-
Pharmacokinetics
How the body handles drugs by drug absorbption, distribution, metabolism, and excretion.
-
Biotransformation
AKA Metabolism
-
Which is absorbed better ionized or non-ionized?
Non-ionized is absorbed better.
-
Once absorbed what are the two main options/categories for drugs?
Active and inactive.
-
What are the ways a drug can be inactive?
- 1) Attached to plasma protein for storage
- 2) Stored in fat
- 3) Stored in bone
-
What are the 4 processes that a drug goes through?
Absorbtion, Deistribution, Metabolism, Excretion
-
What factors influence drug absorbtion?
Drug chemistry (i.e. solubility) route of administration, and coating of drug.
-
What are the routes of administration?
- Oral- Variable, slower absorbtion
- IM- rapid absorbtion (if aqueous), slower if lipid
- IV- fastest absorbtion
- Subcutaneous- same as IM
- Inhalation- rapid absorbtion
- Percutaneous or transdermal- incomplete or erratic absorbton
- Rectal- erratic absorbtion
- Sublingual- eliminates 1st pass effect
- Topical- incomplete erratic absorbtion
-
What type of solubility is required for a drug to be absorbed?
It must be soluble in water (and to a certain extent lipid).
-
Enteric coated
Drugs that are protected from dissolving in stomach, coated with wax that only disloves in alkaline environment (in sm. intestine)
-
What is special about a time release capsule?
Part of drug disolves in stomach and part of drug disolves in sm. intestine.
-
What is the difference between drugs absorbed in the stomach and drugs absorbed in the small intestine?
Drugs absorbed in the stomach are made non-ionized by adding acid (ex. asprin). Drugs absorbed in the small intestine are made non-ionized by adding a base (ex. anphetamines)
-
Explain drug-drug interaction and drug activity.
If a drug (A) is alone 50% may bind to plasma protein and 50% will be active. If drug B is added to the mix, and B has a greater ability to bind to plasma protein, the B will bind to the plasma protein and less of A will bind to the plasma protien so more of A will be active.
-
What are two organs that specialize in acting as a barrier?
Blood-brain barrier and placental barrier
-
Explain the 1st pass effect.
Some drugs that are absorbed in the GI tract are metabolized in the liver before having an effect as an active drug, so a large first dose must be given or a build up of the drug over multiple doses must be done before a drug can be effective.
-
What do Hepatocygtes do?
Hepatocytes contain microsomal enzymes that metabolize drugs in the liver.
-
What are microsomal enzymes?
Enzymes that convert an active drug to a toxic metabolite.
-
What are the 6 metobolic fates of a drug?
- 1) Ative --> Metabolized --> inactive
- 2) Active --> Metabolized --> Less active
- 3) Inactive --> Metabolized --> Active --> (6) less or inactive drug
- 4) Less active drug --> Metabolized --> more active drug --> (6) less or inactive drug
- 5) Ecretion with no metabolization
-
What are some factors that affect hepatic drug metabolism?
Age, nurttional status, genetic makeup, liver disease, hormones
-
What is inhibition?
Inhibiting the liver enzymes in some way sot that the break down of the drug occurs slower; it increases the level of the active drug in the body.
-
What is stimulation?
Simulating the liver enxymes and increases its ability to metabolize other drugs; it decreases the level of the drug in the body.
-
What are the 2 major processes of elimination?
Glomerular flitration and tubular secretion.
-
Glomerular filtration
Filtration moves drugs from blood to urine; protein-bound drugs are not filtered
-
Tubular secretion
Active; tubular "pumps" for organic acids and bases move drugs from blood to urine
-
Tubular reabsorption
Passive; lipid-soluble and nonionized drugs move back into the blood, polar and ionized drugs remain in the urine
-
How do you decrease drug reabsorbtion?
Make the environment in the rine tract more acidic/basic to ionize the drug (ionized drugs will not be reabsorbed)
-
What level is looked at to determine the therapeutic and toxic responses?
The plasma drug level
-
Minimus effective concentraton (MEC)
The plasma drug level below which therapeutic effects will not occur; the lowest level a drug is therapeuticly effective
-
Toxic concentration
The plasma drug level at which toxic effects begin
-
Therapeutic Range
Between the Minimum effective concentration (MEC) and the toxic concentration
-
Onset of action
The time needed for the drug concentration to reach the minimum level
-
Time to peak effect
The time required for the maximum effect to occur after administration
-
Duration of action
The time during which blood levels are above the minimum effective concentration
-
Plasma half-life
The time needed for the plasma concentration of a drug to fall to 50% of its previous concentration; the faster the rate of metabolism, excretion, or both, the shorter the half-life
-
Drug Plateau
When the amout of drug eliminated between doses quals the dose administered, average drug levels will remain constant and plateau will have been reached.
|
|