What it is:A reference appendix, not a disease chapter. It bundles the dosing and nutrition facts that only apply to babies: how to dose pain medication and sedatives across a newborn's fast-changing physiology, how much and how often infants should eat, how to rehydrate a kid with diarrhea, how neonatal antibiotic doses shift week by week, and the specific drugs used to close a patent ductus arteriosus (PDA).
The core problem:Neonates are not just small adults, and they are not even a stable population within themselves. Renal clearance, hepatic metabolism, body water percentage, and blood-brain barrier permeability all change meaningfully between day 1 and day 60 of life. A dose that's safe on day 10 can be dangerous on day 2 and undertreat on day 40.
What you do about it:Before you dose anything neonatal, ask two questions: how many days old (postnatal age, PNA)and what did they weigh at birth (above or below 2,000 g). Nearly every table in this appendix is organized around those two variables.
Think of it as "PNA-tiered dosing."As a neonate's kidneys and liver mature over the first month of life, clearance goes up, so the interval between doses usually gets shorter (dosing more often) even when the mg/kg stays flat or rises slightly. That single idea explains almost every antibiotic table you'll be asked to interpret in peds rotations.
Route selection in kids depends on age, cognitive ability to participate (can they push a PCA button?), and how severe and how long the pain will last. The same opioids show up across routes, but the physiology behind dosing them changes drastically between a 10-year-old and a 28-week preemie.
| Route | Best for | Key point |
|---|---|---|
| Intermittent IV/PO bolus | Moderate pain, not true PRN dosing | Wide peak-trough swings; patient bounces between toxicity and undertreated pain |
| IV continuous infusion | Severe, sustained pain | Loading dose first, then maintenance infusion; neonatal loading doses are infused slowly (over ~90 min), not pushed |
| PCA (patient-controlled analgesia) | Kids who can physically operate a button | Feasible as young as 5-6 years old; smooths out peak-trough swings |
| Epidural / intrathecal | Severe postoperative, chronic, or cancer pain | Doses are far lower than IV equivalents; bupivacaine + fentanyl/morphine/hydromorphone is the typical combo |
| Transdermal | Stable, chronic dosing | Fentanyl or buprenorphine patches; needs a separate short-acting agent for breakthrough pain |
| Transmucosal (fentanyl lozenge) | Procedural pain | Onset ~15 min, lasts 60-90 min, no needle. 10-15 mcg/kg PO ≈ 3-5 mcg/kg IV |
The FDA restricted codeine and hydrocodone cough/cold products under age 18, and separately black-boxed codeine after tonsillectomy or adenoidectomy for OSA following reports of deaths from respiratory depression. The mechanism: 1-7% of the general population (up to 28% of some ethnic groups)carry a CYP2D6 ultra-rapid metabolizer genotype that converts codeine to morphine faster and more completely than expected, producing unpredictable toxicity. IV codeine is never appropriate, it triggers histamine-mediated allergic-type reactions. If it's used at all, lowest dose, shortest duration, true PRN only.
A morphine dose that's routine in an older infant can cause seizures and respiratory depression in a neonate, because neonates have decreased clearance, an immature, more permeable blood-brain barrier, and a higher unbound (active) fractionof the drug in circulation. That's why the neonatal loading dose (0.1 mg/kg) is infused over 90 minutes instead of the faster bolus you'd give an older child (0.05-0.15 mg/kg).
Oxycodone and morphine come in sustained-release formulations, but those are for chronic pain only, never acute pain. The tablet must be swallowed whole; crushing it or giving it through a gastric tube destroys the release mechanism and dumps the full dose at once, which is a dangerous overdose risk.
On epidural/intrathecal dosing: because the drug is delivered essentially at the site of action, the required dose is a fraction of the IV equivalent. Watch for delayed respiratory depression with neuraxial opioids, it can occur hours after administration as the drug migrates rostrally in the CSF.
Feeding volume and frequency follow a predictable curve as gastric capacity grows and metabolic demand per kilogram falls. This matters clinically because a caregiver reporting "he's only eating 4 times a day" needs to be checked against the age-expected pattern before you assume something's wrong.
| Age | Feedings/day | Volume per feeding |
|---|---|---|
| Birth-1 week | 6-10 | 30-90 mL (1-3 oz) |
| 1 week-1 month | 7-8 | 60-120 mL (2-4 oz) |
| 1-3 months | 5-7 | 120-180 mL (3-6 oz) |
| 3-6 months | 4-5 | 180-210 mL (6-7 oz) |
| 6-9 months | 3-4 | 210-240 mL (7-8 oz) |
| 9-12 months | 3 | 210-240 mL (7-8 oz) |
Total daily volume climbs fast in the first month, then the numberof feeds drops while volume per feedkeeps rising. That's stomach capacity catching up to caloric need. A newborn eating every 2-3 hours around the clock is normal; a 9-month-old still doing that usually isn't, and is worth a feeding history.
A baby born at 28 weeks missed the entire third trimester, which is when a fetus normally accretes most of its calcium, phosphorus, and protein stores. Preterm formulas are built to catch that up. Standard term formula runs about 20 kcal/oz; premature formulas come in 20, 24, and 30 kcal/oz densities, with proportionally higher protein, calcium, phosphorus, and vitamin D than term formula or even mature human milk.
| Formula | kcal/oz | Protein (g/dL) | Calcium (mg/dL) | Vitamin D (IU/mL) |
|---|---|---|---|---|
| Mature human milk | 19.5-21 | 1.03 | 20-25 | variable |
| Similac Special Care 20 | 20 | 2.03 | 121.7 | 101.4 |
| Similac Special Care 30 | 30 | 3.04 | 152.2 | 182.6 |
| Enfamil Premature 24 HP | 24 | 2.9 | 134 | 240 |
| Postdischarge: Similac Neosure | 22 | 2.1 | 78 | 52 |
| Postdischarge: Enfamil EnfaCare | 22 | 2.1 | 90 | 53 |
Human milk fortifiersexist because straight breast milk, while immunologically ideal, doesn't hit the calorie/protein/mineral targets a preemie needs. A packet or measured liquid volume of fortifier is mixed into pumped breast milk to bring it up to roughly 24 kcal/oz, while keeping the immune and GI-maturation benefits of human milk. Postdischarge formulas(Neosure, EnfaCare) sit between preemie formula and standard term formula, a bridge for infants going home who still need extra density but no longer need full NICU-level fortification.
Most pediatric dehydration from vomiting or diarrhea can be corrected orally, and the WHO ORS formula is the gold standard, cheap, effective, and it avoids an IV stick. The two things you're calculating are how much volume to replaceand which solution to use, and the second one is where people get tripped up by sports drinks and juice.
| Weight | Age | ORS volume, first 4 hours |
|---|---|---|
| <5 kg | <4 months | 200-400 mL |
| 5-7.9 kg | 4-11 months | 200-400 mL |
| 8-9.9 kg | 12-23 months | 600-800 mL |
| 10-15.9 kg | 2-4 years | 800-1200 mL |
| 16-29.9 kg | 5-14 years | 1200-2200 mL |
| ≥30 kg | ≥15 years | 2200-4000 mL |
If you don't want to use the table, there's a formula: weight (kg) × 75 mLgives the first-4-hour replacement volume. After that, to just prevent ongoing dehydration from stooling, kids under 2 get 50-100 mL per loose stool (cap 500 mL/day), ages 2-9 get 100-200 mL (cap 1000 mL/day), and 10 and up get 100-200 mL or more as tolerated (cap 2000 mL/day).
This is a classic distractor. Juice, soda, and most sports drinks are not rehydration solutions.The WHO reduced-osmolarity formula runs sodium 75 mEq/L, potassium 20 mEq/L, glucose 13.5 g/L, osmolarity 245 mOsm/L, a ratio built to maximize sodium-glucose cotransport absorption in the gut. Juice has sodium around 2 mEq/L and sugar around 69 g/L with osmolarity ~730. That massive sugar load with almost no sodium pulls more water into the gut osmotically and can worsen diarrhea.Standard Gatorade isn't much better (sodium ~20 mEq/L, still high sugar). Save the sports drink talk for exercise-associated fluid loss, not gastroenteritis.
| Category | Example | Sodium (mEq/L) | CHO (g/L) | Osm (mOsm/L) |
|---|---|---|---|---|
| Rehydration (deficit correction) | WHO (UNICEF), modified | 75 | 13.5 | 245 |
| Maintenance (prevent deficit) | Pedialyte | 45 | 25 | 388 |
| Not a rehydration solution | Gatorade (G2) | 20 | 21 | 305 |
| Not a rehydration solution | Juice | 2 | 69 | 730 |
| Not a rehydration solution | Soda | 3 | 70 | 700 |
Practical target for any rehydration/maintenance product: sodium 60-90 mEq/L for active rehydration (45 mEq/L is fine for maintenance-only use), potassium 15-25 mEq/L, and CHO concentration roughly equal to or just below sodium in mmol terms, keeping total osmolarity under about 310 mOsm/L so it doesn't itself drive an osmotic diarrhea.
This is the table that trips people up, because the same drug can have three or four different doses on the same page depending on postnatal age (PNA)and birth weight. The organizing logic: smaller, younger neonates clear drugs more slowly, so they get longer intervals (less frequent dosing) even at similar or lower mg/kg. As they age past the first week, then past 28 days, clearance improves and intervals shorten.
| Drug | PNA 0-7 d, ≤2000 g | PNA 8-28 d, ≤2000 g | PNA 0-7 d, >2000 g | PNA >28 d (all weights) |
|---|---|---|---|---|
| Beta-lactams | ||||
| Ampicillin | 50 mg/kg Q12h | 75 mg/kg Q12h | 50 mg/kg Q8h | 50 mg/kg Q6h |
| Ampicillin (GBS meningitis) | 100 mg/kg Q8h | 75 mg/kg Q6h | 100 mg/kg Q8h | 75 mg/kg Q6h |
| Cefazolin | 25 mg/kg Q12h | 25 mg/kg Q12h | 25 mg/kg Q8h | 25 mg/kg Q8h |
| Cefepime | 30 mg/kg Q12h | 30 mg/kg Q12h | 50 mg/kg Q12h | 50 mg/kg Q8h |
| Cefotaxime | 50 mg/kg Q12h | 50 mg/kg Q8h | 50 mg/kg Q12h | 50 mg/kg Q6h |
| Ceftazidime | 50 mg/kg Q12h | 50 mg/kg Q8h | 50 mg/kg Q12h | 50 mg/kg Q8h |
| Meropenem | 20 mg/kg Q12h | 20 mg/kg Q8h | 20 mg/kg Q8h | 30 mg/kg Q8h |
| Nafcillin/oxacillin | 25 mg/kg Q12h | 25 mg/kg Q8h | 25 mg/kg Q8h | 37.5 mg/kg Q6h |
| Piperacillin/tazobactam | 100 mg/kg Q8h | 80 mg/kg Q6h | 80 mg/kg Q6h | 80 mg/kg Q6h |
| Other antibiotics | ||||
| Clindamycin | 5 mg/kg Q8h | 5 mg/kg Q8h | 7 mg/kg Q8h | 10 mg/kg Q8h |
| Metronidazole | 7.5 mg/kg Q12h | 7.5 mg/kg Q12h | 7.5 mg/kg Q8h | 10 mg/kg Q8h |
| Vancomycin | 15 mg/kg Q12-18h | 15 mg/kg Q8-12h | 15 mg/kg Q8-12h | 15 mg/kg Q6-8h |
| Penicillin G (dose and indication both change the math) | ||||
| GBS meningitis | 150,000 U/kg Q8h | 125,000 U/kg Q6h | 150,000 U/kg Q8h | 125,000 U/kg Q6h |
| Congenital syphilis | 50,000 U/kg Q12h | 50,000 U/kg Q8h | 50,000 U/kg Q12h | 50,000 U/kg Q6h |
| Antiviral / antifungal | ||||
| Acyclovir | 20 mg/kg Q12h | 20 mg/kg Q8h | 20 mg/kg Q8h | 20 mg/kg Q8h |
| Amphotericin B deoxycholate | 1 mg/kg Q24h (all tiers) | 1 mg/kg Q24h | ||
| Liposomal amphotericin B | 5 mg/kg Q24h (all tiers) | 5 mg/kg Q24h | ||
| Fluconazole | 12 mg/kg Q24h (all tiers) | 12 mg/kg Q24h | ||
Penicillin G for GBS meningitis is 150,000 units/kg Q8h, but for congenital syphilis it's 50,000 units/kg Q12hin that same 0-7 day, ≤2000 g neonate. Same drug, same patient population, 3x the dose and a different interval because the indications need different exposure targets. If a question gives you an indication, don't just pattern-match the drug name to a dose you memorized, check what it's being used for.
Fluconazole is loaded at 25 mg/kg, then the 12 mg/kg maintenance dose starts 24 hours later. Adjust for renal function if serum creatinine is ≥1.3 mg/dL. Vancomycin doses above are a starting point only, actual neonatal vancomycin dosing is typically guided by levels given how much clearance varies even within a PNA/weight tier.
The ductus arteriosus stays open in utero because prostaglandin E2 keeps it dilated. After birth it's supposed to close on its own as prostaglandin levels fall and oxygen tension rises; in preemies it often doesn't. The medical options all work by inhibiting prostaglandin synthesis, which lets the ductus constrict and close.
| Drug | Regimen | Notable point |
|---|---|---|
| Indomethacin | IV, 3 doses: PNA <48h 0.1 mg/kg Q12-24h; PNA 2-7d 0.2 mg/kg Q12-24h; PNA >7d 0.25 mg/kg Q12-24h | Dose rises with postnatal age, opposite direction from most antibiotic tables |
| Ibuprofen, standard-dose | 10 mg/kg × 1, then 5 mg/kg Q24h × 2 doses | Reference regimen |
| Ibuprofen, high-dose | 20 mg/kg × 1, then 10 mg/kg Q24h × 2 doses | Higher closure rate than standard-dose, without more adverse effects |
| Acetaminophen | IV, 15 mg/kg Q6h × 3-7 days | Alternative when NSAIDs are contraindicated (renal impairment, active bleeding, thrombocytopenia) |
Acetaminophen doesn't share the NSAID renal, GI, and platelet risks, which makes it the go-to when a baby has oliguria, active bleeding, or thrombocytopenia that rules out indomethacin or ibuprofen. But its monitoring flips too: instead of tracking urine output and creatinine, you're watching liver function tests, since that's the organ acetaminophen stresses instead.
Both indomethacin and ibuprofen require holding the dose for urine output <0.6 mL/kg/h, and indomethacin specifically holds for serum creatinine >1.6 mg/dL. Both need platelet counts and a bleeding assessment before each dose, plus ongoing blood pressure, murmur, respiratory status, and echocardiogram monitoring to confirm the ductus is actually closing.
Neonates, especially preterm ones, are more sensitive to every one of these drugs than older infants because of immature hepatic metabolism, a leakier blood-brain barrier, and less physiologic reserve to tolerate hypotension or respiratory depression. Titration to effect, not a fixed target dose, is the rule across this whole category.
| Agent | Use | Dosing | Watch for |
|---|---|---|---|
| Sucrose 24% | Mild procedural pain | 0.1-0.5 mL/dose by weight, given 1-2 min before procedure, max 3 doses/procedure | Non-pharmacologic; give on pacifier or tongue |
| Acetaminophen (oral) | Mild-moderate pain | GA 28-32wk: 10-12 mg/kg Q6-8h (max 40 mg/kg/day); GA 33-37wk: 10-15 mg/kg Q6h (max 60 mg/kg/day); term ≥10 days: 10-15 mg/kg Q4-6h (max 75 mg/kg/day) | Not effective for acute procedural pain |
| Acetaminophen (IV) | Moderate-severe pain, often with an opioid | PMA 28-32wk: 10 mg/kg Q12h (max 22.5 mg/kg/day); PMA 33-36wk: 10 mg/kg Q8h (max 40 mg/kg/day); PMA ≥37wk: 10 mg/kg Q6h (max 40 mg/kg/day) | Max daily dose scales with maturity, not just weight |
| Morphine | Moderate-severe prolonged/postop pain | Intermittent 0.05-0.1 mg/kg Q4-6h; continuous 0.01-0.03 mg/kg/h | Hypotension, resp depression, apnea in preterm; possible neurodevelopmental effect |
| Fentanyl | Moderate-severe procedural/prolonged pain | Intermittent 0.5-3 mcg/kg Q2-4h; continuous 0.5-3 mcg/kg/h | Bolus over 3-5 min, rapid push risks chest wall rigidity |
| Midazolam | Procedural or prolonged sedation | Intermittent 0.05-0.1 mg/kg; continuous by gestational age, 0.02-0.06 mg/kg/h | Myoclonus, especially preterm; neurodevelopmental concern |
| Dexmedetomidine | Prolonged sedation/analgesia | Continuous 0.1-0.3 mcg/kg/h | Limited neonatal data |
Push fentanyl too fast in a neonate and you can get rigid chest syndrome, muscle rigidity severe enough to prevent effective ventilation. The fix is prevention: always administer the bolus over 3-5 minutes, not as a rapid IV push.
This is the appendix's throughline. A morphine or midazolam dose that's completely standard for a toddler can cause seizures, apnea, or profound hypotension in a neonate, and preterm neonates are more sensitive still. Doses here are consistently lower and intervals longer than what you'd use even in a term infant a few months older, and everything is titrated to effect rather than dosed to a fixed target.
| Parameter | When | Watching for |
|---|---|---|
| Urine output | Before each indomethacin/ibuprofen dose | Hold if <0.6 mL/kg/h, suggests reduced renal perfusion from prostaglandin inhibition |
| Serum creatinine | Before/during PDA-closure NSAID therapy | Hold indomethacin if >1.6 mg/dL; also gates fluconazole renal dosing at ≥1.3 mg/dL |
| Platelets / bleeding signs | Before each PDA-closure NSAID dose | NSAIDs impair platelet function on top of any baseline thrombocytopenia of prematurity |
| Liver function tests | During IV acetaminophen course for PDA | Hepatotoxicity, especially with prolonged 3-7 day courses |
| Vancomycin levels | Around 3rd-4th dose, or per protocol | Table doses are a starting point; actual dosing is level-driven given wide neonatal variability |
| Weight and feeding volume | Daily in NICU, every well visit as outpatient | Growth trajectory; under-volume feeding relative to age-expected table |
| Blood pressure, murmur, echo | Throughout PDA-closure treatment | Confirms actual ductal closure, not just that doses were given |
| Respiratory status / sedation depth | Continuously during any opioid or sedative infusion | Apnea, hypotension, over-sedation, especially in preterm infants |
| Hydration status (weight, mucous membranes, UOP) | Throughout oral rehydration therapy | Ongoing losses outpacing replacement; escalate to IV fluids if ORT fails |