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Drug Action Across the Life Span Chapter 3 Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

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Presentation on theme: "Drug Action Across the Life Span Chapter 3 Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc."— Presentation transcript:

1 Drug Action Across the Life Span Chapter 3 Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

2 Slide 2 Chapter 3 Lesson 3.1 Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

3 Slide 3 Objectives Discuss the effects of patient age on drug action Discuss the role of genetics and its influence on drug action Cite major factors associated with drug absorption, distribution, metabolism, and excretion in the pediatric and geriatric populations Cite major factors associated with drug absorption, distribution, metabolism, and excretion in men and women Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

4 Slide 4 Therapeutic Drug Monitoring Entails measurement of a drug’s concentration in biologic fluids to correlate the dosage administered and the level of medicine in the body with the pharmacologic response Timing of drug’s administration and collection of specimen are crucial to accurate interpretation Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

5 Slide 5 Use of Monitoring Parameters Before administering medicine  Assess expected therapeutic actions, side effects, reportable adverse effects, and probable drug interactions Monitor parameters related to patient’s age  Absorption, distribution, metabolism, and excretion of drugs are different for infants and children Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

6 Slide 6 Use of Monitoring Parameters: Pediatric Patients Infants and young children are more susceptible to dehydration Weight variation affects dosage Aspirin is never administered to children Allergic reactions occur rapidly in children, most commonly to antibiotics Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

7 Slide 7 Use of Monitoring Parameters: Geriatric Patients Drug therapy  Take thorough drug history and nutritional assessment  Determine whether new symptoms have been induced by existing medicines  Gradually taper dosage when discontinuing drug  Start at 1/3 to 1/2 normal dosage when initiating therapy; gradually increase  Review regimen periodically Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

8 Slide 8 Changing Drug Action With Gender Considerations In nearly every body system, men and women function differently Men and women perceive and experience disease differently Pharmacogenetics  Fundamental questions remain about how humans function and the effect of disease on function Polymorphisms  Naturally occurring variations in the structures of genes Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

9 Slide 9 Drug Absorption: Age Considerations Special considerations for pediatric and older adult patients  Differences in muscle mass, blood flow, and inactivity affect medicines given intramuscularly  Topical and transdermal administration differs in the very young and the very old Factors that place older patients at risk  Reduced renal and hepatic function  Polypharmacy – multiple-drug therapy required by chronic illness  A greater likelihood of malnourishment Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

10 Slide 10 Drug Absorption: Age Considerations (cont’d) Gastrointestinal absorption influenced by:  Gastric pH  Gastric emptying time  Enzymatic activity  Blood flow of mucous lining and intestines Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

11 Slide 11 Drug Absorption: Age Considerations for Infants Topical administration in infants is effective because:  Outer layer of skin (stratum corneum) not fully developed  Skin more fully hydrated; plastic diaper increases skin hydration  Inflammation (diaper rash) increases absorption Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

12 Slide 12 Drug Absorption: Age Considerations for Geriatric Patients Difficult to predict in geriatric patients  Dermal thickness decreases with age and may enhance absorption  Drying, wrinkling, and decreased hair follicles decrease absorption  Decreased cardiac output and diminishing tissue perfusion also affect absorption Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

13 Slide 13 Potentially Inappropriate Medications for Geriatric Patients Includes medications that should be avoided and those that are rarely appropriate  Some barbiturates, benzodiazepines, and some narcotics Some are considered appropriate to give only with certain indications but may have potentially adverse reactions Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

14 Slide 14 Drug Absorption: Gender Considerations Increased potential for toxicity and slower absorption times in women  Empty solids more slowly  Have greater gastric acidity  Have lower gastric levels of alcohol dehydrogenase needed to metabolize alcohols Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

15 Slide 15 Drug Distribution Depends on pH, body water concentrations, presence and quantity of fat tissue, protein binding, cardiac output, and regional blood flow Infants have larger volume of water content and require higher dose With age, total body water decreases and fat increases Highly fat-soluble drugs take longer to act and accumulate in fat tissues, increasing potential for toxicity Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

16 Slide 16 Drug Distribution (cont’d) Protein binding  Drugs that are relatively insoluble are transported in circulation by binding to plasma proteins Age considerations  Some drugs have lower protein binding in neonates and require larger loading dose  Albumin levels decrease with age Gender considerations  Some differences between men and women in globulin proteins Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

17 Slide 17 Drug Metabolism Drug metabolism  Process by which the body inactivates medicine  Affected by genes, diet, age  Liver weight and hepatic blood flow decrease with age Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

18 Slide 18 Drug Excretion Metabolites of drugs (and sometimes the drug itself) eventually excreted Preterm infant has 15% of adult renal capacity; fully functional by 9 to 12 months Decreased renal function with age No prediction of renal function can be based solely on age because of wide individual variation in changes Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

19 Slide 19 Use of Monitoring Parameters: Pregnant Women Avoid drugs if at all possible When taking woman’s history, be alert to possibility of pregnancy Instruct patient to avoid drugs, alcohol, and tobacco Try nonpharmacologic treatments before using medicines Avoid herbal medicines Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

20 Slide 20 Drugs Known to be Teratogenic Drug classifications known to be teratogenic  Androgenic and estrogenic hormones  ACE inhibitors, ethanol, tetracycline  Thalidomide, vitamin A, warfarin  Angiotension II receptor antagonists  Anticonvulsants, antimanic agent, antithyroid  Chemotherapy, statins, cocaine Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

21 Slide 21 Use of Monitoring Parameters: Breast-Feeding Infants Some drugs are known to enter breast milk and harm the nursing infant Discuss all medications with physician Take medicine immediately after breast- feeding or just before infant’s longest sleeping period Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.


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