To adequately assess,plan, intervene and evaluate drug effects.
What are the phases of drug action?
1. Pharmaceutic
2. Pharmacokinetic
3. Pharmacodynamic
The 1st phase of drug action when drug is taken post orem also known as the dissolution phase?
Pharmaceutic phase
What are the other types of routes that DO NOT HAVE THE PHARMACEUTIC PHASE?
SubQ — subcutaneous
IM — Intramascular
IV — Intravenous
The process where a drug from solid form, disintegrate into small particles to dissolve into a liquid.
Dissolution
It is the breakdown of a tablet into smaller particles.
Disintegration
Arrange the Pharmaceutic phase in correct order.
I.Dissolution
II.Tablet
III. Disintegration
B. 2,3,1
This are fillers and inert substances that are used in drug preparation to allow the drug to take a
particular size and shape and to enhance drug dissolution.
Excipient
Drugs in _________ form are more rapidly available for GI absorption.
D. Liquid form
Drugs are absorbed faster in _______ fluids.
acidic — with pH 1 and 2 rather than alkaline fluids.
Alkaline drugs would become ionized and have difficulty crossing cell membrane barriers.
True or false.
Young people have more gastric acidity than older adults.
False.
Both young and older adult have less gastric acidity therefore drug absorption is generally slower in the stomach for these ages.
This type of drug form resist disintegration in gastric acid of the stomach. Disintegration occurs until drug reaches the alkaline environment of the small intestine.
It can delay the effect of drug in onset.
Enteric- coated tablets/drugs
⚠️CAUTIONS TO REMEMBER WHEN HANDLING ENTERIC-COATED DRUGS.
Don't crush them to prevent altering their place and time of absorption.
True or false
Food intake can influence the absorption of drugs.
True.
Food in the GI may interfere with the dissolution of certain drugs.
Some drugs irritate the gastric mucosa so fluids or food maybe necessary to dilute the drugs concentration and act as protectant.
It is the process of drug movement to achieve drug action.
Pharmacokinetic phase
What are the 4 mechanisms of pharmacokinetic, in chronological order.
absorption
distribution
metabolism or biotransformation
excretion or elimination
It is the movement of drug from the gastrointestinal tract to the body fluids.
Absorption
From solution form, the particles of drugs are absorbed through the villi of the small intestine to be distributed to the body fluids.
Where does most of the absorption happen?
In the surface area of the mucosal villi, small intestine.
Absorption is reduced if the villi are decreased in number because of disease, drug effect, or the removal of small intestine.
What are the different types of absorption?
Passive
Active
Pinocytosis
Passive absorption occurs mostly by
diffusion or the movement from higher concentration to lower concentration
With this process the drug does not require energy to move across the membrane.
This type of absorption requires a carrier such as enzymes to move the drugs against a concentration gradient.
Active absorption
This type of absorption happens when cells carry drugs across their membrane by engulfing the drug particles.
Pinocytosis
The gastrointestinal membrane is composed mostly of lipid and proteins. So drugs that are _______ soluble pass rapidly through the GI membrane.
lipid
On the other hand _________ soluble drugs need a carrier, either an enzyme or protein to pass through the membrane.
water-soluble
Large particles pass through the cell membrane if they are _________.
non-ionized (have no positive or negative charges)
Therefore characteristics of drugs that can be absorbed rapidly through the GI membrane are (1) and (2).
1. lipid-soluble
2. non-ionized
Compared to water-soluble drugs which will need to have a carrier and ionized drugs.
What factors could affect drug absorption?
pH partitioning absorption - Drugs that are lipid-soluble and non-ionized pass through the GI membrane easily and rapidly.
Blood flow- poor circulation to the stomach as a result of shock, vasoconstrictor drugs or disease hampers absorption.
Surface area- drugs given IM absorb faster in muscles that have more blood vessels (DELTOID), than those that have fewer blood vessels.
Lipid solubility- the GI membrane is composed mostly of lipid and protein, so drugs that are lipid-soluble pass rapidly through the GI membrane. Water soluble drugs need a carrier, either enzyme or protein to pass through the membrane. Large particles pass through the cell membrane if they are non-ionized.
〽️Pain, stress and foods that are solid, hot or high in fat can slow gastric emptying time so drugs remain in the stomach longer.
〽️Exercise can decrease blood flow by causing more blood to flow to the peripheral muscle, thereby decreasing blood circulation to the GI tract.
Most commonly used as intramascular route because it has more blood vessel.
Deltoid muscles
Subcutaneous tissues has fewer blood vessels so absorption is slower in such tissue.
The process by which the drug passes to the liver first before going into the systemic circulation.
Fist-pass effect
Most drug given orally are affected by the first-pass effect.
Some drugs may do not go directly into the systemic circulation following oral absorption but pass from intestinal lumen to the liver via portal vien.
Drugs may be metabolized to an —inactive form— that can then be —excreted,— thus reducing the amount of active drug.
Some do not undergo metabolism at all in the liver. Others may be —metabolized to drug —metabolite which may be equally or —more active than the original drug.
It is the percentage of te drug dose that reaches the systemic circulation.
Bioavailability
___________ route always have less than 100% bioavailability.
E. oral
___________ route always have 100% bioavailability.
D. IV
What are the factors that affect bioavailability?
1.Drug form
2.Route of administration
3.GI mucosa and motility
4.Food and other drugs
5.Changes in liver metabolism caused by liver disfunction.
The process by which the drug becomes available to body fluids and body tissues.
Distribution
Drug distribution is influenced by
Blood flow
Drug's affinity to the tissue
Protein-binding effect
Volume of drug distribution is dependent on ________ and _______ in the body.
drug dose
concentration
Drugs with a larger Vd have a longer half life and stay in the body longer.
Drugs are bound to pair with protein, primarily ___________.
albumin
The portion of drug that is _________ because it is not available to receptors.
inactive
________ drugs are free and _______.
Only this drugs can cause pharmaceutic response.
Unbound
active
True or false
Drug bound protein cannot leave the systemic circulation to get to the site of action.
True
Author
wyn
ID
362738
Card Set
Drug Action: Pharmaceutical, Pharmacokinetic and Pharmacodynamic
