In Vitro 3T3 NRU Phototoxicity Test – OECD 432

Assessing the safety of substances that may interact with light is a critical component of modern product development. Our laboratory offers the In Vitro 3T3 Neutral Red Uptake (NRU) Phototoxicity Test, performed in full compliance with OECD Test Guideline 432, providing reliable data to support regulatory safety assessments across multiple industries.

A phototoxicity test predicts whether a toxic response may arise from skin exposure of a substance followed by subsequent exposure to light. Phototoxic reactions typically occur when compounds absorb energy in the UV or visible spectrum, triggering cellular damage after irradiation. Identifying this potential early is essential for ensuring product safety and regulatory compliance.

The 3T3 NRU Phototoxicity Test is a validated in vitro assay used to evaluate phototoxic potential by measuring the reduction in cell viability through Neutral Red uptake. The assay compares the cytotoxic effects of a test substance in the presence (+UVA) and absence (–UVA) of light exposure, allowing the identification of substances that may induce phototoxic responses.

As part of our In Vitro Toxicology Testing Services, this method represents a scientifically robust and regulatory-accepted non-animal alternative method (NAM) aligned with the 3R principle – Replacement, Reduction and Refinement of animal experiments. Such New Approach Methodologies (NAMs) are increasingly adopted worldwide to support safer, ethical, and more efficient product safety assessments.

Our testing services support regulatory safety evaluation of:

• Cosmetic products and raw materials – including UV filters, sunscreens, leave-on formulations for daily use, and ingredients intended for topical application
• Pharmaceutical substances – active compounds and excipients, particularly those administered dermally with potential exposure to light
• Medical device formulations – especially products containing photo-reactive or UV-absorbing components, such as dermal or ophthalmic applications
• Chemical substances – compounds demonstrating absorption in the UV/visible spectrum that may require phototoxicity evaluation under OECD test guidelines

In addition to phototoxicity testing, our laboratory also offers photostability studies, supporting the evaluation of how substances and formulations behave when exposed to light during storage or use.

Our quality control laboratories operate according to the highest standards, ensuring the reliability and regulatory acceptance of generated data. All studies are conducted in GLP-compliant laboratories guaranteeing rigorous quality systems and scientific integrity throughout the testing process.

With extensive expertise in in vitro toxicology, advanced in vitro assays, and internationally recognized OECD test guidelines, our team supports companies in developing safe and compliant products using state-of-the-art non-animal testing approaches.

By partnering with our laboratory, clients benefit from high-quality In Vitro Toxicology Testing Services, expert scientific guidance, and reliable data to support regulatory submissions and product safety evaluations.