drug absorption, pharmacogenetic and interaction
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What are factors affecting drug absorption?
- Rate of dissolution
- Surface area
- Blood flow
- Lipid SOlubility
- Nervous System
Onset is defined as:
rate of absorption
What are the physiological processes in the GIT?
- Secretion: Transport of fluids, electrolytes, peptides, and proteins into lumen of GIT
Where is most food absorbed?
Proximal area of the small intestine: duodenum
Tell me about the buccal route of administration
- Good blood suppplyfast absorption of drugs
- Bypasses first pass effect
What is the enzyme in buccal area that digests starch?
Ptyalin salivary amylase
What protein is in saliva to help lubricate food?
Mucin a glycoprotein
Tell me about esophagus absorption
Very thick very little absorption, no dissolution, short transit time
Where does enzymatic digestion of proteins and peptide occur?
In the duodenum
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
Tell me about the small intesine
- Long, highly vascularized
- High transit time
- Good adsoprtion
Tell me about the colon
- Limited drug absorption, exception of sustained release
- Bacteria metabolism of drug , efflux pump
Delay in gastric empyting causes what with regard to drugs?
- Delay in drug absorption
- degradation of acidic sensitive drugs
- Gastric irritation by drugs
How does high fat containing food affect absorption of highly lipid soluble drugs?
T/F food can affect the integrity of dosage form
T/F Foods can cause dose dumping
WHat does a high volume of fluid do to the stomach?
Distends the stomach and speeds up emptying
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
the study of genetically controlled variations in drug response/effect
Is due to allelic variation at a single gene
due to variations at two or more genes
frequency occurring monogenic variant
What are the factors that effect genetic polymorphism for pharmacokinetics?
- Plamsa protein binding
What are the factors that effect genetic polymorphism for pharmacodynamic?
- IOn channels
How will a fast acetylaters repond with hypersensitivity?
How will a slow acetylaters repond with hypersensitivity
How does food affect drug absorption? WHY??
- May decrease drug absorption
- Food Drug binding
- Can either increase or decrease drug absorption
Why should some drugs be taken on an empty stomach?
- Food can decrease their absorption
- Food will delay their absorption
What is the consequence of taking drugs with grapefruit juice?
There will be a greater plasma concentration
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
What should patient avoid while taking benzodiazepines?
COFFEE cause an increase excitability decreasing therapetic effects
What are the high risk pt?
elderly, multiple meds, multiple diseases, renal or liver
WHat are high risk drugs?
- narrow therapeutic index
- Enzyme inhibitors and inducers
What are two example of pharmacodynamic drug interaction?
- Increase toxcity of digoxin from diuretics
- Alcohol and benzodiazepines
What is the defintion of pharmacodynamic drug interactions?
Drug a changes patient reponse to drug b without affecting pharmacokinetic of drug b
What is an example of a drug interaction that can happen before administration?
What is the definition of pharmacokinetic drug interaction?
A drug affects the ADME of another drug
How can a drug alter its absorption?
- Changing the gi pH
- drug binding in the gi tract
What are the two types of drug interactions?
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
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
What are the diseases that he listed that affect drug absorption?
- surgical conditions
What are the drug classes that interact with other drugs absorption?
- Anticholinergic; slows gi motility, delay drug absorption
- Metoclopramide: increases peristalsis
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