At the Second World Congress on Chronic Fatigue Syndrome held in Brussels, September 9-12 1999, clinical work with the drug inosine pranobex (Isoprinosine®; Imunovir®) in M.E./CFS patients was reported in a number of presentations.

The objective of this trial was to evaluate Isoprinosine® in the treatment of M.E./CFS patients. The principle investigator was Dr Byron Hyde of the Nightingale Research Foundation, Herridge Clinic and Children's Hospital of Eastern Ontario, Ottawa.

Sixteen CFS patients who conformed to the CDC 1988 and 1992 definitions for CFS, had abnormal brain perfusion SPECT scans and who did not have elevated uric acid levels were enrolled in this treatment study.

The dosing schedule during this trial embraced an initial blinded three months where patients were randomised to groups taking medication or placebo, followed by a one-month dry-out period. In the open phase the patients who had been on placebo were afforded the opportunity to take the medication for a further three months.

Five Isoprinosine® patients demonstrated considerable improvement and elected to continue on the medication. No Isoprinosine® patient became worse while on medication but two of the six placebo patients became significantly worse while on placebo. One placebo patient who then switched to Isoprinosine® then became sufficiently well that he was able to return to full time employment.

Immunological data was the focus of a separate presentation where the effect of Isoprinosine® on the immune markers, CD4, CD8, NK cells, Immune Memory and Cytokines was discussed.

Isoprinosine® is widely available in Europe and Canada as a prescription medication.