[Differentiation of peripheral and central hyperalgesic effects of systemic procaine].

OBJECTIVE

The aim of this study was to differentiate between the peripheral and central analgesic and antihyperalgesic properties of systemic procaine hydrochloride in standardized human pain models.

METHOD: Subcutaneous injections of either 150 mg procaine hydrochloride or saline solution were administered at intervals of 2 weeks on a randomized and double blind basis. During the 90-min infusion and subsequent 60-min monitoring periods, touch sensitivity was determined and in addition two experimental hyperalgesic models were analyzed.

RESULTS

While touch sensitivity was not affected by procaine hydrochloride, development of primary mechanical hyperalgesia was significantly reduced.

CONCLUSION

The concentration of procaine hydrochloride used in our experiment elicited peripheral antihyperalgesic effects without central venous side effects. These results can account for the clinical effect of low-dose procaine hydrochloride in pain conditions exhibiting pronounced hyperalgesia.