Analgesics for obstetrics: Nursing pharmacology

Analgesics are medications used to relieve pain, and can be used for various reasons in obstetrics, such as during pregnancy to manage headaches, back, or pelvic pain during delivery to help reduce pain from uterine contractions, cervical stretching, and vaginal distension; as well as following vaginal delivery for perineal lacerations, and following cesarean delivery for pain at the incisional site.

Commonly used analgesics in obstetric settings include acetaminophen, which is mainly used during pregnancy; as well as systemic analgesics like opioids and regional analgesics like local anesthetics, which are typically used once the client goes into labor.

However, other analgesics like NSAIDs, such as ibuprofen, should be avoided during pregnancy, since they can cause fetal harm, including fetal renal impairment, oligohydramnios, and premature closure of the fetal ductus arteriosus.

Now, opioids can be full opioid agonists like fentanyl and remifentanil; and partial opioid agonists like butorphanol and nalbuphine; whereas regional anesthetics include bupivacaine and ropivacaine.

Now, in general, analgesics act by blocking neurons that transmit pain sensations. Opioids act on opioid receptors called the mu, kappa, and delta receptors. These receptors are typically located on the pre- and post-synaptic membranes of the pain-conducting neurons in the spinal cord and brain.