with ICH S7A and S7B guidelines.
Blood and tissue sampling for Cmax, AUC, clearance, and accumulation profiling to correlate systemic exposure with observed toxicological findings.
Assessment of injection site reactions, vascular compatibility, and extravasation potential for intravenous, intramuscular, or subcutaneous radiopharmaceutical formulations.
Our toxicity assessment workflow is structured to generate regulatory-grade data efficiently while maintaining scientific rigor. Each phase is executed under GLP conditions with continuous quality assurance oversight, ensuring that study outcomes are audit-ready and submission-compliant.
Ready to advance your radiopharmaceutical candidate with confidence? Contact us today to discuss your acute and repeat-dose toxicity assessment needs. Our preclinical toxicology team is prepared to design a customized, GLP-compliant study program that aligns with your regulatory strategy and accelerates your path to first-in-human trials—reach out to us and discover how Protheragen can de-risk your radiopharmaceutical development journey.
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