A guide to particle size analysis in pharmaceutical drug development

Particle size analysis in pharmaceutics can help developers optimize drug bioavailability, ensure consistent formulation, and scale up effectively – if it is precisely controlled.

Selecting the wrong measurement technique, or misunderstanding how particle size behavior differs across materials, can result in inaccurate data and poor formulation decisions. The consequences compound as development progresses, leading to labs falling short of strict regulatory and validation requirements, wasting time and money before they even reach the challenges of scale-up.

Understanding the role of particle sizing for different pharmaceutical materials and ingredients is therefore essential to streamline the pharmaceutical development process. In this blog, we outline how pharmaceutical and biopharmaceutical particle size analysis works across APIs, excipients, and water-soluble drugs, and the instrumentation available to support robust, reliable measurement.

Why is pharmaceutical particle size analysis important?

1. Optimizing bioavailability and solubility 

Particle size has a direct impact on a drug’s bioavailability, dissolution rate, and overall therapeutic efficacy.  

Smaller particles have a greater surface area-to-volume ratio, which enhances dissolution and absorption in the body. However, extremely small nanoparticles have a high surface energy, making them liable to aggregate, reducing their dissolution rate. Precise particle size analysis in pharmaceutics is therefore essential to keep particles within an optimal size range and achieve the desired drug performance. 

2. Enhancing drug delivery and performance 

Particle size also affects the stability of formulations, the uniformity of dosage, and the performance of a drug delivery system. For example, particle size can influence deposition in inhaled therapies, suspension stability in liquid formulations, and the manufacturability of solid dosage forms. 

In tablets and capsules, particle size impacts powder flow, compressibility, and blend homogeneity, all of which are essential for consistent manufacturing and dose accuracy. Careful control of particle size distribution helps manufacturers produce formulations that are stable, reproducible, and capable of delivering consistent therapeutic outcomes. 

3. Ensuring regulatory compliance 

Regulatory agencies expect thorough particle size characterization as part of the quality control process. As a critical material attribute (CMA) for many pharmaceutical products, including solid dosage forms and liquid suspensions, particle size is an essential element of the materials characterization toolkit for pharmaceutical development and manufacture. Robust particle size measurement helps manufacturers establish product specifications, demonstrate batch-to-batch consistency and provide evidence that formulations meet the required quality, safety and performance standards throughout the product lifecycle. 

How particle size distribution affects active pharmaceutical ingredient (API) stability  

Active pharmaceutical ingredients, or APIs, range from small molecules such as peptides and fatty acid derivatives to larger biologics, including proteins and nucleic acids. These materials are highly sensitive to environmental conditions like temperature and pH, with even small fluctuations triggering changes in reactivity, surface charge, or agglomeration.  

These issues with stability and processability can contribute to unexpected failures at scale-up. Pharmaceutical particle size analysis is therefore essential to detect issues early – for instance, aggregates. These are a particular concern for biologics, as they can deactivate therapeutic proteins and even provoke immune responses in patients.  

Dynamic light scattering (DLS) analysis is a rapid measurement technique that enables operators to assess particle stability across many conditions, including pH and temperature. It requires minimal sample volume, making it useful for early-stage formulation screening, and is therefore frequently used during biologic development to detect agglomeration before it stalls scale-up. 

Why particle size distribution control is necessary for effective excipients 

Though not therapeutically active, excipients profoundly affect the physical, chemical, and mechanical properties of a final dosage form. Excipient particle size distribution is therefore an essential control parameter, whether you’re optimizing formulation development, checking the raw materials from suppliers, or conducting quality control at different stages of the manufacturing process.  

Particle size and particle size distribution affect two key excipient properties: 

1. Packing density 

The particle size of excipients such as fillers and binders directly influences powder flow and compaction behavior when mixed with the API.  

The packing density of powders, for example, is highly dependent on their particle size distribution, with a mix of fine and coarse material leading to a higher packing density and lower permeability. This contributes to slower tablet disintegration, which can be desirable for extended and targeted release drugs. 

2. Blending uniformity and even drug distribution 

Consistent blending of the API and the excipients is necessary to ensure uniform drug distribution throughout the formulation, regardless of drug delivery method. A mismatch in particle size between the API and excipients can lead to segregation during mixing or compression, resulting in non-uniform drug distribution, dosage inconsistency, and falling short of potency specifications.  

Why is particle size distribution important for water-soluble drugs? 

Particle size control is important for the development of water-soluble drugs because it influences the rate and completeness of dissolution in specific dosage contexts – for example, very coarse particles may dissolve too slowly relative to gastric emptying time, potentially reducing absorption. It has different impacts on different forms of water-soluble drugs, for instance: 

Drug delivery method	What pharmaceutical particle size analysis is used for	Why it’s important
Injectable formulations	Confirming particles meet size limits for sterile filtration Detecting unwanted particulate matter	Preventing adverse reactions such as embolism or immune responses
Oral solid dosage forms (including soluble drugs)	Optimizing flow Getting the right bulk density  Ensuring correct compressibility	Enabling consistent manufacturing
Liquid suspensions	Optimizing colloidal stability	Maintaining dose uniformity  Ensuring physical stability

Compliant particle size analysis in pharmaceutics: Which technologies fit within regulatory guidelines? 

Regulatory agencies require accurate and properly recorded analytical data, including particle size analysis as part of the drug approval process, to demonstrate that a pharmaceutical product has the necessary quality and safety for patient use. With Malvern Panalytical, you can speed up your product development with accurate, reliable instrumentation that complies with essential pharmaceutical regulations. 

FDA compliance in the United States 

Malvern Panalytical instruments, such as Mastersizer 3000+, can be integrated with OmniTrust to  support 21 CFR Part 11 compliance.  OmniTrust provides electronic signatures, secure records management, and audit trails to help maintain data integrity and simplify achieving regulatory compliance. 

EMA regulations in Europe 

The EMA framework governs all stages of pharmaceutical drug development in the EU, from early-stage assessments to post-authorization monitoring.  

For drug products involving particulate systems, such as nanoparticles, liposomes, or inhalation formulations, rigorous characterization is a core Chemistry, Manufacturing and Controls (CMC) requirement. Laser diffraction, light scattering, and nanoparticle tracking analysis can all support compliance via high-quality and reproducible size and stability data. 

Alignment with GMP guidelines 

Good Manufacturing Practices (GMP) guidelines call for strong quality assurance, detailed SOPs, and consistent results. In pharmaceutical development, this is crucial for the production, testing, and distribution of novel drug formulations. Malvern Panalytical’s instruments are trusted worldwide for quality control, excellent reproducibility, and advanced method development such as SOP Architect software feature for the Mastersizer 3000+. 

6 essential techniques for pharmaceutical and biopharmaceutical particle size analysis 

Below, you’ll find a complete overview of the different particle sizing techniques used in the particle size analysis of pharmaceutical products.  

Product	Technology	Measurement range	Key benefit for pharma particle size analysis
Mastersizer range	Laser diffraction	0.01 µm – 3500 µm	Rapid, reproducible measurements across a wide size range in wet and dry dispersion. Suitable from formulation development through to quality control
Zetasizer Advance range	Dynamic light scattering	0.3 nm – 10  µm	Precise sizing and stability characterization of particles and molecules in suspension
Morphologi range	Static image analysis and MDRS	0.5 µm – over 1300 µm	Combined size, shape, and chemical identification for particles where morphology impacts processing or performance
NanoSight range	Nanoparticle tracking analysis	10 nm – 2 µm	Visualization and counting of individual nanoparticles in suspension
Insitec range	Laser diffraction	0.1 µm – 2500 µm	Continuous, real-time particle size measurement directly in the process stream
Micromeritics SediGraph	X-ray sedimentation	0.1 µm – 300 µm	Accurate size distribution for fine powders

Enhancing particle size analysis in pharmaceutics is essential for smooth scale-up 

Effective pharmaceutical particle size analysis is the cornerstone of successful drug development and scale-up. It requires correct, compliant measurements at the right point in your processes – and the right technologies can deliver. 

Laser diffraction is the go-to technique for particle size analysis, and the Mastersizer 3000+ is considered the gold standard for particle size analysis in pharmaceutical development, scale-up, manufacturing and QC. 

Complementary techniques such as dynamic light scattering with Zetasizer can be used to characterize nanoparticles and colloidal drug delivery systems, while Sedigraph analysis is well suited to the measurement of fine powders and suspensions. 

Whatever your application, Malvern Panalytical has the instrumentation and expertise to support you. Find out more about our world-leading particle size analyzers.