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Pharm 5018 ETSU NP
Ch 2 Basic Principles of pharm
Question | Answer |
---|---|
Independent prescribing or prescriptive authority for APRNS | APRNs to prescribe w/o limitation, legend(prescrip) and control drugs/devices/services. No collaborate with MD. To get a APRN Consensus Model. |
Tennessee licensure and regulatory req. are full, reduced or restricted practice? | Restricted practice: Regulatory Agency: Board of Nsg Licensure Req: RN lic/grad deg/natl cert. Nurse Practice Act |
Who can prescribe? Are controlled substances III-V included? Requirements for controlled substances? Collaborative practice agreement required? | CNP, CNS, CNM, CRNA (key points) Yes DEA # Preauthorization is required for off-formulary medications and for schedule II or III opioid prescriptions of more than 30-day supply. |
Is physician involvement required for NP prescriptive authority? | Yes, medical supervision and mutually-approved formularies for NPs who prescribe are required |
Factors that foster positive outcomes | |
cultural and ethnic influences in pharmacotherapeutics | |
an introduction to pharmacotherapeutics | |
nutrition and nutraceuticals, herbal therapy and nutritional Supplements | |
informational technology and pharmacotherapeutics | |
pharmacoeconomics | |
over-the-counter Medications | |
How are new drugs developed? | 1st - preclinical stage: ID drugs/test in animals on cells, tissues, organs to ID promising compounds |
Phase I clinical trials Phase II clinical trials Phase III clinical trials | have biological effects and safe dosages New drugs treat disease in small number of pts Compare new med to standard therapy in lg number |
pharmacokinetics: Absorption/distribution through body | Absorption Distribution Metabolism Elimination |
Pharmacodynamics: Effect of drugs on the body | Drug-receptor interaction Drug-receptor activity Dose-response relationship Drug potency and efficacy |
Drug-Receptor Interactions | Most drugs work by binding to receptors. Receptors are located on the cell surface. The drug molecule must “fit” into the receptor. Like a lock and key mechanism |
Drug-Receptor Binding | Drug-receptor binding is reversible. Drug-receptor binding is selective. Drug-receptor binding is graded. |
Drug-Receptor Binding | The more receptors filled, the greater the pharmacological response. Drugs that bind to receptors may be agonists, partial agonists, or antagonistic. |
How Drug Dose Is Determined | Dose-response relationship Therapeutic index Plasma level profile Half-life Bioavailability |
Drug-Dose Relationship 1 | Dose-response curve: depicts the relation between drug dose and magnitude of effect Doses below the curve do not produce a pharmacological response. |
Drug-Dose Relationship 2 | Doses above the curve do not produce much additional pharmacological response. May have unwanted effects → toxicity |
Plasma Level Profile | Onset of action: time between administration and first sign of drug effect Peak of action: maximum concentration of drug Point at which amount of drug being absorbed and distributed is equal to amount being metabolized and excreted |
Plasma Level Profile | Duration of action: continued entry of drug into body with levels above minimum effective concentration Termination of action |
Minimum Effective and Minimum Toxic Concentration | Minimum effective concentration (MEC): level below which therapeutic effects will not occur Minimum toxic concentration (MTC): level above which toxic effects begin Therapeutic index or range: MTC to MEC |
Drug Bioavailability | Percentage of drug that is absorbed and available to reach the target tissues By definition, when a medication is administered IV, its bioavailability is 100%. |
Drug Bioavailability | When a medication is administered via other routes (e.g., PO), its bioavailability decreases due to incomplete absorption and first-pass metabolism. |
Therapeutic Blood Level | It usually takes 4 to 5 ½ lives to get to steady state blood levels. Loading dose It takes 4 to 5 ½ lives to totally eliminate a drug from the body. |
Absorption | Definition: movement of a drug from its site of administration into the blood |
Absorption | Variables that influence absorption : Nature of the cell membrane, Blood flow at site of administration, Solubility of drug, pH, Molecular weight, Drug concentration, Dosage form |
Distribution | Definition: movement of absorbed drug in bodily fluids throughout body to target tissues Distribution requires adequate blood supply. Drug distributed to areas of high blood flow first Areas of low blood flow |
Protein Binding | In circulation, drugs are bound to protein. Some drug is not bound and is called free drug. Free drug + Bound drug = Drug-protein complex Dynamic Free drug is active drug. |
Degree of Drug Binding | Drugs exist in bound and unbound states. Travel when bound, cross membranes when unbound “Highly” protein-bound |
Degree of Drug Binding | Ratio of bound drug usually remains stable Low plasma proteins (low albumen) will result in more free drug in circulation. |
Competition for Protein-Binding Sites | Finite number of plasma proteins Compete and displace each other → more free drug Higher risk for toxicity More drug may be eliminated |
Tissue Distribution | Fat: Lipid-soluble fats have a high affinity for adipose tissue. Adipose tissue has low blood flow. |
Tissue Distribution | Bone: Some drugs have affinity for bone. For example, tetracyclines deposit in bones and teeth. |
Tissue Distribution | Blood-brain barrier The blood-brain barrier is relatively impenetrable. Usually protective Only lipid-soluble drugs cross barrier. |
Tissue Distribution | Placental barrier Many drugs pass barrier. Low molecular weight drugs pass easier. |
Metabolism: biotransformation | Definition: chemical change of drug structure to: 1. Enhance excretion/2. Inactivate the drug 3. Increase therapeutic action/ 4. Activate a prodrug 5. Increase or decrease toxicity |
Factors That Influence Metabolism | Age/Genetically determined differences/Pregnancy/Liver disease/Time of day/Environment/Diet/Alcohol/Drug interaction |
Factors That Influence Metabolism | Drugs undergo one or both of two types of chemical reactions in the liver: Phase I: oxidation, hydrolysis, or reduction to increase water solubility of drug molecules Phase II: conjugation or union of drug molecule with water-soluble substance |
Phase I Enzymes: Cytochrome P450 Isoenzymes | The majority of drugs are metabolized in the liver by the hepatic isoenzymes. Cytochrome P450 isoenzymes CYP 450 Most common: 1A2, 2C9, 2C19, 2D6, 3A4 (3A3/4) |
CYP 450 Enzymes | There are developmental differences in the isoenzymes. There are genetic differences in isoenzymes. Some disease states alter isoenzyme activity. For example, cystic fibrosis has altered CYP 2D9 activity. |
Phase I Enzymes: CYP 450 | The enzymes may be slowed (inhibited) or increased (induced). Concurrent therapy with an inhibitor or inducer may alter the metabolism of a medication. |
Prodrug Metabolism | A prodrug is a drug which is administered in an inactive (or significantly less active) form. Once administered, the prodrug is metabolized in the body into the active compound. |
Elimination: excretion | Definition: removal of the drug from the body by organs of elimination Most drugs are eliminated by the kidneys. |
Elimination: excretion | Drugs are also eliminated by Lungs/(GI) tract/Sweat and saliva/Mammary glands (breast milk) |
Renal Elimination | Passive glomerular filtration Active tubular secretion Tubular reabsorption |
Glomerular Filtration | The availability of the drug for glomerular filtration Drug must be unbound from protein Free-, unbound, and water-soluble metabolites are filtered by the glomeruli. |
Factors That Affect Renal Excretion | Kidney function/Age/Hydration/Cardiac output |
GI Tract Excretion | Biliary excretion: After being metabolized in the liver, the metabolite is excreted into the bile. Some drugs may then be reabsorbed in the intestine. Enterohepatic cycle Fecal excretion |
Lung Excretion | Gases General anesthetics and volatile liquids Rate of excretion is based on respiratory rate and pulmonary blood flow. |
Sweat/Salivary Excretion | Not very many drugs Excretion in sweat may be a cause of adverse effects, such as a rash (dermatitis). |
Sweat/Salivary Excretion | Salivary excretion May be the reason patients complain of “taste” in their mouth with certain drugs |
Mammary Excretion | Many drugs are excreted in breast milk. Smaller molecular weight Lipid soluble Breast milk is acidic. |