GENERAL PRINCIPLES OF PHARMACOLOGY - PHARMACOKINETICS Flashcards
Pharmacokinetics
The study of absorption, distribution, metabolism and excretion of drugs.
What does “pharmacokinetics” include?
- Drug biotransformation in the organism
- Distribution of drugs in the organism
- Excretion of substances
The main mechanism of most drugs absorption in GI tract is
Passive diffusion (lipid diffusion)
What kind of substances can’t permeate membranes by passive diffusion?
Hydrophilic substances
A hydrophilic medicinal agent has the following property
Low ability to penetrate through the cell membrane lipids.
What is implied by «active transport»?
Transport against concentration gradient
What does the term “bioavailability” mean?
Fraction of an uncharged drug reaching the systemic circulation following any route administration.
The reasons determing bioavailability are
Extent of absorption and hepatic first-pass effect
Pick out the appropriate alimentary route of administration when passage of drugs through liver is minimized
Rectal
Which route of drug administration is most likely to lead to the first-pass effect?
Oral
What is characteristic of the oral route?
Absorption depends on GI tract secretion and motor function.
Tick the feature of the sublingual route
Pretty fast absorption
Pick out the parenteral route of medicinal agent administration
Inhalation, IV.
Parenteral administration
Usually produces a more rapid response than oral administration
What is characteristic of the intramuscular route of drug administration?
Oily solutions can be injected
True or False. Intravenous injections are more suitable for oily solutions.
FALSE.
True or False. Intravenous administration provides a rapid response
TRUE
True or False. Intramuscular administration requires a sterile technique
TRUE
True or False. Subcutaneous administration may cause local irritation
TRUE
True or False. Most of drugs are distributed homogeneously.
FALSE
Biological barriers include
- Cell membranes
- Capillary walls
- Placenta
What is the reason of complicated penetration of some drugs through brain-blood barrier?
Absence of pores in the brain capillary endothelium
The volume of distribution (Vd) relates
The amount of a drug in the body to the concentration of a drug in plasma.
For the calculation of the volume of distribution (Vd) one must take into account
Concentration of a substance in plasma
True or False. Small amount of the volume of distribution is common for lipophylic substances easy penetrating through barriers and widely distributing in plasma, interstitial and cell fluids.
FALSE
The term “biotransformation” includes
Process of physicochemical and biochemical alteration of a drug in the body.
Tick the drug type for which microsomal oxidation is the most prominent
Lipid soluble
True or False. Microsomal oxidation results in an increase of ionization and water solubility of a drug
TRUE
Stimulation of liver microsomal enzymes can
Require the dose increase of some drugs.
Metabolic transformation (phase 1) is
Transformation of substances due to oxidation, reduction or hydrolysis.
Biotransformation of a medicinal substance results in
Faster urinary excretion.
Conjugation
Coupling of a drug with an endogenous substrate
Which of the following processes proceeds in the second phase of biotransformation
Acetylation
Conjugation of a drug includes
- Glucoronidation
- Sulfate formation
- Methylation
True or False. Metabolic transformation and conjugation usually results in an increase of a substance biological activity
FALSE
In case of liver disorders accompanied by a decline in microsomal enzyme activity the duration of action of some drugs is
Enlarged
Half life (t ½) is the time required to
Change the amount of a drug in plasma by half during elimination.
Half life (t ½) doesn’t depend on
Time of drug absorption
Half life (t ½) depends on
- Biotransformation
- Concentration of a drug in plasma
- Rate of drug elimination
Elimination is expressed as
Clearance of an organism from a xenobiotic.
Elimination rate constant (Kelim) is defined by the following parameter
Half life (t ½)
True or False. The most rapid eliminated drugs are those with high glomerular filtration rate and actively secreted but aren’t passively reabsorbed
TRUE
Systemic clearance (CLs) is related with
Volume of distribution, half life and elimination rate constant.
