We tested the in vitro activity of
pleconaril and
AG7088 against five numbered human rhinovirus (HRV) serotypes and 46 clinical HRV isolates of undefined serotype recovered from patients with
common colds.
Antiviral effect of
pleconaril and
AG7088 were assessed by cytophathic effect (CPE) inhibition assays in Ohio HeLaI cells using microscopic and spectrophotometric methods. Both compounds were tested at concentrations of 1.0, 0.1 and 0.01 microg/ml. For the numbered HRV serotypes, the median EC(50) value determined by the microscopic CPE inhibition was slightly better for
AG7088 compared to
pleconaril (P=0.02) but was similar by spectrophotometric assay (P=0.15). For clinical HRV isolates the median EC(50) value determined microscopically was 0.01 microg/ml range, <0.01-0.04 microg/ml) for
AG7088 compared to 0.07 microg/ml (range, <0.01->1 microg/ml) for
pleconaril (P<0.001). The median EC(50) value determined by spectrophotometric assay was 0.01 microg/ml (range, <0.01-0.04 microg/ml) for
AG7088 compared to 0.04 microg/ml (range, <0.01->1 microg/ml) for
pleconaril (P<0.001). By either the microscopic or spectrophotometric methods the median EC(50) value of
AG7088 was <1.0 microg/ml for all isolates and was >10.0 microg/ml of
pleconaril for approximately 9% of isolates. In vitro
AG7088 appeared to be more potent and to have a broader antirhinoviral spectrum than
pleconaril among clinical HRV isolates. The clinical relevance of these in vitro results needs to be determined in controlled clinical trials.