Pyrithione zinc, or zinc pyrithione or zinc pyridinethione, is a coordination complex consisted of pyrithione ligands chelated to zinc (2+) ions via oxygen and sulfur centers. In the crystalline state, it exists as a centrosymmetric dimer. Due to its dynamic fungistatic and bacteriostatic properties, pyrithione zinc is used to treat dandruff and seborrheic dermatitis. Dandruff is a common scalp disease affecting >40% of the world’s adult population, and may be caused by fungi such as Malassezia globosa and M. restricta. Pyrithione zinc is commonly found as an active ingredient in OTC antidandruff topical treatments such as shampoos. It mediates its action by increasing the cellular levels of copper, and damaging iron-sulfur clusters of proteins essential for fungal metabolism and growth. Due to low solubility, pyrithione zinc released from the topical formulations is deposited and retained relatively well onto the target skin surfaces. Other uses of pyrithione zinc include additive in antifouling outdoor paints and algaecide. While its use has been approved in the early 1960’s by the FDA, safety and effectiveness of pyrithione zinc has been reported for decades. It is not shown to have any significant estrogenic activity according to the in vivo and in vitro assays.
Science-backed PDE/ADE, OEL & OEB derivation by certified toxicologists with ex-agency experts -
Pyrithione
Drug Overview
What is Pyrithione?
To derive PDE/ADE, OEL, and OEB values, Masuu Global follows a scientifically justified, risk-based toxicological assessment approach in accordance with internationally recognized guidelines and industry best practices that are widely accepted by regulatory authorities, including European Medicines Agency (EMA), Pharmaceutical Inspection Co-operation Scheme (PIC/S), and Agência Nacional de Vigilância Sanitária (ANVISA).
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View Inquiry List →Full OEL derivation · ADE/PDE value · Control band assignment · All cited references · EMA / ICH Q9 compliance
Regulatory Framework
Assessment Methodology
Masuu Global follows a scientifically justified, risk-based toxicological approach aligned with internationally recognized guidelines accepted by EMA, PIC/S, and ANVISA.
EMA – Guideline on Setting Health-Based Exposure Limits (HBELs)
Provides the framework for establishing scientifically justified PDE/ADE values for use in shared manufacturing facilities.
PIC/S – Shared Facilities and Contamination Control Guidance
Supports the application of HBEL-based approaches for cross-contamination prevention and cleaning validation.
ICH Q9 – Quality Risk Management
Provides a structured methodology for risk identification, assessment, control, communication, and review.
ICH M7 – Assessment and Control of DNA-Reactive (Mutagenic) Impurities (where applicable)
Applied for compounds with potential mutagenic or genotoxic concerns.
Risk-Based Toxicological Assessment
Comprehensive evaluation of available toxicological and pharmacological data, including NOAEL, LOAEL, BMDL, pharmacological potency, carcinogenicity, reproductive and developmental toxicity, sensitization potential, and target organ toxicity.
Weight-of-Evidence (WoE) Approach
Integration and critical review of all relevant data sources, including non-clinical studies, clinical studies, human exposure data, pharmacological information, post-marketing safety data, and structure–activity relationship (SAR/QSAR) assessments.
How We Work
Report Preparation Process
Every assessment moves through a rigorous five-stage workflow — from data gathering to regulatory-ready delivery.
Comprehensive Data Review
Assessment of pharmacology, toxicology, clinical data, literature, and available regulatory information.
Scientific Evaluation
Identification of critical endpoints and selection of appropriate exposure limits.
PDE / HBEL Derivation
Transparent and scientifically justified calculations aligned with global toxicological principles.
Ex-Agency Expert Review (Our Differentiator)
Reports are reviewed with an ex-agency perspective, bringing regulatory expectations, inspection readiness, and practical implementation into every assessment.
Final Report Delivery
Regulatory-ready reports with scientific rationale, calculations, and clear recommendations by certified toxicologists (ERT, UKRT and DABT).
Ex-Agency Advantage
Why Masuu Global?
Our ex-agency toxicologists bring a practical regulatory perspective that transforms how assessments are built, reviewed, and defended.
Regulatory expectation–driven assessments aligned with how authorities actually evaluate submissions.
Inspection-ready reports — scientifically defensible and audit-prepared from day one.
Faster review cycles with direct decision support from certified toxicologists (ERT, UKRT, DABT).
Practical implementation recommendations that translate science into actionable contamination control.
Reduced internal effort — offload complex assessments without sacrificing quality or defensibility.
Global reach across PDE/ADE, HBEL, OEL, OEB, cleaning validation, and impurity assessments.
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