Life Span Consideration Chapter 7

Drug Absorption Absorption: Process by which a drug is transferred from its site of body entry to circulating body fluids (blood, lymph) for distribution

Drugs applied to the Skin Absorption of drugs applied to the skin (topical) is usually effective in infants Outer layer of skin not fully developed Skin is more fully hydrated Enhanced with plastic-coated diapers Plastic increase hydration of the skin Inflammation of skin also increases the amount of drug absorbed Ex. Diaper Rash Skin absorption in older patient is often hard to predict Drier skin Wrinkled skin Decreased number of hair follicles Decreased cardiac output Decreases the amount of blood flow to tissues

Drugs Given Orally Most drugs are administered orally Some tablets and capsules are too large for children and older patients With permission some tablets can be crushed & mixed with food Some tablets cannot be crushed: Timed-release Enteric-coated Sublingual Liquids can also be ordered

Oral Medications Factors to consider: Teeth: Saliva flow: Do not give chewable tablets to anyone lacking teeth or loose teeth Saliva flow: Lessens with age

Gastrointestinal Absorption GI absorption of drugs is influenced by disease processes other factors including: Gastric pH: Gastric emptying Motility of the GI tract Blood flow

Drug Distribution Distribution: Mode in which drugs are transported by circulating body fluids to the sites of action (receptors) and to the sites of metabolism and excretion. Most drugs are transported: Dissolved in the circulating body water (blood) Bound to plasma proteins with the blood

Drug Metabolism Metabolism: Process by which the body inactivates drugs Enzymes are factors in drug metabolism Enzymes: Substances produced by body cells Enzymes break down glucose and other nutrients to release energy for cellular work. Enzyme systems in the liver provide the major pathway for drug metabolism Liver weight, number of functioning liver cells and liver blood flow decrease with age, therefore metabolism is slower in elderly Other factors that may affect metabolism include: Genetics, smoking, diet, gender, liver disease, other medications

Drug Excretion Excretion: Elimination of a drug from the body Metabolites of drugs, and sometimes the drug itself, are eventually excreted from the body Excreted mainly through urine and feces Minor routes of excretion include: Skin Lungs Saliva Breast Milk

Therapeutic Drug Monitoring Measurement of a drug’s concentration in body fluids Completed in order to determine the drug dosage and the blood level of the drug in relation

Assisting with the Nursing Process Vital signs & urinary output are used to plan dosages and monitor the effects of drug therapy Children: Great risk of complications as bodies & organs are developing Elderly: Great risk for drug interactions and/or drug toxicity Assist through the use of drug organizers, destroying old prescriptions, and breaking/crushing large tablets if allowable Pregnancy / Breast Feeding: Risk of injuring developing fetus