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Pharmacology - Chapter 3

Terms in this set (43)

Effects of drugs can be defined as systemic or local; define both
systemic - reaches widespread areas of the body (ex. Tylenol)
local - limited to area of the body where it is administered (ex. ointments)
Define pharmacokinetics
what happens to a drug as it moves throughout our body
Name the four drug processes
ADME
1. Absorption
2. Distribution
3. Metabolism
4. Excretion
Absorption
Passage of a substance through a membrane into bloodstream (mucosa of stomach, mouth, small intestine, rectum; blood vessels in muscles or subcutaneous tissues; dermal layers)
Distribution
Moving from the bloodstream into the tissues and fluids of the body (circulatory system, through capillaries and across cell membrane)
Metabolism
Physical and chemical alterations that the substance undergoes in body (liver, small intestine)
Excretion
Eliminating waste products of drug metabolism from the body (kidneys, sweat glands, lung or intestines)
Absorption depends on these three factors:
1. pH - acidic drugs in acidic stomach
alkaline drugs in small intestine
2. Lipid (fat) solubility
3. Presence/Absence of food in stomach - empty stomach will facilitate faster absorption, but food may be necessary for drugs that irritate the stomach
Failure to excrete drugs before next dose may result in _____________
cumulative effect
Condition that results from exposure to either a poison or dangerous amount of a dug
toxicity
Range of drug levels in the blood that will give the desired effect without causing side effects
therapeutic range
Drugs that are inactive until they are metabolized by liver
prodrugs
Effects of age on drug action
1. Metabolism and excretion are slower in older adults
2. Children react more rapidly and sometimes unexpectantly
Effects of weight on drug action
In most cases the bigger the person the bigger the dosage. Exception, obese people it may be best in some instances to calculate dosage based on ideal body weight than actual body weight
Effects of gender on drug action
Ratio of fat per body mass differs, as do hormone levels
Effects of psychological state on drug action
The more positive a patient feels about medication the more positive the physical response (placebo effect)
Synergism
The actions of two drugs working together in which one helps the other simultaneously for an effect that neither could produce alone. Drugs that work together are said to be synergistic.
Potentiation
The action of two drugs in which one prolongs or multiples the effect of the other (often used in pain medications)
Antagonism
The opposing action of the two drugs in which one decreases or cancels out the effect of the other drug
Define dosage
Amount of a drug to be given for a particular therapeutic or desired effects
Minimum dose
Smallest amount of a drug that will produce a therapeutic effect
Maximum dose
Largest amount of a drug that will produce a desired effect without producing symptoms of toxicity
Loading dose
Initial high dose (often max dose) used to quickly elevate the level of a drug in the blood (often followed by series of lower maintenance doses)
Maintenance dose
Dose required to keep the level of a drug in the blood at a steady state in order to maintain desired effect
Toxic dose
Amount of drug that will produce harmful side effects or symptoms of poisoning
Therapeutic dose
Dose that is customarily given (average adult dose based on body weight of 150 lb); adjusted according to variations from the norm
Pharmacogenomics
Science that examines how our genes may explain if a drug should work and if it will be toxic to our bodies
Most common routes of drug administration may be grouped into two main categories:
1. Enteral or GI tract routes
2. Parenteral routes
Parenteral routes of administration
1. Sublingual (under tongue) or buccal (absorbed through mucosa
2. Injection (intravenous, intramuscular, subcutaneous, intradermal -- intracardiac, intraspinal, intraventricular, intrascapular)
3. Topical (dermal, mucosal, transdermal (skin patch))
4. Inhalation
Enteral or GI tract routes of administration
1. Oral
2. Nasogastric tube
3. Rectal
Advantage/Disadvantage of oral route
Easiest. Slower effects because of time required for dissolution
Advantages of intravenous route
Fastest; drugs enter bloodstream immediately
Advantage of transdermal route
Allows for slower consistent drug absorption over time
Advantage of inhalation route
Fast acting due to large surface area of lungs and rich blood supply
When are parenteral routes chosen:
1. Patient cant take anything by mouth
2. Drug is not suitable for GI absorption
Adverse drug reactions
Unintended side effects from medication
Teratogenic effect
Effect from maternal drug administration that causes physical defects in a fetus
Idiosyncratic reaction
Unique, unusual, unexpected response to drug
Paradoxical reaction
Opposite effect from that expected
Tolerance
Decreased response to a drug that develops after repeated doses are given
Dependence
Acquired need for a drug that may produce psychological or physical symptoms of withdrawal when drug is discontinued
Psychological - craving
Physical - cells need drug
Hypersensitivity
Immune response (allergy) to a drug
- may be mild with no immediate effects
- may develop after uneventful previous uses
- more likely to exist in patients with other allergies
Anaphylactic reaction
Severe, possibly fatal, allergic response
- Signs: itching, urticaria (hives), hyperemia (reddened, warm skin), vascular collapse, shock, cyanosis, laryngeal edema, dyspnea
- Common cases: antibiotics (penicillin), X-ray dyes containing iodides (angiogram dye, gallbladder dye), foods (shell-fish, peanuts), insect stings (bee, ant)
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