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What Every Pharmacist Should Know About Pediatric Pharmacy
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Here is a cheat sheet on information related to infants and older kids.
The motto of most pediatric pharmacists is “kids are not just little adults." Dealing with pediatric patients can be super-fulfilling but also crazy-challenging. When a pharmacist needs to check pediatric orders, there are a few key considerations to keep in mind. These quick points are for infants and older kids.1 Neonates have their own set of rules.
Breakdown of ages. This is important to be aware of, because dosing ranges often are broken down by age and weight ranges. There is some variance, but these are the age breakdowns that are generally agreed upon:
o Neonates: birth to 28 days of life (the first 4 weeks)
o Infants: 29 days to 12 months
o Children: 1 to 12 years
o Adolescents: 13 to 17 years
o Young adults: 18 to 24 years
Is this dose OK? The first thing to do when checking a pediatric order or prescription is to break it down to mg/kg/dose and mg/kg/day. When talking about pediatric dosing, always think in terms of mg/kg. Then remember that most medications max at adult doses. For example, the typical dose of acetaminophen is 15 mg/kg/dose, and max dose for adults is 650 to 975 mg/dose. A 20-kg kid’s dose would be 300 mg/dose. A 70-kg kid’s dose would be 15 mg/kg x 70 kg = 1,050 mg, but this dose should be maxed out at 650 mg to 975 mg/dose.
Maintenance fluid rate. These calculations are different for kids. Typically, in babies and kids older than 1 month, we use the 4-2-1 rule. This calculation is 4 ml for the first 0 to 10 kg, plus 2 ml for 11 to 20kg, plus 1 ml for 21+ kg. For example, a 25-kg kid would get 65 m/hr:
o 10 kg x 4 ml = 40 ml
o 10 kg x 2 ml = 20 ml
o 5 kg x 1ml = 5 ml
Add it all together, and the maintenance fluid rate = 65 ml/hr.
Starting boluses for infants and kids are usually 10 to 20 ml/kg for normal saline and 5 ml/kg dextrose boluses. Also of note, when giving a dextrose bolus, we usually use the max concentration of D10 vs D50 in adults.
Pharmacokinetics. This is a whole different ballpark when it comes to kids. All those remembered half-lives for drugs in adults can be tossed out the window. On average, infants and kids often metabolize medications faster than adults. For example, a vancomycin starting dose for a typical 4-year-old would start with q6h dosing, and linezolid would be given q8h. Babies and kids have different drug absorption, metabolism, and volume of distribution than adults. Their pharmacokinetics vary throughout childhood, so always research pharmacokinetics for each medication for kids.
What weight to use? In adults, we sometimes use the ideal body weight or adjusted body weight in overweight/obese adults. When it comes to kids, there is no easy calculation to determine if they need to have adjusted body weight or what their body mass index should be at different ages. We use the Centers for Disease Control and Prevention and World Health Organization growth charts.2 They are available at cdc.gov.
Creatinine clearance. This is also calculated differently for children. We usually use the Schwartz Equation:
o CrCl (ml/min/1.73m2) = [k x L] ÷ sCr
o K = proportionality constant
o L = length in centimeters
o sCr = serum creatinine in mg/dL
Patient type
K value
Low birth weight infants <1 year
0.33
Term infants <1 year
0.45
2 to 12 years (male or female)
0.55
13 to 21 years (female only)
0.55
13 to 21 years (male only)
0.70
A little trick is to memorize the Bedside Schwartz Equation for kids younger than 1 year. It is a bit easier because the K value is assumed at 0.413. Bedside Schwartz Equation: CrCl = [0.413 x L ]/sCr
Quite often in practice, the Cockcroft-Gault and Jeliffe equations are used once kids are in their later teens and taller than 5 feet.
Vital signs. These are totally different in pediatric patients. If an adult had a heart rate of 130 beats per minute, that would be considered high, but it is normal for a 3-month-old. Blood pressure, heart rate, and respiratory rate ranges vary based on age, gender, and height. There are a few references that can be used. One is from the Pediatric Advanced Life Support guidelines from the AHA3:
General Vital Signs and Guidelines
Age
Heart Rate
(beats/min)
Blood Pressure
(mmHg)
Respiratory Rate
(breaths/min)
Premature
110 to 170
SBP 55 to 75, DBP 35 to 45
40 to 70
0 to 3 months
110 to 160
SBP 65 to 85, DBP 45 to 55
35 to 55
3 to 6 months
110 to 160
SBP 70 to 90, DBP 50 to 65
30 to 45
6 to 12 months
90 to 160
SBP 80 to 100, DBP 55 to 65
22 to 38
1 to 3 years
80 to 150
SBP 90 to 105, DBP 55 to 70
22 to 30
3 to 6 years
70 to 120
SBP 95 to 110, DBP 60 to 75
20 to 24
6 to 12 years
60 to 110
SBP 100 to 120, DBP 60 to 75
16 to 22
>12 years
60 to 100
SBP 100 to 135, DBP 65 to 85
12 to 20
References. These can be every pharmacist’s lifeline. The go-to references for pediatric pharmacy include NeoFax (a subset of Micromedex) and Lexicomp. Pediatric Injectable Drugs: The Teddy Bear Book, (American Society of Health-System Pharmacists, 2013) is priceless when configuring IV medications for kids. And of course, there is always the primary literature.
Communication. This is always key. In pediatric pharmacy, we often interact with the parents. We need to remember that kids are people, too. It is important to assess and understand the involvement that the patient has in his or her care. I had a 20-year-old patient who refused to discuss her care or even look up from her cell phone. On the other hand, I had an 8-year-old discuss his complex diagnosis, medications, and dosing schedule with me. Just remember to be respectful and talk on their level, without being condescending.
How does it taste? Working as a pediatric pharmacist can be fun. The environment is filled with squeals, smiles, toys, and bright-colored walls. It is also filled with kids strongly protesting and refusing to take their medications. Here are some tips:
o Keep in mind that some kids can swallow pills at about age 6, so that is often the easiest option if they are open to it. Others will not swallow pills until they are 25.
o Use capsules or tablets that can be opened and put into formula, breast milk, applesauce, or pudding.
o FLAVORx has specific recipes for flavoring different medications.
o Chocolate sauce covers the flavor of the most pungent medications.
References
1. Benavides S and Nahata M. Pediatric pharmacotherapy. American College of Clinical Pharmacy. accp.com/store/product.aspx?pc=TH_01PPG. Accessed November 21, 2017.
2. Centers for Disease Control and Prevention. Clinical growth charts. cdc.gov/growthcharts/clinical_charts.htm. Updated June 16, 2017. Accessed November 19, 2017.
3. United Medical Education. PALS algorithms 2017 (pediatric advanced life support). acls-pals-bls.com/algorithms/pals/. Accessed November 19, 2017.
