Pharmacology wk#2 Test#1

What is minimum effective concentration (MEC)?
The lowest plasma concentration required to cause measurable response.

what is onset of action?
Onset of action is when plasma concentration reaches the minimum effective concentration. Length of time before med starts to work.

What does peak mean?
Peak is the highest plasma concentration. This is when drug will have strongest effect.

When is the greatest risk for toxic or adverse reaction?
at the peak plasma concentration

What is duration of action?
Duration of action is the time period when plasma concentration is above MEC.

What is therapeutic index?
The ratio between the toxic dose and the effective dose. Ratio between LD50 (lethal dose in 50% of the population) and ED50 (effective dose in 50% of the population)

The closer the therapeutic index is to ___ the more narrow the therapeutic index.
1

What should you do if there is a narrow TI/range?
monitor plasma drug levels and drug effects. The goal is to keep plasma levels within therapeutic range, but below toxic levels.

What is half life?
the time it takes, after absorption, for 50% of the drug to be eliminated.

How many half lives does it take to eliminate 98% of the drug?
It takes approximately 4-5 half lives.

What helps to determine duration of action?
half life (it helps determine how much time separates each dose)

Dose approximately every_____ in order to maintain steady state blood levels (an equilibrium between drug transfer in and out of plasma).
half life ( it takes 4-5 half lives to reach steady state blood levels.

What is a loading dose?
This means to give a higher than maintenance dose in order to rapidly reach steady state blood levels.

Nursing implications for peak and trough drug levels
wait until steady state is reached (after at least 4 doses given). Give drug on time and document. Draw blood at proper time. For peak draw blood at peak of drug action. For trough draw blood immediately before next dose of drug.

Drug receptor interaction theory?
drugs interact with receptor in lock and key fashion. Only certain keys fit certain locks.

Rate interaction theory?
The rate of binding determines the type and intensity of response. A drug with a greater affinity or greater concentration will attach to more receptors, and more often, resulting in a more intense response.

What does agonist mean?
combines with receptor and produces a response (activates receptors). When drugs act as agonist, they simply bind to receptors and mimic the actions of the body’s own regulatory molecules.

What does antagonist mean?
combines with receptor and inhibits action of agonist (prevents receptor activation).

What does competitive antagonist mean?
has a higher affinity for receptor. If an agonist and a competitive antagonist have equal affinity for a particular receptor, then the receptor will be occupied by whichever agent agonist or antagonist is present in the highest concentration.

What does noncompetitive antagonist mean?
it cannot be overcome by higher concentrations of agonist. Because the binding of noncompetitive antagonist is irreversible, inhibition by these agents cannot be overcome, no matter how much agonist may be available.

The combined effect of 2 similar drugs that act at the same receptor is called?
addition (additive)

The effect of one drug increased by the second is called?
potentiation. 1+1+2
This can work in many ways.
1. increased concentration at the receptor.
2. increased concentration at the receptor
3. decreased metabolism
4. slow excretion

What does synergism mean?
combined effect greater than each drug given alone. 1+1=3

What is inhibition? Inhibitory?
Interactions that result in reduced drug effects.
1. any decrease in effect
2. decrease in absorption (1st drug decreases absorption of 2nd drug).
3. decrease concentration at receptor
4. increase metabolism
5. increase excretion

What does side effect (secondary effect) mean?
any effect other than the primary therapeutic effect.

What is an adverse drug reaction?
Noxious, unwanted or unintended reaction occurring at ” normal doses”.

What is a severe adverse effect?
toxicity (may be due to excessive dosing)

What does toxicity mean?
an adverse drug reaction caused by excessive dosing. In everyday parlance the term toxicity has come to mean any severe ADR, regardless of the dose that caused it.

Acceptable adverse reaction
risk vs benefit is acceptable (nausea w/opioids). doesn’t require stopping the drug.

Unacceptable adverse reaction
causes higher risk vs benefit (anaphylactic reaction). requires stopping the drug.

Adverse drug event
considered reportable to FDA or monitoring agencies.

What does hypersensitivity mean?
Any excessive reaction

What does idosyncratic effect mean?
uncommon response, may be due to genetic predisposition.

What is an allergy?
Histamine mediated immune response. requires sensitization. it’s a state of hypersensitivity.

Allergic reactions
severity may vary from uncomfortable hive,s and itching to life threatening anaphylaxis.

Anaphylaxis is?
abrupt onset, massive histamine release.

S/S of anaphylactic reaction
edema at injection site, erythema, anxiety, restlessness, coughing, sneezing, itching (throat, mouth, palms, soles of feet), bronchospasm (wheezing), laryngospasm (stridor, airway compromised), vascular collapse (hypotension, tachycardia).

Anaphylaxis treatment
Epinephrine- 1mg IV or ET.
less severe reaction: 0.3-0.5mg.
IM (SQ also recommended)
Airway management: intubation PRN, O2.
Antihistamine: diphenhydramine (benadryl) IV.
Corticosteroids: methylprednisolone(IV)
Fluid resuscitation: increasing blood volume will increase BP. Vasopressores (dopamine) and cardiac monitoring.

What is serum sickness?
Type III hypersensitivity reaction.
S/S: Skin rashes, edema, fever, joint pains. **anaphylaxis may follow if untreated**
Tx: stop drug, corticosteroids, anti inflammatory drugs (NSAIDS), antihistamines.

What is erythema multiformae?
delayed hypersensitivity reaction.
S/S: circular, edematous lesions, **target lesions, or bulls eye lesions**, necrosis of lesions may occur. (lesions are not typical hives. they have a dip in the middle of the hive)
Tx: stop the drug, corticosteroids (debatable), lesions may become necrotic (wound care)

What is Stevens Johnson syndrome?
A more severe form of erythema multiformae.
S/S: target lesions that involve mucous membranes as well as skin, lesions erode (painful), joint pains, fever, malaise.
Tx: stop drug, symptom management, corticosteroids, antibiotics, wound care.
Death may result from infection of lesions.

What is toxic epidermal necrolysis?
A more sever form of erythema multiformae where the skin sloughs.
Tx: stop drug, antibiotics, corticosteroids, wound care, isolation if needed.

Other skin reactions
Drug eruptions- drug rash, a fine rash with small bumps.
Eczema- pruritis, edema
Contact dermatitis- skin irritation because of direct contact w/drug.

What is photosensitivity?
skin reactions- rash, sunburns easily.
Tx: avoid sun exposure, wear proper clothing, sunscreen. teach clients to avoid sunburn. Some drugs increase sensitivity to sun and cause sunburn.

What is pseudomembranous colitis?
overgrowth of clostridium dificile in gut.
S/S: worsening diarrhea that is bloody and contains mucus. Tx: stop drug, hydrate.

What is ototoxicity?
toxicity to the eighth cranial nerve. S/S: tinnitus, vertigo, hearing loss. Tx: stop drug, hearing loss may be irreversible. Prevent: monitor, teach people to report symptoms.
Drugs: aspirin, loop diuretics (furosemide, lasix)

What is Encephalopathy?
Brain dysfunction. S/S: reduced LOC, seizures, risk greater with pre-existing neurologic disease or injury. Tx: stop drug, manage symptoms.

What are paradoxical reactions?
opposite of expected therapeutic effects.
Children- excitement with some sedatives.
Elderly- similar reactions (agitation w/sedative)

What is extrapyramidal reactions?
AKA parkinsonian symptoms. S/S: disturbances in motor function, tremor, gait distrubances, rigidity (looks like parkinson’s disease). Psychotropic and antiemetic agents worst. Tx: stop drug, reduce dose, anticholinergic agents.

What are the cardiovascular reactions?
arrhytmias (dysrhytmias)- irregularities in cardiac rhythm. “Arrhythmogenc” drugs- may directly interfere w/cardiac conduction OR Sensitize myocardium to Epi/NorEpi, Stimulatns (acti like Epi), some anesthetics. Tx: stop drug, cardiac monitoring, treat dysrhythmias.

What is myocardial toxicity?
direct damage to myocardial tissue. Causes: cardiomyopathy- can lead to congestive HF. Drugs (lead, some antineoplastics, illicit drugs). Tx: stop drug, monitor cardiac functions, symptom management.

What does cardiac vasoconstriction do?
causes reduced circulation to the myocardium, myocardial infarction if severe. Tx: stop drug, manage symptoms. Drugs-cocaine, meth.

what is a blood dyscrasia?
dysfunction of the blood forming organs.

What happens with a hematologic reaction such as bone marrow depression?
1.reduced WBC- neutropenia, rick of infection.
2.reduced RBC- anemia, fatigue, lower O2 carrying capacity.
3. reduced platelets- risk of bleeding

Hematologic reaction: Severe aplastic anemia
lack of production of all cells. Tx: 1.Reduced White Cells-Prevent infection, isolation, Neupogen (neutrophil colony stimulating factor) 2.Reduced Red Cells – Oxygen, Transfusion, Epogen (stimulate RBC production) 3.Reduced Platelets – Safety, Platelet Transfusion, Oprevelkin (stimulate platelets)

Hematologic reaction: Hemolytic anemia
direct red blood cell destruction. this can cause renal failure if heme molecules clump in glomerulus. Tx: stop drug, corticosteroids,

Hepatotoxicity: Toxic Hepatitis
look like viral form(elevated enzymes- ALT, AST, jaundice). Tx: stop drug, corticosteroids. Drugs: acetaminophen, antilipemic drugs.

What is Carcinogenicity?
the ability to cause cancer. dose related risk (higer dose, higher risk). Drugs: antineoplastics, anabolic steroids. Prevent: minimize exposure.

What is Teratogenicity?
ability to cause birth defects. most risk in 1st trimester- as most organ systems are differentiating at this time. Teach: avoid drugs throughout pregnancy- only with approval of Dr. Agents: many alcohol, antineoplastics, anticonvulsants, etc.

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