[Differentiation of peripheral and central hyperalgesic effects of systemic procaine]. / Differenzierung peripherer und zentraler antihyperalgetischer Effekte einer systemischen Procaindauerinfusion.

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.