Ch 3-4 Flashcards
Area of pharmacology that focuses on the method for achieving effective drug administration
Biopharmaceutics
Study of drugs in living systems
The branch of medicine concerned with the uses, effects, and modes of action of drugs
Pharmacology
A substance into which a drug is compounded for initial delivery into the body
Drugs are placed into these by the manufacturing process
Ex: any substance that can serve as a mode of transportation of the drug, like food or water
Drug vehicle
3 dosage forms
Solid
Liquid
Gas
Must be capable of releasing its contents so that the drug can be delivered to the site of action
Dosage form
Dosage form used for oral administration
Solid
3 types of solid dosage forms
Tablets
Capsules
Troches
3 things solid dosage forms are composed of
Active ingredient
Filler
Disintegrators/dyes/flavoring agents/outside coating
Active ingredient
Drug
Hold the tablet in shape, gives bulk in manufacturing
Filler
Aid in chemical disintegration when introduced to water or temperature (heat)
Disintegrators
For drug identification
Dye
For palatability
Flavoring
Having a pleasant/tolerable taste
Palatability
For ease of swallowing and protect drug inside
Outside coating
7 types of tablets
Compressed Sugar-coated Film-coated Enteric-coated Multiple-compressed Effervescent Buccal or sublingual
Compacted tablet, no special coating
Degraded by the environment
Ex: Tylenol
Compressed tablet
Table with a thin layer of sugar coating, will look glossy
Masks bad tastes
Protects active ingredient from environment
Ex: some anti-inflammatory medicines (like Advil)
Sugar-coated tablet
Tablet with a thin coating of material other than sugar
Serves the same function as sugar coating but is less expensive to the manufacturer
Ex: Metformin (medication used for diabetes)
Film-coated tablet
Tablet that passes through the stomach and releases active ingredients in small bowel
Keeps stomach acid from destroying it
Prevents some substances from upsetting the stomach
Ex: Naproxen (treats rheumatoid arthritis)
Enteric-coated tablets
Tablet usually in capsule form Protects against oxidation Palatability Allows for timed or periodic release; dissolves slower in order to be released slower Ex: Morphine
Multiple compressed or controlled release tablet
Being combined chemically with oxygen
Ex: a fresh apple turns brown
Oxidation
Tablets that contain sodium bicarbonate with organic acids: citrate and tartrate
Solid dosages that produce gas
Ex: Alka-Seltzer (disintegrate into an effervescent solution when dropped in water)
Effervescent tablets
Tablets designed to disintegrate in sublingual space (under tongue)
High blood supply and very vascular, fast absorption rate
Sublingual
Tablets designed to disintegrate in the cheek area
Absorbed by vasculature, allows for rapid absorption and drug action
Greater potency (bypasses the liver, stomach and intestines)
Ex: Nitroglycerin (treats chest pain)
Buccal
A soft or hard shell that encloses the active ingredient
Contains the drug in a powder
Masks bad taste
Allows for easier swallowing and controlled/timed release
Capsules
Solid medications designed to dissolve in the mouth
Ex: lozenges/cough drops, some anesthetics
Troches
Solid dosage form that melts by body heat and releases medication into the vasculature
Primarily rectal or vaginal
Ex: enema for constipation, Monistat for yeast infection
Compressed suppositories or inserts
Dosage form used to administer medications by all routes but are usually given orally or parenterally
Fastest absorption rate; travels through the body and has the largest surface area for it to be absorbed
Liquid dosage form
5 liquid dosage forms
Orally Rectally Vaginally Transdermally Parenterally
Medication given across the skin, ex: nicotine/pain patch
Transdermally
Any route other than the digestive system
Parenterally
Under the skin, ex: insulin injection
Low blood supply, slow absorption rate
Subcutaneous
Within the skin, ex: TB test
Intradermal
Within a sheath, ex: sheath of the spinal cord
Intrathecal
Into the brain, ex: to treat meningitis (bacterial infection of membranes of spine/brain
Intracisternal
Into the muscle, ex: in the tricep or quadriceps (Diazepam for anxiety)
Intramuscular
Into a vein, ex: contrast used in x-ray
Intravenous
Into an artery, ex: chemo drugs
Intra-arterial
7 parenteral routes
Subcutaneous Intradermal Intrathecal Intracisternal Intramuscular Intravenous Intra-arterial
3 vehicle forms for parenteral drugs
Solution
Suspension
Emulsion
Drug is dissolved in water or saline, ex: IV contrast (can’t see particles because they’re dissolved)
Solution
Undissolved (liquid or solid) drug particles suspended in a suitable liquid medium, will be thicker
Ex: barium
Suspension
A mixture of two liquids, one suspends in the other
Ex: oil in water
Emulsion
Dosage form used in oxygen therapy and aerosol inhalers that contain liquid medication dispersed in a gas propellant (ex: albuterol- a bronchodilator that treats asthma)
Almost all of these use lungs as entry site into body
Gas dosage form
Generally considered the beginning of the pharmacokinetic phase, how the drug moves
Disintegration and dissolution
A process of how a drug is absorbed, distributed, metabolized (biotransformation), and eliminated/excreted
Pharmacokinetics
Progress of a drug from the time it’s administered through the time it passes to the tissues, until it becomes available for use by the body
Absorbed
Process by which the drug is delivered to the tissues and fluids of the body
As soon as a drug is absorbed into the bloodstream, it’s this throughout the body by the circulatory system
Distributed
The body’s ability to change a drug from its dosage form to a more water-soluble form that can later be excreted
Chemical alteration of a substance, especially of a drug, within the body, as by the action of enzymes
The drug is chemically inactivated by being converted into a water soluble compound (metabolite) and excreted from the body
Form of the drug elimination process
May lead to toxicity if delayed
Metabolism/biotransformation
Elimination of the drug from the body
Eliminated/excretion
2 factors of absorption
Surface area
Blood flow
What medication has the slowest absorption rate?
Enteric coated tablets
A large surface area allows for _________ absorption than a smaller area
Better
More blood flow, _______ absorption
More
Narrowing due to excessive plaque buildup
Stenosis
The amount of a substance that will dissolve in a given amount of another substance
The more of this the drug, the more rapidly it will be absorbed
Solubility
Fat solubility, how well the drug “likes” fat
Human cells have a double layer of fats (lipids) that a drug must cross in order to be absorbed
Drugs with good lipid solubility (dissolve) will easily cross this membrane
Lipophilicity
An increase in the strength of a fluid by evaporation
Concentration
Movement of molecules from areas of high concentration to areas of low concentration in the cell membrane (wants equilibrium)
Does not require energy or work of the molecules
Most common
Passive diffusion
Contains a carrier protein to which a drug attaches
Protein gives drug a “piggyback ride”
Movement of molecules from low to high concentration in the cell membrane
Sometimes a cell has to work and use some energy to maintain a proper balance of ions and molecules
Active transport
A substance that yields hydrogen ions
Acids
A substance that can accept hydrogen ions
Bases
A neutrally charged (non-ionized) particle crosses a cell membrane ________ than does a charged (ionized) particle
Better
A weak acid crosses barriers _______ when in an acid medium
Ex: aspirin is a weak acid, when it arrives in the stomach, it enters an acidic environment, the acidic aspirin is in an acidic environment which makes it non-ionized or neutrally charged, this creates an easy pathway through the membrane for the drug to enter the blood. Once absorbed, aspirin is in the bloodstream, it is in the base (alkaline) environment; it becomes ionized and cannot cross the cell membrane back into the stomach
Best
Some drugs interact with other chemicals to form insoluble (undissolved) precipitates; in turn, absorption is significantly decreased
Ex: barium (undissolved suspension) is toxic IV but ok for oral GI; not absorbed by intestinal membrane, you will pass it
Compatibility
Settling or particles in solution
Precipitate
3 factors that affect drug distribution
Cardiac output
Regional blood flow
Drug reservoirs (drug pooling)
The amount of blood pumped by the heart each minute
Cardiac output
The amount of blood supplies to a specific organ or tissue (vascular)
Regional blood flow
Storage reservoirs that allow a drug to accumulate by binding to specific tissues in the body, like plasma, fat, or bone
Drug reservoirs (drug pooling)
2 barriers to the distribution of drugs
Blood-brain barrier
Placental barrier
A filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances
Blood-brain barrier
5 things that can break down the blood-brain barrier
Hypertension (high blood pressure opens it)
Development (not fully formed at birth)
Radiation (opens it)
Infection (exposure to infectious agents opens it)
Trauma, ischemia, inflammation, pressure (injury to the brain)
Which organ’s primary function is metabolism?
Liver
Exchange between mother and fetus
Placental barrier
Which organ’s primary function is excretion?
The kidneys filter the blood and remove unbound water-soluble compounds
3 other ways drugs can be excreted besides the kidneys
Intestine: feces
Respiratory system: gases, breathing
Breast milk, saliva, sweat
Refers to drugs
Pharmaco
Refers to what happens when two things meet and interact
Dynamics
The study of how the effects of a drug are manifested
Pharmacodynamics
Refers to treatment or therapy
Therapeutics
The use of drugs to prevent and treat diseases
Pharmacotherapeutics
Used for those who are symptomatically ill and require therapy to correct an underlying condition
Acute therapy
Based on practical experience rather than on pure scientific data
When a drug is primarily used for one thing, but it is found to help with another symptom
Empiric therapy
Used to treat chronic conditions that can’t be cured (like RA)
Maintenance therapy
Replenish or substitute missing substances such as hormones in the body
Supplemental/replacement therapy
Doesn’t effectively treat the cause of the disease but goal is to help the patient’s well being
Supportive therapy
Used to treat end stage or terminal diseases to make the patient as comfortable as possible
Palliative therapy
Method by which a drug responds to its effects
Most compounds involve a chemical interaction between the drug and a functionally important component of a living system
Mechanism of action
A specialized location on a cell membrane or inside a cell
Specific biologic sites located on a cell surface or within a cell
Like keyholes for specific drugs
Receptors
3 affinities/attractions drugs have for their specific receptors
Agonist
Antagonist
Mixed agonist/antagonist
Drug or natural substance that combines with receptors and initiates a series of biochemical and physiological changes
It simply stimulates or enhances the body’s natural response to stimulation
Ex: given epinephrine for someone with asthma like symptoms, this is a bronchodilator, no new function was developed only enhanced to make the person be able to breath properly again
Agonist
Drug ability is able to produce a response
Intrinsic activity
Block receptors
Doesn’t stimulate the receptor
It will inhibit or counteract effects produced by other drugs or undesired effects
Antagonist
Ant-
Against
A substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction
Enzyme
The increase in the rate of a chemical reaction due to the participation of an additional substance
Catalysis
Some ointments or skin creams may physically block underlying tissues from the outside environment; like a barrier
Nonspecific drug interactions
The degree to which a drug is able to produce a desired effect
Ex: if drug A reduces pain from severe to moderate and drug B reduces pain from severe to none at all, drug B has more of this; basically how well it works, Drug B works better
Efficacy
The relative concentration of that drug required to produce the desired effect
Ex: if both drug A and drug B provide total pain relief but drug A requires 2000mg and drug B requires 500mg, drug B is more potent because it only took a small amount to produce the same effect
Basically how much it takes to produce a desired effect
Potency
Interval between the time a drug is administered and the first sign of its effects
Onset of action
Period from onset of drug action to the time when response is no longer perceptible (up to peak and down)
Duration of action
Reached when the absorption rate equals the elimination rate
Peak concentration
Point at which a drug effect is no longer seen
Termination of action
When drug is given
Administration of drug
Process of a drug from the time its administered through the time it passes to the tissues, until if becomes available for use by the body
Absorption
Highest plasma concentration attained from a dose
Peak serum concentration
Produces toxic effect
Ex: given too high of a dose
Toxic level
Lowest plasma concentration that produces the desired drug effect
Minimal effective concentration
A ratio that compares the blood concentration at which a drug becomes toxic (or its adverse effect potential) and the concentration at which the drug is effective
Ratio between lethal and effective dose
If it takes a lethal dose to obtain a therapeutic effect, you may kill your patient at the same time you are trying to cure them
Therapeutic index
The dose at which a drug is lethal to 50% of the population
Lethal dose
The dose required to produce a therapeutic effect in 50% of the population
Effective dose
What is the therapeutic index ratio?
TI= LD50/ED50
The closer the ratio to 1, the greater the danger involved in administering the drug to humans. The larger the therapeutic index, the safer the drug
Time required for 50% of the drug to be eliminated
Dosage amount generally won’t change this
Half life/half life of elimination
2 things the half life is determined by
Rate of biotransformation (metabolism)
Excretion
What is the half life of radiographic contrast?
6 hours
Drugs can react in the body to produce unpredictable and harmful responses
No drug is totally safe and absolutely free of toxic effects
This is the reason for warning labels
May require a lower dosage
Any unwanted effect
Adverse effects
Predictable actions, other than the intended actions of the drug; can be good or bad
Ex: Benadryl causes drowsiness; IVP dye can cause flush feeling, sensation to urinate, metallic taste
Side effects
Directly related to the dose
The higher the dose, the greater these effects
A normal dose may become this if metabolism or elimination is impaired, for instance if your patient only has one kidney, because it can’t filter as fast or an impairment to the liver
Toxicity
4 adverse effects
Side effects
Toxicity
Allergic reactions
Iatrogenic effects
Results from an immune-mediated response by the body against the drug and is not necessarily related to dose
Absolutely no drugs are completely safe
Allergic reactions
3 adverse response variables
Age (children and elderly are highly responsive to drugs; infants have immature hepatic and renal system and elderly have deteriorated hepatic/renal function) Body mass (the relationship between body mass and drug amount influences the distribution and concentration of the drug) Time of administration (some drugs are absorbed better by empty stomach while others are irritating to the stomach and need to be taken with food or water)
Of or relating to illness caused by medical examination or treatment
A new medical problem has cropped up as a result of the actions of the medical provider
Example: a patient becomes infected because a doctor or nurse didn’t wash his/her hands after touching a previous patient
Iatrogenic effects
Occurs when the effects of one drug are modified by prior or concurrent administration of another drug
These interactions may either be positive or negative
Ex: positive = probenecid (used to treat gout) prolongs the action of penicillin and can help some antibiotics work better; negative = receiving IV contrast while on Glucophage can damage kidneys
Drug-drug interactions
Two drugs act together to give a pharmacologic response that is greater than the additive response expected
The combined effect is greater than either drug can produce when taken alone
Synergism
When two drugs with different chemical composition are placed together, they may chemically destroy their activity
Basically the drug for either may not work at all
Chemical incompatibility
5 types of drug orders
Standard written orders Single orders Stat orders Standing orders Verbal orders
Orders written by the health care provider
Standard written orders
Orders written for a medication given only once
Single orders
Orders that must be done immediately with a quick diagnosis
Stat orders
Orders to establish guidelines for treatment, like a lab draw every six months
Standing orders
Medication orders that are given orally
Verbal orders
