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. |