USP <1788> Explained: How the Raptor 1788 Adds Dynamic Image Analysis to Subvisible Particle Testing#

Subvisible particulate matter is under more scrutiny than ever in parenteral and ophthalmic drug products.
USP <1788> and <1788.3> now explicitly recommend flow imaging / dynamic image analysis (DIA) as a key orthogonal method alongside traditional light obscuration (LO) and membrane microscopy.

This guide explains what USP <1788> means, why it matters, and how the Vision Analytical Raptor 1788 helps pharmaceutical QC labs meet these expectations without replacing their existing LO system.

Contents#

  1. Why USP <1788> Matters

  2. How USP <1788> Relates to USP <787>, <788>, and <789>

  3. What USP <1788> Actually Says

  4. USP <1788.3>: Flow Imaging / DIA for 2–100 µm

  5. Limitations of Light Obscuration

  6. Introducing the Raptor 1788

  7. Key Use Cases

  8. How to Implement USP <1788> in Your Lab

  9. FAQ

  10. Next Steps

1. Why USP <1788> Matters#

Subvisible particles (typically 2–100 µm) are considered a critical quality attribute for parenteral and ophthalmic products. They help assess:

  • Foreign particulate contamination

  • Formulation stability (especially for biologics/proteins)

  • Container/closure integrity

  • Particles inherent to manufacturing processes

Traditional compendial methods (USP <787>, <788>, <789>) focus on numerical limits using LO and membrane microscopy. But these methods alone cannot fully characterize many particle types — especially protein aggregates, silicone oil droplets, fibers, and other irregular particles.

USP <1788> steps in to guide better testing practices and encourage orthogonal methods like DIA.

2. How USP <1788> Relates to USP <787>, <788>, and <789>#

Think of the normative chapters as “what you must do”, and USP <1788> as “how to do it well.”

  • USP <787> – Therapeutic protein injections

  • USP <788> – Particulate matter in injections

  • USP <789> – Particulate matter in ophthalmic solutions

  • USP <1788> – Describes how to apply LO, microscopy, and imaging methods correctly

USP <1788> emphasizes:

  • Proper sample handling and mixing

  • Calibrations, system suitability, and method control

  • Strengths and limitations of each technology

  • The value of orthogonal methods like flow imaging/DIA

3. What USP <1788> Actually Says#

USP <1788> covers three main analytical families:

  • Light obscuration (LO)

  • Membrane microscopy (MPC)

  • Flow imaging / dynamic image analysis (DIA) — detailed in USP <1788.3>

USP highlights several important themes:

1. Use multiple orthogonal techniques#

LO is essential, but imaging provides particle identity, not just counts.

2. Method-dependent differences are normal#

Different technologies “see” particles differently — and that’s expected.

3. Sample handling matters#

Mixing, sample viscosity, container type, and environmental controls can dramatically change results.

4. USP <1788.3>: Flow Imaging / DIA in the 1–100 µm Range#

USP <1788.3> provides technical guidance for imaging-based methods like the Raptor 1788.

Flow imaging / DIA typically covers:

  • 2–100 µm for subvisible particles

  • Larger particles beyond 100 µm (instrument dependent)

  • Ability to discriminate particle types and morphologies

What imaging adds:#

  • Shape descriptors (aspect ratio, circularity, elongation).  The more shape descriptors available, the more capable software is to differentiate one particle population from another.

  • Opacity/brightness

  • Texture features

  • Thumbnail images of each particle

  • Classification of particle types

This is crucial for biologics, where protein aggregates may be inherent but foreign contaminants are not.

5. Limitations of Light Obscuration Alone#

LO remains the primary compendial method, but it cannot:

  • Identify particle type

  • Distinguish silicone oil droplets from solid particulates

  • Detect low-refractive-index (soft/transparent) particles well

  • Provide visual proof during investigations

  • Determine morphology

This is exactly why USP <1788> recommends orthogonal methods like DIA to complement LO.

6. Introducing the Raptor 1788: DIA Optimized for USP <1788>#

The Vision Analytical Raptor 1788 is a purpose-built dynamic image analysis module that enhances your existing LO workflow.

6.1 Dynamic Image Analysis for Subvisible Particles#

Raptor 1788 captures detailed images of each particle and provides:

  • Multiple size metrics and shape descriptors of particles down to 1 micron due to high-resolution optical components.

  • Texture and brightness features

  • Image thumbnails for each detected particle

This enables classification such as:

  • Protein aggregates

  • Silicone oil droplets

  • Glass fragments

  • Fibers

  • Rubber or elastomer particles

  • Manufacturing/packaging contaminants

6.2 Retrofit, Don’t Replace#

Raptor 1788 can operate stand-alone or can be integrated with your existing LO system:

  • No need to replace validated methods

  • Minimal workflow changes

  • Uses similar sample volumes

  • Allows LO to remain your primary compendial method

6.3 Built for USP <1788> and <1788.3>#

  • Designed around the 1 – 100 µm range

  • Supports trending, risk assessments, and investigations

  • Provides the morphological detail USP recommends

  • Helps meet expectations for advanced biologics

7. Key Use Cases#

7.1 Therapeutic Proteins & Biologics#

  • Differentiate protein aggregates from contaminants

  • Trend aggregation under stress/storage

  • Support USP <1787>-recommended risk assessments

7.2 Cell & Gene Therapy / High-Value Low-Volume Products#

  • Reduce sample volume needs

  • Extract maximum data per microliter

  • Analyze morphology-rich particle profiles

7.3 Pre-Filled Syringes & Silicone Oil#

  • Identify and quantify silicone droplets

  • Distinguish droplets from harmful particulates

  • Study formulation–container interactions

  • Run samples directly from your pre-filled syringe in order to eliminate external sources of contamination.

8. How to Implement USP <1788> with Raptor 1788#

A practical rollout strategy:

Step 1 — Map your current testing#

Identify where LO alone is insufficient (biologics, new containers, investigations).

Step 2 — Define where imaging adds value#

Use Raptor 1788 for:

  • Investigations

  • Comparability studies

  • Stability studies beyond LO

  • Characterization of protein particles vs silicone

Step 3 — Develop a DIA method aligned with USP guidance#

Include:

  • Mixing procedures

  • System suitability checks

  • Method verification

  • Data review criteria

Step 4 — Integrate Raptor 1788 into your LO workflow#

LO stays your primary compendial test; DIA adds orthogonal confidence.

Step 5 — Use images for root-cause analysis#

Build particle libraries and reduce deviations.

9. FAQ#

Is USP <1788> mandatory?#

No. It’s informational — but widely considered modern best practice.

Does Raptor 1788 replace my LO system?#

No. It enhances LO by adding imaging and morphology.

What size range does Raptor 1788 cover?#

Typically, 1–100 µm for subvisible particles (configuration dependent).

Can Raptor 1788 identify particle types?#

Yes — via morphology, brightness, and image inspection.

Is this only for biologics?#

No — it’s useful for any parenteral or ophthalmic product.

10. Next Steps: Evaluate Raptor 1788 for Your Lab#

USP <1788> represents a shift from simply counting particles to actually understanding what they are.

With the Raptor 1788, you can:

  • Add dynamic image analysis without replacing your LO

  • Follow USP <1788> recommendations

  • Improve investigations and root-cause analysis

  • Future-proof your QC for advanced therapies

👉 Want help integrating USP <1788> into your workflow?
Reach out here: Contact Vision Analytical