Pharm - Principles of Pharm II
Terms
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- What is Half-life?
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time required for the amount of drug in the body to decrease by 50%
*shorter the half-life, the quicker it leaves the body - What is the half-life of Morphine?
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3 hours
- (body stores will decrease by 50% every 3 hours) - What is the plateau principle?
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- the amount of drug eliminated between doses = the amount administered
- the steady level achieved after REPEATEDLY administering doses of a drug
- What factors affect therapeutic drug levels?
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1. half life
2. dosing frequency
3. plasma drug levels
4. dosage amount
5. rate of absorption
6. route
7. metabolism
8. excretion - What is Dose-Response Relationships?
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- the relationship between the size of an administered dose and the intensity of the response produced
- what is the minimal amount of drug needed to get maximum response? - What is maximum efficacy?
- the largest effect that a drug can produce (height of curve)
- What is relative potency?
- the amount of drug we must give to elicit an effect (length of curve)
- What is agonist?
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- molecules that activate receptors
- bind to receptors and micmic actions of the body's own regulatory molecules
- has affinity and intrinsic activity (produces a response) - What is antagonist?
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- produce effects by preventing receptor activation
- exert no effect of their own
- affinity but no intrinsic activity - What are the 2 types of antagonists?
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1. Non-competitive (insurmountable)
*irreversibly bind to receptors
2. Competitive (surmountable)
*bind reversibly
* produce receptor blockade
* competes with agonists - What are 4 types of receptors?
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1. cell membrane-embedded enzymes
*span membrane
*response aided by enzymes
2. Ligand gated ion channels
*span membrane
*ligand binds and channel opens
3. G-protein coupled receptor systems
*ligand binds and activates receptor
*G-proteins are activated & activate effectors
4. Transcription Factors
*within cell
* located on DNA
*activate by lipid soluble ligands
*regulates protein synthesis - What is therapeutic index?
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a measure of drug's safety
ex. LD50 - average lethal dose (dose that is lethal to 50% of animals treated)
ED50 - dose required to produce a defined therapeutic response in 50% of the population
- the higher the TI, the greater the range (less change for toxicity) - What is the formula for therapeutic index (TI)?
- TI = LD50/ED50
- What is an adverse drug reaction?
- - any noxious, unintended and undesired effect that occurs at normal drug doses
- Who are vulnerable to adverse drug reactions (ADRs)?
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- young: their ability to metabolize and excrete drugs is lower
- elderly
- ill
***ADRs are the 4th leading cause of death! - What is an allergic reaction?
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- a sensitivity to a specific substance called an allergen (antibody generator) that is contacted through the skin, lungs, swallowing, or injection
- an immune response - What is Idiosyncratic Effect?
- an uncommon drug response resulting from a genetic predisposition
- What is an iatrogenic disease?
- disease produced by drugs
- What is a side effect?
- a nearly unavoidable secondary drug effect produced at therapeutic doses
- What is toxicity?
- an adverse drug reaction caused by excessive dosing
- What is carcinogenic effect?
- the ability of certain medications and other chemicals to cause neoplastic diseases (cancer)
- What is a teratogenic effect?
- drug induced birth defect
- What factors affect one's response to drugs?
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1. body weight
2. age
3. gender
4. pathophysiology
5. tolerance
6. placebo effect
7. genetics
8. variability in absorption
9. compliance
10. diet
11. attitude
12. economic resources
13. cultural differences
14. drug interactions - What are some nutrient-drug interactions?
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1. presence of food in stomach - slows absorption (food becomes ionized and can't cross CM)
2. Ca+ (milk) & high fiber slows absorption
*grapefruit juice can slow metabolism of drugs
3. high calorie content increases absorption - What is synergism?
- 2 drugs work side by side
- What are some consequences of drug interactions?
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1. Potentiation (adverse effects)
- warafin/aspirin
2. Inhibitory
- Morphine/Naloxone
3. Direct physical/chemical interaction
- precipitate forms
4. Displacement from plasma proteins
5. Antagonism - compete
6. Altered absorption - ex. laxative (may decrease the amount of time for drugs to absorb because of increased peristalsis)
7. Stimulation / inhibition of metabolism
8. Competition for transport / elimination
- What factors affect compliance?
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1. Complexity of treatment
2. Pathophysiology (psychiatric patients)
3. Treatment period
4. side effects
5. relationship with health professional
6. support/assistance
7. perceived benefits
8. attitude
9. Cost
10. personal limitations (vision, dexterity, intellect) - Is insulin an agonist or antagonist?
- agonist