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year 3 exam 1 > biopharmaceuticals > Flashcards

biopharmaceuticals Flashcards

1
Q

what are the four barriers to oral drug delivery

A

physiochemical - pH/lipophilicity physiological - mucus clinical - disease states biopharmaceutical - efflux transporters

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2
Q

what is the role of mucus

A

ubiquitous protective layer against physical, pathogenic attack and lubrication

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3
Q

what is mucus made of

A

mucins, water, salts bile acids and proteins

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4
Q

what are mucins

A

highly o-glycosylated glycoproteins that are highly extended, free or membrane bound on epithelial surface

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5
Q

what type of mucus is found in the intestines

A

MUC2

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6
Q

what type of mucus is found in the airway

A

MUC5

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7
Q

what type of mucus is found in the cervix

A

MUC5B

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8
Q

what is the intestinal mucosa like and how does this affect drug delivery

A

SI - thin allows small molecules through LI - thick, nothing through need to create steep drug gradient at point of absorbance

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9
Q

what are the two approaches to getting drugs through the mucus layer

A

mucoadhesive and mucopenetrant

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10
Q

how do mucoadhesive drugs work

A

adheres to mucus as it moves down the GIT, released on the way

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11
Q

how do mucopenetrant drugs work

A

penetrates mucus to get to epithelium - requires nano-sized vehicle with stealth coating - such as PEG

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12
Q

what are the 4 routes of drug delivery from intestinal lumen

A

transcellular via passive diffusion paracellular via tight junctions transcellular via active transport lipid absorption via micelles/bile salts particulate absorption via GALT

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13
Q

how are drugs absorbed via transcellular via passive diffusion from the intestine

A
  • High conc on apical side of cell, low conc inside - Molecule moves into cell and then out the other side to bloodstream
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14
Q

how are drugs absorbed via Paracellular via tight junctions from the intestine

A

Tight junctions essential for GIT structure - tight junction proteins between cells, drug moves between those

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15
Q

how are drugs absorbed via Transcellular via active transport from the intestine

A
  • Molecule piggybacks into cell using transporter for natural substrates - Often against a concentration gradient - Restricted to specific segments of mucosae
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16
Q

how are drugs absorbed via Lipid absorption via micelles/bile salts from the intestine

A
  • Lipids hydrolysed by lipases to form mixed micelles of mono-glycerides, fatty acids and bile salts - Lipidic molecules absorbed either directly in micelle or by partition from micelle into the cell
17
Q

how are drugs absorbed via Particulate absorption via GALT (gut associated lymphatic tissue) from the intestine

A
  • Endocytosis via membranous cells in payers patches of GALT in SI- Subsequent absorption into lymph Eventual distribution into liver and spleen
18
Q

what types of drugs can be absorbed Transcellular via passive diffusion

A

neutral, unionised drugs high LogP - if too high will not pass out other side larger molecules can pass but they are slower

19
Q

what is the effect of a higher Log P on drug absorption

A

○ Decreased solubility ○ Increased plasma protein binding Increased binding to non-target sites

20
Q

what are three drugs that are absorbed transcellularly via diffusion

A

propranolol - LP: 2.6testosterone - LP : 3naproxen - LP : 3.3

21
Q

what types of drugs can be absorbed Paracellular via tight junctions

A

small hydrophilic

22
Q

what are two drugs that are absorbed Paracellular via tight junctions

A

cimetidine - LP : 0.4atenolol - LP : 0.2

23
Q

what types of drugs can be absorbed Transcellular via active transport

A
  • Levodopa/D-Cycloserine utilise amino acid transporters ACEi utilise oligo 2-3 peptide transporter
24
Q

what are three drugs that are absorbed Transcellular via active transport

A
  • Cefalexin (LogP : 0.7) - Levodopa (LogP : -2.4) - Captopril (LogP : 0.3)
25
Q

what types of drugs can be absorbed Lipid absorption via micelles/bile salts

A

poorly water soluble drugs

26
Q

what types of drugs can be absorbed Particulate absorption via GALT (gut associated lymphatic tissue)

A
  • Macromolecules - Microparticles (>10um)
27
Q

what two enzymes can reduce drug absorption in the gut

A

CYP and P-gp

28
Q

what does CYP do to reduce drug absorption

A

acts to reduce the amount of drug absorbed into the gut

29
Q

what does P-gp do to reduce drug absorption

A

ATP dependent, saturable efflux pump, pumps drug back into intestinal lumen

30
Q

what issues are associated with CYP enzymes

A
  • Many drugs act as a substrate, structurally diverseLarge interpersonal variation in levels of CYP3A4
31
Q

what are some cyp inhibitors

A

ketoconazole grapefruit juice

32
Q

what are some CYP inducers

A

rifampicin phenytoin dexamethasone phenobarbital

33
Q

what are some issues with p-gp

A
  • Structurally diverse substrates - Compounds can be both inducers and inhibitors - Overlap with CYP
34
Q

what inhibits P-gp

A

verapamil ketoconazole tweens PEGs

35
Q

what induces P-gp

A

rifampicin phenytoin dexamethasone phenobarbital

year 3 exam 1 (44 decks)

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