Solutions and Answers to Mechanics of Materials
drug response - ANSWERSthe intensity of the drug response is directly related to the
concentration of the drug at the SITE OF ACTION
Goal is to:
- maximize the beneficial effects- concentration high enough for desired response
- minimize harm- avoid to high a concentration
Three phases of drug action - ANSWERS1. pharmaceutic phase (dissolution)
2. pharmacokinetic phase (drug moving through the body)
3. pharmacodynamic phase (what the drug does to the body)
1. pharmaceutic phase - ANSWERSthe drug goes into solution
- Dissolution: the process by which a drug goes into solution and becomes available for
absorption
- must be dissolved before it can be absorbed
- most absorption takes place in the small intestine
2. pharmacokinetic phase: four processes - ANSWERS"what the BODY does to the drug"
- absorption
- distribution
- metabolism/ biotransformation
- exertion
,pharmacokinetic phase: Absorption - ANSWERS(small intestine) the movement of a drug from
its site of administration into the blood
pharmacokinetic phase: Distribution - ANSWERSdrug moves from blood --> cell membrane
pharmacokinetic phase: Metabolism/biotransformation - ANSWERSlipid soluble metabolite
(liver) --> a water soluble metabolite
pharmacokinetic phase: Excretion - ANSWERSwater soluble metabolite (kidneys)
liver - ANSWERSbreaks down the drug
kidneys - ANSWERSexcretes the drug
Pharmacokinetic phase movement process - ANSWERSorally --> stomach --> SI --> bloodstream
--> site of action --> liver (broken down) --> kidneys (excreted)
IV --> bloodstream --> cite of action --> liver --> kidneys
drugs crossing the cell membranes phospholipid cell layer - ANSWERS-drugs must be LIPID
SOLUBLE in order to pass through the membrane
- WATER SOLUBLE drugs penetrate the cell membrane through channels and pores
Absorption
1. direct penetration of the membranes
,2. channels and pores
3. transport systems - ANSWERSthe movement of a drug from its site of administration to the
blood
How do drugs cross membranes?
1. Direct penetration of the membranes - ANSWERS- use by MOST drugs
- most drugs to large to pass thru channels and pores
- most drugs lack transport systems
- drugs must be lipid soluble to be able to penetrate cellular membranes = lipophilic drugs
2. channels and pores - ANSWERSonly very small ions such as potassium and sodium can pass
through cell membranes
3. transport systems - ANSWERS- are carriers that can move drugs from one side of the
membrane to the other
- are selective
Movement of drugs across membranes - ANSWERS-drugs must cross membranes (pass through
cells) to enter the blood from their site of administration
- drugs must then leave the blood (vascular systems) to get to their SITE OF ACTION
- drugs must then cross membranes again to be metabolized and excreted
pharmacokinetic phase: Absorption - ANSWERSprocess that occurs between the time a drug
enters the body and the time it enters the bloodstream to be circulated
, - Rate of absorption -> depends on the formulation of drug (tablet, liquid, etc.)
- Amount of absorption -> how effective drug will be absorbed
Major determinants of rate of absorption:
- blood flow -> higher blood flow, the faster the drug is absorbed
- lipid solubility -> higher lipid soluble drugs faster than drugs whose lipid solubility is low
- pH -> acidity of the stomach can break down the drug
what is the first-pass effect? - ANSWERSaffects amount of drug absorbed
- the metabolism of a drug by the liver BEFORE it reaches systemic circulation
- is the % of the drug that is broken down in the liver
- "bioavailability" : the fraction of administered drug that actually reaches systemic circulation
- IV bioavaiability= 100%
- oral bioavailability will vary
Three Routes of Absorption - ANSWERS1. Enteral
2.Parenteral
3. Topical
Enteral route of absorption - ANSWERSDefined by the way of GI tract (oral/gastric mucosa, small
intestine, rectum)
- any drug given via GI tract
- EC (enteric coated): intended to break down in the small intestine NOT the stomach --> must
undergo the "first pass effect"
- PO --> portal circulation --> must undergo the first pass effect
drug response - ANSWERSthe intensity of the drug response is directly related to the
concentration of the drug at the SITE OF ACTION
Goal is to:
- maximize the beneficial effects- concentration high enough for desired response
- minimize harm- avoid to high a concentration
Three phases of drug action - ANSWERS1. pharmaceutic phase (dissolution)
2. pharmacokinetic phase (drug moving through the body)
3. pharmacodynamic phase (what the drug does to the body)
1. pharmaceutic phase - ANSWERSthe drug goes into solution
- Dissolution: the process by which a drug goes into solution and becomes available for
absorption
- must be dissolved before it can be absorbed
- most absorption takes place in the small intestine
2. pharmacokinetic phase: four processes - ANSWERS"what the BODY does to the drug"
- absorption
- distribution
- metabolism/ biotransformation
- exertion
,pharmacokinetic phase: Absorption - ANSWERS(small intestine) the movement of a drug from
its site of administration into the blood
pharmacokinetic phase: Distribution - ANSWERSdrug moves from blood --> cell membrane
pharmacokinetic phase: Metabolism/biotransformation - ANSWERSlipid soluble metabolite
(liver) --> a water soluble metabolite
pharmacokinetic phase: Excretion - ANSWERSwater soluble metabolite (kidneys)
liver - ANSWERSbreaks down the drug
kidneys - ANSWERSexcretes the drug
Pharmacokinetic phase movement process - ANSWERSorally --> stomach --> SI --> bloodstream
--> site of action --> liver (broken down) --> kidneys (excreted)
IV --> bloodstream --> cite of action --> liver --> kidneys
drugs crossing the cell membranes phospholipid cell layer - ANSWERS-drugs must be LIPID
SOLUBLE in order to pass through the membrane
- WATER SOLUBLE drugs penetrate the cell membrane through channels and pores
Absorption
1. direct penetration of the membranes
,2. channels and pores
3. transport systems - ANSWERSthe movement of a drug from its site of administration to the
blood
How do drugs cross membranes?
1. Direct penetration of the membranes - ANSWERS- use by MOST drugs
- most drugs to large to pass thru channels and pores
- most drugs lack transport systems
- drugs must be lipid soluble to be able to penetrate cellular membranes = lipophilic drugs
2. channels and pores - ANSWERSonly very small ions such as potassium and sodium can pass
through cell membranes
3. transport systems - ANSWERS- are carriers that can move drugs from one side of the
membrane to the other
- are selective
Movement of drugs across membranes - ANSWERS-drugs must cross membranes (pass through
cells) to enter the blood from their site of administration
- drugs must then leave the blood (vascular systems) to get to their SITE OF ACTION
- drugs must then cross membranes again to be metabolized and excreted
pharmacokinetic phase: Absorption - ANSWERSprocess that occurs between the time a drug
enters the body and the time it enters the bloodstream to be circulated
, - Rate of absorption -> depends on the formulation of drug (tablet, liquid, etc.)
- Amount of absorption -> how effective drug will be absorbed
Major determinants of rate of absorption:
- blood flow -> higher blood flow, the faster the drug is absorbed
- lipid solubility -> higher lipid soluble drugs faster than drugs whose lipid solubility is low
- pH -> acidity of the stomach can break down the drug
what is the first-pass effect? - ANSWERSaffects amount of drug absorbed
- the metabolism of a drug by the liver BEFORE it reaches systemic circulation
- is the % of the drug that is broken down in the liver
- "bioavailability" : the fraction of administered drug that actually reaches systemic circulation
- IV bioavaiability= 100%
- oral bioavailability will vary
Three Routes of Absorption - ANSWERS1. Enteral
2.Parenteral
3. Topical
Enteral route of absorption - ANSWERSDefined by the way of GI tract (oral/gastric mucosa, small
intestine, rectum)
- any drug given via GI tract
- EC (enteric coated): intended to break down in the small intestine NOT the stomach --> must
undergo the "first pass effect"
- PO --> portal circulation --> must undergo the first pass effect
