PHARMACOKINETICS
is the study of drug movement throughout the body. It involves 4 processes:
1. ABSORPTION
refers to what happens to a drug from the time it is introduced to the body until it reaches the circulating fluids and tissues.
Areas where drug can be absorbed:
GI tract (oral/rectal)
mucous membrane
skin
lungs
muscle
subcutaneous tissues
Factors Affecting Drug Absorption in the body:
a. Circulation/blood perfusion on the site of absorption
- poor circulation due to shock, vasoconstrictor drugs, or disease hampers absorption
b. Temperature
- cold causes vasoconstriction and decreases absorption; heat causes vasodilation and increases absorption
c. Drug Solubility
- the quality or condition of being soluble or the amount of a substance (water/oil) that can be dissolved in a given amount of solvent.
Lipid-soluble drugs can be easily absorbed than water-soluble drugs that usually need a carrier to be able to pass through lipid membranes.
d. Rate Limiting
Disintegration - the breakdown of a tablet into a smaller particles
Dissolution - dissolving of the smaller particles into the GI fluid before absorption; the rate of dissolution is affected by the acidity of the GI tract.
e. Route of administration
IV drugs are easily absorbed than IM, SQ and oral drugs.
ORAL MEDICATION ABSORPTION
IV MEDICATION ABSORPTION
f. First-pass Effect
-the process in which the drug passes to the liver first, which results to a large percentage of the oral dose being destroyed, never reaching the tissues.
2. DISTRIBUTION
the process by which the drug becomes available to body fluids and body tissues.
FACTORS AFFECTING DRUG DISTRIBUTION
DRUG-BINDING
NICOTINE RECEPTORS IN THE BRAIN
3. METABOLISM (BIOTRANSFORMATION)
- process by which drugs are changed into new, less active chemicals. Liver is the primary site for metabolism.
Most drugs are inactivated by liver enzymes and are then transformed by hepatic enzymes to inactivate metabolites or water-soluble substances for excretion.
4. EXCRETION
-refers to the manner at which the drug leaves the body.
BN 221, please post your reflections on the comment box.
nice video clips,well explained.On the oral medication shows and explain how the drug transport to the G.I tract,when the drugs already in the stomach only the acidic been absorb because our stomach have an acid.the alkaline drugs can't be absorb by the stomach.On the I.V medication absorption show's the first- pass effect when giving an i.v through the venus blood pass through bracial to the forearm and then going to the right side of the heart. In the drug binding,shows how the drugs enter to the cell membrane...The nicotine receptors in the brain video show's the bad effect of the nicotine when enters to the brain.through airway were the air pass going to the lungs and then pass through he alveoli and so on and so forth...until it reaches the brain.through this video explaining the drug absorption,drug distribution,drug metabolism and drug excretion..
ReplyDeletethe video emphasizes on different types of drug absorptions inside the body system.the action of drugs as it enters the mmouth down to the stomach and so the process of drug starts to work in different parts of human organ.the iv insertion and its fast effectiveness inside the system.and the video tells that drug dependency is not good in the body.and what calls my attention is how the nicotine works in the brain and its dependency.smokers are not aware of this dangerous effect of the nicotine in the brain but they tend to play safe only to find out that this nicotine destroys their systems.its really knowledgeable and supplementary to my own learning. i appreciate the video very well.
ReplyDeletethe video shows the route of administration,the drugs enter into the stomach and it develop inside.the acidic can only absorb into the stomach because of the acid content inside nor the alkaline are cannot absorb into the stomach.some drugs are catalyze into the liver.the iv insertion is the most fast and effectiveness drugs that enter in our body.from the brain videos the nicotine has the bad affects in our brain,because nicotine is a harmful substance that contained a tobacco.that can damage to our brain and to our health too.
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