What concentration of medication is recommended for a pediatric patient, should I use the strongest available concentration?

Medication Concentration Selection for Pediatric Patients

No, you should not automatically give pediatric patients the strongest available concentration—instead, select concentrations that minimize calculation errors and reduce the risk of dosing mistakes, which are the primary safety threats in pediatric medication administration. 1

Primary Safety Principle

The greatest risk in pediatric medication administration is dosing calculation errors, not the concentration itself. The complexity of weight-based dosing combined with variable medication concentrations significantly increases the risk for harm when dose calculations are inaccurate. 1

Concentration Selection Strategy

Use Standard, Lower Concentrations When Possible

• Lower concentrations reduce the magnitude of error if a calculation mistake occurs—administering the wrong volume of a dilute solution causes less harm than the same volume error with a concentrated solution. 1
• Standard concentrations across your practice setting minimize confusion and calculation complexity. 1

Specific Clinical Contexts Where Concentration Matters

Local Anesthetics:

• Maximum safe doses are weight-based (mg/kg), not concentration-dependent. 2
• For lidocaine: maximum 7 mg/kg with epinephrine or 4.4 mg/kg without epinephrine. 2
• Using lower concentrations (e.g., 0.5% vs 2% lidocaine) provides a larger margin of safety—you can administer more volume before reaching toxic doses, making it harder to accidentally exceed maximum mg/kg limits. 2
• Doses should be reduced by 30% in infants younger than 6 months due to immature metabolism. 2

Diphenhydramine:

• The American Academy of Pediatrics recommends 1-2 mg/kg per dose (maximum 50 mg single dose). 3
• Oral liquid formulations are preferred over tablets for acute allergic reactions due to more reliable absorption. 3
• Using standard pediatric syrup concentrations (12.5 mg/5 mL) rather than adult concentrations minimizes measurement errors. 3

Epinephrine (Adrenaline):

• Critical concentration distinction: 1:1000 (1 mg/mL) for IM anaphylaxis vs 1:10,000 (0.1 mg/mL) for IV/IO cardiac arrest. 4
• Using the wrong concentration is a potentially fatal error—a 10-fold dosing mistake. 4
• For continuous infusions in shock, concentrations should be standardized within your institution to prevent calculation errors. 4

Key Dosing Principles Beyond Concentration

Age-Based Physiologic Considerations

Infants <2 months:

• Extreme caution required for hepatically metabolized drugs due to immature enzyme systems. 5
• Dosing should be based on therapeutic drug monitoring and clinical response rather than standard calculations. 5

Ages 2-6 months:

• Weight-based dosing generally appropriate for most medications. 5

After 6 months:

• Body surface area (BSA) becomes a better marker for most drugs. 5
• Exception: Drugs metabolized by CYP2D6 and UGT should remain weight-based even after 6 months. 5

Critical Pitfalls to Avoid

1. Never simply scale adult doses by weight—pediatric drug clearance is highly variable and unpredictable based on adult data alone. 6

2. Avoid "strongest concentration" thinking—this increases the risk of catastrophic overdose if volume calculations are wrong. 1

3. Beware of formulation-specific issues:

   • Lack of pediatric formulations increases dosing error potential. 7
   • Crushing tablets or diluting adult formulations introduces additional error opportunities. 8

4. Account for organ maturation, not just size:

   • Renal function should be assessed by serum creatinine and clearance markers in the first 2 years. 5
   • Hepatic metabolism varies by specific enzyme system maturation. 5

Practical Algorithm for Concentration Selection

1. Identify if a pediatric-specific concentration exists—use it preferentially. 7, 8

2. Calculate the required dose in mg/kg (or appropriate unit). 5

3. Select the concentration that allows:

   • Measurable volumes (not too small to draw accurately)
   • Reasonable injection/administration volumes (not excessively large)
   • The lowest concentration that meets these criteria 1

4. Double-check that maximum safe doses (mg/kg) are not exceeded regardless of concentration used. 2, 3, 4

5. Standardize concentrations within your practice setting to reduce cognitive load and error risk. 1

Evidence Quality Note

The recommendation against using "strongest available" concentrations is supported by high-quality safety data from EMS and emergency medicine settings, where medication errors are well-documented. 1 The physiologic dosing principles come from established pharmacokinetic guidelines. 5 The specific medication examples are from authoritative society guidelines (American Heart Association, American Academy of Pediatrics). 2, 3, 4