Adding a drug called neostigmine to epidural analgesia reduces dose needed during labor

Jul 27 2009

Adding a drug called neostigmine to epidural analgesia during labor can reduce the amount of anesthetic drug required, while avoiding potential complications caused by morphine-like "opioid" drugs, according to a study in the August issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).

The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.

The addition of neostigmine - a drug used in the treatment of the rare disease myasthenia gravis - may improve the quality of epidural pain relief, according to the new research, led by Dr. James Eisenach of Wake Forest University School of Medicine, Winston-Salem, N.C.

After a pilot study to establish the safety of epidural neostigmine, the researchers performed a randomized trial in 40 women giving birth by planned cesarean section. All patients received patient-controlled epidural analgesia using the local anesthetic bupivacaine. Half of the women received a combination of neostigmine plus bupivacaine; the rest received bupivacaine alone.

The pilot study showed no ill effects of neostigmine in either the mother or fetus. In the randomized trial, women receiving neostigmine used significantly less local anesthetic - 19 percent less, on average, than women receiving epidural bupivacaine without neostigmine. For women who required epidural analgesia for four hours or longer, the difference was 25 percent. Both groups had excellent pain control, despite the lower dose of local anesthetic.

Neostigmine may have caused some mild sedation in the mothers, but there were no problems with nausea. All other outcomes - including the fetal heart rate, a key indicator of the baby's well-being during labor - were similar with or without bupivacaine.

Anesthesiologists in developed countries primarily provide analgesia for women in labor by giving them an epidural anesthetic, which blocks the pain of labor contractions from reaching the spinal cord and brain. Epidural anesthesia almost always consists of a cocktail comprised of a local anesthetic, such as bupivacaine, and a morphine-like drug, such as fentanyl. However, these opioid drugs can cause significant side effects, including abnormalities of the fetal heart rate.

The new study suggests that adding neostigmine instead of opioids can improve the quality of epidural pain relief for women in labor, while decreasing the amount of local anesthetic required. "This represents an important advance in providing safe and effective pain relief for women in labor, because it may allow anesthesiologists to replace the morphine-like drugs with less toxic drugs such as neostigmine," according to an accompanying editorial by Dr. Cynthia Wong of Northwestern University, Chicago. However, Dr. Eisenach notes that large safety studies are still needed provide assurance that neostigmine itself has an adequate safety profile to permit widespread clinical use.