Pediatric Drug Calculations

•Drug dosages differ greatly from adults because of physiologic differences

•Neonates and infants have immature kidney and liver function-delays metabolism and elimination of many drugs

•Decreases drug absorption- neonates have delayed gastric emptying, children younger than 3 years old has decreased gastric secretions

•Have lower concentration of plasma proteins – can cause toxicity with highly protein bound drugs

•Young children have less total body fat and more body water

•All injections must be given in a manner that minimizes physical and psychosocial trauma

Fried’s Rule

•applies to children younger than 1 year of age

Child’s dose (age <1 yr) = infant’s age (in months) x average adult dose150 months

Young’s Rule

• for children 1 to 12 years of age

Child’s dose (1- 12 yrs) = child’s age (in years) x average adult dose Child’s age (in yrs) + 12

Clark’s Rule

•uses the child’s weight to calculate and assumes that the adult dose is based on a 150 lb person

Child’s dose =weight of child ( in pounds) x average adult dose 150

Paediatric Guidelines for IM injections According to Muscle Group

Amount by Muscle Group (ml)

AGE Vastus lateralis

Gluteus Maximus

Ventrogluteal Deltoid

Birth to 4months

0.5-1 Not safe 0.5-1 Not safe

Infants 0.5-1 Not safe 1 Not safe

Toodlers 0.5-2 0.5-1 0.5-1 0.5-1

Preschool and older children

2 0.5-2 2-3 0.5-1

Adolescents 2 2 2-5 1-1.5

TEMPERATURE CONVERSION•Fahrenheit to Celsius

C= F- 32 C = F-32 x 5 1.8 9

•Celsius to Fahrenheit

F= 1.8 C +32 F= [(C x9)/ 5] + 32

LIFE SPAN CONSIDERATIONS

•Beginning to end of life –body changes in many ways

•Changes that have an effect on the four phases of drug action

Drug Therapy during Pregnancy•A fetus is exposed to many of the same

substances as the mother, including any drugs that she takes.

•First trimester – period of greatest danger of drug induced developmental defects.

•The FDA classifies drugs according to their safety for use during pregnancy

FDA Pregnancy Categories•Category A – no risk to fetus•Category B – little or no risk•Category C – animal studies shows risk to

fetus•Category D – risk to human fetus has

been proven; may be used in life-threatening conditions

•Category X – avoid during pregnancy due to proven risk to human fetu

Neonatal and Pediatric PatientsCLASSIFIACTION OF YOUNG PATIENTS

AGE RANGE CLASSIFICATION

Younger than 38 week gestation Premature or preterm infant

Younger than 1 month Neonate or newborn infant

1 month to younger than 1 year Infant

1 year to younger the 12 y/o child

Absorption•Gastric ph is less acidic because acid-

producing cells in the stomach are immature until approximately 1-2 years of age.

•Gastric emptying is slowed because of slow or irregular peristalsis

• First pass elimination by the liver is reduced because of the immaturity of the liver and reduced level of microsomal enzymes

• Intramuscular absorption is faster and irregular

Distribution

•Total body water is 70% to 80% in full term infants, 85% in premature NBs, 64% in children 1-2 years

•Fat content is lower in young patients because of greater total body water

•Protein binding is decreased •More drugs enter the brain because of

immature blood brain barrier

Metabolism

•Levels of microsomal enzymes are metabolism because the immature liver has not yet producing enough

•Older children may have increased and require higher dosages once hepatic enzymes are produced

Excretion

•GFR and tubular secretion and reabsorption are all decreased in young patients because of kidney immaturity

•Perfusion to the kidneys may be decreased and result in reduced renal function, concentrating ability, and excretion of drugs

NB : Strictly follow the guidelines for Pediatric dosage calculations

The Elderly PatientsPHYSIOLOGIC CHANGES

SYSTEM PHYSIOLOGIC CHANGE

Cardiovascular Dec. CO = Dec. Absorption and Dist. Dec. Blood flow=Dec. Absorption and

Dist.

Gastrointestinal Increased PH = altered absorptionDecreased peristalsis =dec. Gastric

emptying

Hepatic Decreased enzyme and blood flow =decreased metabolism

Renal Decreased blood flow, function, and GFR =dec. excretion

Absorption•Gastric PH is less acidic because of gradual

reduction in the production of HCL acid in the stomach

•Gastric emptying is slowed because of a decline in smooth muscle tone and motor activity

•Movement throughout the GIT is slower• Blood flow to the GIT is reduced by 40%-

decreased CO and Perfusion• Absorptive surface area is decreased because

the aging process blunts and flattens villi

Distribution

•40 to 60 y/o, total body water is 55% in males, 47% in females, over 60 y/o, total body water 52% in male, 46 in females

•Fat content is increased because of decreased lean body mass

•Protein binding sites are reduced because of decreased production of proteins by the aging liver and reduced protein intake

Metabolism

•The levels of microsomal enzymes are decreased because the capacity of the aging liver to produce them is reduced

•Liver blood flow is reduced by approximately 1.5% per year after 25 years of age, which decreases hepatic metabolism

Excretion

•GFR is decreased by 40% to 50% primarily because of decrease blood flow

•The number of intact nephrons is decreased

MEDICATION ERRORS

Medication error• defined as any preventable event that may cause

or lead to inappropriate medication use or patient harm, while the medication is in the control of the health care professional, patient, or consumer.

• Such events may be related to professional practice, health care products, procedures, and systems including: prescribing; order communication; product labeling, packaging, and nomenclature; compounding; dispensing; distribution; administration; education; monitoring; and use.

Types of Medication Errors

Common types of medication errors include:• Administering the wrong dosage• Prescribing the wrong dosage• Prescribing the wrong medication all together• Prescribing medication that cannot safely be mixed with

other medications the patient is currently taking• Failing to check a patient’s medical history to determine

whether or not the patient can safely consume the drug• Dispensing the wrong medication• Including the wrong dosage instructions on the prescription

bottle

Contributing factors• Miscommunication• Look-alike medication names• Confusion of generic and brand namesMajor causes of error:▫Distractions and interruptions during

administration▫ Illegible written orders▫ Incorrect dosage calculations▫Similar drug names and packaging

Examples of Errors• Prescribing: Illegible handwriting or unclear orders• Non-compliance with order-writing guidelines• Wrong order form used• Therapeutically incorrect orders• Decimal point errors• Documenting -Improper therapeutic screening of order at

time of taking• order off by nursing or pharmacy (dose, allergy check)• Incorrect/incomplete transcription of order on MAR or

Kardex• Not transcribed onto MAR or Kardex• Pharmacy transcription error• Incorrect documentation of medication administered

• Incorrectly dispensed/reconstituted/labeled by pharmacy• Incorrectly diluted/reconstituted/labeled by nursing• Administration -Misread orders/MAR/Kardex/label• Forgot to give• Incorrect pump setting/drip rate• Gave to wrong patient• Incorrect dose calculation• Incorrect administration• Equipment/device/tubing problem (e.g., tubing

disconnects, tubing• clamped)• Monitoring -Improper monitoring of drug effect (e.g.,

narcotic administered to patient with low RR

Reporting and Responding to Medication Errors•Checking the patient by assessing all

relevant parameters and documenting accordingly

•Assessing patient for effects of the drugs and consulting reference materials and colleagues as needed.

•Performing medication reconciliation to verify all of the patient’s correct medications at each point of care

•Regularly asking the patient to verify his or her identity and date of birth

•Completing ME reporting forms after contacting the health care team.

•Monitoring the progress of patient’s condition regularly

•Thinking and acting critically and modifying nursing practice to prevent further errors

Medication Reconciliation

•A procedure that seeks to prevent medication errors through the ongoing assessment and updating of every patients’ list of medications throughout the health care process and the timely communication of such information to both patients and health care team.

• Involves three steps

1. VERIFICATI ON- Collection of patient’s medication

information with a focus on medications currently used ( Prescription and OTC)

2. Clarification- Professional review of this information to

ensure that medications and dosages are appropriate for the patient

3. RECONCILIATION- Further investigation of any discrepancies

and documentation of relevant communications and changes in medication orders.

To ensure ongoing accuracy of medication use, these steps should be repeated at each stage of health care delivery:1. Admission2. Status Change ( Critical to stable)3. Patient Transfer4. Discharge

Nursing Measures to Prevent Medication Errors•Minimize the use of verbal and telephone

orders•List the indication next to drug order on

the medication record•Avoid use abbreviations, medical

shorthand, and acronyms•Never assume anything about any drug

order or prescription including route

• If a medication order is questioned for any reason, never assume that the prescriber is always correct. Always act as patients’ advocate.

•Do not try to decipher illegibly written orders

• If in doubt of the correctness of the order, double check with the prescriber

•Compare the medication order against what is on hand

•Never use trailing zeros

Other measures....

•Carefully read all labels for accuracy, expiration dates, and dilution requirements

•Be familiar with techniques of administration

•Encourage the use of both trade and generic name in drug orders

•Always double check a medication product’s labeling

•Always verify new medication administration records if they have been rewritten or re entered for any reason

Client Education for Medication Usage

• Find out what drug you're taking and what it's for. Rather than simply letting the doctor write you a prescription and send you on your way, be sure to ask the name of the drug. 

• Find out how to take the drug and make sure you understand the directions

• Keep a list of all medications, including OTC drugs, as well as dietary supplements, medicinal herbs, and other substances you take for health reasons, and report it to your health care providers.