Thymopoietin pentapeptide (thymopentin, TP-5) in the treatment of rheumatoid arthritis. A compilation of several short- and longterm clinical studies.

Thymopentin (TP-5), the active side of thymopoietin, was shown to affect immunoregulation. The effect of this drug in the treatment of rheumatoid arthritis (RA) was evaluated. Three trials were performed: a six month double-blind trial comparing TP-5 administered subcutaneously to placebo at 3 different dosages, an open longterm study in which the same dosage of the drug was administered subcutaneously, and a shortterm (3 weeks) double-blind trial in which the drug was given intravenously at a high dosage (100 mg/day). In none of these 3 studies were statistically significant improvements registered in the TP-5 treated patients, although there were important improvements in individual patients. Serious side effects were not encountered, but the majority of patients did not improve or were withdrawn because of ineffectiveness. The beneficial effect of TP-5 on the clinical evolution of RA, reported elsewhere, could not be confirmed by these studies.