Long-term follow-up observations of the therapeutic effect of PVNO on human silicosis.

The effect of PVNO treatment on human silicosis was observed in 7 cases over a period of 9 years lasting from 1965 to 1974. The drug was given intramuscularly and by way of inhalation, respectively. The comparison of the radiographs taken before, during and 3 years after the administration of PVNO showed that during treatment the tendency of fibrotic progression was delayed in 4 cases while 2 cases were slightly progressive, and one was markedly progressive, 3 years after discontinuation of the PVNO treatment, only one case remained stable, two cases were slightly and 4 cases markedly progressive. These observations indicate that PVNO treatment may have an effect on the delay and control of silicosis progression in a portion of patients, but after discontinuation of the treatment further progression is possible.