Pharmacologic Principles Flashcards
A Drug
Any chemical that affects the physiologic process of a living organsim
Pharmacology
- the study or science of drugs
- what do thee chemicals we call drugs do to us and what do we do to these chemicals we call drugs-
Pharmaceutics
how dosage forms influence pharmacokinetics and pharmacodynamics
Pharmacokinetics
what the body does to the drug
Pharmacodynamics
What the drug does to the body
Pharmacotherapeutics
the more clinically focused arm of pharmacology. the study of drug actions when implementing drug therapy on specific clinical indications to prevent and treat disease
Toxicology
seeks to study the adverse effects of drugs on living organisms
Pharmacognosy
the study of natural drug sources (both plant and animal)
Classifying drugs:
- can be classified by — actions
- can be classified by its — action
- therapeutic actions (what is being treated) - antihypertensives, analgesics
- chemical action on the body’s physiology (pharmacological classification) - cholinergics, adrenergics, narcotics
Chemical names:
describes the drug’s chemical composition and molecular structure (4-hydroxyacetynalide)
Generic name (non-proprietary names)
Describes the chemical substance of pharmacological property of the drug (acetaminophen)
Trade name (proprietary name)
Tylenol
Clues to Pharmacologic Class
- generic names of drugs in the same pharmacologic class often have the same suffix.
ex. beta-blockers, antihypertensives, end in -olol
Benzodiazepines
-epam (diazepam)
5-HT3 antagonists (nausea)
- setron (ondansetron)
HMG-CoA reductase inhibitors (cholesterol lowering)
- statin (rosuvastatin)
Monoclonal antibodies
-mab (rituximab)
ACE inhibitors
-pril (quinapril)
ARBS
- artan (losartan)
Corticosteroid
- sone (cortisone)
Proton pump inhibitors
-prazole (omeprazole)
Antifungals
-azole (clotrimazole)
Calcium channel blockers
- dipine (nifedipine)
Low molecular weight anticoagulant
-parin (tinzaparin)
Similar Attributes of Drugs in a pharmacologic class (5)
- indications
- mechanisms of action
- contraindications and precautions
- interactions
- adverse reactions and effects
Differences between drugs in a pharmacological class
- dosage and potency (first, second, third or more generation of drugs)
- time action profile
- availability
Summary: Drugs can be classified as: (6)
- Their action on a symptom/sign/condition
(Antihypertensives, Antiemetics, Anticoagulants) - Their action on a body system (drugs that affect the CNS, the Respiratory, the GI, the Endocrine systems)
- Their chemical nature (benzodiazepines, dopaminergics, glycosides, nitrates/nitrites)
- Their chemical action within the body (alpha blockers, beta blockers, opiods, vasodilators, bronchodilators)
- Their prescription category or OTC availability
- Their clinical considerations (administration concerns)
Absorption
the movement of a substance from its site of administration across body membranes to circulating fluids
Distribution
the transportation and holding areas of the drug in the body until it reaches its site of action
- the transport of a drug in the body by the bloodstream to its site of action
Metabolism
biological transformation (biotransformation) chemically converting a drug to a form that is more easily removed from the body
Excretion
How is the drug removed from the ody
Factors that increase or decrease the absorption of a drug
- route of administration
- dosage: larger dose, increased rate of absorption and sooner therapeutic effect
- digestive motility
- blood flow
why would you not crush an enteric coated pill? (3)
- the enteric coating protects it from the gastric juices when it needs to be absorbed in the small intestine
- some can damage the stomach lining and cause nausea and vomiting
- medication that is ionized will not be well absorbed
Greatest barrier to drugs reaching their target cells is…
crossing the membranes. Are thy lipid soluble, water soluble, ionized, polarized?
Hepatic First-Pass Effect
A drug given via the oral route may be extensively metabolized by the liver before reaching the systemic circulation (= high first-pass effect) and its target organ
- the same drug - given parenterally bypasses the liver, preventing the first-pass effect from taking place, and more drugs get into the general circulation and reach its target organ
Parenteral (first pass or not)
no first-pass effect
Topical
no first-pass effect
Mucosal
no first-pass effect
Enteral
yes, first-pass effect
What factors would affect the distribution of a drug?
- poor circulation
- lipid-solubility
Blood Flow: areas of rapid distribution and areas of slower distribution and slowest distribution
- highly vascularized, or sites with large blood volume (heart, kidneys, brain) = rapid distribution
- less vascularized, less blood volume (muscle, skin) = slower distribution
- least vascularized, lease blood volume (bone, fat) = slowest distribution
Lipophilic Drugs
readily cross cell membrane. nonionized. nonpolar. distributed easily
Water soluble drugs
only cross a cell membrane by active transport. charged and polar.
Tissue Storage
- some meds have an affinity with bones, or tissues, and will stick around for longer.
Protein Binding- affects distribution
- Not all drugs’ molecules in plasma will reach their target cells as they become bound to plasma protein especially albumin to form drug-protein complexes
- Drugs bound to proteins will circulate in plasma until they are released or displaces
- A drug can only be freely distributed to extravascular tissues if it is not bound to protein thus it is not available for distribution
- Drug-drug interaction is when two drugs are administered that both are protein binding drugs, each will compete for albumin sites and the result will be difficult to predict and manage
Blood-Brain Barrier
- prevents just anything from going up and effecting the brain
- anti-anxiety meds can, anticonvulsants
Fetal-Placental Barrier
- alcohol, cocaine, and caffeine can cross this barrier and can effect the fetus
Metabolism
the biological transformation of a drug into:
- an inactive metabolite (which will be stored or excreted)
- a more soluble compound which will be more readily be excreted
- more potent metabolite which may be excreted or may be distributed to the target organ site
Age and liver damage can influence drug metabolism
- if the liver is not functioning properly we want to decrease the number of medications
Diagnostics of a poorly functioning liver:
- jaundice
- LFT (liver function test)
- serum albumin test
Liver failure can lead to… (3)
- accumulation of drugs in the body, possibly to lethal levels
- prolonged action of the drugs on the target organ
- increased drug metabolism causes - diminished pharmacologic effects because it is being broken down to quickly
Where does elimination of drugs from the body take place? (5)
- kidneys in urine
- lungs in exhalation
- breast milk
- saliva
- feces
Slow vs Fast Acetylators
- certain ethnic groups are fast and certain are slow
- “Acetylators” - refers to rate of sulfamethazine acetylation (a necessary metabolic step in breaking down sulfa drugs and some common meds)
- slow acetylators have increased free drug available for longer.
- fast acetylators will clear a drug before it reaches therapeutic level.
- Isoniazid (TB) monitor in slow acetylators
small to moderate changes in renal status can cause rapid changes in…
serum drug levels
What Should RN monitor regarding kidney function?
- Blood tests for kidney function (GFR <60, high creatinine level) - NSAIDs can have an impact on kidney function
pH
- certain drugs may be excreted more quickly if the pH of the filtrate changes. nurses need to be aware of foods that alter pH since they may affect the excretion and duration of action of certain meds.
- non-ionized and lipid soluble drugs cross renal tubular membranes easily and return to circulation.
- ionized and water-soluble drugs are easily filtered out and excreted
What to do about overdose of ASA
- administer sodium bicarb which makes the urine more basic, ionizing the ASA and excreting it more readily
Onset
when the medication begins to take effect. Oral med: 20-30 min. Sustained or extended release can take much longer or enteric coated.
Peak
the highest concentration of the medication in the blood. As much as possible has been absorbed.
Duration
how long the drug is in therapeutic range. From onset of action to termination of action.
half-life
the time it takes for one half of the original amount of the drug in the body to be removed or eliminated.
- a measure of the rate at which the drugs are removed from the body.
which med would you give more frequently? one with a short-half life or on with a long half life?
- short half life. because it is being eliminated from the body more frequently. it works for a shorter amount of time.
Steady State
- levels of a drug when the amount of the drug eliminated is equal to the amount of the drug administered with each drug. The body has reached a certain amount of saturation. Maintaining steady therapeutic level.
- takes about 4-5 half lives.
- consistent levels of the drug in the body to achieve the desired therapeutic effect
- longer half-life means it will take longer to achieve this
Loading Dose
- trying to achieve a therapeutic level of a drug really quickly
- larger dose, once or twice to achieve therapeutic dose in blood stream.
