[Hiring] Senior Principal Scientist, Drug Substance @Loyal

Role Description

Loyal is seeking a Senior Principal Scientist, Drug Substance to serve as the technical leader for drug substance process development and manufacturing from early development through commercialization. This high-impact, externally-facing role will drive drug substance process development and manufacturing, and deliver flawless execution across CDMO partners while serving as the internal subject matter expert informing cross-functional decision-making and long-term development strategy across Loyal's growing pipeline.

You will be reporting to our VP of Manufacturing.

Your daily work will include:

• Lead end-to-end drug substance process development and manufacturing for small molecule APIs from synthetic route assessment and impurity control through scale-up, technology transfer, and commercial manufacturing readiness at CDMOs.
• Serve as the primary technical interface with drug substance CDMOs spanning partner selection, day-to-day oversight, troubleshooting, PAI preparation and performance management; ensure drug substance supply continuity, including second source qualification and starting material supply risk strategy, in support of clinical and commercial manufacturing.
• Lead RSM designation, ICH Q11 assessments, impurity fate and purge strategies and ICH M7 mutagenic impurity risk assessments; establish CQAs, CPPs, and ICH Q6A-aligned control strategies.
• Lead drug substance process validation from PPQ protocol development through batch execution and CPP/CQA verification; align PPQ timelines and batch disposition with drug product process validation and registration batch campaigns.
• Author, review, and approve drug substance CMC sections for regulatory submissions (VMF, INAD/NADA); represent drug substance CMC in agency interactions and ensure a technically integrated and consistent regulatory package.
• Partner with drug product development to translate drug substance CQAs into formulation design, excipient selection, container closure strategy and final dosage form decisions.
• Partner with analytical development to define method development, qualification, and validation strategy for drug substance release and stability testing.
• Partner with Quality to align drug substance specifications, batch disposition, and GMP compliance across CDMOs, and to support inspection and regulatory submission readiness.
• Manage drug substance post-approval change control strategy for manufacturing changes at CDMOs.

Qualifications

• Ph.D. in Chemistry, Chemical Engineering, Biochemistry, or a related discipline.
• 12+ years of industry experience in drug substance process development and manufacturing, with demonstrated ownership from early development through regulatory submission and commercialization phase.
• Hands-on expertise in small molecule API process development, including synthetic process understanding, impurity profiling, ICH Q11 RSM assessment, and ICH M7 mutagenic impurity control.
• Proven experience selecting, managing, and technically overseeing CDMOs for small molecule drug substance development, scale-up, technology transfer and PPQ.
• Demonstrated experience authoring and defending drug substance CMC regulatory submissions (INAD/NADA, VMF or equivalent) and interacting with regulatory agencies on CMC questions.
• Deep knowledge of applicable regulatory frameworks: ICH Q7, Q8, Q9, Q10, Q11, Q6A, M7, and relevant VICH guidelines for veterinary drug substances.
• Demonstrated ability to operate effectively in a dynamic, fast-paced startup environment with a high degree of autonomy and accountability.
• Experience with large biomolecule drug substance development (peptides, proteins, or other biological entities) preferred but not required.
• Veterinary dosage form experience preferred but not required.

Requirements

• Salary Range: $175,000 - $230,000

Benefits

• Full-coverage health insurance — medical, dental and vision — for you and your dependents.
• $1,000 home office equipment stipend.
• $1,200/year learning budget for books, courses, etc.
• $250/month wellness budget for gym, cleaners, spa, food, etc.
• All 3-day weekends are turned into 4-day weekends 🎉.
• Unlimited vacation and paid holidays.
• Paw-ternity leave — adopt a dog and get a day off with your new family member 🐶.
• Competitive salary.
• Company equity options grant for new hires.