LP 1 Flashcards
Pharmacology
Study of the biological effects of drugs
Pharmodynamics
Drugs actions on target cells and resulting reaction in the body
Pharmacokinetics
- drug movement in the body to achieve action
Four processes important in Pharmacokinetics
- Absorption
- Distribution
- Metabolism
- Excretion
Absorption
- As the movement of a drug from its site of administration into the blood stream to be circulated.
- The rate of absorption determines how soon effects will begin
Factors Affecting Absorption
- Rate of dissolution: drugs that have rapid dissolution will have a faster onset
- Surface Area: the larger the surface area, the faster the drug is absorbed. PO drugs usually absorbed in small intestine (stomach has small surface area).
- Blood Flow: drugs absorbed most rapidly from sites where blood flow is high
Presence of food: usually slows absorption of a drug can lead to incomplete absorption - Lipid Solubility: highly lipid- soluble drugs are absorbed more rapidly than drugs whose lipid solubility is low
Bioavailability
- how much of the drug reaches the systemic circulation and can act on body cells
Distribution
- The movement of drugs throughout the body, carried by the blood to sites of action, metabolism and excretion
Protein Binding
- Free or unbound drug is active and can cause a pharmalogical response.
- ** the portion of drug that is bound to protein is inactive because it is not available to receptors**
Metabolism
- method by which drugs are inactivated by the body
- takes place in the liver
What is the first pass effect?
- the drug is sent straight to the liver and then becomes inactive
Liver enzymes
- initially inactive until they are metabolized by the liver, then they become active
Excretion
- elimination of drugs from the body
- most excretion is done by the kidneys
What is critical concentration?
- the amount of a drug that is needed to cause a therapeutic effect
What is toxic concentration?
- the drug at which toxicity begins to occur
What is onset of action?
- the time it takes for a drug to elicit a therapeutic effect
- also called the minimum effective concentration
What is the peak of action?
- the time when the drug reaches its highest blood or plasma concentration
- also called the maximum therapeutic response
What is the steady state concentration?
- maintaining of a steady concentration in the blood, it takes about 4-5 half lives to achieve
What is peak and trough?
- high and low concentrations of medication in the body
What is the drug index?
- the margin of safety of a drug
What is the window?
- the concentration of the drug in plasma needed for obtaining the desired drug action and having few toxic effects
What is the loading dose?
- a large initial dose of the medication given to achieve minimum effective concentration
Wha is the maintenance dose?
- quantityof drug needed to keep blood levels at steady state
Serum half life
- the time required for the amount of the drug in the body to decrease by 50%