Immunoactivation by pidotimod in children with recurrent respiratory infections.

The therapeutic activity and safety of pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid, PGT/1A, CAS 121808-62-6), a new synthetic "biological response modifier", were examined in a double-blind, placebo-controlled, multicentre trial in 101 children, including 53 boys and 48 girls aged 2-13 years (mean +/- SD: 4.7 +/- 2.1 years) with a history of recurrent respiratory infections (RRI). Pidotimod (400 mg/day) or placebo were administered orally for 60 consecutive days, followed by a further 60-day follow-up period. The trial was completed by 89.1\% of patients. The results indicate that pidotimod has a beneficial effect in children with recurrent respiratory infections: the percentage of patients presenting symptoms affecting the upper and lower airways was significantly lower after treatment with the active drug than after treatment with placebo. Relevant side effects were not reported during the trial. An evaluation of the expression of CD25 (after in vitro stimulation of circulating mononuclear cells with PHA) before and after treatment with the two products revealed a significant increase in CD25+ cells in the group treated with pidotimod but not in the group treated with placebo.