magnesium sulfate + fentanyl

Magnesium sulfate + fentanyl is a combination of two agents used primarily as an adjuvant regimen in anesthesia and pain management, especially for neuraxial (spinal or epidural) analgesia. Magnesium sulfate acts as a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, blocking NMDA channels in a voltage-dependent manner and reducing central sensitization to pain. Fentanyl is a potent synthetic opioid that acts mainly as an agonist at the mu-opioid receptor, providing strong analgesic effects. When administered together intrathecally or epidurally, magnesium sulfate has been shown to prolong the duration of fentanyl-induced spinal analgesia without increasing adverse events[1][3][5]. This combination is used off-label in perioperative and obstetric settings to enhance and extend opioid-based pain relief.