Favipiravir for Lassa fever: an open-label, randomized controlled phase 2 trial

Area of Science:

• Virology
• Infectious Diseases
• Clinical Pharmacology

Background:

• Lassa fever (LF) is a severe hemorrhagic fever endemic to West Africa with limited treatment options.
• Ribavirin is the current standard treatment, but its efficacy is debated.
• Favipiravir, an antiviral, shows promise in preclinical studies for LF treatment.

Purpose of the Study:

• To evaluate the safety, tolerability, and pharmacokinetics of favipiravir compared to ribavirin in treating acute Lassa fever.
• To determine if favipiravir is a viable alternative antiviral treatment for LF.

Main Methods:

• A randomized, open-label, phase 2 clinical trial was conducted in Nigeria.
• 41 hospitalized adult patients with confirmed LF were randomized to receive either favipiravir or ribavirin.
• Primary endpoints included pharmacokinetic parameters (Cmax, Tmax, AUC, half-life, Vd) and safety/tolerability assessments.

Main Results:

• Pharmacokinetic analysis of favipiravir showed reliable exposure with a half-life of 10.9 hours.
• Treatment-emergent adverse events were evenly distributed; favipiravir group had 16 events, none severe or serious.
• Anemia was common with ribavirin, while vomiting was most frequent with favipiravir; all participants survived.

Conclusions:

• Favipiravir demonstrates potential as a safe and well-tolerated alternative treatment for Lassa fever.
• Pharmacokinetic data support further clinical evaluation of an optimized favipiravir regimen for LF.
• The study provides crucial data for developing improved Lassa fever treatment strategies.