Drug Interactions Flashcards
T/F: 20% of Americans are taking 5 or more prescription drugs.
True
What is the difference between ED50 and EC50?
They are the same thing!
Amount of drug that produces 50% maximal response
What is the TD50?
The amount of drug needed for someone to get 50% of the toxic effects
What is the therapeutic index?
The ratio of TD50/ED50
T/F: The safest drugs have a very large therapeutic index.
True
Why is a combination of penicillin and tetracycline not as effective as either drug taken alone?
They have an antagonistic relationship
Tetracycline inhibits protein synthesis that is necessary for penicillin to kill the bacteria
Why does antacid use diminish the effects of tetracycline?
Antagonistic relationship
What is potentiation?
A second drug with a different activity enhances the activity of the first drug
What are some methods of potentiation?
Drug B enhances absorption, alters distribution, or inhibits elimination of Drug A
T/F: Sometimes two drugs taken together will create a new response not caused by either drug alone.
True
Why is disulfiram used to treat alcoholism?
Initially used to treat parasite infection, it has an unexpected outcome of interfering with alcohol metabolism causing sever headaches when taken together.
What is the difference between additive, infra-additive and supra-addtive summation?
Additive: drugs are interchangeable when dosed at fractions of EC50s
Infra-additive: yield less than additive response
Supra-additive: yield more than additive response
What is synergism?
The combined activity of two drugs is greater than maximal effect of either taken alone
What is a pharmaceutical interaction?
Drug incompatible due to physical or chemical reasons
What are the four types of pharmacokinetic drug interactions?
- Altered absorption
- Altered distribution
- Altered metabolism
- Altered excretion
