Dosing Considerations for Vulnerable Populations

Copyright © 2015 F.A. Davis Company

Davis’s Drug Guide for Nurses,14th EditionDavis’s Drug Guide for Nurses,14th Edition

Dosing Considerations for Dosing Considerations for Vulnerable PopulationsVulnerable Populations



Vulnerable PopulationsVulnerable Populations

Are groups of patients with a high risk for

adverse drug effects

Require careful dosing and/or medication selection



At-Risk Groups IncludeAt-Risk Groups Include

Men and women of reproductive age

Pregnant or breastfeeding women

Children and infants

Elderly patients

People with renal or hepatic disease

Obese or underweight patients



Reproductive AgeReproductive Age

In women: Drugs can affect fertility or damage ova

In men: Drugs can alter sperm quality and quantity



Pregnancy Safety CategoriesPregnancy Safety CategoriesA, B, C, D, XA, B, C, D, X

A: Studies have not shown a risk to the fetus B: Studies have not shown a risk to an animal

fetus; however, there are no well-controlled studies in humans

C: Animal studies show an adverse effect and there are no adequate studies in pregnant women or no animal studies have been conducted and there are no adequate studies in pregnant women Many drugs fall in category C



Pregnancy Safety Categories (cont’d)Pregnancy Safety Categories (cont’d)

D: Studies in pregnant women have shown a risk to the fetus; benefits may outweigh potential risks

X: Studies in animals and pregnant women have shown evidence of fetal abnormalities; the drug is contraindicated in women who are or may become pregnant



Drug Properties Impacting Drug Transfer Drug Properties Impacting Drug Transfer to Fetusto Fetus

Dosage Drug chemistry Lipid solubility Protein binding



Pregnant WomenPregnant Women

First trimesterFirst trimester

A woman is least likely to know she is pregnant

Exposure of fetus to drugs is most harmful during the first trimester

Teratogenic drugs may lead to fetal malformation or miscarriage



Pregnant Women (cont’d)Pregnant Women (cont’d)

Third trimesterThird trimester Drugs may not be safely metabolized and

excreted by the fetus

After deliveryAfter delivery Infants no longer have the placenta to help with

drug excretion, and drugs given before delivery may cause toxicity



Pregnant Women (cont’d)Pregnant Women (cont’d)

For pregnant women who require medication, both mother and fetus must be considered

Weigh risks and benefits

Rule of thumb:

LOWEST EFFECTIVE DOSE

for the

SHORTEST PERIOD OF TIME



LactationLactation

Many drugs are known or thought to be excreted in breast milk

Dose in breast milk will be low, but still may cause adverse effects in the infant

Some drugs interfere with milk supply

American Academy of Pediatrics (AAP) lists drugs usually compatible with breastfeeding: http://pediatrics.aappublications.org



Lactation (cont’d)Lactation (cont’d)

AAP encourages breastfeeding if drug is unlikely to cause harm

In poorer nations, bottle feeding may not be an alternative

Research medication at LactMed: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT



Pediatric ClassificationsPediatric Classifications

Premature Infant: <38 week gestation

Neonate/newborn: Younger than 1 month

Infant: 1 month up to 1 year

Child: 1 year up to 12 years



Pediatrics: Pediatrics: Neonates and PreemiesNeonates and Preemies

Difficulty in dosing is secondary to

Immature function of body systems

Rapid weight changes

Progressive maturation of hepatic and renal function



Pediatric DosingPediatric Dosing

Doses for children are not automatically less than those for adults

Higher metabolic rate in children causes drugs to be processed more quickly

Higher doses are needed to maintain therapeutic blood levels



Pediatric Dosing (cont’d)Pediatric Dosing (cont’d)

Medication doses are based on body weight or body surface area (BSA)

Body weight doses expressed as mg/kgmg/kg

BSA doses expressed as mg/mmg/m22



GeriatricsGeriatrics Physiological changes of people 65 and older affect the

action of many drugs

Beers criteria: Drug classes found to increase the risk of adverse effects in older adults. See Davis’ Drug Guide under Medication Safety Tools

Age-related changes affect pharmacokinetics

Absorption: Gastric pH less acidic, gastric emptying slowed, peristalsis slowed, reduction of blood flow in the GI tract



Geriatrics (cont’d)Geriatrics (cont’d) Distribution: Decrease in lean body mass, increase in fat

content, reduction in total body water content, protein-binding sites are reduced caused by aging liver

Metabolism: Aging liver, decrease in liver blood flow causes a decrease in liver metabolism

Excretion: Decreased renal filtration rate due to reduction in blood flow, decrease in amount of nephrons

Aging changes lead to greater incidence of toxicity

Prescribe lowest possible dose at initiation of drug(s)



Geriatrics (cont’d)Geriatrics (cont’d)Monitor for

Signs and symptoms of toxicity and side effects

Drug interactions

Usage and complications of OTCs and herbal drugs

Effectiveness



Patients With Renal DiseasePatients With Renal Disease

Kidneys are the major organ of drug elimination

Failure to account for decreased renal function is a preventable source of adverse drug reactions

Assess Creatinine clearance

BUN and creatinine

Medication blood levels



Patients With Liver DiseasePatients With Liver Disease

The liver is the major organ of metabolism

The liver changes drugs from fat soluble to water soluble so that kidneys can excrete them

Liver damage leads to higher levels of active drug and more toxicity



Patients With Liver Disease (cont’d)Patients With Liver Disease (cont’d)

Monitor Liver enzymes Albumin, total protein

Assess patient for Enlarged liver Ascites, jaundice



Obese patients Drug dosing often based on body weight

Some drugs do not penetrate fatty tissues

To prevent toxicity when giving drugs that do not penetrate fatty tissue (e.g., digoxin), determine dose by ideal body weight or estimated lean body mass

Patients With Extremes of Body SizePatients With Extremes of Body Size



Underweight patients likely to be Chronic alcoholics Patients with AIDS

Patients terminally ill with cancer and other debilitating illnesses

Patients with amputations

No standard formula for calculating dose in underweight patients; watch for toxicity

Patients With Extremes of Body Size (cont’d)Patients With Extremes of Body Size (cont’d)

Dosing Considerations for Vulnerable Populations

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