Pharm: ADME 1 (Overview) Flashcards
Drugs produce their effects as a result of their presence at appropriate ____ at their ____ ____ ____.
concentration at their site of action
The minimum toxic concentration is also referred to as what?
the maximum tolerable concentration
It is the goal of the clinician to maintain drug concentrations where?
in the therapeutic window, which is higher than the minimum effective concentration and the minimum toxic concentration
With IV administration, therapeutic drug concentrations are achieved _____, whereas with oral administration drug concentrations are achieved _________.
rapidly; in delayed fashion
The onset and termination of drug action occurs when?
onset is when the drug concentration rises above the minimum effective concentration, and termination is when it falls below the minimum effective concentration
The decline of drug concentration over time depends on what?
characteristic metabolic and elimination processes associated with the drug
What is the intensity of drug action? (from graph)
the interval that extends from the minimum effective concentration to the maximum concentration achieved; this is variable
Pharmacokinetics is concerned with what?
the fate of the drug within the body, determined by dynamics of drug absorption, distribution, metabolism, and excretion
Absorption is a process reflecting what processes?
the rate at which a drug leaves its site of administration and the rise in drug concentration as it enters the systemic circulation; also describes the extent to which that occurs
Within the systemic circulation, what 2 forms can a drug take? Which form makes the drug available to the tissue?
free or bound form; in free form it is available to bind tissue/cell receptors
What process is responsible for the decline of drug concentration?
metabolism, as it converts drugs to metabolites to be excreted
True or false: free drug can be directly excreted through the process of elimination.
True *(it doesn’t always have to be metabolized first)
The process of distribution involves the movement of drug through/between what?
the systemic circulation, various tissues/sites of action, and sites of elimination
What is the difference between the rising and falling phases of the plasma concentration vs. time plot?
in the rising phase, drug absorption activity is higher than metabolism and excretion; whereas in the falling phase metabolism and excretion are greater than absorption
What two factors are manipulated by the clinician in order to vary the concentration-time profile of a given preparation?
- different doses
2. different administration frequencies
What is the therapeutic index? What do different TI values indicate?
MTC/MEC - min. toxic conc. over min effective conc.
- high ratio - large window, relatively “safe”
- low ratio - use caution to keep drug concentration within the window
What size molecules of drugs may pass through cell membrane pores?
low MW, like 100-200 Da
True or False: cell membranes are permeable to proteins and peptides.
False - they are relatively impermeably to proteins/peptides
Which of the following compounds can pass through cell membranes:
- lipophilic or lipophobic?
- polar or non-polar?
- ionized or non-ionized?
- lipophilic (recall: membranes like higher partition coefficients)
- non-polar
- non- ionized
What are the 3 ways that drugs can be biotransported?
- Passive diffusion
Carrier-mediated biotransport: - Facilitated diffusion
- Active transport
Most drugs pass biological membrane by ____ ____.
passive diffusion
The rate of diffusion is governed by what?
Fick’s law - depends on the distribution of concentrations, size of drug (smaller the better), partition coefficient (lipid solubility), surface area (larger the better), membrane thickness (thinner the better), and ionization (less charged better)
Carrier-mediated biotransport is used for drugs that are too what?
too large or too polar
True or False: transport cycles are irreversible processes of biotransport.
False - they are reversible