Related Experiment Video
Updated: Jul 15, 2026
13:08
Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Japanese collaborative study to assess inter-laboratory variation in factor VII activity assays
O Takamiya1, S Ishikawa, O Ohnuma
1Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University, Matsumoto, Japan. itosamu@gipac.shinshu-u.ac.jp
Journal of Thrombosis and Haemostasis : JTH
|May 10, 2007
Summary
Inter-laboratory variability in measuring low factor VII activity (FVII:C) is significant. Standardized methods reduce this variability for very low FVII:C levels, improving diagnostic accuracy.
Area of Science:
- Hematology
- Clinical Chemistry
- Coagulation Science
Background:
- Clinical presentation in factor VII (FVII) deficiency often mismatches laboratory predictions.
- Significant lack of data exists regarding inter-laboratory measurement variability for low and very low plasma FVII activity (FVII:C).
Purpose of the Study:
- To assess the inter-laboratory variability of FVII:C measurements.
- To evaluate the impact of standardized reagents on FVII:C measurement consistency.
Main Methods:
- Three FVII-deficient plasma samples were sent to 58 laboratories in Japan.
- Immunoaffinity chromatography was used for sample preparation.
- Standardized reference plasma and recombinant thromboplastin were supplied as common reagents.
Main Results:
- Standardized reference plasma and thromboplastin significantly reduced inter-laboratory measurement variability for a sample with very low FVII:C.
- Variability was notably influenced by plasma dilution series, calibrator type, and thromboplastin used for very low FVII:C samples.
- Similar variability reduction was not observed for samples with moderate FVII:C.
Conclusions:
- Measurement results for very low FVII:C are highly sensitive to assay methodology, including dilution and reagent choices.
- Standardized reagents improve FVII:C measurement consistency, particularly for critically low levels.
- Development of a more sensitive and accurate FVII:C measurement system is crucial for effective diagnosis and treatment of FVII deficiency.
Related Concept Videos
01:17Factors Affecting Activity Coefficient
The extended Debye-Hückel equation indicates that the activity coefficient of an ion in an aqueous solution at 25°C depends on three partially interdependent properties: the ionic strength of the solution, the charge of the ion, and the ion size.
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a decrease in the...
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a decrease in the...
01:13Bioequivalence studies: Biowaivers
In certain scenarios, in vitro dissolution tests can replace in vivo bioequivalence studies. This is particularly true when a drug product, though available in varying strengths, maintains proportional similarity in its active and inactive ingredients. In such cases, the need for in vivo bioequivalence studies for lower strength variants may be waived, provided dissolution tests and in vivo studies on the highest strength yield satisfactory results.Bioequivalence can be indicated through...
01:09In Vitro Drug Dissolution: Compendial Testing Models II
Various dissolution methods are utilized to assess a drug’s dissolution rate, including the flow-through cell, paddle-over-disk, cylinder, and reciprocating disk methods.The flow-through cell apparatus (USP (United States Pharmacopeia) method 4) comprises a reservoir for the dissolution medium and a pump that propels the medium through the cell containing the test sample. This method is crucial for assessing modified-release dosage forms with minimally soluble active ingredients, maintaining...
01:20Drug Product Performance: In Vitro–In Vivo Correlation
In pharmaceutical development, it's crucial to establish a predictive in vitro–in vivo correlation (IVIVC) for two or more formulations to gain a comprehensive understanding of release properties. IVIVC reduces the need for costly in vivo studies and facilitates the establishment of meaningful dissolution specifications with significant cost savings and decreased regulatory burden. Furthermore, a meaningful IVIVC should predict Cmax and AUC within 20%, aligning with FDA guidance while adhering...
01:13In Vitro Drug Dissolution: Compendial Testing Models I
Compendial dissolution methods are standardized procedures defined by pharmacopeias to evaluate the rate at which a drug dissolves in a specific medium. These methods ensure batch-to-batch consistency, enable quality control, and support the prediction of drug bioavailability. They are critical for both immediate and modified-release drug products.The apparatuses used for dissolution testing differ in their design and mechanical function, but all aim to simulate the physiological environment of...
01:20Measurement of Bioavailability: Pharmacodynamic Methods
Pharmacodynamic methods provide insights into a drug's effects on physiological processes over time and play a crucial role in understanding bioavailability and therapeutic efficacy. These methods can be broadly classified into acute pharmacological and therapeutic response approaches, each with distinct mechanisms and applications.The acute pharmacological response method directly correlates a drug's physiological effects, such as ECG or pupil diameter changes, to its time course in the body.