Principal Scientist, Long-Acting Injectable Sterile Product Development

Job Description

The Sterile Product Development group is responsible for the development of parenteral dosage forms, including long-acting injectables (LAIs), across small molecules, peptides, and biologics from preclinical development through commercialization. Our teams enable robust and scalable drug product and delivery solutions through deep scientific understanding of formulation, drug-excipient interactions, delivery system performance, and manufacturing processes, ensuring product quality, safety, efficacy, and patient-centric design.

This role is a Principal Scientist-level technical leadership position with a primary focus on long-acting injectable drug products, including depot formulations, extended-release systems, and injectable sustained-delivery technologies. The successful candidate will serve as a scientific leader across multidisciplinary teams, shaping LAI formulation and development strategy across the portfolio.

Primary Duties

• Serve as a principal-level LAI formulation scientist, providing scientific leadership for the design, development, and lifecycle management of long-acting injectable drug products, including depot, sustained-release, and controlled-delivery parenteral dosage forms
• Lead LAI formulation and delivery strategy development, including selection and optimization of release mechanisms (e.g., polymer-based depots, suspensions, microspheres, in situ forming systems), excipient systems, and delivery approaches to meet target product profiles
• Provide strategic technical leadership on cross-functional program teams, ensuring alignment of formulation, drug substance properties, delivery system performance,
• container/closure systems, manufacturability, and clinical use considerations throughout development
• Design and interpret studies to understand and control release kinetics, stability, and performance, including:
• Drug-excipient and drug-polymer interactions
• In vitro and in vivo performance relationships
• Physical stability, aggregation, and particle size control
• Syringeability, injectability, and device compatibility
• Support early- and late-stage development programs, including:
• Selection of scalable manufacturing processes for LAIs
• Definition of formulation and process design space
• Support for clinical and commercial process scale-up and validation
• Technology transfer to GMP manufacturing facilities
• Partner closely with Clinical, Non-Clinical, Quality, Regulatory, Manufacturing, and Engineering teams to:
• Define critical quality attributes (CQAs) and critical process parameters (CPPs) relevant to LAI performance
• Support clinical strategy through formulation design and risk mitigation
• Contribute to CMC regulatory submissions and health authority interactions
• Provide scientific oversight and mentoring to junior scientists, fostering capability development in LAI formulation science, experimental design, and data-driven decision making
• Maintain awareness of emerging LAI technologies and delivery platforms, contributing to internal capability assessments, external collaborations, and innovation initiatives aligned with portfolio and organizational strategy

Minimum Education Requirements

• Ph.D. with 7+ years industry experience, or
• M.S. with 10+ years, or
• B.S. with 14+ years in Pharmaceutics, Pharmaceutical Sciences, Chemical Engineering, Biochemical Engineering, Chemistry, Materials Science, or a related discipline

Required Experience and Skills

• Deep expertise in parenteral drug product development, with demonstrated experience in long-acting injectable or sustained-release formulations
• Strong scientific understanding of:
• Controlled-release mechanisms and LAI delivery systems
• Drug-polymer and drug-excipient interactions
• Formulation stability and performance characterization
• Experience applying Quality by Design (QbD) principles and DOE approaches to formulation and process development
• Experience supporting process scale-up, validation, and technology transfer for sterile injectable products
• Working knowledge of CMC regulatory expectations for parenteral and extended-release products, including development-stage and commercial submissions
• Demonstrated ability to lead cross-functional teams, influence strategy, and communicate complex scientific concepts clearly
• Proven mentoring and scientific leadership skills at the senior/principal level

Preferred Experience and Skills

• Experience with LAI-specific platforms, such as polymer depots, microspheres, nanosuspensions, or in situ forming systems
• Experience with device-drug product integration, including prefilled syringes or delivery systems relevant to LAIs
• Understanding of clinical and patient-centric considerations influencing LAI design (e.g., dosing interval, injection volume, administration route)
• Experience supporting global regulatory filings and health authority interactions
• Track record of contributing to publications, patents, or external scientific collaborations in drug delivery or formulation science

Required Skills:
Cell Culture Process Development, Cell Line Development, Chemical Engineering, Combination Products, Finite Element Analysis (FEA), GMP Compliance, Pharmaceutical Process Development, Pharmaceutical Sciences, Project Manufacturing, Quality by Design, Quality Control Management, Quality Management, Stability Calculations, Strategic Thinking, Technology Transfer

Preferred Skills:

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As an Equal Employment Opportunity Employer, we provide equal opportunities to all employees and applicants for employment and prohibit discrimination on the basis of race, color, age, religion, sex, sexual orientation, gender identity, national origin, protected veteran status, disability status, or other applicable legally protected characteristics.--As a federal contractor, we comply with all affirmative action requirements for protected veterans and individuals with disabilities.- For more information about personal rights under the U.S. Equal Opportunity Employment laws, visit:

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The salary range for this role is
$173,200.00 - $272,600.00

This is the lowest to highest salary we in good faith believe we would pay for this role at the time of this posting. An employee's position within the salary range will be based on several factors including, but not limited to relevant education, qualifications, certifications, experience, skills, geographic location, government requirements, and business or organizational needs.

The successful candidate will be eligible for annual bonus and long-term incentive, if applicable.

We offer a comprehensive package of benefits.- Available benefits include medical, dental, vision healthcare and other insurance benefits (for employee and family), retirement benefits, including 401(k), paid holidays, vacation, and compassionate and sick days. More information about benefits is available at .

You can apply for this role through (or via the Workday Jobs Hub if you are a current employee). The application deadline for this position is stated on this posting.

San Francisco Residents Only: -We will consider qualified applicants with arrest and conviction records for employment in compliance with the San Francisco Fair Chance Ordinance

Los Angeles Residents Only: -We will consider for employment all qualified applicants, including those with criminal histories, in a manner consistent with the requirements of applicable state and local laws, including the City of Los Angeles' Fair Chance Initiative for Hiring Ordinance

Search Firm Representatives Please Read Carefully-
Merck & Co., Inc., Rahway, NJ, USA, also known as Merck Sharp & Dohme LLC, Rahway, NJ, USA, does not accept unsolicited assistance from search firms for employment opportunities. All CVs / resumes submitted by search firms to any employee at our company without a valid written search agreement in place for this position will be deemed the sole property of our company. -No fee will be paid in the event a candidate is hired by our company as a result of an agency referral where no pre-existing agreement is in place. Where agency agreements are in place, introductions are position specific. Please, no phone calls or emails.-

Employee Status:
Regular

Relocation:
Domestic

VISA Sponsorship:
Yes

Travel Requirements:
10%

Flexible Work Arrangements:
Not Applicable

Shift:
Not Indicated

Valid Driving License:
No

Hazardous Material(s):
n/a

Job Posting End Date:
08/1/2026
*A job posting is effective until 11:59:59PM on the day BEFORE -the listed job posting end date. Please ensure you apply to a job posting no later than the day BEFORE the job posting end date.

Requisition ID: R405908