Pharmacolgy Flashcards
Pharmacology
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Pharmacokinetics
What the body does to the drug
Pharmacokinetics - 4 process
- Absorption
- Distribution
- Metabolism
- Excretion
Oral - absorption
- Drugs need to be in a solution for it to be absorbed
- 1st the solid drug requires breaking into smaller particles = DISINTEGRATION
- 2nd the particles are dissolved into a solution = DISSOLUTION
Pathway for the Drugs
Stomach/ intestine - muscle walls - vascular - liver - distribution
Factor that affects absorption (oral)
Perfusion (blood flow)
Barrier
Presences of food in the stomach
Empty stomach
Acidity of the stomach
Presence of interacting drugs
Factors that affect absorption ( rectal / vaginal / urethral )
Perfusion
Barrier
Length of time retained
Factors that affect absorption ( mucous membrane – sublingual / buccal cavity )
Perfusion
Barrier
Length of time retained
Integrity of membrane
Factors that affect absorption ( IM / SC / IV / ID )
Perfusion
Fat content
Temperature
Injections
Intra Muscular ( 90 degrees ) Subcutaneous ( 45 degrees ) Intra Venous ( 25 degrees ) Intra Derma (10-15 degrees )
Skin layers
Epidermis
Dermis
Subcutaneous tissues
Muscle
Factors that affect absorption ( inhalation )
Perfusion
Integrity
Technique
Factors that affect absorption ( topical )
Perfusion
Integrity
Dose
Distribution
- Majority of drugs need to be transported to their point of action
- Majority of drugs are carried systematically by the plasma proteins in the blood
Metabolism
- Drugs need to be broken down / repackaged enabling to the body to eliminated them
- Majority of the drugs are metabolised in the liver however this occurs in the lungs, skin and kidneys
Elimination
Kidneys – URINE
GIT – FAECES
Lungs – EXPIRING
Glands – MILK
Drugs can be administered - 3 ways
1) Enteral
2) Topical
3) Parenteral
1) Enteral - enters the body
Mouth
Rectal
Urethral
2) Topical - on top of the body
Inhalers
Lotions / creams
Ointment
Patches
Parenteral
Injections
IV / SC / ID / IM
Sublingual – under the tongue
Buccal cavity – in the cheek
Drugs that goes in the sublingual & buccal cavity ….
Doesn’t get absorbed into the GI system the drugs instead get absorbed directly into the vascular beds under the cheek / under the tongue
Digestion - 1st pass effect (oral)
- Drugs that go to the stomach have to broken down which is called DISSOLUTION
- The drug then gets broken down into smaller particles so that it can be absorbed by the body
- BIOTRANSFORMATION occurs in the liver where the drug is further broken down into METABOLITES that can be used to the treat the body
Absorption (oral)
- The metabolites crosses into the bloodstream then travels to either the kidneys and are eliminated or travels to the tissues receptors and treat the part of the body that needs the drug
- RECEPTORS are structures in the cell that tell the cells what to do
Elimination (oral)
Most drugs are eliminated through the kidneys
• But people with kidney damage / disease can’t effectively eliminate the drug properly so the drug builds up in the body
Absorption - Topical / Parenteral
Topical-
Subcutaneous-
IM- medication is absorbed through the outer layer eg. skin / fat tissues / muscle
IV- medication is given directly through the vein and straight into the bloodstream
ID-
Biotransformation - Topical / Parenteral
Occurs into the liver
Elimination- Topical / Parenteral
Occurs into the kidneys
Speed of absorption- Topical / Parenteral
Depends on the route of administration for example intravenous is the quickest route for the drug to travel to the bloodstream
Distribution
•Drugs are distributed and transported throughout the body via the blood
There are 3 things that affect the drug distribution to the body
1) Protein binding
2) Lipid solubility
3) Circulation
1) Protein binding
- the protein “ ties / blinds” on the drug
- if a drug is bound by protein its not available to treat the body
2) Lipid solubility
- the cell membrane has a high lipid concentration
- highly lipid soluble drugs pass more easily through the cell membranes
3) Circulation
- drugs rely on circulation to get to the target tissue
- blood volume will make a huge difference low blood volume means that not a lot of blood is being delivered to the target tissues
- vascular resistance the constricted vascular space ( narrow blood vessels ) / small spurts of blood gets into the tissues at a time
- cardiac output means that the heart is not effectively pumping a lot of blood to circulate around the body so the drug isn’t be circulated around the body to get to the target tissue
Pharmacodynamics
The effects of the drug on the body
