Can You Give 1500 Units of ATS to an Infant?
No, you should not administer 1500 units of antitoxin serum (ATS) to an infant without first clarifying which specific antitoxin is being referenced and the clinical indication, as dosing varies dramatically by product and condition.
Critical Clarification Needed
The term "ATS" is ambiguous and requires immediate clarification before any dosing decision:
If this refers to Botulism Antitoxin (BAT): The FDA-approved dose for infants (<1 year) is 10% of the adult dose, regardless of weight 1. The standard adult BAT dose is one vial, so 1500 units would need to be evaluated against the specific product's unit concentration 1.
If this refers to diphtheria antitoxin: Dosing is based on disease severity and site, not age or weight, and typically ranges from 20,000-120,000 units for clinical diphtheria. A 1500-unit dose would be grossly insufficient for therapeutic purposes.
If this refers to tetanus antitoxin: Modern practice uses tetanus immune globulin (TIG), not equine antitoxin, with pediatric dosing of 250-500 units IM.
Botulism Antitoxin Dosing in Infants (Most Likely Scenario)
For infant botulism, BAT is NOT the appropriate treatment—BabyBIG (Botulism Immune Globulin Intravenous) is the specific product indicated for infants 1.
If Foodborne Botulism is Suspected in an Infant:
- Dose: 10% of the adult BAT dose 1
- Key principle: Antitoxin dosing should be based on toxin load, not body weight, because the amount of circulating toxin is independent of patient size 1
- Monitoring: Infants treated with weight-based dosing should be monitored closely for worsening paralysis, as the dose may be insufficient if toxin load is high 1
Critical Dosing Principle:
The absolute amount of botulinum toxin in an infant may be no different from—or could even exceed—the amount in an adult who consumed the same contaminated food, because toxin distribution in food varies widely 1. Therefore, toxin-load-based dosing may require the same or greater dose than for an adult 1.
Practical Considerations for Infant Dosing
General Principles:
- Infants are not simply "small adults": Pharmacokinetic parameters differ significantly due to immature drug elimination pathways 2
- Volume of distribution: Hydrophilic drugs with high Vd should be normalized to body weight in children <2 years 3
- Hepatic metabolism: Extreme caution is required for drugs metabolized by the liver until 2 months of age 3
- Renal excretion: Dosing should be based on markers of renal function (serum creatinine, creatinine clearance) in the first 2 years of life 3
Why 1500 Units Requires Verification:
Without knowing the specific antitoxin product and its unit concentration per vial, it is impossible to determine if 1500 units represents:
- An appropriate fraction of the adult dose
- A dangerous overdose
- An insufficient therapeutic dose
Immediate Action Required
Before administering any antitoxin to an infant:
- Confirm the specific product name and indication (botulism, diphtheria, tetanus, other)
- Verify the unit concentration per vial or mL
- Calculate the appropriate dose based on:
- Consult with poison control or infectious disease specialist for confirmation, especially given the rarity of these conditions and the high-stakes nature of antitoxin therapy 1
Common Pitfalls to Avoid
- Do not assume linear weight-based scaling from adult doses: This results in underdosing in infants for most medications 2
- Do not delay antitoxin administration while calculating precise doses if botulism is strongly suspected—early administration improves outcomes 1
- Do not use equine-derived antitoxins without skin testing for hypersensitivity when human-derived products are available 1
- Do not administer a second dose within 24 hours unless there is clear progression of paralysis with high diagnostic confidence 1