# Why do infants require smaller doses of medications than adults?

## Why do infants require smaller doses of medications than adults?

Drug actions in infants are variable because of the infant’s physiological attributes: small body mass, high relative body water content, low body fat, greater membrane permeability of the skin, and blood-brain barrier and reduced plasma-binding abilities.

Why are pediatric doses calculated by weight instead of age?

Body-surface area estimates are more accurate for calculation of paediatric doses than body weight since many physiological phenomena correlate better to body surface area.

How does Pediatrics affect drug dosing?

Infants have a higher percentage of extracellular water, and stores of body fat increase throughout childhood. Changes in volume of distribution can alter the drug’s half-life, requiring adjustment of the dosing interval, as seen with digoxin.

### How do you calculate pediatric antibiotics?

Pediatric Dosage Calculations [Internet]….Example 2.

Step 1. Calculate the dose in mg: 18 kg × 100 mg/kg/day = 1800 mg/day
Step 2. Divide the dose by the frequency: 1800 mg/day ÷ 1 (daily) = 1800 mg/dose
Step 3. Convert the mg dose to mL: 1800 mg/dose ÷ 40 mg/mL = 45 mL once daily

Why do children need different doses of medication than adults?

Pharmacokinetics of drugs in children may differ from adults for several reasons: variability due to age, gender, body composition, functionality of liver and kidneys and maturation of enzymatic systems throughout the life span from neonates to adults are all potential sources of pharmacokinetic differences [5].

Do children have greater hepatic capacity than adults?

Therefore, young children have an increased ability (greater than that of adults) to metabolize drugs eliminated by CYP-dependent metabolism. By puberty, CYP enzymatic activity has decreased to adult levels.

#### What is Clark’s rule formula?

Clark’s rule equation is defined as the weight of the patient in pounds divided by the average standard weight of 150 pounds (68 kg) multiplied by the adult dose of a drug equals the pediatric medication dose, as is demonstrated below: (Weight* divided by 150 lbs.) x Adult Dose** = Pediatric Dosage.

How are pediatric doses determined?

Most drugs in children are dosed according to body weight (mg/kg) or body surface area (BSA) (mg/m2). Care must be taken to properly convert body weight from pounds to kilograms (1 kg= 2.2 lb) before calculating doses based on body weight.

What are the three steps required for calculating dosages in the ratio and proportion method?

Step one: Set up ratios. Step two: Multiply means and extremes Step three: Solve for “x” algebraically. Use drug calculations when calculating the quantity of medications needed for a patient and the strength of medication is already known.

## Why do children react differently to medication?

… Children can respond differently to many drugs and can present different ADRs than adults [2,3] . The reason is mainly the variation in the pharmacokinetic and pharmacodynamic profiles between pediatric and adult patients [13, 14] .

Why do you think doses aren’t the same for all age groups?

Because vaccines do not work like medications, in many cases the same vaccine dose can be given to different age groups; however, in some cases, different versions of vaccines are available for different age groups.

At what age is a child’s liver fully developed?

The switch to the adult pattern occurs at approximately 12 years of age. In addition, infants have a greater capacity to synthesize glutathione, thereby inactivating toxic metabolites of acetaminophen more effectively.

### What is Fred’s rule?

Fried’s rule is a method of estimating the dose of medication for a child by dividing the child’s age in months by 150 and multiplying the result by the adult dose. Pediatric dose = child’s age in months. 150. x Adult Dose.

What is Cowling’s rule?

(kowl′ĭng) A method for calculation of pediatric drug dosages in which the age of the child at the next birthday is divided by 24. However, the most safe and accurate methods of pediatric dosage calculation include the weight and body surface area or both of the patient.

What is the three step process for calculating dosages?

There are 3 primary methods for calculating medication dosages; Dimensional Analysis, Ratio Proportion, and Formula or Desired Over Have Method. We will explore the Desired Over Have or Formula Method, one of these 3 methods, in more detail.

#### What is the ratio proportion method?

The proportion method is based on writing two ratios. One ratio is the percent ratio, written as 100 percent . The second ratio is the amount-to-base ratio, written as base amount .

What is the most common adverse drug effect seen in the elderly?

Adverse drug reactions (ADRs) are common in older adults, with falls, orthostatic hypotension, delirium, renal failure, gastrointestinal and intracranial bleeding being amongst the most common clinical manifestations.