Isoprinosine does not protect against frequent respiratory tract infections in childhood

Isoprinosine, an in vitro immune-enhancing agent principally acting by stim ulating T-lymphocytes, is one of a number of agents sometimes used in an at tempt to prevent recurrent respiratory infections in children, although the re are no formal trials for this particular drug. We performed a placebo-co ntrolled double-blind trial to assess the efficacy of isoprinosine (50 mg/k g per day) for 6 weeks followed by 50 mg/kg per day twice weekly for 6 week s in the prevention of frequent acute respiratory tract infections in 102 c hildren aged 4-8 years. A total of 43 children treated with isoprinosine an d 41 with placebo finished the study. Despite a transient increase in the t otal number of CD3 +, CD4+ and CD8 + T-lymphocytes after 6 weeks of daily i soprinosine treatment, there was no difference in the number and length of duration of acute respiratory infections, number of antibiotic courses and number of days with cough, pharyngitis, rhinitis and increased body tempera ture (greater than or equal to 37.0 degrees C and greater than or equal to 38.0 degrees C). There were no changes in markers of T- or B-lymphocyte act ivation (CD25, HLA-DR, CD45RA/RO, CD23). Conclusion Attempts at immunomodulation using isoprinosine in the dose and for the duration used may increase the total numbers of both CD4 and CD8 TT -lymphocytes but is ineffective in prevention of respiratory tract infectio ns in childhood.