Coamatic Factor VIII

Product Overview:

Coamatic Factor VIII is a chromogenic method for the in vitro photometric determination of factor VIII activity in plasma. It is intended for identifying factor VIII deficiency, monitoring patients on replacement therapy, and for potency estimation of FVIII concentrates. In vitro diagnostic kit for professional use only.

Principle and Application:

This assay measures Factor VIII (FVIII) activity based on its cofactor role in the Factor IXa (FIXa) mediated activation of Factor X (FX) to Factor Xa (FXa). In the presence of calcium ions and phospholipids, and with optimal amounts of FIXa and an excess of FX, the rate of FX activation is directly proportional to the FVIII activity in the sample. The generated FXa then hydrolyses the chromogenic substrate S-2765, releasing the chromophore para-Nitroaniline (pNA). The colour intensity, measured photometrically at 405 nm, is proportional to the FVIII activity. The included synthetic thrombin inhibitor, I-2581, prevents interference from any thrombin formed during the reaction.

Product Composition and Specifications:

• S-2765 + I-2581 (1 vial): Contains chromogenic substrate (N-a-Z-D-Arg-Gly-Arg-pNA, 7.7 mg) and a synthetic thrombin inhibitor (0.2 mg), lyophilized with mannitol as a bulking agent.
• Factor reagent (2 vials): Contains bovine Factor IXa (0.3 U), Factor X (2.7 IU), and Thrombin (1 NIH-U), co-lyophilized with CaCl₂ (40 mmol) and phospholipid (0.2 mmol).
• Buffer, stock solution (1 vial): 24 mL of concentrated Tris buffer containing NaCl and BSA. Characteristics of diluted buffer (1:10) are: Tris 0.025 mol/L, pH 7.9, I = 0.08, 1% BSA.

Determinations per Kit:

• Microplate method: 120 tests
• Test Tube method: 30 tests

Performance Characteristics:

• Specificity and Interfering Factors: The inclusion of polybrene in the reaction system minimizes interference from heparin up to 1.0 IU/mL in plasma. Polybrene does not influence the assay in heparin-free plasma. No other drug interferences have been reported.
• Detection Limit (Microplate and Manual method):
  • Normal range: 0.05 IU/mL
  • Low range: 0.005 IU/mL
• Linearity (Microplate and Manual method):
  • Normal range: 0.05-1.5 IU/mL
  • Low range: 0.005-0.05 IU/mL
• Sensitivity (Microplate method):
  • Normal range: 0.4 ΔAbs per 1 IU/mL of FVIII activity
  • Low range: 3.0 ΔAbs per 1 IU/mL of FVIII activity
• Precision (Microplate method):
  • 1.0 IU/mL (n=42, N=7): Within series CV 2.4%; Between series CV 2.1%
  • 0.25 IU/mL (n=42, N=7): Within series CV 2.6%; Between series CV 5.9%
  • 0.03 IU/mL (n=42, N=7): Within series CV 3.0%; Between series CV 3.9%
• Correlation: The assay shows a strong correlation (r) with the Coatest FVIII method on various systems.
  • Manual Method (n=25): y = 0.94x + 0.07; r = 0.97
  • Microplate (n=25): y = 1.09x – 0.11; r = 0.96
  • ACL (n=25): y = 1.16x – 0.13; r = 0.97
  • Cobas Mira (n=25): y = 1.15x – 0.10; r = 0.98
  • Hitachi (n=29): y = 1.05x – 0.09; r = 0.98
  • Electra MLA 900 (n=25): y = 1.03x – 0.06; r = 0.98
  • Technicon RA-1000 (n=25): y = 0.95x – 0.02; r = 0.99

Storage and Stability:

• Unopened Vials: Store at 2-8°C. Stable until the expiration date printed on the label.
• Reconstituted/Diluted Reagents:
  • S-2765 + I-2581: Stable for 1 month at 2-8°C.
  • Factor reagent: Stable for 12 hours at 2-8°C, 2 weeks at -30°C, or 1 month at -70°C. Avoid storing at -20°C.
  • Diluted Buffer: Stable for 1 month at 2-8°C.

Disclaimer:

The information on this page is for informational purposes and serves as a general summary. It is imperative that all users read and strictly follow the Instructions for Use (IFU) document provided with the reagent or kit they are using. This online description must not be a substitute for the official product documentation.