Magnesium Sulfate Pretreatment to Alleviate Pain on Propofol Injection: A Comparison with Ketamine or Lidocaine

Background and Propofol causes pain and hypotension when it was injected. Magnesium (Mg) and ketamine are antagonists of the N-methyl-d-aspartate (NMDA) receptor ion channel and cause analgesia. In view of the analgesic activity of Mg and ketamine, we tested the effect of intravenous administration of magnesium sulfate in reducing pain induced by propofol. Two hundred ASA I-II adults patients undergoing elective ophthalmic surgery were randomly assigned into four groups of 50 subjects in each groups. Group M received magnesium sulfate 2.48 mmol, Group K received ketamine 10 mg, Group L received lidocaine 1% (30 mg) and Group C received normal saline, all in a volume of 5 mL followed by 5 mL of 1% propofol 30 s later. Pain was assessed on a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain at the time of pretreatment and propofol injection. Eighty-eight percent of patients in the control group had pain during iv propofol as compared to 34%, 28%, and 18% in the magnesium, ketamine, and lidocaine groups respectively (P<0.01). Incidence of mild, moderate, and sever pain were significantly lower in groups K, L, and M compared to group C (P<0.05). Ketamine, lidocaine, and magnesium pretreatments were same effect in attenuating pain during the propofol injection (P>0.05). Intravenous pretreatment of magnesium, ketamine, and lidocaine are same effect in attenuating propofol-induced pain.