Janssen's R170591, a topically applied compound with a reported EC 50 against RSV of <1 nM, is in preclinical study; Bristol-Myers Squibb's BMS-433771, an orally bioavailable compound with a reported EC 50 against RSV of 10 nM, is in preclinical study; and ViroPharma's VP14637, a compound delivered by small particle aerosol (SPA) inhalation with an EC 50 against RSV of <1 nM, is completing phase 1 studies.