title: Analgesic effect of L-arginine in patients with persistent pain.
abstract: Our previous pharmacological studies using animals indicated that a systemic administration of L-arginine induces an antinociceptive effect and an increase in the brain level of kyotorphin (L-tyrosinyl-L-arginine) which is an endogenous analgesic peptide and a methionine-enkephalin releaser in the brain. The aims of this study were to investigate the analgesic effect of L-arginine, a precursor of kyotorphin, in persistent pain. We selected 12 patients with various kinds of pain of at least 6 months duration. L-Arginine (10% solution, 300 ml (30 g)/patient) was administered by intravenous drip at a rate of 5 ml (0.5 g)/min during a period of 60-70 min. Pain was assessed by the patient using a 10-cm visual analogue scale (VAS), before and after the L-arginine infusion. L-Arginine treatment resulted in slight analgesia at 10-15 min after the onset of infusion and in marked analgesia at 30-40 min after that. This effect lasted for 6-24 h. L-Arginine-induced analgesia was dose-dependent and blocked by intravenous injection of naloxone. In each case, the L-arginine-induced analgesia was statistically significant as compared with the saline-induced effect. Side effects of L-arginine were a slight decrease in mean blood pressure (10-15 mm Hg), and dryness of the month. A suppressive role of a functional link between the L-arginine-kyotorphin system and the enkephalin system of the brain in persistent pain is suggested.
authors.affiliation: Department of Anaesthesiology, Kyoto University, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Harima
authors.forename: H
authors.initials: H
authors.lastname: Shimizu
authors.forename: H
authors.initials: H
authors.lastname: Takagi
mesh_terms: D000368:Aged; D000700:Analgesics / Q000627:therapeutic use*; D001120:Arginine / Q000009:adverse effects / Q000037:antagonists & inhibitors / Q000627:therapeutic use*; D002908:Chronic Disease; D003027:Cluster Headache / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement
chemical_list: D000700:Analgesics; D009270:Naloxone; D001120:Arginine