Calculation of dose in pediatrics by syeda shiza aleem

The most important aspect for selection of a drug and establishment of the proper pediatric dosage is the acknowledgment that the pediatric patient is not just a small adult. Newborns, children and adolescents have different physiological, pharmacokinetic and pharmacodynamic parameters compared to adults. The differences are mainly related to the changes occurring during growth and maturation and require individual dosages. Thus, guidelines of specific dosages and useful means for calculation of pediatric dosages must be developed in order to enhance the effectiveness and therapeutic limit and prevent serious adverse effects

1. Calculation of Dose In Pediatrics Presented By: Syeda Shiza Aleem , PharmD Sultan Ul Uloom College Of Pharmacy Guided By: Dr S . P. Srinivas Nayak , Assistant Professor, SUCP, Hyd

2. The most important aspect for selection of a drug and establishment of the proper pediatric dosage is the acknowledgment that the pediatric patient is not just a small adult. Newborns, children and adolescents have different physiological, pharmacokinetic and pharmacodynamic parameters compared to adults. The differences are mainly related to the changes occurring during growth and maturation and require individual dosages. Thus, guidelines of specific dosages and useful means for calculation of pediatric dosages must be developed in order to enhance the effectiveness and therapeutic limit and prevent serious adverse effects Introduction

3. As per ICH (2000) ,Childhood is divided in Age: UPTO 28 DAYS (NEONATE) Age: UPTO 1-24 MONTHS (INFANTS ) Age: 2-11 YEARS (CHILDREN) Age: 12-18 YEARS (ADOLESCENTS)

4. Lack of data on important pharmacokinetic and pharmacodynamic differences has led to several terrible situations in pediatric care. One is an ethical issue, the inability to obtain true informed consent. The second obstacle is inherent to children; they grow and change rapidly. Infancy and childhood is rapid stage of development and various organs, enzymes and body systems that handle drugs and their dosage are different in time. So, Drug studies must be performed on children at each stage of their development to determine appropriate usage. Highly Critical aspects in child treatment are Pharmokinetic parameters Method of drug administration Dose & dosage forms Importance of drug handling:

5. Growth and development are important indicators of a child’s general well-being and pediatric practitioners should be aware of the normal development milestones in childhood. The World Health Organization (WHO) has publised the widely used growth charts. Three important tools in developmental assessment. Height Weight Head circumference The Normal Child:

6. In addition to the above, assessments of hearing, vision, motor development and speech are undertaken at the child health clinics.

7. Monitoring parameters: Pediatric vit a l si g ns, Bioche m ica l and haematology par a m e ter s c h a nge t hr o ughout the childhood. I t gi v es ide a abo u t t h erapy m a nage m ent in prolonged treatment. VITAL SIGNS Parameters Age (2-5 years) Age (5-12) years Heart rates (beats/ min) Systolic Blood pressure (mmHg) Respiratory rates (beats/ min) 100-120 80 - 90 25 - 30 80-100 90 - 110 1 6 - 25

8. Biochemical Parameters Parame t ers Albumin (g/L) Bilirubin ( micr o mol /L) Creat i nine ( micromol /L) Hemoglobin(g/ dL ) WBC (*10 9 /L) Age (2-12 years) Age (>18 years) 30-50 35-55 <17 5 -14 3. 5 -11 1 1- 14 30-80 13.5-18(male) 12-16(female) 50-120 <15

9. Dose calculation :- Height and Weight growth are rapidly changing factors in childhood, which also influence significantly some pharmacokinetic parameters. So,these factors should be considered during therapy. Doses should be obtained from pediatric book for children. For example, In india IAP-Drug formulary is reliable source for pediatric practice and their important drugs. For many years, pediatric dosage calculations used pediatric formulas such as Fried’s rule , Young’s rule , and Clark’s rule . These formulas are based on the weight of the child in pounds, or on the age of the child in months, and the normal adult dose of a specific drug.

10. Dose calculation related to age: Youngs Rule: Child’s Dose = Age(Years)/Age(Years)+12 X Adult Dose Dillings Rule: Child’s Dose = Age (Year)/20 X Adult Dose Frieds Rule: Child’s Dose = Age(Month)/150 X Adult Dose

11. The adult and/or children’s doses of a number of drugs in the Pharmacopoeia are based on the body weight of the patient on the theory that the concentration of a drug at its site of action will often be influenced by the size of the patient and, therefore, a heavily-built individual should receive a larger dose than someone of normal weight. Clark’s Rule: Child’s Dose = Body weight (lb)/150 X Adult Dose Child’s Dose = Body weight (kg)/70 X Adult Dose *1kg = 2.2 lb Dose calculation related to body weight:

12. Dose calculation related to surface area: The methods based on age and body weight are not entirely satisfactory. Hence, a method based on surface area of the body is devised. As the dose to be given depends on factors such as metabolic rate, lean body mass and extracellular fluid volume, which are more closely related to surface area than to age or weight, the method seems to be a reasonable one. Child’s Dose = Child’s body surface area/Average adult’s body surface area X Adult dose Body surface area: BSA (m 2 ) = (height (cm) x weight (kg)/3600) ½

13. Thank You