CHPPC Module 9, Section 2: The General Pediatric Patient
MODULE 9: SPECIALIZED CARE: WOMEN & CHILDREN

Section 2: The General Pediatric Patient (Peds)

Welcome to a specialty where your core skill of weight-based dosing becomes the foundation for a new level of clinical vigilance. In this section, you will learn to see children not as “little adults,” but as a series of unique, rapidly changing physiological states, each with its own pharmacological rules and risks.

Masterclass: Developmental Pharmacokinetics & Pharmacodynamics

Why a child is not just a “little adult.”

In your community practice, you are an expert in pediatric dosing. You flawlessly calculate amoxicillin suspension doses and double-check every calculation, knowing that a simple decimal error can lead to a ten-fold overdose. This skill is the absolute bedrock of pediatric pharmacy. In the hospital, you will elevate this skill by adding a deep understanding of developmental pharmacology—the science of how a child’s body handles a drug differently from an adult’s, and how that changes as they grow. The most dangerous assumption in medicine is that a child is simply a smaller version of an adult. The truth is that from neonate to infant to toddler to adolescent, a child is a series of distinct, rapidly evolving physiological beings, each with a unique pharmacokinetic profile.

Retail Pharmacist Analogy: From Adjusting a Recipe to Engineering a New Oven

Think of your current weight-based dosing skill like being an expert baker who can perfectly scale a recipe. You know that to make a small cupcake instead of a large cake, you can’t just use a “little bit” of flour; you have to precisely scale every single ingredient down by a specific ratio. Your calculations are flawless.

The inpatient pediatric pharmacist is not just scaling the recipe; they must also re-engineer the oven itself for each different type of pastry.

  • The Neonate (A Microwave Oven): The heating elements (liver enzymes) are weak and underdeveloped. Things cook slowly and can easily be “overcooked” (toxicity). The ventilation (kidney function) is poor. You need lower temperatures and much longer cooking times (lower doses, longer intervals).
  • The Toddler (A Convection Oven): This oven runs incredibly hot! The metabolism is hyperactive, often exceeding adult levels. It burns through ingredients (drugs) at an astonishing rate. You often need higher temperatures and more frequent re-baking (higher mg/kg doses, shorter intervals) than for an adult cake.
  • The Adolescent (A Standard Oven in Flux): The oven is starting to resemble the adult model, but its thermostat and wiring are still unpredictable due to hormonal changes. It requires careful monitoring.

Your new role is to be the engineer who understands how each “oven” works, allowing you to not only scale the recipe but also to set the exact right temperature and time to achieve a perfect, safe outcome every time.

A Deep Dive into ADME: The Pediatric Difference

Let’s break down how each phase of pharmacokinetics (Absorption, Distribution, Metabolism, Elimination) is profoundly different in children.

PK PhasePhysiological Difference in PediatricsClinical Implication & Your Focus
Absorption Oral (PO): Gastric pH is higher (more alkaline) in neonates and infants. Gastric emptying time is prolonged.
Intramuscular (IM): Reduced muscle mass and erratic blood flow in neonates.
Topical: Thinner stratum corneum and higher body-surface-area-to-weight ratio.		 Oral absorption of acid-labile drugs (e.g., penicillins) may be increased, while absorption of weakly acidic drugs (e.g., phenobarbital) may be decreased. IM shots are unreliable in newborns. Topical absorption is dramatically enhanced, increasing the risk of systemic toxicity from creams (e.g., corticosteroids, lidocaine).
Distribution Body Water: Neonates are ~80% total body water, compared to ~60% in adults. This means a larger volume of distribution ($V_d$) for hydrophilic drugs.
Protein Binding: Lower concentrations of albumin and alpha-1-acid glycoprotein lead to less protein binding and a higher fraction of “free,” active drug.		 For water-soluble drugs like aminoglycosides (gentamicin), you will need a higher mg/kg loading dose to fill this larger volume and achieve a therapeutic peak. For highly protein-bound drugs (ceftriaxone, phenytoin), the higher free fraction increases the risk of toxicity, which is why ceftriaxone is contraindicated in neonates due to the risk of bilirubin displacement (kernicterus).
Metabolism Phase I (CYP450 Enzymes): Hepatic enzymes are immature at birth and mature at different rates. CYP3A4 is low at birth but matures over the first year. CYP2D6 activity is highly variable.
Phase II (Conjugation): Glucuronidation pathways are significantly underdeveloped in neonates.		 This is the most critical area. The classic example is the “Gray Baby Syndrome” with chloramphenicol, caused by neonates’ inability to glucuronidate the drug, leading to fatal accumulation. You must know that neonates are “slow metabolizers” for many drugs (like caffeine, whose half-life is >80 hours vs 6 hours in adults). Conversely, toddlers and young children (ages 1-5) often have a period of hyperactive metabolism, requiring higher mg/kg doses than adults for some drugs.
Elimination Glomerular Filtration Rate (GFR): The GFR is dramatically reduced at birth and does not reach adult values until about 1-2 years of age. For renally cleared drugs (penicillins, aminoglycosides, vancomycin), you must use longer dosing intervals in neonates and young infants to prevent accumulation and toxicity. For example, gentamicin might be given every 24, 36, or even 48 hours in a preterm neonate, compared to every 8 hours in an older child.

Masterclass: Common Pediatric Emergencies

Your role when every second counts.

Deep Dive: Status Epilepticus Protocol

Status epilepticus—a continuous seizure lasting more than 5 minutes, or multiple seizures without a return to baseline—is a life-threatening neurological emergency. Your role is to be the STAT pharmacist who ensures rapid access to anticonvulsants and verifies the correct, weight-based doses and infusion rates under extreme pressure.

The Tiered Approach to Status Epilepticus

Management is a rapid, stepwise algorithm. Your job is to know what comes next.

PhaseTimingFirst-Line Therapy & Your Role
Initial Therapy (0-5 min) Immediate Benzodiazepines. Your role is to ensure these are immediately available. You will verify the STAT order:
– IV Lorazepam: 0.1 mg/kg (max 4 mg).
– IM Midazolam: 0.2 mg/kg (max 10 mg).
– Rectal Diazepam (Diastat): 0.2-0.5 mg/kg.
Second-Line Therapy (5-20 min) If seizures continue after 2 doses of benzos. IV Antiepileptics. This is your most critical verification step. You must verify the drug, dose, and infusion rate.
– IV Fosphenytoin: 20 mg PE/kg (Phenytoin Equivalents). Rate not to exceed 3 mg PE/kg/min due to risk of hypotension/arrhythmia.
– IV Levetiracetam: 60 mg/kg. Can be infused more rapidly over 15 minutes.
– IV Valproic Acid: 40 mg/kg.
Third-Line Therapy (20-40 min) Refractory Status Epilepticus. Repeat a second-line agent or add another. If seizures persist, the patient is moved to the PICU for continuous infusions of Midazolam or Pentobarbital, requiring mechanical ventilation.

Deep Dive: Severe Dehydration & Rehydration

Children have a higher metabolic rate and higher body surface area, making them far more susceptible to rapid dehydration from vomiting, diarrhea, or fever. Severe dehydration is a medical emergency requiring immediate IV fluid resuscitation. As a pharmacist, you are a guardian of fluid and electrolyte management.

The “Bolus”: Immediate Resuscitation

The first step is to rapidly restore intravascular volume. This is done with an IV fluid bolus.

  • The Fluid: Always an isotonic crystalloid. 0.9% Sodium Chloride (Normal Saline) is the most common choice.
  • The Dose: 20 mL/kg infused rapidly over 5-20 minutes.
  • Your Role: Verify the STAT order. For a 15kg child, this would be a 300 mL bolus. You ensure the correct fluid is dispensed and the pump is programmed correctly.

Maintenance Fluids: The “4-2-1” Rule

Once the patient is resuscitated, you must calculate their daily maintenance fluid requirement. The Holliday-Segar method, or “4-2-1 rule,” is the universal standard you must master.

Masterclass: Calculating Maintenance Fluids

  • For the first 10 kg of body weight: 100 mL/kg/day
  • For the next 10 kg of body weight (11-20 kg): 50 mL/kg/day
  • For each kg above 20 kg: 20 mL/kg/day

Example: A 25 kg child.

  • First 10 kg: 10 kg * 100 mL/kg = 1000 mL
  • Next 10 kg: 10 kg * 50 mL/kg = 500 mL
  • Last 5 kg: 5 kg * 20 mL/kg = 100 mL
  • Total Daily Fluids = 1600 mL/day.

You would then divide this by 24 hours to get the hourly infusion rate: 1600 mL / 24 hr = ~67 mL/hour. Your verification of this calculation and the chosen IV fluid (often containing dextrose and electrolytes) is a core daily function.

Masterclass: Guardian Against Dosing Errors

Your role as the ultimate safety net in pediatric pharmacotherapy.

The risk of medication errors is 3 times higher in pediatric patients than in adults. The reasons are numerous: the need for complex weight-based calculations, the use of liquid formulations requiring measurement, and the simple fact that a standard adult dose can be a massive overdose for a small child. As a pharmacist, you are the final and most important barrier to preventing these errors from reaching the patient.

The “Ten-Fold Error”: A Pharmacist’s Nightmare

The most common and catastrophic pediatric dosing error is the ten-fold overdose, almost always resulting from a misplaced decimal point. This is where your relentless attention to detail is life-saving.

Case Scenario: A 10kg infant is ordered IV morphine 1 mg for pain. The standard dose is 0.1 mg/kg. Your brain must immediately perform the dose check: 10 kg * 0.1 mg/kg = 1 mg. The dose is correct. But the nurse calls you and says, “Are you sure this dose is right? The vial is 10 mg/mL, so I’m supposed to draw up 0.1 mL? It seems like such a tiny amount.”

Now another order comes in for a different 10kg infant: IV morphine 10 mg. Your brain fires: 10 kg * 0.1 mg/kg = 1 mg. The ordered dose is 10 times the correct dose! This is a classic ten-fold error, likely from a misplaced decimal or a calculation mistake. Your intervention to stop this dose is the difference between analgesia and fatal respiratory depression.

System-Level Defenses: Your Role as a Safety Architect

While individual vigilance is key, the modern hospital pharmacist’s role is to build systems that make it hard to do the wrong thing. You are not just a checker; you are a safety engineer.

System-Level DefenseYour Role as an Inpatient Pharmacist
Standardized Concentrations You will help lead the initiative to standardize all pediatric infusions. Instead of having multiple concentrations of a dopamine drip, the hospital will choose ONE standard concentration. This dramatically reduces the chance of a calculation error during preparation or programming.
Smart Pump Guardrails You will be responsible for programming the hospital’s infusion pumps with pediatric-specific drug libraries. You will build in “soft” and “hard” limits for every high-risk drug. A nurse trying to program a heparin infusion at 10 times the normal rate will be met with a “hard stop” alert that cannot be overridden without a pharmacist’s intervention.
Dose Range Checking You will help build dose range checking alerts into the EHR. An order for ceftriaxone that exceeds the maximum recommended mg/kg dose for a child’s weight will automatically fire a clinical alert that the physician must address.
Eliminating Ambiguity You will champion policies that eliminate dangerous abbreviations and practices. This includes banning the “trailing zero” (e.g., writing “1.0 mg” which can be misread as “10 mg”; it must be “1 mg”) and always requiring a “leading zero” (e.g., writing “0.1 mg” instead of “.1 mg” which can be misread as “1 mg”).