Chapter 1: Common Medications

Azithromycin

• 500 mg, diluted in 20 mL of normal saline (NS)/lactated Ringers, infusion slowly over 1 hour.

• 4 mg of Ondansetron intravenously (IV) before infusion due to significant nausea and vomiting.

• Indications: intrapartum cesarean section, spontaneous rupture of membrane.

• Reference: N Engl J Med. 2016;375:1231-1241.

Bicitra

• Generic name: sodium citrate/citric acid; 30 mL per container.

• Per os (PO), before epidural placement and before cesarean delivery.

Chloroprocaine

• 3% chloroprocaine, preservative free (PF).

• Alkalization: In a 30-mL syringe, add 2 mL of 8.4% bicarbonate to 20 mL of chloroprocaine.

• Use for emergent cesarean delivery or for forceps delivery.

• STAT Cesarean Kit: Prepackage in obstetric anesthesia office: (1) 3% chloroprocaine; (1) 8.4% bicarbonate; (1) 30-mL syringe; (1) blunt needle. Replace it after use.

Dexmedetomidine

• Dilute 200 µg in 20 mL of NS, final concentration 10 µg/mL.

• Indications:

  • Severe shivering after delivery: 10 µg IV, may repeat up to 30 µg.

  • Severe pruritus associated with epidural fentanyl, see Chapter 6.

• Reference: Int J Obstet Anesth. 2021;45:49-55.

Ephedrine

• Premixed by pharmacy, 5 mg/mL.

• Historically, ephedrine was used as the “Gold standard” for spinal hypotension.

• Higher placental transfer than phenylephrine; it can cause clinically insignificant fetal acidosis.

• Since late 1990s, used as a second-line medicine for maternal hypotension.

• References: Am J Obstet Gynecol. 1968;102:911.

  • Anesthesiology. 2009;111:506-512.

Epinephrine

• Add 250 µg to 150 mL premixed bupivacaine/fentanyl epidural solution; final concentration will be 1.67 µg/mL.

• Add 5 µg/mL of epinephrine into 2% lidocaine for cesarean delivery.

• Mechanisms: alpha-2 synergic effect, alpha-1 vasoconstriction to prolong the duration of anesthesia and decrease systemic absorption.

• Reference: J Anesth Perioper Med. 2019;6:1-7.

Lidocaine

• 2% lidocaine, PF.

• Alkalization of lidocaine: in a 30-mL syringe, add 2 mL of 8.4% bicarbonate to 20 mL of lidocaine.

• For cesarean delivery, add 5 µg/mL of epinephrine.

Magnesium

• 2 g/h infusion as maintenance dose.

• For preeclampsia, continue magnesium for entire cesarean delivery.

• For fetal neuroprotection, discontinue magnesium after delivery.

• Reference: The Magpie Trial. Lancet. 2002;359:1877-1890.

Morphine

• 0.5 mL/mL, PF, pre-made by pharmacy, stored at 4°C.

• Indications:

  • Cesarean delivery—spinal 250 µg, epidural 3 mg.

  • Labor CSE for dysfunctional labor—spinal 100 µg.

  • After third degree vaginal laceration repair—epidural 2 mg.

• Refer to Chapters 2, 41, and 42 for details.

Nitroglycerin

• 400 µg/mL, light sensitive. Kept in Omnicell in the operating room. Dilute to 100 µg/mL.

• Dose: 100 µg IV, may repeat, titrate to effect.

• Indications: cervico-uterine relaxation, inverted uterus, difficult extraction at cesarean delivery.

• Reference: Am J Obstet Gynecol. 1998;179:813.

Phenylephrine

• Pre-made by pharmacy, 100 µg/mL.

• Indications: first-line medication for maternal hypotension.

• Phenylephrine use is associated with a decrease in maternal cardiac output, but the clinical significance is not clear.

• Infusion at 0.5 to 0.7 µg/kg/min or bolus 100 µg, titrate to effect.

• Reference: Anesth Analg. 2012;114:377.

Terbutaline

• 1 mg/mL, use 0.25 mg, subcutaneously, administrated by the nurse.

• Indications:

  • Tachysystole contraction with associated fetal heart rate changes.

  • Before external cephalic version at obstetrician’s discretion.

• ACOG Practice ...