21.2 Pediatric Prescribing, OTC Therapy & Adherence
Key Takeaways
- Dose in milligrams per kilogram from a current weight, convert to milliliters from the actual liquid concentration, and never use a kitchen teaspoon — oral syringes in mL only
- OTC acetaminophen is typically 10–15 mg/kg/dose and ibuprofen 5–10 mg/kg/dose (generally not under 6 months); FDA advises against OTC cough/cold products under age 2, many labels say under 4, and AAP generally advises against them under 6
- Do not prescribe antibiotics for viral URIs; off-label pediatric use is common but still must be evidence-based — off-label is not a license for codeine or adult dosing
- PNCB items use common generic names and often list both names; boxed warnings you must counsel include SSRI suicidality and codeine (contraindicated under 12 and after tonsillectomy/adenoidectomy)
- Adherence fails on palatability, school dosing, and cost; stimulant and SSRI monitoring follows the mental-health chapter (cardiac/growth for stimulants; close early follow-up after an SSRI start)
Domain III.B wants a safe prescription. PNCB's published FAQ is blunt on names: items use common generic names; when a brand still matters, the stem typically lists both. Study amoxicillin, acetaminophen, ibuprofen, albuterol, methylphenidate, fluoxetine — not a trivia deck of every trade sticker. This section is how you dose, when you do not prescribe, and how you keep the family on the plan. Stimulant and SSRI monitoring is the same work as Chapter 9; here it is the prescribing-safety frame.
Quick Answer: mg/kg from a current weight, volume from the labeled concentration, mL oral syringe, never a kitchen teaspoon. Acetaminophen 10–15 mg/kg/dose; ibuprofen 5–10 mg/kg/dose (generally ≥6 months). No OTC cough/cold under age 2 (FDA); many products <4 years; AAP generally against under 6. No antibiotic for a viral URI. Counsel SSRI suicidality and codeine boxed-warning stories. Off-label is common in pediatrics and still has to be evidence-based.
Weight-based dosing is arithmetic you show
Pediatric doses are mg/kg (occasionally mg/m²). Use today's weight, not last year's well-visit card. Convert pounds ÷ 2.2 = kg if the scale printed lb. Calculate the milligram dose, then the milliliter volume from the product in the bottle, then check the adult maximum so a large adolescent does not get a super-therapeutic "pediatric" dose.
Volume (mL) = dose (mg) ÷ concentration (mg/mL).
Worked example. A child weighs 22 kg. Acetaminophen 15 mg/kg = 330 mg. Oral liquid is standardized at 160 mg/5 mL (32 mg/mL). Volume = 330 ÷ 32 ≈ 10 mL per dose. Interval is every 4–6 hours, typically no more than 5 doses/24 hours (~75 mg/kg/day), and never above the adult daily ceiling (4,000 mg). Ibuprofen 10 mg/kg = 220 mg. Children's suspension 100 mg/5 mL (20 mg/mL) → 11 mL every 6–8 hours. Infant concentrated ibuprofen (50 mg/1.25 mL) is a different strength — mixing those bottles is a classic overdose path.
Amoxicillin suspensions come as 125, 200, 250, or 400 mg/5 mL. Writing "1 teaspoon of amoxicillin" without a concentration is an incomplete order. High-dose AOM therapy is 80–90 mg/kg/day of amoxicillin divided twice daily when you are treating AOM — still with a listed concentration and a max (often taught around 3 g/day; do not exceed the adult dose).
Never a kitchen teaspoon. Teaspoons in drawers range from about 2.5 to 7 mL. FDA and AAP: metric dosing, oral syringe marked in mL. Write the volume in milliliters on the prescription and show the syringe in the room (show-back from 21.1).
Renal and hepatic function change clearance. Reduce or extend intervals for many drugs when GFR is reduced. Avoid ibuprofen in significant dehydration, suspected acute kidney injury, or some bleeding risks. Acetaminophen overdose is a hepatic emergency — counsel the daily max and hidden acetaminophen in combination products. Neonates have immature hepatic metabolism and longer half-lives; ceftriaxone plus calcium in neonates is a teaching contraindication; sulfonamides in young jaundiced infants raise kernicterus concern. You do not need a neonatology formulary. You need to notice age and organ function before you copy an adult tablet regimen.
Off-label is common; unsafe is not "off-label"
A large share of pediatric prescriptions have historically been off-label (age, indication, or route not in the FDA label). That is not a scandal on this exam and not a free pass. Off-label use must still rest on AAP/IDSA/NHLBI/GLAD-PC-quality evidence, a pediatric reference (Lexicomp, Harriet Lane), and a documented indication. Off-label does not mean codeine for toddlers, adult azithromycin "Z-packs" by habit, or skipping monitoring because "pediatrics is all off-label anyway."
OTC therapy you actually recommend
| Product | Primary-care use | Hard stop |
|---|---|---|
| Acetaminophen | 10–15 mg/kg/dose q4–6h; comfort from fever or pain | Exceeding 75 mg/kg/day or 4,000 mg/day; hidden combo products |
| Ibuprofen | 5–10 mg/kg/dose q6–8h | Generally not under 6 months; dehydration/renal risk; not a Kawasaki substitute for aspirin |
| Aspirin | Kawasaki disease is a specialist-protocol exception | Reye syndrome — do not use for viral illness in children |
| Nasal saline, suction | Infant URI | — |
| Emollients | Atopic dermatitis, dry skin (Chapter 10) | Steroid phobia that leaves the child raw |
| Honey | Cough if >12 months | Never <12 months (botulism) |
| OTC cough/cold (antihistamine/decongestant/antitussive combos) | Not a toddler therapy | FDA 2008: do not use under 2 years (serious adverse events, including deaths). Many manufacturers later labeled do not use under 4. AAP generally advises against these products under age 6 because benefit is poor and harm is real |
Supportive URI care is saline, suction, fluids, honey if old enough, acetaminophen/ibuprofen for comfort — not a multi-symptom night syrup. Promethazine carries a boxed warning: contraindicated under 2 years (respiratory depression).
Antibiotic stewardship and when not to prescribe
Viral URI, bronchiolitis, and most watery gastroenteritis do not get antibiotics. That is the highest-yield "when not to prescribe" item in Domain III.B. Colored snot is not a sinus-antibiotic indication. AAP AOM guidance still allows observation for selected non-severe cases (especially ≥2 years, or unilateral non-severe 6–23 months) with a 48–72 hour safety net; treat if severe, otorrhea, or bilateral AOM in 6–23 months. Confirm GAS pharyngitis before treating a sore throat. Sinusitis needs time-and-pattern criteria, not day-3 congestion. When an antibiotic is indicated, prefer narrow, weight-based, correct duration (high-dose amoxicillin for many AOM/outpatient CAP cases) — not default azithromycin for every cough.
Other "do not prescribe" items: codeine and tramadol (below); aspirin for viral illness; ibuprofen in a dehydrated infant; OTC cough/cold in young children; benzodiazepines as routine pediatric insomnia therapy; empiric broad-spectrum when a narrow agent is first-line.
Boxed warnings, drug–drug interactions, stimulant/SSRI monitoring
Know the story, not the Federal Register.
- SSRIs: boxed warning for increased suicidal thinking and behavior in children, adolescents, and young adults. Fluoxetine is FDA-approved for childhood and adolescent depression; escitalopram for adolescents. Counsel the warning. Start a pediatric dose. Arrange close follow-up in the first weeks (FDA's historical cadence was weekly × 4, every 2 weeks × 4, then monthly; GLAD-PC/AAP still demand early contact). This matches Chapter 9 — do not invent a 6-month silent gap. Atomoxetine also carries a suicidal-ideation boxed warning.
- Codeine: FDA contraindicated under 12 years for pain and cough; contraindicated under 18 years after tonsillectomy/adenoidectomy. CYP2D6 ultra-rapid metabolizers convert codeine to morphine quickly — respiratory depression and death. Tramadol follows a similar pediatric restriction story. Do not write "weak narcotic cough syrup" after T&A.
- Stimulants: boxed warning for abuse and dependence. Before start: cardiac history and exam (Chapter 9). Monitor BP, HR, height, weight, sleep, appetite. Recheck about 2–4 weeks after start or dose change.
- Montelukast: boxed warning for neuropsychiatric events — counsel mood/sleep/behavior changes; it is not a casual allergy add-on without a reason.
Drug–drug. Fluoxetine (and paroxetine) inhibit CYP2D6 and can raise atomoxetine levels and block codeine activation. Serotonergic stacks (SSRI plus St. John's wort, plus some migraine drugs) raise serotonin-syndrome risk. NSAIDs plus volume depletion injure kidneys. Strong CYP3A4 inhibitors (e.g., ritonavir) can potentiate some inhaled corticosteroids. Macrolides plus other QT-prolonging drugs deserve a second look. You will not memorize every CYP table. You will pause when two new psychoactive or cardiac drugs meet.
Adherence: palatability, school, cost
A perfect mg/kg dose that stays in the bottle is a failed Domain III.B plan. Palatability: flavoring, chewables, orally disintegrating tablets, sprinkle/capsule contents when the label allows. School dosing: prefer once-daily extended-release ADHD and asthma controllers that do not need a noon nurse; if a school dose is required, write the school order and a 504 path. Cost: generic first, 90-day fills when stable, prior-authorization letters as advocacy (21.3), discount programs. Ask what they will pay at the counter before they leave. Simplify to the fewest daily administrations. Set a reminder that matches this family's phone, not a lecture on responsibility.
Clinic vignette. You calculate ibuprofen 10 mg/kg beautifully, say "a teaspoon," and skip the concentration. The infant-drops bottle is at home. That is how OTC becomes an ED visit. Write mL, name the concentration, hand a syringe, teach-back the max daily acetaminophen, and do not add a cough/cold product because the caregiver asked for "something for the cold."
An 18-month-old has a 3-day viral URI. The caregiver wants OTC cough syrup and plans to give acetaminophen with a kitchen teaspoon. What should the CPNP-PC do?
A well-appearing 4-year-old has 3 days of rhinorrhea, cough, and low-grade fever. Tympanic membranes are not consistent with AOM, lungs are clear, and there is no pneumonia. What is the correct prescribing decision?
You start fluoxetine for a 14-year-old with moderate depression and no suicide plan. Which counseling and monitoring plan matches pediatric prescribing safety?