How to calculate child dose

Young's Rule - StatPearls - NCBI Bookshelf

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Christian I. Wade; Thirsa Martinez.

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Last Update: February 17, 2022.

Definition/Introduction

Young's Rule is an equation used to calculate pediatric medication dosage based on the patient's age and the known recommended adult dose. The definition of Young's Rule is the age of the patient, divided by the age added to twelve, all multiplied by the recommended adult dose. This formula appears below:

[Age / (Age + 12)] x Recommended Adult Dose = Pediatric Dose

Young's Rule can be applied to quickly approach a situation in which the patient's weight is unknown. Other approaches to pediatric dosing that also use age include Webster's Rule and Fried's Rule.

If the weight of the patient is known, Clark's Rule or the Body Surface Area rule can be implemented.[1]

Issues of Concern

Pediatric dosing based on one's age has the potential for suboptimal therapeutic levels due to the broad range of potential weight, especially with increasing childhood obesity.[2][3]

Clinical Significance

In situations where the pediatric patient's weight is unknown, for instance, at the point of injury, then Young's Rule can be safely implemented if their age and the recommended adult dosing are known. Additionally, certain classes of medications require weight-based dosing, such as antibiotics and antiepileptics. Ultimately, age-based dosing has been demonstrated to be a safe and effective approach. However, caution should be used depending on the class of the drug.[4][5]

Nursing, Allied Health, and Interprofessional Team Interventions

Knowledge of Young's RUle can serve several purposes in pediatric drug dosing, and members of the interprofessional healthcare team would do well to be familiar with the rule. The most obvious use is for the clinician when calculating the dose for a pediatric patient. A secondary use can be to verify that the dose ordered or prescribed is not outside of the parameters for the child. This is where nurses, during administration or pharmacists, when filling an order or prescription, can apply the rule and potentially stop a toxic dose or a therapeutically insufficient dose. In an open, interprofessional team environment, this can improve patient outcomes and prevent adverse events. [Level 5]

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References

1.: Delgado BJ, Safadi AO, Bajaj T. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jun 29, 2021. Clark's Rule. [PubMed: 31082148]
2.: Ogden CL, Carroll MD, Lawman HG, Fryar CD, Kruszon-Moran D, Kit BK, Flegal KM. Trends in Obesity Prevalence Among Children and Adolescents in the United States, 1988-1994 Through 2013-2014. JAMA. 2016 Jun 07;315(21):2292-9. [PMC free article: PMC6361521] [PubMed: 27272581]
3.: Kendrick JG, Carr RR, Ensom MH. Pharmacokinetics and drug dosing in obese children. J Pediatr Pharmacol Ther. 2010 Apr;15(2):94-109. [PMC free article: PMC3018176] [PubMed: 22477800]
4.: Elias GP, Antoniali C, Mariano RC. Comparative study of rules employed for calculation of pediatric drug dosage. J Appl Oral Sci. 2005 Jun;13(2):114-9. [PubMed: 20924533]
5.: Kendrick JG, Carr RR, Ensom MH. Pediatric Obesity: Pharmacokinetics and Implications for Drug Dosing. Clin Ther. 2015 Sep 01;37(9):1897-923. [PubMed: 26361823]

This book is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, a link is provided to the Creative Commons license, and any changes made are indicated.

Bookshelf ID: NBK554603PMID: 32119490

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Definition/Introduction
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Clinical Significance
Nursing, Allied Health, and Interprofessional Team Interventions
Review Questions
References

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Young's Rule - StatPearls - NCBI Bookshelf

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.

StatPearls [Internet].

Show details

Search term

Christian I. Wade; Thirsa Martinez.

Author Information

Last Update: February 17, 2022.

Definition/Introduction

[Age / (Age + 12)] x Recommended Adult Dose = Pediatric Dose

Young's Rule can be applied to quickly approach a situation in which the patient's weight is unknown. Other approaches to pediatric dosing that also use age include Webster's Rule and Fried's Rule.

If the weight of the patient is known, Clark's Rule or the Body Surface Area rule can be implemented.[1]

Issues of Concern

Pediatric dosing based on one's age has the potential for suboptimal therapeutic levels due to the broad range of potential weight, especially with increasing childhood obesity.[2][3]

Clinical Significance

Nursing, Allied Health, and Interprofessional Team Interventions

Review Questions

Access free multiple choice questions on this topic.
Comment on this article.

References

1.: Delgado BJ, Safadi AO, Bajaj T. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Jun 29, 2021. Clark's Rule. [PubMed: 31082148]
2.: Ogden CL, Carroll MD, Lawman HG, Fryar CD, Kruszon-Moran D, Kit BK, Flegal KM. Trends in Obesity Prevalence Among Children and Adolescents in the United States, 1988-1994 Through 2013-2014. JAMA. 2016 Jun 07;315(21):2292-9. [PMC free article: PMC6361521] [PubMed: 27272581]
3.: Kendrick JG, Carr RR, Ensom MH. Pharmacokinetics and drug dosing in obese children. J Pediatr Pharmacol Ther. 2010 Apr;15(2):94-109. [PMC free article: PMC3018176] [PubMed: 22477800]
4.: Elias GP, Antoniali C, Mariano RC. Comparative study of rules employed for calculation of pediatric drug dosage. J Appl Oral Sci. 2005 Jun;13(2):114-9. [PubMed: 20924533]
5.: Kendrick JG, Carr RR, Ensom MH. Pediatric Obesity: Pharmacokinetics and Implications for Drug Dosing. Clin Ther. 2015 Sep 01;37(9):1897-923. [PubMed: 26361823]

Bookshelf ID: NBK554603PMID: 32119490

PubReader
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Cite this Page

In this Page

Definition/Introduction
Issues of Concern
Clinical Significance
Nursing, Allied Health, and Interprofessional Team Interventions
Review Questions
References

Bulk Download

Related information

Calculation of the dose of a medicinal substance for a child.

Calculation of the dose of a medicinal substance for a child.

: Acidberry10; June 5th, 2013

Current Location:: In the same place, where

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I know that among my readers there are several people who graduated from the medical faculty, but who want to go to pediatrics. Especially for them, I would like to provide information on the calculation of doses for children. Perhaps this information will also give food for thought to adult doctors who do not understand that in body weights of 50 kg and 100 kg, a dose of 15 mg of some pentaxicillin will be distributed differently. And you yourself know about such features of the body as kidney, liver failure, individual characteristics of detoxification systems and the binding of drugs to albumins :).

State Pharmacopoeia (Edition X) recommends calculation based on the age of the child. The adult dose is taken as a unit, the children's unit is a part of this dose:

children up to a year 1/24-1/12,
2 years old - 1/8,
4 years old - 1/6,
6 years - 1/4,
7 years - 1/3,
14 years - 1/2,
15-16 years - 3/4.
This method of calculation is not accurate enough, since the weight of children of the same age may vary

According to Young's rule, the children's dose is determined as follows

where Fd is the children's dosage (filii dosis), Ad is the adult dosage (adult dosis) A is the age (anno). The formula is actually written in Russian letters, but since I'm dibilko, and I don't know how to use an online editor for formulas, I had to pervert inventing the letter designation of the variable.

according to Clark's rule, the calculation is as follows

Where m is the body weight in kg (of the same ones) on which the medicinal substance will act.
For ease of calculation, I would like to provide a

calculator

A more perfect calculation of the pediatric dose using the Fd factor: the adult dose is recalculated per 1 kg of body weight by dividing by 70, then multiplied by the child's body weight and by Fd.

Age	up to 1 year	1-6 years old	6-10 years	10-12 years	13-15 years old
Fd	1.8	1.6	1.4	1.2	1. 1 or 1.0*

*if the weight and height of the child's body are close to those of adult family members.

Determining the dose of the drug by body surface area.

Body weight, kg	Estimated age	Body surface area, m2	percentage of the average single (daily) adult dose
3	newborn	0.2	12
6	3 months	0.3	18
10	1 year	0.45	28
20	5.5 years old	0.8	48
30	9 years	1	60
40	12 years old	1.3	78
50	14 years old	1. 5	90
60	adult	1.7	102
70	adult	1.76	103

Children's dosage: measure correctly - Letidor

Despite the fact that the dosages are indicated in the instructions for the drug, the question: "How to calculate the amount of medicine for a child?" - I hear it very often. And this is good. It is much worse if the mother does not think about it and gives the baby an extra second or even third pill to enhance the effect.

But even if parents understand the meaning of children's dosage, they do not always know the practical details. For example, not all tablets can be cut in half, and not all teaspoons are equally useful in measuring five milliliters.

Limits of the norm

There are two main doses for any drug:

Maximum single dose - how much you can drink at one time
Maximum daily is the total amount of medication per day.

They are especially important for over-the-counter products, the instructions for which parents rarely read, considering them harmless. Which is not true at all. These doses should not be exceeded in any case, the consequences can be varied, but always unpleasant, sometimes even downright dangerous. From the instructions, you can generally learn a lot of interesting things, for example, that acetylsalicylic acid should not be given to children under 12 years old.

Under 16 and over

Children's doses are calculated based on body weight. Age also matters, but if a too well-developed girl weighs 40 kg at 10 years old, she will need the same amount of the drug as a 15-year-old asthenic boy with the same weight. That is why all instructions indicate not only the age, but also the weight category of the child.

Example: Maximum daily doses of paracetamol (do not forget to count ALL paracetamol included in hot drinks, syrups, suppositories, etc. ).

up to 6 months (up to 7 kg) - 350 mg
from 6 months to a year (up to 10 kg) - 500 mg
1-3 years (up to 15 kg) - 750 mg
up to 22 kg) — 1 g
6–9 years (up to 30 kg) — 1.5 g
9–12 years (up to 40 kg) — 2 g

Important! There are no universal rules for calculating the dose that could guarantee the effectiveness and safety of the use of drugs in children, especially newborns. The pediatrician should correctly prescribe the drug.

Indivisible whole

Many people think that it is enough to split a tablet in half and the required dosage will be observed! You can break it only if there is a special groove. In other cases, special medicines with multiple doses are required. Why is it so?

Firstly, during production it is almost impossible to mix the mass to a homogeneous state and make sure that exactly 50% of the necessary ingredients are in the half. Studies have shown that this percentage ranges from 20 to 80. And the spread of dosages will be the higher, the more components in the drug.

Secondly, in addition to the main active ingredient in the tablet, there is also a lot of auxiliary, added not at all in a 1:1 ratio. And when dividing them, it will turn out less than what is required for the correct "work" of the medicine.

_ Important! Never replace "baby" doses with half or quarter "adult" doses. This is fraught with an overdose, especially in young children. _

A spoon for mother

Liquid dosage forms are sometimes measured incorrectly. Most people are sure that a teaspoon is 5 ml, a dessert spoon is 10 ml, and a tablespoon is 15 ml. But firstly, there are tablespoons and 20 ml each, and teaspoons - 7.5 ml each. Secondly, not everyone fills even a standard spoon exactly to the brim.

American scientists from Cornell University conducted a study, and it turned out that when using medium-sized spoons, patients receive 8. 4% less of the drug, and 11.6% more when measuring the remedy with large spoons. At the same time, every fifth participant in the experiment was sure that in both cases the medicine would give the same effect.

The consequences of a single over- or underdose are negligible, but for people forced to take the medicine every 4-8 hours for several days, this difference between the recommended and actual dose can be significant.

_ Important! Use cutlery only if the medicine does not come with a special measuring container - a cap or a spoon. _

Herbs for the baby

The most difficult situation is with the use of medicinal plants in children. Unfortunately, the recommendations on the packages, as a rule, apply only to adult patients. Many mothers brew herbs for a child “as written on the pack”, that is, an adult dose, and at the same time receive an overdose of a medicinal substance, which can result in allergic, toxic reactions, and deterioration in well-being. But the herbs will be completely innocent! So that they give only strength and health, we present the most commonly used children's dosages.

Dosages of herbs and herbs (based on 2 days):

4-5 years - 0.5 l dessert spoon

6-7 years - 0.5 l tablespoon

- 8-10 years - 0.5 l heaping tablespoon

11 -12 years - 1.5 tablespoons per 0.5 l

13-15 years - 2 tablespoons per 0.5 l

immediately for 2 days. Store it in the refrigerator and warm up to room temperature before use.

The child should drink half of the prepared dose per day (about a glass on average). Divide it into 3-5 doses. Up to 3 years old - from 1 to 3 tablespoons per dose, over 3 years old - about 1/3 cup.

It is desirable to vary the daily dose depending on the constitution and weight of the children. For thin people, we reduce it by about 1/5. We increase the "dumplings" by the same amount. Usually these variations come down to the presence or absence of a slide in a spoonful of dry grass. If you use medicinal plants and fees in filter bags, be guided by such children's dosages (based on 2 days):

Restrictions on the use of herbs in children of the first year of life are mainly due to the immaturity of most enzyme systems. They are not always able to provide an adequate response to the entry of new chemicals into the body, therefore, an allergic or toxic reaction may develop, explains _ Olga DANILYUK , phytotherapeutist, candidate of medical sciences, assistant of the Department of Phytotherapy of the FPCMR PFUR._

For example, the younger the baby , the higher the risk of toxic effects of peppermint and menthol essential oils on the central nervous system. With their overdose, convulsions and vomiting are possible, especially in children of the first 6 months of life. Mint is not prescribed for children of the first year of life. With age, the threat of poisoning with peppermint oils or menthol decreases markedly, and after 3 years there is no danger anymore.
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