Quantitative Analysis of Favipiravir Spiked in Plasma Using by HPLC

Significance of the topic

Monitoring plasma levels of favipiravir, a repurposed antiviral for COVID-19, is essential to ensure therapeutic efficacy and avoid toxicity. A reliable, high-sensitivity assay supports dose optimization, patient safety and pharmacokinetic studies without the need for advanced mass spectrometry.

Objectives and Study Overview

The study aimed to develop and validate a sensitive, quantitative HPLC method using only standard equipment and fluorescence detection to measure favipiravir in human plasma. Key goals included achieving linearity across relevant concentrations, robust precision and accuracy within accepted bioanalytical criteria.

Methodology and Instrumentation

The workflow encompassed:

• Sample preparation by protein precipitation. 25 µL plasma mixed with 100 µL methanol, centrifuged, then supernatant diluted 15-fold with mobile phase.
• Chromatographic separation on a Shim-pack Scepter C18-120 column with gradient elution (phosphate buffer pH 6.9 and methanol) at 1.0 mL/min, 30 °C.
• Detection by fluorescence (Ex. 360 nm, Em. 433 nm).

Main Results and Discussion

Calibration over 1–100 µg/mL demonstrated excellent linearity (R2 = 0.999, 1/C weighting). Intra-assay precision ranged 0.21–0.31 %RSD and accuracy 92.1–106 %. Validation with quality control samples at 2, 45 and 90 µg/mL yielded precision 0.18–0.35 %RSD and accuracy 96.5–100 %, meeting acceptance criteria.

Practical Benefits and Applications

This HPLC-fluorescence method offers:

• Cost-effective implementation on standard HPLC systems.
• High sensitivity and reproducibility for therapeutic drug monitoring.
• Applicability in pharmacokinetic and clinical trials without specialized MS instrumentation.

Future Trends and Potential Applications

Emerging needs include multiplexed assays for combination therapies and miniaturized platforms for point-of-care testing. Integration with automated sample handling and data processing could further streamline routine monitoring.

Conclusion

A robust HPLC method with fluorescence detection was established for favipiravir quantification in plasma, delivering high sensitivity, accuracy and precision using only standard chromatographic equipment. This assay can support clinical and research applications where fast and reliable drug level measurement is required.

Instrumentation Used

• Nexera XR HPLC system
• Shim-pack Scepter C18-120 analytical and guard columns
• Fluorescence detector RF-20A
• TORAST-H glass vials

Reference

1. Gowen BB, et al. Alterations in favipiravir (T-705) pharmacokinetics and biodistribution in a hamster model of viral hemorrhagic fever. Antiviral Research. 2015.
2. Takashita E, et al. Antiviral susceptibility of influenza viruses isolated from patients pre- and post-administration of favipiravir. Antiviral Research. 2016.
3. Shiraki K, et al. Favipiravir, an anti-influenza drug against life-threatening RNA virus infections. Pharmacology & Therapeutics. 2020.