Subvisible particles detection in parenteral drugs
Parenteral drugs are delivered into the body by directly injecting into the intravenous, subcutaneous, or intramuscular routes. Subvisible particle counting in parenteral drugs is described in USP <788>, a common application for the AccuSizer® SIS system. The same system can also be used for USP <789> test for ophthalmic solutions and the new USP <787> test for therapeutic protein injections.
The USP <729> test for globule size distribution in lipid injectable emulsions calls for systems like the AccuSizer APS for Method II and the Nicomp DLS system for Method I.
USP <788> Particle Counting
Parenteral drugs administered by injection to patients should be essentially free of visible particles. Subvisible particles in parenteral drugs are detected using a light obscuration particle counter, microscopic inspection on a filter, or both. The light obscuration particle count test applies to large volume injections with total volume >100 mL unless specified in the individual monograph. The test applies to single dose or multiple dose injections of solutions or solutions constituted from sterile solids containing <100 mL (small volume parenteral drugs) where a test for particulate matter is required in the individual monograph.
The AccuSizer A2000 SIS system meets all USP <788> system requirements including:
- Method: light obscuration
- Sensor concentration limits
- Sensor dynamic range
- Sample volume accuracy
- Calibration methodSensor resolution
- Particle counting accuracy
Follow the instruction provided in USP <788> for sampling and liquid preparation, pooling units if required. Degas the sample if required. Place the sample beaker on the AccuSizer A2000 SIS sstem and begin the measurement - all of which is automated. The drug product meets the requirement if the average number of particles/mL does not exceed the stated limits shown:
|>10 µm||>25 µm|
|SVP||6000||600 per container|
The AccuSizer software allows users to enter test and product details such as volume/container and number of containers pooled for the measurement. The USP <788> result report shown below is automatically generated upon completion of the test protocol. Other automated reports include sensor resolution and USP count test results.
If the average number of particles exceeds this limit the user must perform the microscopic particle count test. Advantages of the AccuSizer A2000 SIS system for this test over older particle counters include:
- Greater particle size reslution - into 512 channels
- Better definition of particle size range can help identify sources of contamination
- Enhanced sensor performance
- A wider dynamic range allows for testing at smaller sizes
- The standard sensor coveres 0.5-400 µm
USP <787> Subvisible Particulate Matter in Therapeutic Protein Injections
The new USP <787> Subvisible Particulate Matter in Therapeutic Protein Injections test can be used as an alternative to USP <788>. USP <787> is meant for therapeutic protein injections, making changes for smaller test product volumes, and smaller test aliquots. The AccuSizer SIS system is the best instrument for performing USP <787> for many reasons, including:
- Wide dynamic range LE400 sensor; 0.5-400 µm
- Optional FX Nano sensor extends range down to 0.15 µm
- Sample volumes as small as 150 µL
- Advanced software automates many functions including
- Automated USP <787> testing and reporting
- Automated sensor resolution testing and reporting
- Automated USP count standard testing and reporting
- Clean glassware testing and reporting
- Autosamplers; both the AccuSizer autosampler and the A2000 MPA microplate analyzer
- Up to 512 sizes channels
- Optional sample conversation
The AccuSizer SIS system with LE400 sensor is ideal for USP <787> release testing. The dual sensor FX-Nano system is used in protein aggregation studies where extending the range to 150 nm provides additional insight into aggregation dynamics.
USP <729> Emulsion Size Testing
The size of the lipid droplets is critical because larger-size fat globules (>5 µm) can be trapped in the lungs and are also an indicator that the emulsion is destabilizing. The USP <729> test requires two analytical techniques: DLS or laser diffraction to measure the mean and standard deviation of the distribution and light obscuration to measure the large tails >5 µm.
Method I: Mean and standard deviation of the distribution by DLS:
- Test the system with PSL standards at 100, 120, and 400 nm
- The coefficient of variation (COV) must be <10% of the reference values
- Measure the sample, report the intensity-weighted mean, which must be less than 500 nm
Method I is best measured using the Nicomp N3000 system.
Method II: Large-diameter droplet tail (>5 µm) by a single particle optical sizing (SPOS):
- Perform a dilution study to achieve a COV <10% between samples
- Test the sizing and counting accuracy at 5 µm and 10 µm
- The size and count should be within 10% of the certified vales
- Set the lower size limit at 1.8 µm and upper limit at 50 µm
- Vary the measurement time so that there is a factor of two difference >5 µm between two runs
- The volume-weighted result >5 µm (PFAT5) must be <0.05%
Method II is best measured using the AccuSizer APS system.
USP Test Automation
All USP tests can be automated using either the Autosampler or AccuSizer A2000 MPA microplate analyzer. The Autosampler (shown here) is designed for typical USP <788> testing while the A2000 MPA is designed for lower volume USP <787> testing.