Enteral Routes Flashcards
Enteral drug administration
Involves absorption of the drug via the GI tract
Enteral drug administration via created tracts examples:
Nasogastric (reaching/supplying stomach via nose)
Nasojejunal (soft tube put in through nose that goes through stomach and ends in jejunum, part of small intestine )
Gastronomy (surgical procedure used to insert a tube for feeding/vent stomach for air/drainage)
Jejunostomy (surgery to create opening into sejunum)
Sub-lingual administration
Under the tongue
Buccal
Given between gums/inner lining of mouth check
GTN spray is used to treat? given via what route?
Angina via sub-lingual
Amylase
Break down carbohydrates
Lipase
Break down/ fat digestion
Mouth has pH of?
6
Drug goes to the oesophagus by?
Peristalsis - (series of wave-like muscle contraction that move food through the digestive tract)
Layers of the stomach and small intestine
Mucosa- lots of vili which increase SA
Submucosa
Muscle
Serosa
Pancreatic secretions contain alot of bicarbonates for?
Reducing acidity
Most drugs absorbed in?
Small intestine
Large intestine is responsible for?
Forming the remanence into faeces, which will then be excreted by the rectum and then the anus
Transcellular transfer of nutrients/drugs:
Paracellular
Diffusion through lipidmembrane/aqueous channels
Membrane transporter
Lipid solubility of a drug is dependent on?
Ionisation of molecules which is dependent on pH of the body fluid that the drug is in
Venous drainage from stomach and intestines goes into?
Portal vein, which then goes into the liver
First pass metabolism
When drug is metabolised in liver before going into systemic circulation
Lower third of rectum drains by middle and interior rectal veins. Why is this important for drugs given via rectal route?
Drain directly into the systemic circulation, bypassing the hepatic portal circulation
Majority of drugs absorbed in gi tract will pass through?
The liver
Enterohepatic recirculation
Process by which biliary excreted drug is reabsorbed in the intestine instead of being removed from the body. Can result in a lagging secondary absorption process and increases in drug absorption
For drugs with hepatic elimination, may be immediately excreted where?
In bile, then may be reabsorbed
Examples of enteral formulations
Tablet, capsule, liquid, foam, water, suppository (administer through rectum), granules, lozenges
Final stage in production of a medicine
Drug formulation (combining the active molecule with other molecules)
Difference in absorption of drugs administered by oral, buccal, sublingual and rectal routes
Oral- most absorbed in small intestine
Buccal, sublingual and rectal-direct absorption from check into systemic circulation
Drug factors
Concentration —> higher dose= higher/faster absorption
Formulation
Molecular size
Other properties - lipid solubility, pH
Gastrointestinal factors
-Motility affected by peristalsis
-Blood supply–> if low = less absorption into systemic circulation
- absorption surface
-Gastric content ( some drugs need food /empty stomach) + some drugs taken at the same time may interact
-Bile
- enteric bacteria ( gut bacteria = activate/inactivate drug)
enteral drug administration can be via:
oral
direct absorption
via created tracts
enteral drug administration via direct absorption: examples
rectal
buccal
sub-lingual
What is responsible for the initial breakdown of food and drugs?
mouth
Mouth contains what to help with breakdown of food and drugs?
saliva contains enzymes such as : amylase and lipase
Pathway of food/ drug to stomach
-Mouth responsible for initial breakdown of food/drugs
-drugs goes to the oesophagus via peristalsis
-drug ends up in the stomach where it is broken down by stomach acid
stomach acid pH? why?
1-3
protect against pathogens that cause infection & start denaturing proteins
bile emulsifies fat which is important for?
lipid soluble nutrients, drugs or vitamins
After drug absorption in small intestine, substance goes to where?
ileum –> large intestine —> rectum—> anus
Cellular physiology of small intestine
mucosal epithelium
intestinal villi
Transcellular transfer of nutrients/drugs
why is pH important?
for drug movement across the membrane: lipid solubility is dependent on ionisation of molecules which is in turn dependent on pH of the body fluid the drug is in
significance of portal circulation:
drugs can be hepatic metabolism or hepatic elimination
How ca motility affect the GI
if motility is slower, drug sitting in the lumen for longer –> need more time for it to absorb
