Itching after intrathecal morphine. Incidence and treatment

This study was designed to determine whether low doses of intrathecal morph ine still result in itching and it evaluates the outcome of a standardized treatment using promethazine and - for intractable itch - naloxone. Patient s (n = 143) scheduled for total hip surgery were allocated to four groups ( in a double blind manner) with bupivacaine 20 mg in 4 mL but different dose s of intrathecal morphine: Group I, 0.025 mg, Group II, 0.05 mg, Group III, 0.1 mg and Group IV, 0.2 mg. The presence or absence of itching was noted every three hours for a 24-h period. When required, standardized treatment was provided. The incidence of itching was: Group I: 14.3%; Group II: 21.6% ; Group III: 48.6%; and, Group IV: 61.7%. Itch was treated by administering promethazine intramuscularly in 2.9% (Group I); 8.1% (Group II); 10.8% (Gr oup III), and 8.9% (Group IV), respectively. Only in group IV there was a s ingle patient who needed naloxone to treat itching. The incidence and sever ity of itching is a dose-related side-effect in the dose range of 0.025-0.2 mg of intrathecal morphine. Itching still occurs after the low doses of in trathecal morphine, but symptoms vanish after promethazine 25 mg intramuscu larly.