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What are factors affecting drug absorption?
- Rate of dissolution
- Surface area
- Blood flow
- Lipid SOlubility
- pH-partioning
- GI-hormones
- Nervous System
- Disease
- Drugs
- Food
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Onset is defined as:
rate of absorption
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What are the physiological processes in the GIT?
- Secretion: Transport of fluids, electrolytes, peptides, and proteins into lumen of GIT
- Digestion
- Absorption
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Where is most food absorbed?
Proximal area of the small intestine: duodenum
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Tell me about the buccal route of administration
- Good blood suppplyfast absorption of drugs
- Bypasses first pass effect
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What is the enzyme in buccal area that digests starch?
Ptyalin salivary amylase
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What protein is in saliva to help lubricate food?
Mucin a glycoprotein
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Tell me about esophagus absorption
Very thick very little absorption, no dissolution, short transit time
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Where does enzymatic digestion of proteins and peptide occur?
In the duodenum
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Where does maximum absorption
occur and why?
In the duodenum because there is a high surface area with the micro villi, villi, brush border and very good perfusion
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Tell me about the small intesine
- Long, highly vascularized
- High transit time
- Good adsoprtion
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Tell me about the colon
- Limited drug absorption, exception of sustained release
- Bacteria metabolism of drug , efflux pump
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Delay in gastric empyting causes what with regard to drugs?
- Delay in drug absorption
- degradation of acidic sensitive drugs
- Gastric irritation by drugs
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How does high fat containing food affect absorption of highly lipid soluble drugs?
Enhances absorption
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T/F food can affect the integrity of dosage form
T
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T/F Foods can cause dose dumping
T theo-24
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WHat does a high volume of fluid do to the stomach?
Distends the stomach and speeds up emptying
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What are methods of studying factors affecting drug absorption?
- Gamma scintograph, labels drug with gamma rays and use a gamma camera to track the drug
- Mannitol: effect small intestine transit time, reducig drug uptake
- Codeine: slows down the GI transit diminish drug absorption
- Lactulose: accelerates GI transit time, enhacer drug absorption
- Remote drug delivery capsule: cotains a pH sensor, and radio transmitter
- Osmotic pump system
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Pharmacogenomics
the study of genetically controlled variations in drug response/effect
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monogentic
Is due to allelic variation at a single gene
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Polygentic
due to variations at two or more genes
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POlymorphic
frequency occurring monogenic variant
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What are the factors that effect genetic polymorphism for pharmacokinetics?
- Transporters
- Plamsa protein binding
- Metabolism
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What are the factors that effect genetic polymorphism for pharmacodynamic?
- Receptors
- IOn channels
- Enzymes
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How will a fast acetylaters repond with hypersensitivity?
Decrease hyper
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How will a slow acetylaters repond with hypersensitivity
INcrease hyper
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How does food affect drug absorption? WHY??
- May decrease drug absorption
- Food Drug binding
- Can either increase or decrease drug absorption
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Why should some drugs be taken on an empty stomach?
- Food can decrease their absorption
- Food will delay their absorption
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What is the consequence of taking drugs with grapefruit juice?
There will be a greater plasma concentration
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What are the active ingredients in grapefruit juice to make them interact?
- Naringen, metabolized by enteral bacteria to NARINGENIN = a specific 3a4 inhibitor
- Furanocoumarins = cyp inhibitor
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What should patient avoid while taking benzodiazepines?
COFFEE cause an increase excitability decreasing therapetic effects
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What are the high risk pt?
elderly, multiple meds, multiple diseases, renal or liver
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WHat are high risk drugs?
- narrow therapeutic index
- Enzyme inhibitors and inducers
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What are two example of pharmacodynamic drug interaction?
- Increase toxcity of digoxin from diuretics
- Alcohol and benzodiazepines
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What is the defintion of pharmacodynamic drug interactions?
Drug a changes patient reponse to drug b without affecting pharmacokinetic of drug b
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What is an example of a drug interaction that can happen before administration?
IV compatability
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What is the definition of pharmacokinetic drug interaction?
A drug affects the ADME of another drug
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How can a drug alter its absorption?
- Changing the gi pH
- drug binding in the gi tract
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What are the two types of drug interactions?
- unidirectional
- bidirectional
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What is the example of drug inteaction that affects drug absorption that he keeps on talking about?
Ca and tetratcycline
Tetra forms a complex with Ca making it an insoluble complex
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What is an example of a drug interaction that affects drug elimination?
- Probenecid and pen vk
- INcrease in renal blood flow inhibition of active tubular secretion
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What are the diseases that he listed that affect drug absorption?
- Parkinsons
- Achalasia
- Achlorydria
- surgical conditions
- HIV
- CHF
- Crohns
- Celiac
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What are the drug classes that interact with other drugs absorption?
- Anticholinergic; slows gi motility, delay drug absorption
- Metoclopramide: increases peristalsis
- Antacids:
- Cholesteramine
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