The immunopotentiator effects of nefopam.

The effects of opiate analgesics and non-steroidal anti-inflammatory drugs on the immune functions have been reported. The effect of the non-opiate analgesic nefopam on the immune functions has not yet been investigated. Male Swiss albino mice were treated with either heat killed E. coli or saline. They were classified into 12 groups. The effects of subacute (15 mg/kg/12 h S.C. daily for one week) and chronic (10 mg/kg/12 h S.C. daily for one month) treatment with nefopam on the levels of interferon-gamma (IFN-gamma) and total immunoglobulins were examined in both normal and immunized mice. Also, the effect of the chronic administration of nefopam on the phagocytic activity of peritoneal macrophage was evaluated in both normal and immunized mice. Subacute and chronic administration of nefopam induced no significant raise in the level of interferon-gamma (IFN-gamma) or in the level of total immunoglobulins in non-immunized animals, while subacute and chronic treatment with nefopam augmented markedly the immunization induced increase of level of interferon-gamma (IFN-gamma). Furthermore, chronic treatment with nefopam potentiated significantly the production of total immunoglobulin induced by heat killed E. coli. Chronic treatment with nefopam also was associated with significant enhancement of innate immune response reflected in the pronounced increase in the phagocytic activity of macrophages in non-immunized and immunized animals. The enhancement of phagocytic activity of macrophages by nefopam in immunized animals was significantly higher than that of non-immunized animals. These findings revealed that nefopam has the ability to trigger the immune response for bacterial antigen. The mechanism behind the immunostimulatory effect of nefopam requires further investigation, but it may be due, at least in part, to the inhibitory effect of nefopam on the serotonin and norepinephrine reuptake at nerve endings. In conclusion, our findings postulated that nefopam stimulated the immune functions and improved the defence mechanism. This information may be of future therapeutic value in diseases that need immunologic enhancement.