Chapter 7 Geriatric Pharmacology Flashcards
Geriatric Meds (ADME)
Absorption: Drug absorption in the GI tract is slowed in the older adult due to reduced gastric blood flow, slowed gastric emptying, and a decrease in gastric acid production.
Distribution: Older adults have a decline in muscle mass and increase in fat which means lipid-soluble drugs have a greater volume of distribution, increased drug storage, reduced elimination, and a prolonged period of action. There is also a loss of protein-binding sites for drugs, which causes increased circulation of free drug and increased chance for adverse drug reactions.
Metabolism/Biotransformation: Hepatic blood flow in the older adult is decreased and aging causes a decrease in liver size. Liver dysfunction also causes decreased enzyme function, which decreases the liver’s ability to metabolize and detoxify drugs. To assess liver function, look at liver enzymes; elevated levels indicate possible liver dysfunction.
Excretion: Cardiac output and blood flow are decreased in older adults which affects function of the kidneys and liver. Renal size and volume are also decreased. Kidney function is monitored by these lab values: BUN, creatinine and creatinine clearance. When the efficacy of the hepatic and renal systems is reduced, the half-life of the drug is prolonged and the possibility of drug toxicity increases.
Adverse Reactions: Factors contributing to adverse reactions in older adults include loss of protein binding sites, first pass effect metabolism, and prolonged half-life of the drug because of decreased liver and kidney function.
Med considerations in Geriatric Patients
Hypnotics: Insomnia is a frequent problem in the older adult population. For the older patient, low doses of benzodiazepines with short or intermediate half-lives are usually prescribed. Triazolam (Halcion) is frequently prescribed for the older adult. Lorazepam (Ativan) and oxazepam can be taken for insomnia and have intermediate half-lives and should be taken one hour before bedtime.
Diuretics and Antihypertensives: Diuretics are frequently prescribed for treatment of hypertension or heart failure. For the older adult, the dose is usually reduced because of dose-related side effects. Hydrochlorothiazide is generally prescribed in low doses of 12.5mg/day. Higher doses of 25 mg/day with chronic use may cause electrolyte imbalances. Many older adults are hypertensive. Nonpharmacologic methods such as exercise, reduction in salt intake, and adequate rest are recommended. Calcium blockers, angiotensin-converting-inhibitors (ACE) and A-II blockers are frequently the agent of choice because of their low rate of electrolyte imbalance and CNS side effects.
Cardiac Glycosides: Digoxin (Lanoxin) is commonly prescribed for older adults, however long-term use should be monitored because of digoxin’s narrow therapeutic range (0.5 to 2 ng/mL) and the possibility of digoxin toxicity.
Anticoagulants: Bleeding may occur with chronic use of anticoagulants in older patients. Warfarin (Coumadin) is 99% protein bound with a decrease in serum albumin common in older adults. Therefore, the risk of bleeding is increased. PT/INR should be checked regularly. Also, older adults are more at risk for falls and injury that can cause bleeding.
Antibacterials: Penicillin, cephalosporins, tetracyclines and sulfonamides are considered safe for older adults. If renal clearance is decreased, the drug will have a prolonged half-life and the drug dose should be decreased.
Gastrointestinal Drugs: Histamine (H2) blockers and sucralfate are safer drugs than other antiulcer drugs for the treatment of peptic ulcer disease. Laxatives are frequently used by older adults and fluid and electrolyte imbalances may occur as a result.
Antidepressants: An antidepressant drug dose for older adults is normally 30% to 50% of the dose for young and middle-aged adults.
Opioid Analgesics: Opioids can cause dose-related adverse reactions in older adults.
Nursing Implications :Drug Dosing and Monitoring
Older adults are twice as likely as younger adults to visit the ED with adverse drug events and are seven times more likely to be hospitalized. Most visits and hospitalizations occur due to reactions to blood thinners, drugs used to treat diabetes and seizures, cardiac drugs, and drugs used for pain control.
According to the WHO, ADEs are “unintended and undesired effects of a drug at the normal dose.” There are five types of ADEs…
Older adults have multiple risk factors for ADEs, including frailty, multiple comorbidities, polypharmacy, and cognitive issues.
Adherence
Patient may not fully understand drug regimen.
Nonadherence may cause underdosing.
Nonadherence may cause overdosing.
Barriers to effective drug use by the older adult
Medication education extremely important
Health Teaching With the Older Adult
Have patient’s senses as sharp as possible.
Wearing clean eyeglasses.
Make sure that functional hearing aids are in place.
Speak in tones such that patient can hear.
Face patient when speaking.
Limit distractions.
Treat patient with respect.
Expect that the patient can learn.
Use large print and bright colors in teaching aids.
Review all medications at each visit.
Instruct patient to take the list of all drugs taken to all health appointments.
Encourage a simple dosing schedule.
Consider pill organizers.
