L11 - Physiology of the Mouth and the Oesophagus - Absorbtion through the Mouth and Oral Problems

Question 1

difference between buccal and sublingual delivery

Answer 1

buccal through cheek

sublingual is under the tongue

Question 2

how does absorbtion takes place in the mouth

Answer 2

• drug needs to cross epithelium (oral mucosa)
• enters bloodstream directly

Question 3

what are the benefits of absorbtion through the mouth

Answer 3

• rapid
• results in greater bioavailability

Question 4

how does it result in the drug having a greater bioavailability

Answer 4

• does not need to go through the digestive system so avoids first pass metabolism
  
  • loss of drug during absorbtion via gut wall

Question 5

describe the oral mucosa

what are the 3 layers

Answer 5

• rich blood supply
• limited surface area
  
  • around 200cm²

Question 6

what are the consideration for buccal administartion of drugs

Answer 6

• drug must dissolv ein saliva so hydrophobicity is an issue
• need to consider swallowing reflex for buccal delivery
  
  • retention in mouth is important
  • taste must be bland
• SA is limited
  
  • around 200cm² compared to GI tract 350,000cm²
• must be kept in position
• must not irritate mouth

Question 7

what are the barriers to absorption

Answer 7

• drug must diffuse across lipophillic cell membrane and hydrophillic interior of the cell
• enzymatic barrier
  
  • aminopeptidase
  • present in buccal tissue
  • causes rapid degradation of peptides and proteins
  • limits transport across epithelium

Question 8

xerostomia

Answer 8

dry mouth

Question 9

problems with xerostomia

Answer 9

• can lead to oral ulcers and dental caries
• can affect digestion and drug absorption

Question 10

what is a potential cause of xerostomia and how is it treated

Answer 10

• side effect of drugs
• treated with an artificial saliva preperations
  
  • lozenge/spray/gel

Question 11

oral ulcer treatment

Answer 11

• usually clear up without treatment
• sometime require anti-inflammatory (corticosteroid) and anti-microbial mouthwash to prevent infection

Question 12

oral thrush

causes and treatment

Answer 12

• yeast infection
• caused by
  
  • over-use of antibiotics
    
    • wipes out healthy oral bactewria
  • poor immune system
  • underlying disease
  • smoking
  • dentures
• treatment aimed at reducing fungal infection using oral anti-fungal gel
  
  • e.g. miconazole and nystatin