Flashcards in 9.7 Pharmacology 5 Deck (32):
1
bioavailability
extent to which drug reaches systemic circulation
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What does bioavailability depend on?
- route of administration
- drug's ability to cross membrane barriers
3
drug movement
- passive diffusion
- active transport
- facilitated diffusion
- endocytosis
4
Why does ionization state affect absorption?
pH of digestive system interacts with the drug
5
- excretion
- how quickly and easily it is to get rid of the drug
clearance rate
6
volume of distribution
people who weight more require larger amts of the medicine for it to work
7
factors affecting distribution of drugs in the body
- tissue permeability
- blood flow
- binding to plasma proteins
- binding to subcellular components
- volume of distribution
8
major tissue permeability concern
blood brain barrier
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blood flow and distribution of drugs in the body
- drugs have higher access to well-perfused areas
- why foot wounds don't heal unless peripheral blood flow is adequate
10
Which drugs can reach a target to create a pharmacologic effect?
only unbound or "free" drugs
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bound drugs
- drug remains bound to a protein and is sequestered in the vascular system
- doesn't produce a therapeutic response
12
binding to subcellular components
- drug is "trapped" by organelles within a cell
- can't be distributed to other target areas
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example of subcellular binding
certain antidepressants and antipsychotics with relatively high pH are attracted to the acidic lysosome
14
volume of distribution: important considerations
- may be possible to increase dosage to achieve therapeutic effect
- only if TI permits
15
What tissues might drugs be stored in that could have adverse effects?
- adipose tissue
- bone
- muscle
- organs
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most common site for drug storage - why?
- adipose tissue
- most drugs are lipid-soluble
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How long do drugs stay in adipose tissue and why?
tends to stay a long time
- low metabolic rate
- poor blood perfusion
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What can concentrate heavily in adipose tissue?
- anesthetics (barbiturates)
- inhaled anesthetics (halothane)
19
bone and drugs
- some drugs can bind to skeletal matrix
- tetracycline
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What is a toxic substance that can bind to bone?
lead
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How do drugs get stored in muscle?
binds to:
- proteins
- nucleoproteins
- phospholipids
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example of drug that gets stored in muscle
antimalarial: quinacrine
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most common organs for drug storage
- liver
- kidneys
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What drugs are commonly stored in the liver and kidneys?
antimicrobials
- gentamycin
- streptomycin
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Problems with drug storage in tissue
- can damage, even in therapeutic doses
- can prevent medicine from reaching target tissue
- can redistribute the drug unpredictably
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What are ways that are used to combat drug storage problems?
- controlled-release preparations
- implanted
- targeting drug to specific cell or tissue
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benefit to controlled-release preparations
- prevents large fluctuations in plasma
- sustained levels
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controlled-release preps are useful for these types of meds
- cardiovascular (beta and calcium channel blockers)
- narcotics
- anti-Parkinson drugs
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How do implanted drugs work?
- small, measured dose on a programmed schedule into a specific body part
- epidural or subarachnoid
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examples of implanted drugs
- spasticity: baclofen or lioresal
- insulin pump into fatty tissue
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How can a drug be targeted to specific cells or tissues?
- use of a "prodrug" or inactive form
- converts to active form when specific enzymes or biochemical properties of the target tissue recognize it
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