DRUG ACTION: PHARMACEUTIC, PHARMACOKINETIC, AND PHARMACODYNAMIC PHASES Chapter 1 DRUG ACTION: PHARMACEUTIC, PHARMACOKINETIC, AND PHARMACODYNAMIC PHASES

The Two Pharmaceutic Phases Are Disintegration and Dissolution. Nursing Process Pharmaceutic Disintegration and dissolution Refer to Figure 1-1, The Two Pharmaceutic Phases Are Disintegration and Dissolution. The Two Pharmaceutic Phases Are Disintegration and Dissolution. Rate limiting

Pharmacokinetics Absorption Processes of drug absorption Refer to Figure 1-2, The Three Major Processes for Drug Absorption Through the GI Membrane Are Passive Absorption, Active Absorption, and Pinocytosis. The Three Major Processes for Drug Absorption through the Gastrointestinal Membrane Are Passive Absorption, Active Absorption, and Pinocytosis

Pharmacokinetics (cont’d) Absorption Water-soluble and lipid-soluble drugs First-pass effect Bioavailability

Pharmacokinetics (cont’d) Distribution Protein-binding Free drugs Volume of drug distribution (Vd) Refer to Table 1-1, Protein-Binding and Half-Life of Drugs. Refer to Figure 1-3, Drug Distribution. Drug Distribution.

Pharmacokinetics (cont’d) Metabolism (biotransformation) Half-life (t½) Excretion (elimination) Kidneys Creatinine clearance Liver Feces Lungs Refer to Table 1-1, Protein-Binding and Half-Life of Drugs. Refer to Table 1-2, Half-Life of 650 mg of Aspirin.

Pharmacodynamics Dose response and maximal efficacy Onset, peak, and duration of action Refer to Figure 1-4, The Time-Response Curve Evaluates Three Parameters of Drug Action: (1) Onset, (2) Peak, and (3) Duration. The Time-Response Curve Evaluates Three Parameters of Drug Action: They are (1) Onset, (2) Peak, and (3) Duration. MEC, Minimum effective concentration; MTC, minimum toxic concentration.

Pharmacodynamics (cont’d) Receptor theory Agonists and antagonists Refer to Figure 1-5. Two Drug Agonists Attach to the Receptor Site. The drug agonist that has an exact fit is a strong agonist and is more biologically active than the weak agonist. Two Drug Agonists Attach to the Receptor Site. The drug agonist that has an exact fit is a strong agonist and is more biologically active than the weak agonist.

Pharmacodynamics (cont’d) Nonspecific drug effect Refer to Figure 1-6, Cholinergic Receptors In the Bladder, Heart, Blood Vessels, Stomach, Bronchi, and Eyes. Cholinergic Receptors Are Located in the Bladder, Heart, Blood Vessels, Stomach, Bronchi, and Eyes.

Pharmacodynamics (cont’d) Nonselective drug effect Figure 1-7, Epinephrine Affects Three Different Receptors: Alpha1, Beta1, Beta2. Epinephrine Affects Three Different Receptors: Alpha1, Beta1, and Beta2.

Pharmacodynamics (cont’d) Categories of drug action Stimulation or depression Replacement Inhibition or killing of organisms Irritation

Therapeutic Index The Therapeutic Index. It measures the margin of safety of a drug. It is a ratio that measures the effective therapeutic dose and the lethal dose. A Low Therapeutic Index Drug Has a Narrow Margin of Safety. The drug effect should be closely monitored. A high therapeutic index drug has a wide margin of safety and carries less risk of drug toxicity. Refer to Figure 1-8, The Therapeutic Index. It measures the margin of safety of a drug. It is a ratio that measures the effective therapeutic dose and the lethal dose. Refer to Figure 1-9, A. Low Therapeutic Index Drug Has a Narrow Margin of Safety. The drug effect should be closely monitored. B. A high therapeutic index drug has a wide margin of safety and carries less risk of drug toxicity.

Therapeutic Index (cont’d) Therapeutic range (therapeutic window) Peak and trough levels; see Table 1-4 Loading dose Side effects, adverse reactions, and toxic effect Pharmacogenetics Tachyphylaxis Placebo effect Refer to Figure 1-8, The Therapeutic Index. It measures the margin of safety of a drug. It is a ratio that measures the effective therapeutic dose and the lethal dose. Refer to Table 1-4, Aminoglycoside Antibiotics: Peak and Trough Levels.

The Three Phases of Drug Action. Summary The Three Phases of Drug Action. Refer to Figure 1-10, The Three Phases of Drug Action.

Nursing Process Assessment Nursing interventions Cultural considerations Evaluation Refer to Nursing Process.

Determinants That Affect Drug Therapy Refer to Figure 1-11, Determinants That Affect Drug Therapy. Determinants That Affect Drug Therapy

Practice Question #1 A client has liver and kidney disease. He is given a medication with a half-life of 30 hours. The nurse expects the duration of this medication to A. increase. B. decrease. C. remain unchanged. D. dissipate.

Practice Question #1 (cont’d) Answer: A Rationale: Metabolism and elimination affect the half-life of a drug. With liver or kidney dysfunction, the half-life of the drug is prolonged and less drug is metabolized and eliminated.

Practice Question #2 In older adults and those with renal dysfunction, the nurse knows that creatinine clearance is usually A. substantially increased. B. slightly increased. C. decreased. D. in the normal range.

Practice Question #2 (cont’d) Answer: C Rationale: Creatinine clearance is the most accurate test to determine renal function. Creatinine is a metabolic byproduct of muscle that is excreted by the kidneys. Creatinine clearance varies with age and gender. Lower values are expected in older adult and female clients because of their decreased muscle mass. A decrease in renal GFR (common in older adults) results in a decrease in urine creatinine clearance.

NURSING PROCESS AND CLIENT TEACHING Chapter 2 NURSING PROCESS AND CLIENT TEACHING

Nursing Process Assessment Subjective data Current health history Client symptoms Current medications Past health history Client’s environment Primary language and communication needs

Nursing Process (cont’d) Assessment Objective data Physical assessment Laboratory tests Diagnostic studies

Nursing Diagnoses Common nursing diagnoses related to drug therapy Deficient knowledge about drug action, administration, and side effects related to cultural/language barrier Noncompliance related to forgetfulness Ineffective therapeutic regimen management Refer to Box 2-1, Wellness Nursing Diagnoses Grouped According to Functional Health Patterns.

Qualities of Effective Goals Client-centered; clearly states the expected change Acceptable to both client and nurse Realistic and measurable Shared with other health care providers Realistic deadlines Identifies components for evaluation

Planning Characterized by goal setting Example: The client will independently administer prescribed dose of albuterol by the end of the first session of instruction.

Implementation Nursing actions necessary to accomplish the goals Client teaching General Self-administration Diet Side effects Cultural and genetic considerations Refer to Box 2-2, Culturally Sensitive Health Teaching Tips Refer to Box 2-4, Top 10 Tips for Successful Teaching Sessions

Helpful and Healthful Points to Remember Take medication as prescribed by your healthcare provider. If you have questions, call. Keep medication in original labeled container and store as instructed. Keep all medicines out of reach of children. Remind grandparents and visitors to monitor their purses and luggage when visiting. Refer to Box 2-3, Helpful and Healthful Points to Remember

Helpful and Healthful Points to Remember (cont’d) Before using any OTC drugs (including aspirin and laxatives), check with your healthcare provider. Pharmacists are good resources to ask before buying or using a product. Bring all medications with you when you visit the healthcare provider. Refer to Box 2-3, Helpful and Healthful Points to Remember

Helpful and Healthful Points to Remember (cont’d) Know why you are taking each medication and under what circumstances to notify the health care provider. Alcohol may alter the action and absorption of the medication. Use of alcoholic beverages is discouraged around the time you take your medications and is absolutely contraindicated with certain medications. Refer to Box 2-3, Helpful and Healthful Points to Remember

Helpful and Healthful Points to Remember (cont’d) Smoking tobacco alters absorption of some medications Theophylline-type drugs Tranquilizers Antidepressants Pain medications Consult your health care provider or pharmacist for specific information. Refer to Box 2-3, Helpful and Healthful Points to Remember

Checklist for Health Teaching in Drug Therapy Comprehensive drug and health history Reason for medication therapy Expected results Side effects and adverse reactions When to notify health care provider or pharmacist Interactions Drug-drug, drug-food Drug-laboratory Drug-environment interactions Refer to Box 2-5, Checklist for Health Teaching in Drug Therapy

Checklist for Health Teaching in Drug Therapy (cont’d) Required changes in activities of daily living (ADLs) Demonstration of learning methods Listening Discussion Return demonstration of psychomotor skills Insulin administration Medication schedule Associated with ADLs Related drug level of action Refer to Box 2-5, Checklist for Health Teaching in Drug Therapy

Checklist for Health Teaching in Drug Therapy (cont’d) Recording system Discussion and monitoring Financial resources Medication Associated equipment Development and support of backup system Community resources Refer to Box 2-5, Checklist for Health Teaching in Drug Therapy

Evaluation Ongoing and related to progress and goal achievement Related to achievement of goals If not met, reassess and continue Determine need for follow-up Refer to community resources

Practice Question #1 Which of the following is a correctly written goal by the nurse? A. Client will administer the prescribed dose. B. Client will learn to administer insulin. C. Client will know how to take insulin correctly. D. Client will independently administer prescribed dose of insulin at end of 1 hour of instruction.

Practice Question #1 (cont’d) Answer: D Rationale: The goal “Client will independently administer prescribed dose of insulin at end of 1 hour of instruction” meets the following criteria of planning: This goal is client centered, clearly states expected change, is realistic and measurable, has realistic deadlines, and identifies components for evaluation.

Practice Question #2 Which of the following should the nurse expect in the implementation phase of the nursing process? (Select all that apply.) A. Cost of drugs B. Administration technique C. Instructions regarding drug discontinuation D. Foods to avoid when taking a certain drug E. Side effects to report to health care provider

Practice Question #2 (cont’d) Answer: B, C, D, E Rationale: Client teaching should include general information (e.g., instructions for taking drug, importance of compliance, monitoring of laboratory values); self-administration (drug administration, route, appropriate technique); diet (foods to include or avoid in the diet); side effects (which side effects to expect and which to report to HCP); and cultural considerations.