WEEK 1 Flashcards
What is pharmacology?
The study of drugs and their interactions w/ living systems
What is clinical pharmacology?
The study of drugs in humans
What is Therapeutics( Pharmacotherapeutics)?
Use of drugs to diagnose, prevent, or treat disease or prevent pregnancy; the
medical use of drugs
What are the most important properties of a drug?
- Effectiveness(MOST IMPORTANT)
- Safety( risk-benefit ration)
- Selectivity( only does what you want it to do)
What are some desirable properties of a drug?
- Reversible action
- Predictability
- Ease of administration
- Freedom from drug interactions
- Low cost
- Chemical stability
- Possession of simple generic name
What is the objective of drug therapy?
Provide maximum benefit w/ minimal harm
What determines the strength of a drug response?
- Dosage of medication
- Route medication is given
- Timing in b/w doses
- Unique patient individual differences
- Pharmacokinetics(ADME) ( Movement of the drug through the body)
- Pharmacodynamics( Effects of the drug on the body)
What are the 6 rights of medication?
- Right drug
- Right patient
- Right dose
- Right route
- Right time
- Right documentation
Additional considerations
- Right assessment
- Right evaluation
- Right to education
- Right to refusal
What is the Nurse’s Role in Pharmacology?
- Appropriate assessment before, during and after administering the drug
- Evaluating the safety of the drug for this unique client
- Minimizing and evaluating adverse effects
- Educating the client and/ or family
What is pharmacokinetics?
Movement of a drug thought the body
What are the 4 phases of pharmacokinetics?
ADME= NCLEX Trick: “Add Me”)
Absorption
Distribution
Metabolism
Excretion
What is absorption in pharmacokinetics?
Movement of drug from the site of administration to the bloodstream
What factors affect absorption of a drug?
- Rate of dissolution
- Surface area: better absorption in the small intestine
- Blood Flow: inc BF= inc absorption
- Lipid solubility
- Ion trapping
What are some routes of administration of drugs?
- Intravenous( IV- Parenteral)
Fastest Route of Absorption
Skips the stomach and liver - Intramuscular (IM- Parenteral)/
Subcutaneous(SubQ- Parenteral)
Faster Route of Administartion= due to greater supply of blood vessels than skin (the subcutaneous route is slower) - Oral(PO- Enteral)
Slowest Route of Absportion(First Pass Metabolism) - Subcutaneous medications
Slower Absoption= can be over 24 hours - Sublingual
Faster than Oral(PO) medications
Skips stomach and liver - Inhaled medications
Faster Route of Absorption
Skips the stomach, liver, veins, and initial cardiac circulation - Rectal medications
Faster Route of Absorption
Skips about 2/3 of the First Pass Metabolism and will reach the circulation w/ less compromise to the medication concentration
What are some Oral Preperations?
- Tablets
Made from powdered drugs that have been compressed or molded into solid shapes - Enteric- Coated
Protects the drug from being inactivated in the stomach. It also reduces the chance that the drug will irritate the gastric mucosa. - Sustained Release
Drugs w/ coating that dissolves at different rates. Reduces # of daily does but the higher cost and more variability in absorption
What is distribution in pharmacokinetics?
- Medication materials that have been absorbed and make their way into the targeted organs or various body compartments
- Movement of drugs through the body
What influencers affect distribution?
- Solubility of the medication
Different medications have different solubility making it difficult to get medication where it is intended - Protein binding
Some medications must be attached to a protein for the medication to be delivered to the body - Blood Flow
A decrease in cardiac output can greatly affect getting the medication to the intended location. Need to address the lack of volume prior to medication administration
What is Metabolism in pharmacokinetics?
- Enzymatic alteration of drug structure
- Mainly takes place in the liver and is a Two-Step Process
- The two-step process is
Activation= medication can work in the body
If the mediation doesn’t activate it will not work
Excretion= removing the medication from the body
If the medication doesn’t work it cannot be excreted causing an inc in the medication through the system
What is Excretion in pharmacokinetics?
- How the medication is removed from the system
- It can be done in two ways
Hepatobiliary System
*Metabolizes in the liver< Excretaes medication into the bile< Removed via the stool
Kidney System - Filters inside the glomerulus< Nephron< Collecting duct< removed via the urine
What influencers affect excretion?
- Low Glomerular Filtration Rate(GFR)
GFR estimates how much blood passes through the glomeruli each minute. Glomeruli have tiny filters in the kidneys that filter waste from the blood
If the glomeruli are not filtering blood< kidneys are not functioning appropriately< less excretion of the medication
- Damage to the liver
If the liver is not functioning appropriately< less excretion of medication
How do we compensate for the reduction in excretion?
Decrease the dose or decrease dose frequency to avoid toxicity
What influencers affect excreation?
- Concentration of medication in the plasma
The higher the medication accumulation the faster the system will clear(excrete) the medication - Glomerular Filtrationn Rate(GFR)
If the glomeruli are not filtering blood< kidneys are not functioning appropriately< less excretion of the medication
What is Medication Clearance?
The pharmacokinetic measurement of the volume of plasma from which a substance is completely removed.
Timing of Medication Clearance?
- Half-Life: length of time required for the concentration of medication to decrease to half of its starting does in the body
Metabolize and excrete half the medication - Longer half-life requires less medication
*Shorter half-life requires more medication - Onset: duration of time it takes for medication effects to become effective
- Peak: when the concentration of the medication is at its highest and strongest effect
- Duration: length of time the medication is effective
What are the four effects of medication administration?
- Therapeutic Effects
Expected response for the medication
*Pain medication should reduce pain - Side Effects
Predictable effects from the medication
*Most common side effect is nausea - Adverse Effect
Negative effects related to a severe response to a medication
*Cushing’s syndrome from prednisone administration - Toxic Effect
Excessive amount of medication in the system
Long-term intake of medication that accumulates in the system either through excessive ingestion or damaged system
*Important to know the medications half-life to decrease toxic effects
What is pharmacodynamics?
The effect drugs have on the body
What is the diference b/w pharmacokinetics and pharmacodynamics?
Pharmacokinetics: the study of how our bodies affect a drug
Pharmacodynamics: the study of how a drug affects our bodies
What happens when we give a drug to a patient ?
Drug< administered to patient< arrives at site of action< produces an effect
How do most drugs work?
By binding to a receptor (chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems).
Tue or False: Each drug has an affinity for its receptor?
True
What do Dose- Response relationships help determine?
- They help determine the minimum amount of drug needed to cause response
- The max response the drug can cause
- How much to increase the dosage to reach a desired response
What is maximal efficacy?
- Largest effect that a drug can produce
- Larger efficacy is not always desired- match the efficacy to patient’s need
What is potency?
The amount of drug we must give to elicit an effect
- RARELY AN IMPORTANT characteristic
What are receptors?
- Any functional macromolecule in a cell to which a drug binds to produce its effects
What is a ligand?
Molecule that bind to a receptor and changes its’ function
Types of receptor families?
- Cell membrane- embedded enzymes: Ligand binding domain on cell surface; enzymes catalytic site indie. Insulin
- Ligand- gated ion channels: Regulates flow of ions, specific to an ion, direction of flow determined by concentration gradient. Very rapid response.
- G protein-couple system: Receptor, G protein, effector
- Transcription factors; Found within the cell, delayed response. regulates protein synthesis.
How to achieve selectivity?
- Ideal drugs will interact with only one type of receptor
- Selectivity does not equal safety
What is simple occupancy theory?
- Simple theory assumes that all drugs affecting a receptor are identical in ability to bind and influence the receptor.
What is affinity?
Strength of attraction b/w the drug and receptor
What is intrinsic activity?
Ability of the drug to activate the receptor once bound
- This is reflected in maximal efficacy
What are agonists?
- Molecules that mimic endogenous molecules and activate receptors
- Has both affinity and high intrinsic activity
What are antagonist?
- Molecules that produce their effects by preventing receptor activation by endogenous molecules
- Affinity but no intrinsic activity- prevents activation by agonists
- Two types:
Noncompetitive: Bind irreversibly
Competitive: Bind reversibly - Respond is relative to amount of agonist present
Receptor Sensitivity
Desensitization: When a receptor is repeatedly exposed, may down-regulate, decrease in # or modification of receptor
Hypersensitization: When exposed to antagonists, may up-regulate- synthesize more receptors
What is ED50?
Average effective dose: the dose that is required to produce a defined therapeutic response in 50% of the population
- Helps determine standard dose
What is Therapeutic Index(TI)?
- Measure of drug’s safety
- The higher the TI, the safer the drug
How do Drug-Drug Interactions happen?
- Direct chemical or physical interactions
- Pharmacokinetic interactions
- Pharmacodynamic interactions
- Combined toxicity
- The more drugs a patient is taking, the higher the risk of interactions
What are some Drug- Food Interactions?
- A drug may have an inc or dec absorption in the presence of food
- Grapefruit juice
- Drug- food toxicity: Compounds in certain foods can increase the toxicity of some drugs
- Components of foods can have an effect on drug action
- To administer a drug on an empty stomach means to administer it at least 1 hr before or 2 hours after a meal
Adverse Drug Reactions Definitions
Side Effect
Toxicity
Allergic reactions
Idiosyncratic effect:
Paradoxical effect:
Iatrogenic disease
Physical dependence
Carcinogenic effect
Teratogenic effect
Side effect: Nearly unavoidable secondary drug effect produced that therapeutic doses.
Predictable and dose-dependent
Toxicity: The degree of detrimental physiologic effects caused by excessive drug dosing
Allergic reaction: Immune response; must be prior sensitization. Largely independent of dosage.
Idiosyncratic effect: Uncommon response due to genetic predisposition
Paradoxical effect: Opposite of intended response
Iatrogenic disease: Disease produced by drugs or treatment
Physical dependence: Abrupt withdrawal causes harm or symptoms
Carcinogenic effect: Ability to cause cancers
Teratogenic effect: Ability to cause birth defects
What are Hepatoxicity?
- Drugs that can cause damage to the liver
- Combinations of hepatotoxic drugs increase risk (Tylenol, ETOH)
- Patients taking hepatotoxic drugs often undergo periodic liver function tests (LFTs)-enzymes
produced by the liver that increase when liver cells are damaged
What are QT Interval Drugs?
- Drugs that prolong the QT interval, risk for arrhythmias
- QT interval is the time required for the ventricles to repolarize after contraction.
- Prolongation can cause fatal ventricular fibrillation
- Women at increased risk because QT interval longer at baseline
What should your patient know in regards to medication?
- Name of drug and indication
- How should take the drug?
◦Include dosage, timing, information about overdose and missed dose - What should the patient avoid?
◦Activities, other medications, pregnancy, breast feeding - What are the most common side effects?
- Information about safety and efficacy
Types of Medication Errors
Wrong patient
Wrong drug
Wrong route
Wrong time
Wrong dose
Omitted dose
Wrong dosage form
Wrong diluent
Wrong strength/concentration
Wrong infusion rate
Wrong technique
Deteriorated drug
Wrong duration of treatment
What affects drug response?
- Body weight and composition
◦Body surface area vs. weight - Age
◦Significant variability with age
◦Infants and older patients especially sensitive to drugs
◦Infants: Organ immaturity
◦Older patients: Organ degeneration
◦Due to increased severity of illness, multiple pathologies, treatment with multiple drugs - Pathophysiology
Kidney disease
◦Reduced excretion and increased toxicity
◦ Liver disease
◦Reduced metabolism and increased toxicity
◦Acid-base imbalance
◦pH changes that alter absorption, distribution, metabolism, and excretion of drugs
◦Altered electrolyte status
◦Rare for electrolyte changes to have a significant impact on drug responses - Gender
◦Alcohol is metabolized more slowly by women than by men
◦Certain opioid analgesics are much more effective in women than in men
◦Greater QT interval prolongation in women than in men - Race
◦Genetic variations
◦Psychosocial factors - Comorbidities
◦Increased likelihood of drug interactions - Diet
◦Starvation or poor nutritional status can reduce protein binding of drugs
◦Monoamine oxidase inhibitors: Malignant hypertension triggered by foods that contain tyramine
What is Tolerance?
- Decreased responsiveness to a drug as a result of repeated drug administration
- Higher doses required
- Two main types of tolerance
◦Pharmacodynamic tolerance: Due to chronic receptor activation. Minimum effective
concentration increases. Common with opioid analgesics
◦Metabolic tolerance: Increased hepatic enzymes. Minimum effective concentration does NOT
increase
What is a placebo effect?
- Any response that a patient has to a placebo is based solely on his or her psychologic reaction to the idea of taking a medication and not to any direct physiologic or biochemical action of the
placebo itself - Nurses need to present a positive but realistic assessment of the effects of therapy(BFFR)
- Placebos are primarily used for the control groups in clinical trials
Reasons for a patient may fail to take medication as prescribed?
- Manual dexterity( may not be able to use their hands and fingers to open bottles, etc)
- Visual acuity
- Intellectual capacity
- Psychologic state
- Attitude toward drugs
- Ability to pay
- Side effects
