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What is Transdermal Products?
- Administered through a patch.
- Negative effect: it could be washed off. Allergy to the sticky parts. It needs to be careful when dispose.
- It acts with diffusion ( High concentration to Low concentration.
- ex) Nicotine patch
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Oral Administration
- Most common, involves taking medication from the mouth.
- Safest and most convinient route.
- Food/empty stomach can effect absorption.
- Ease of removal of OD(Over dose)
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Parenteral Administration
- is any route that does NOT involve the GI tract. This includes IV, IM, inhalation, topical, etc.
- fastest rout = IV/IM
- IV/IM have increased risks such as infection and overdose.
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What is drug administration?
This referes to the entrance of a drug into the blood stream.
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How drugs pass through membranes?
- by Passive transport, Active transport(require ATP)
- Filtration after it has been dissolved in body fluids.
- Passive transport: drug molecules pass from an high concentration to a low concentration
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Active Transport
involves the use of ATP - energy to bring drug into blood.
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What is the speed and rate of transport of the drug dependent on?
Lipid solubility and the degree of drug ionization
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How does Lipid Solubility affect to the drug absorption?
Since the cell walls are comprised primarily of lipids, the more lipid soluble the drug is, the faster it will pass through the membrane.
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What are most drug's solubility?
Primarily water soluble & partially lipid soluble
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What influences the absorption of water soluble drugs?
Degree of drug Ionization
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What form of drug is being absorbed the best?
Unionized (uncharged) form of the drug that is required in order for absorption to occur.
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When are Acid drugs most absorbed?
- Acid drugs are most unionized when they are in stomach acid, as a result drug absorption is favored.
- Acid drugs are most ionized theyn they are in an alkaline environment so absorption is not favored.
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When are the Basic drugs most absorbed?
- Basic drugs are mostly unionized when they are in an alkaline fluid (Lower GI tract) = absorbed well.
- Basic drugs are ionized in the stomach, so it isn't absorbed fast.
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What form of drug do kidneys excrete?
Ionized form
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In order to increase excretion of an acidic drug, is urine acidic or alkalized?
- Alkalized - to because acidic drugs are mostly ionized and rapidly excreted.
- Basic drugs are unionized
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What happens after drug is absorbed into blood?
ditributed to various tissues and organs
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What are the 3 factors that determine how much drug reaches the organ/area?
- Plasma Protein Binding
- Blood Flow
- Blood Brain Barrier
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What does Plasma Protein do?
- Helps regulate osmotic pressure, transports hormones and vitamins.
- Many drugs are attracted to Plasma Protein
- Increase concentration of free drug (unbound=exert a pharmacological response) --> incease pharmacological effect
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Blood Flow
Various organs in body receive different amounts of blood.
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What are the 3 organs that have the largets blood supply?
- Liver
- Kidney
- Brain
- --> they are exposed to the largest amount of drug
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How is the blood flow of Adipose tissue?
- Low
- --> Less chance of accumulation except for highly lipid soluble drugs
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What is Blood Brain Barrier?
- A barrier that protects the brain by restricting the passage of electrolytes and other water soluble substances.
- Encases the brain and Spinal cord
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What is Blood Brain Barrier composed of?
- Lipid
- --> Lipid soluble drugs readily pass through
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Drug Metabolism?
- - is also known as Biotransformation.
- - Body's attempt to eliminate a foreign substance by chemically altering (変える) before it is excreted.
- * benefit of drugs that don't transform --> longer duration of action ex) UTI. the drug is excreted w/ urine.
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Which organ is mainly involved in drug metabolism?
Liver
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What is the enzyme in the liver?
Drug Microsomal Metabolizing System
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What is Drug Microsomal Metabolising System?
- This system is to take Lipid soluble drugs and chemically alter them so that they become water solule
- --> b/c only water soluble compunds can be excreted by the kidneys.
- --> Lipid soluble compounds that are left are repeated reabsorbed into the blood.
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What is Enzyme induction?
- increase in the amount of drug-metabolizing enzymes after repeated adinistration of certain drugs.
- --> as a result, you get faster rate of drug metabolism.
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In an event there are other drugs that need to be metabolized, what can occur?
- The duration of all the drug that must be metabolized is decreased.
- The other drugs will NOT get a chance to be metabolized & can cause an increase in the level of drug circulating in the blood.
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What is First Pass Effect?
- After oral administration, all drugs are absorbed into portal circulation
- Some drugs can be metabolized when it first enters the liver and therefore reduces the amount of active drug that reaches the general circulation.
- 90% of oral drug get destroyed and metabolized by liver before it gets to the heart.
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Common pathways of drug excretion
- Renal excretion: Urine
- GI excretion: Fecal
- Respiratory excretion:
- Misc: sweat, saliva, tears, other body fluids
- Through the placenta during pregnancy
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Renal excretion
- Blood is filtered through the glomerulus & nephrons of the kidneys
- Most filtered substances are reabsorbed into the blood except urinary waste and other unabsorbable products
- Drug/drug metabolite must be in Ionized form. (Water soluble form)
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