Compared with the adult dose, the succinylcholine dose for a 14-day-old neonate with bowel obstruction should be:

Compared with the adult dose, the succinylcholine dose for a 14-day-old neonate with bowel obstruction should be:

• A. Diminished because of immature nervous system
• B. The same as the adult dose
• C. Increased because of greater volume of distribution
• D. Decreased because of decreased acetylcholine receptors

Answer: (C)

Neonates have a higher total body water and a larger extracellular fluid volume than adults, so hydrophilic drugs like succinylcholine distribute into a bigger volume. Because the distribution volume per kilogram is greater, a higher mg/kg dose is needed to achieve the same peak plasma concentration and rapid onset of neuromuscular blockade in a 14-day-old neonate. It’s important to note that while immature plasma cholinesterase in neonates slows metabolism and prolongs the duration of action, that affects how long the blockade lasts rather than how much dose is required to achieve onset. The idea of decreased acetylcholine receptors isn’t the driving factor for the increased initial dose in a normal neonate.

Neonates have a higher total body water and a larger extracellular fluid volume than adults, so hydrophilic drugs like succinylcholine distribute into a bigger volume. Because the distribution volume per kilogram is greater, a higher mg/kg dose is needed to achieve the same peak plasma concentration and rapid onset of neuromuscular blockade in a 14-day-old neonate. It’s important to note that while immature plasma cholinesterase in neonates slows metabolism and prolongs the duration of action, that affects how long the blockade lasts rather than how much dose is required to achieve onset. The idea of decreased acetylcholine receptors isn’t the driving factor for the increased initial dose in a normal neonate.