PK Studies in Patients: Choosing the Right Study Design for Faster Drug Development

Drug development begins with one fundamental question:

How does the body handle a drug and how does the drug affect the body?
The answer comes from pharmacokinetic (PK) and pharmacodynamic (PD) studies, which form the backbone of early clinical development. Whether developing a new molecular entity, a generic drug or a biosimilar, sponsors rely on pharmacokinetics studies to understand absorption, distribution, metabolism and excretion (ADME), while PD assessments determine whether the drug produces the intended biological effect.

Although many early-phase PK studies are conducted in healthy volunteers, several therapeutic areas, including oncology, autoimmune diseases, rare diseases and advanced biologics, require PK evaluation directly in patients because of safety considerations, ethical constraints or disease-specific pharmacology. Choosing the appropriate study population is therefore a scientific and regulatory decision rather than a one-size-fits-all approach.

The Growing Demand for PK Studies in India and Globally
The demand for pharmacokinetics studies continues to grow across every stage of drug development. From first-in-human trials in healthy volunteers to complex patient-based studies supporting oncology drugs and biosimilars, PK studies generate the critical evidence needed to optimize dosing, establish bioequivalence or biosimilarity and meet increasingly rigorous regulatory expectations.

India has emerged as a preferred destination for clinical PK studies, driven by its experienced investigators, globally compliant clinical research infrastructure, cost efficiency and access to both healthy volunteers and diverse patient populations. These strengths enable sponsors to conduct a broad range of pharmacokinetic studies, from early-phase pk study programs in healthy volunteers to complex pk/pd studies in patients across multiple therapeutic areas.

According to MarknTel Advisors, the Indian preclinical research market was valued at USD 175 million in 2024 and is projected to reach USD 300 million by 2030, growing at a CAGR of 11.5%. This growth reflects increasing investment in drug discovery and development, expanding outsourcing by global pharmaceutical and biotechnology companies, and the continued strengthening of India's clinical research ecosystem. While preclinical research is distinct from clinical PK evaluation, the overall expansion of the R&D landscape is contributing to greater demand for integrated pk-studies and translational development services.

The rapid growth of biosimilars is another major driver of pk and pd studies. According to Fortune Business Insights, the global biosimilars market is projected to grow from USD 23.96 billion in 2023 to USD 73.03 billion by 2030, at a CAGR of 17.3%. As patents for blockbuster biologics continue to expire, sponsors are increasingly investing in comparative pharmacokinetics study programs to demonstrate biosimilarity. Regulatory agencies, including the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA), recognize comparative PK assessment as one of the most sensitive clinical tools for establishing that a proposed biosimilar has no clinically meaningful differences from its reference product in terms of pharmacokinetics, safety, efficacy and immunogenicity.

Demand for pharmacokinetic studies also varies across therapeutic areas, reflecting disease burden, product complexity, and regulatory requirements. According to Precedence Research, oncology accounted for the largest share (43.2%) of the global pharmacokinetics services market in 2025. This growth is driven by the expanding pipeline of targeted therapies, immunotherapies, antibody-drug conjugates (ADCs) and biosimilars, all of which require robust pk pd studies to characterize drug exposure, optimize dosing strategies, and evaluate exposure-response relationships. India continues to experience a significant cancer burden, with more than 1.4 million new cancer cases diagnosed annually, further increasing the need for specialized patient-based PK research and early-phase oncology studies.

Beyond oncology, therapeutic areas such as endocrinology, respiratory diseases, cardiovascular disorders, infectious diseases, immunology and rare diseases continue to fuel demand for pharmacokinetics studies. These trends underscore the growing importance of scientifically rigorous clinical PK studies that combine operational excellence, advanced bioanalytical capabilities and regulatory expertise to accelerate drug development and improve patient access to innovative therapies.

What are PK Studies?
A pharmacokinetics study evaluates how quickly and efficiently a drug is absorbed into the bloodstream, distributed throughout the body, metabolized and ultimately eliminated. These studies generate critical parameters such as Cmax, Tmax, AUC, half-life, clearance and volume of distribution.

When combined with pharmacodynamic endpoints, PK/PD studies help establish exposure-response relationships that guide dose selection, optimize treatment regimens and support regulatory submissions.

When are PK Studies Conducted?
One of the most common questions sponsors ask is whether PK studies should be performed in healthy volunteers or patients.

The answer depends on multiple factors, including the drug's mechanism of action, anticipated safety profile, therapeutic indication and regulatory expectations.

PK Studies in Healthy Volunteers
Healthy volunteer studies are typically the preferred option during Phase I clinical development because they minimize biological variability, allowing researchers to characterize a drug's intrinsic pharmacokinetic profile with greater precision. Lower variability often translates into smaller sample sizes, faster recruitment and more efficient study execution.

Healthy volunteer PK studies are commonly conducted for:

• First-in-human studies with acceptable safety margins
• Generic bioequivalence studies
• Drug-drug interaction studies
• Food-effect studies
• Dose-escalation studies
• Clinical PK studies supporting dose optimization

Healthy volunteers are generally not used when the investigational product has significant toxicity (for example, cytotoxic oncology therapies) or when the drug's pharmacology is meaningful only in the presence of disease.

PK Studies in Patients
Patient-based PK studies become essential when disease pathology influences drug disposition, when safety prevents administration to healthy individuals, or when regulatory agencies require pharmacokinetic evaluation in the intended treatment population.

Patient pharmacokinetic studies are routinely performed in:

• Oncology
• Autoimmune disorders
• Hematological diseases
• Rare diseases
• Advanced biologics and cell therapies
• Certain anti-infective therapies

Disease-related changes in organ function, inflammatory status, protein binding or concomitant medications can significantly alter pharmacokinetics, making patient-derived data critical for dose optimization and labeling.

Why PK/PD Studies Matter

While PK describes drug exposure, PD measures biological response.

PK PD studies help sponsors determine:

• the optimal dose
• dosing frequency
• therapeutic window
• exposure-response relationships
• safety margins
• probability of clinical success

Integrated PK and PD modeling has become an increasingly important component of Model-Informed Drug Development (MIDD), an approach actively encouraged by regulators including the US FDA to support evidence-based dose selection and development decisions.

Biosimilar Development Depends on Robust PK Studies

Biosimilars represent one of the fastest-growing areas of pharmaceutical development.

Regulatory agencies consider comparative PK assessment one of the most sensitive tools for detecting potential differences between a biosimilar and its reference product. Demonstrating comparable exposure is therefore a critical milestone in establishing biosimilarity before confirmatory clinical evaluation.

Running processes in parallel instead of sequentially:
Traditional approaches complete feasibility, then site selection, budget negotiation, regulatory document collection and training one after another. Leading sponsors run feasibility, site selection and budget negotiation simultaneously using digital Study Start-Up platforms, saving 6-8 weeks alone.

Automating regulatory document collection, tracking, review and approval:
Chasing 1572 forms, CVs, medical licenses, and training certificates via email leads to chaos, lost documents, and version conflicts. Digital systems automate requests, track submissions in real-time, send reminders and flag missing items immediately sites submit directly, eliminating email attachments and version control issues.

Deploying centralized site activation tracking:
When sponsors, CROs, and sites use different trackers or spreadsheets, status visibility suffers. Centralized CTMS platforms provide real-time oversight of every site's progress, enabling study managers to identify blockers instantly and intervene proactively rather than discovering issues weeks later.

Front-loading protocol training before Site Initiation Visits (SIVs):
Traditional SIVs become 3-4 hour training marathons. Leading sponsors deploy eLearning modules for role-based training on staff's schedules before SIVs, turning the visit into a focused review and Q&A session cutting SIV time by 50% and allowing more sites to be scheduled per week.

Our wide network of sites across India facilitates rapid enrollment in diverse patient populations, supported by an experienced team of specialists under the oversight of a senior governance team that ensures strategic alignment and risk mitigation.

For biosimilars, Navitas excels in comparative PK studies, leveraging our MD/MV capabilities to demonstrate equivalence, supporting abbreviated approvals and cost savings while maintaining high standards of immunogenicity and safety assessments.

Our proven track record in high-enrollment PK studies spanning oncology, cardiovascular, and infectious diseases has earned repeat business from industry leaders, transforming complex challenges into streamlined successes.

Whether conducted in healthy volunteers or patients, pharmacokinetic research provides the evidence needed to make informed development decisions, optimize dosing strategies, and support successful regulatory submissions. Selecting the appropriate study population, integrating PK with PD endpoints and ensuring high-quality bioanalytical and operational execution are essential for accelerating development while maintaining scientific rigor.

With extensive expertise in healthy volunteer and patient-based PK programs, integrated clinical operations, bioanalytical excellence and regulatory-compliant execution, Navitas Life Sciences helps sponsors advance innovative therapies, generics and biosimilars from early development to approval.

 

Learn more about our services and solutions by reaching out to us at This email address is being protected from spambots. You need JavaScript enabled to view it..