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Healthy Body > SIU 1 GI tract And Metabolism > Flashcards

SIU 1 GI tract And Metabolism Flashcards

1
Q

What are cyclodextrins?

A

They are enzymatically modified starches

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2
Q

What are the three types of cyclodextrin? And how many glucopyranose units are there for each one of them?

A

Alpha, beta and gamma
Alpha cyclodextrin has a ring of six units
Beta has seven
Gamma has eight

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3
Q

What are the enzymes in stomach contribute to drug metabolism?

A 
HCl  
Pepsin ( protease ) protein into small polypeptides (stable)
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4
Q

Enzymes present in duodenum involved in metabolism

A

Trypsin, chymotrypsin, elastase, lipase, carboxypeptidase A B

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5
Q

Enzyme that present in SI?

3

A

Cytochrome P450 enzymes, particularly CYP 3A4 in upper epithelial cells
High conc of villus tips of the upper and middle third of the intestine

Esterase and glucurinosyl transferase, transfer glucoronic acid to nucleophilic sites on drug

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6
Q

Functions of the ANS

A

1) contraction and relaxation of SM in blood vessels and organ
2) regulation of glandular secretion ( endow and exocrine)
3) control of heart rate
4) metabolism

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7
Q

Effect of sympathetic nerve on pupils

A

Adrenergic R- contraction of radial muscle- dilate pupils

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8
Q

Which part of the body does cranial nerve controls?

A

Upper part

Eye, lacrimal gland, salivary gland, heart , lung, upper GI tract

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9
Q

Which part of nerve controls Lower Gi tract?

A

Sacral
Nervi erigentes
Via pelvic ganglia

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10
Q

How does sympathetic Nerve travel to target organ?

A

Preganglion projects to paravertebral sympathetic chain

Postganglion In sympathetic chain send long axonal projections that synapse on the target organ

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11
Q

How does parasympathetic nerve travel to target organ?

A

Pregang send long axonal projection to parasympathetic ganglia (in or near the organ)

Postgang send short axonal projection which synapse on target organ

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12
Q

What are the 2 types of cholinergic R?

A

Nicotinic

Muscarinic

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13
Q

What type of receptor is nicotinic R?

A

Ligand gated ion channel

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14
Q

What type of R is muscarinic R?

What are the 2 families?

A

G protein coupled R

EVEN and ODD

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15
Q

Muscarine poisoning lead to parasympathic rxn SLUDGE, DUMBBELS

A 
Salivation 
Lacrimation cry
Urination
Diarrhoea 
Gastric upset 
Emesis vomit 
Diarrhoea
Urination 
Miosis (pinpoint pupil)
Bradycardia (slow HR)
Brochoconstriction 
Emesis
Lacrimation 
Salivation
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16
Q

What’s is the pH partition hypothesis?

A

Drug accumulates on the side of the membrane where pH favours ionisation

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17
Q

What’s the limitation of pH partition hypothesise?

A

Doesn’t take into account of

Type of epithelium
SA if absorption site
IONISED drug will be absorbed to a small extent
Active transport of drug
Residence time of drug delivery sites
Mass transfer of fluid
CHARGED drug may form ION PAIRS with oppositely charged spp.- ideal for absorption!

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18
Q

What bond must be broken before drug enters the membrane?

How does it affect absorption?

A

H bond- the more H bonds there are, the more E needed to break bond- the higher the MP
The fewer the H bonds the easier the partition (CL rather than OH)

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19
Q

Lipinski’s rule of 5 only works on what type of drug? And what type of absorption?

A 
Oral 
Simple diffusion ( not involve biological transporters)
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20
Q

What’s the Lipinski’s rule of 5?

A

MW<500
0< LogP <5
H bond donor (NH,OH)<5
H bond acceptor (N,O) <10

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21
Q

What are the options for drug within solution category?

A

Elixirs- API in sweetened aqueous alcoholic vehicle

Syrups- Sucrose

Solution- aqueous

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22
Q

What is a suspension?

A

Fine particle of drug that are insoluble
Enables larger dose to be given
Immediate dissolution and rapid absorption
Good for children

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23
Q

What Are the 4 junctions involved in paracellular absorption?

A

1 tight junction (smallest) connection bw cell surface protein

2 adherence junction
Connection bw actin protein filament in the cytoskeleton

3 desmosome (most common)
Fibrous protein, anchor keratin filaments in cytoskeleton together

4 gap junctions (aqua pores)
Intercellular hydrophilic pores. Allows direct cell to cell electrical conductance

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24
Q

K - partition coefficient is largely affected by what which can be affected by what?

A 
Lipophilicity of drug
That can be affected by 
drug structure (with or w/o alky group attach) 
PH /ionisation 
Hydrogen bonding
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25
Q

How does surfactant affect on the diffusivity?

A

Reduced surface tension

Greater diffusivity

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26
Q

An example for prodrug increases permeability

A

Bacampicillin is an inactive prodrug of ampicillin but more lipophilic
Increase absorption
Breakdown by esterase to reveal active drug ampicillin

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27
Q

Other strategies (beside prodrug) that increase permeability of drug

A 
Lipidisation (covalently attach lipid to drug)
Penetration enhancer (partially solubilising the epithelial membrane to increase absorption )
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28
Q

Methods to improve absorption of drug (in drug design)

A

Prodrug -increase lipophilicity
P-GP inhibitor -prevent efflux pump
Mucoadhesive patches -drugs within mucoadhesive layer, bind to mucus hold the dosage form in place, increase residence time, insoluble coating ensures diffusions occur in one direction to epithelial membrane

Nanoparticulates -protect from acid
Cytoadhesion- targeting drugs to specific areas or cells in gi tract

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29
Q

What’s the advantage of the third generation of g GP inhibitor?

A

1st&2nd inhibit CYP3A4 causing reduced drug tolerance

Third more specific!!for the transporter. E.g. Topotecan and g gp inhibitor elacridar

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30
Q

What is solubility of absolute

A

The max conc of a solute that can be attained in a given solvent (unit vol) under given condition

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31
Q

What are the steps involved in decision tree of salt selection?

A

1) crystallinity (crystalline salt can be prepared)
2) hygroscopicity (salt can’t deliquesce at high humidity)
3) solubility
4) stability
5) polymorphism (final product)
If multiple polymorphs of salt
6) control (to produce desired form)
7) secondary/ final candidate

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32
Q

Describe the salt formation of drug

A

Solids phase :drug , counterion
Liquid phase : ionised drug, ionised counterion

Ionic interaction
- controlled microcrystalisation (vapour diffusion, vapour in eqm. 1) sitting 2) hanging drop

Drug salt

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33
Q

What’s the pKa change of the weak acid and base required for salt formation?

A

3

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34
Q

Pros and cons of pharmaceutical salts?

A 
Pros - enhance solubility 
Increase dissolution rate 
Easier synthesis and purification 
Better taste 
Improved photo stability 
High bioavailability 
Higher melting point 
Cons- decreased % of drug 
Increased hygroscopicity
Additional manufacturing steps 
Increased toxicity
Decreased Chem stability
No change in solubility at different pH in Gi tract 
Increase number of polymorphs
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35
Q

Define solution

A

Molecular dispersion formed by 2 or more components which form a one phase homogenous system

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36
Q

Define solvent

A

The component that determines the phase of the solution

-largest proportion of system

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37
Q

What are pyranose

A

Carbohydrates that have a chemical structure that include a six membered ring consisting of five carbon atoms and one oxygen atom

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38
Q

Describe the structure of a cyclodextrin

A

Cylindrical-Hydrophilic outer surface

Lipophilic nonpolar internal surface

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39
Q

Where can the lipophilic molecule binds to A cyclodextrin?

A

The lipophilic molecule can be accommodated wholly or partially in the Nonpolar cavity
The host and guest ratio usually one to one however one, two or three cyclodextrin molecule complexing with one or more drug is possible

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40
Q

What are the stages of cyclodextrin action

A

First, binding with poorly soluble drug

  • form crystalline complex
  • after five minute water dissolve- dissolution
  • dissociations
  • recrystallisation of cyclodextrin
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41
Q

Give an example of cyclodextrin in improving The solubility of drug

A

Beta- cyclodextrin improving the solubility of ibuprofen

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42
Q

What are the side effects of cyclodextrin?

A

Di-O-methyl beta-CD has strong affinity for cholesterol and is haemolytic however it is One of the best solubiliser

Overdose by increasing the solubility of progesterone -toxic

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43
Q

What is the surface activity of a surfactant?

A

The ability to reduce the surface tension at an interface without requiring large concentrations

The lower concentration required for a given effect, the better surface activity properties of a solute

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44
Q

Describe the molecular structure of a surfactant

A

Hydrophilic /polar head: unionic, ionic

Lipophilic/ non polar chain

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45
Q

What are the physical properties of surfactants solution at dilute solution?

A

They act as normal solutes (and normal electrolytes)

The amphiphiles exist separately and have ‘sub-colloidal’ size

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46
Q

What are the properties of surfactant Solutions at concentrated solutions?

A

Aggregate into micelles over a narrow concentration range, over 50 monomers
Size of colloidal -protein/ bacteria size

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47
Q

Define critical micelle concentration CMC

A

The concentration of monomer at which micelles form

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48
Q

Define aggregation number of the micelle

A

The number of surfactant monomers that aggregate to form a micelle

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49
Q

What is the Kraft point? Describe what happens at either end of KP?

A

Temperature at which the solubility becomes equal to the CMC (for a soap/surfactant)

At T< Kraft point, CMC> sol. No micelles formation

At T< Kraft point, CMC< sol. Micelles–> self solubilisation

Un-associated surfactant has a limited solubility micells are highly soluble and can accommodate a large amount of the surfactant

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50
Q

What would happen if T< Kraft point

A

The CMC > solubility

Micelles can’t form

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51
Q

What would happen if T> Kraft point

A

Surfactant forms micelles, self- solubilisation

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52
Q

Define solubility in quantitative term

A

The maximum mass or volume of solute that will dissolve in a given mass or volume of solvent at a particular temperature

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53
Q

How to increase the solubility of a drug and how to reduce it?

A

Use of the salt form

Esterification

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54
Q

What are the other purposes of esterification?

A

Mask the taste
Protect from degradation in GI (Erythromycin propionate instead of erythromycin -less soluble and less readily degraded)
Facilitate absorption from GI Tract (erythromycin propionate more readily absorbed- lipophilic )

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55
Q

How does Salt form increase the solubility of drug?

A

By increasing interaction with the solvent increase Solubility

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56
Q

What reactions belong to phase 1 metabolism?

A 
Oxidation, 
Hydration
Hydrolysis
Isomerisation 
Dethioacetylation
Reduction (rare)
57
Q

Where are CYP450 found?

A

Endoplasmic reticulum aka microsomes

58
Q

What are the other enzymes required in CYP450 reaction?

A

NADPH, O2, NADPH-cytochrome P450 reductase, lipid

59
Q

Where are the more selective CYP oxygenases (oxidase system) found in cell? And what they oxidise?

A

In mitochondria

Steroid

60
Q

What’s the most common type of oxidative rxn of an aromatic ring in phase 1 metabolism by CYP450?
Is the reaction specific?

A

Hydroxylation
Yes - stereoslective
Regiospecifc

61
Q

What would happen in metabolism of a chiral drug?

A 
Diff stereoisomers 
Diff drugs
Metabolised by diff enzymes (in CYP450 fam)
To diff products 
With diff kinetic
62
Q

What is cosolvency

A

For phenomenon where a solute is more soluble in a mixture of solvent then in one alone.

63
Q

What is a cosolvent

A

(In combination) increases the solubility of solute

64
Q

What are the purpose of cosolvency?

A

1) obtain aqueous based system in which the drug solubility is higher than the aqueous solubity
2) formulate higher conclusions of drug
3) improve stability of formulation

65
Q

What are the requirement to be a cosolvent?

A
  1. Organic compounds
  2. Miscible with water
  3. Better solvent than water for drug - H bond donor/acc
    - small CH chain
  4. Liquid -ethanol/ glycerol
  5. Or highly soluble solids -urea
66
Q

What is the effect of cosolvent on nonpolar semipolar and polar solute?

A

Increase the solubility of non and semipolar solute
Decrease the solubility of polar solute
As solute becomes more polar. Cosolvency becomes less efficient

67
Q

How does polarity of solution affects its surface tension?

A

The less polar the solution. The smaller the surface tension!
(Fewer interaction between molecules within the solution)
(Longer CH chain, greater tendency of adsorbing surfactant mol at surface)

68
Q

Define lundelius’s rule

A

Any factor that tends to decrease solubility of the surfactant promotes surface activity

69
Q

What is an emulgent?

A

Surfactant that are used to stabilise emulsions (each type of oil requires an emulgent of a particular HLB number)

70
Q

What is phase inversion temperature (PIT) of an emulgent?

A

T at which it changes from being an O/W emulgent (HLB 8-16) o an W/O emulgent (3-7)

71
Q

What are the treatment for peptic ulcer which belongs to H2 receptor antagonist?

A

Cimetidine- lots of interactions
Ranitidine
Famitidine

72
Q

What are the advantages of pharmaceutical oral solutions?

A

1 easier to swallow (elderly, infants)
2 faster therapeutic response
3 homogenous system- no issues with dose variation due to phase separation (on storage, unlike emulsions, suspensions)
4 reduced irritation, immediate dilution by gastric contents (aspirin tablet can irritate gastric mucosa if localised in one area)
5 taste masking

73
Q

What is the assumption on concentration of the suspension we made for sedimentation?

A

Dilute suspension < 2% w/v
Spherical particle uniform size
No P-P,P-medium interactions

74
Q

Are there any problems associated with pharmaceutical oral solutions?

A
  1. Problem with manufacture transport (leakage) and administration
  2. Growth of microorganisms
  3. Poorer stability of ingredients in aqueous solution than solid. Stability of excipients
  4. Shorter half life than solid dosage form
  5. Dose accuracy-patient using spoons
  6. Taste
  7. And suitable for drugs chemically unstable in water
  8. Expensive to ship, bulky to carry
75
Q

Methods for preparation of vehicle for oral solution?

A

Distillation, ion exchange or reverse osmosis

76
Q

The solid residue of the vehicle of an oral solution must be under what concentration?

A

Solid residue obtained after evaporation <1 mg/100 ml

77
Q

List 4 co solvents that are used in drug formulation for solution (increase sol.)

A 
1 glycerol 
2 alcohol e.g. Ethanol 
3 propylene glycol - lipophilic 
4 PEG :poly(ethylene glycol) -repeating units of ethylene oxide - hydrophilic 
PEG200,400
78
Q

What are the excipients used in pharmaceutical oral solutions?

A

1 buffer -control pH, acetates 1-2%, citrate 1-5%, phosphate 0.8-2%
2 sweeting agent -sucrose, glucose, aspartame (diabetes)
3 viscosity enhancing agent -non ionic: methylcellulose, PVP. ionic hydrophilic polymers: sodium alginate/ carboxymethylcellulose (anionic)
Or syrups (inherent viscosity)

79
Q

What’s the MIC of preservative?

A

Minimum inhibitory concentration required to inhibit microbial growth

80
Q

What are the three factors that directly affect the efficacy of preservatives in oral solution?

A

1 the pH of formulation
2 the presence of micelle
3 the presence of hydrophilic polymers

81
Q

Which form of preservative has antimicrobial property? IONISED or unionised?

A

Unionised form of acid

E.g. Benzoic acid

82
Q

What’s the mechanism of preservative in cells?

A

Diffuse across membrane in unionsed form , into cytoplasm
Neutral pH in cytoplasm
Enable acidic preservative to dissociate
Acidification of cytoplasm
Inhibit growth

83
Q

How does presence of micelles affect the preservative efficacy?

A

Preservative has lipophilic properties (cuz unionised form of acidic preservatives)
Partition into micelles
Reduced availability C of preservative in solution

Has to increase C of preservative, > = MIC

84
Q

How does presence of hydrophilic polymers affect the preservative efficacy?

A

Preservatives undergoes chemical reaction with dissolved polymer

Has to increase C of preservatives

Cationic hydrophilic polymers should not be used with acidic preservatives ( electrostatic interaction)

85
Q

What are the oral syrups components?

A

Purified water

Sucrose 60-80%
High conc of sucrose –> high viscosity, no sweetener/ viscosity modifying agents
–> reduced room for water , thus no addition of preservatives

Non sucrose bases : sorbitol solution 64%w/w

Flavours

Colours

86
Q

At what alcohol concentration does elixirs not need for preservatives? I.e. Already have antimicrobial property
An example?

A

> 12% v/v alcohol

Theophylline elixir -20%

87
Q

The cloud point applies to which type of surfactant?

A

Non ionic

88
Q

What would happen if there is an increase in temperature for non ionic surfactant? (Cloud point)

A

Dehydration of POE chains
Decrease water solubility
Formation of very large micelles
Solution becomes cloudy

89
Q

What’s the reverse process of forming cloudy large micelles solution called? Mechanism? For non ionic

A

Cooling
Formation of small micelles
Clarification

90
Q

Where are the histamine sources in body?

A

Tissue mast cells
ECL cells
CNS
Food: fish cheese salami

91
Q

Physiological roles of histamine?

A

Beneficial inflammation

  • supply plasma (antibodies and WBC) to tissues and organ
  • flush and remove parasites from gut

Gastric acid

CNS-awakefulness

92
Q

What are the pathophysiological roles of histamine?

A

Hypersensitive response:
Allergic rhinitis -hay fever
Urticaria -skin rush
Anaphylactic shock -food allergy

93
Q

What are the 9 ideal properties of preservatives?

A

1 Broad spectrum of antimicrobial activity
2 Rapid kill
3 Chemically stable and effective at product pH
4 Good solubility in water (where microbes grow), low sol in oil
5 compatible with formulation/ packaging
6 physically undetectable
7 constitute very small proportion of drug
8 safe
9 cost effective

94
Q

What’s the purpose of preservatives?

A

Reduce the risk of microbial contamination throughout product shelf life NOT to mask a poor manufacturing process

95
Q

What are the 5 factors affecting choice of preservative?

A 
1 Intended application 
2 No. and type micro-org present
3 Safety, stability and cost 
4 Micro- environment 
5 Properties of chemical agent
96
Q

What are the most likely contaminating organisms for oral products?

A

Bacteria: Escherichia coli, Staphylcoccus Aureus, Pseudomonas aeruginosa, Clostridium sp.
Fungi: candida sp, other fungi

97
Q

What are the rick factors of NAFLD?

A

1 obesity
2 type 2 MD (insulin R)
3 dyslipidemia (abnormal amount of lipids in blood)
4 metabolic syndrome

98
Q

What are the syndromes of alcohol induced acute hepatitis?

And at what point of drinking will the symptoms show?

A

Raised WCC- infection
Fever
Deterioration in clotting
Large rise in ALT - alanine transminase- liver enzymes in response to damage in hepatocytes

Comes on 5-10 days after cessation of drinking

99
Q

What are the sign for CLD?

A 
Jaundice 
Bruising- lack of clotting factor 
Spider naevi 
Dupuytren's contractures- scar tissues
Palmer erytheme-red palm
Gynaecomastia- man boobs
Ascites
100
Q

What is a lead compound?

A

Prototype chemical structure with desired biological activity

101
Q

Is omeprazole a racemic product?

If so, which is the chiral centre

A

Yes

The S atom is tetrahedral

102
Q

Which enantiomer of omeprazole has a better potency and PK profile? How does it relate to the patent of omeprazole

A 
S- enantiomer
S enantiomer is launched after omeprazole patent expired. 
Chiral switching
Extend the patent life time of a drug
Esomeprazole
103
Q

What’s the reason for S enantiomer of omeprazole having a better performance?

A

Less hydroxylation by CYP450
Reduced clearance rate
No difference in MOA

104
Q

What are the 2 main metab rxn for omeprazole?

A 
Benzylic hydroxylation (S 46%)
O-dealkylation (R 94%)
Metabolism is stereoselective
105
Q

Characteristics of bacteria?

A

No men enclosed organelles
Mircro m in size
Gram +be/ -ve
Mostly non pathogenic

106
Q

What are the components a gram +be bacteria has?

A

Peptidoglycan
Teichoic acid- anchor to cell
Lipoteichoic acid- anchor to bacteria mem
Cytoplasmic mem

107
Q

What are the components a gram -ve bacteria has?

A 
Much thinner peptidoglycan
Lipopolysaccharide LPS- cause fever
Porin- allow sm mol in/ out 
Outer mem 
Periplasm 
Cytoplasmic mem
108
Q

Why are biofilms such a problem?

A

More R to antibiotics (1000x)
More R to biocides ;bleach)
More difficult to phagocytose (embedded in slime)

109
Q

What microorganism can R sterilising process the most?

A

Porin

Gram +ve spores

110
Q

Describe the process of sporulation

A 
1 asymmetrical cell division 
2 formation of septum 
3 engulfment of spore (internalised)
4 additional cost &amp; proteins around spore 
5 cell lysis 
6 release of spores
111
Q

When does sporulation occur?

A

When nutrients run out n bac. Stops dividing

112
Q

What type of bac. Is Clostridium difficile?

A

Obligate anaerobic - only fire without air

113
Q

What are the properties of the spores of C. Difficile?

A

Can survive aerobic environment

Spores larger than mother cells

114
Q

What are the common preservative agents that are used in the UK?

A

Organic acid : Benzoic acid, Sorbic acid

Parabens; ester of p-hydroxybenzoic acid : propyl paraben

115
Q

What type of drug tends to be re-Absorber by the liver?

A

Lipophilic drugs

116
Q

Why are lipophilic drugs more likely to undergo enterohepatic circulation?

A

Intestinal wall is consist of long chain of fatty acid

Lipophilic drugs can re-enter the blood and go back to live by passive diffusion down concentration gradient

117
Q

Lipophilic or hydrophilic drug in general, which one of those has a longer half life? What’s the indication

A

Lipophilic
Greater toxicity
Side E

118
Q

What are the two types of peptidase?

A

Endo and exo
Endo: cleave from outside of the chain
Exo: cleave from middle of the chain

119
Q

Why do we have those exo and endo peptidase

A

Cleave for digestions and nutrition

120
Q

What is the concentration of any drug in our body

A

A drug has an affinity of nanomolar nM

121
Q

What is the concentration of GSH in our body?

A

1 mM

122
Q

Why can’t GSH get degraded by peptidase? Eg trypsin, chymotrypsin

A

Because GSH has gamma not alpha glutamine (stereochemistry

123
Q

What’s the MOA of El+ that can produce toxicity?

A

El+ react with nu- (on protein side chain)
Acylation of protein
Cytotoxicity

124
Q

What is mutagenesis?

A

Cancer

125
Q

What’s the causation of mutagenesis (relate to structure of DNA

A 
DNA and rna mol have many O2 and N atoms that are rich in LP
Nu- 
React with El+ 
Acylation
Mutagenesis
126
Q

What is the result of acylation for lysine

A

NH group react with el+

No longer be able to carry/ transport Vit B6

127
Q

How does GC separation occur?

A

Different vapour pressure of compounds (rate of evap.)

128
Q

Water octane ethanol

Place in order of increasing vapour pressure

A

Water ethanol octane

129
Q

What’s the relation between H bond and vapour pressure

A

More H bonds (OH, phenol, COOH)
Harder to evaporate (break the bonds) not volatile
Lower vap pressure

130
Q

How to improve volatility of compound with OH group?

A 
React w Me3SiCl trimethylsily TMS
Base Et3N
Form silyl ester - high MW 
fewer H bond 
more volatile
131
Q

How to improve resolution in GC?

A 
Lower temperature 
Longer contact time bw stationary (liquid) and mobile (gas) phase 
Bigger separation of peaks
Longer retention time
Greater resolution
132
Q

To increase peak separation in GC what factor should be changed? And in HPLC?

A

GC temperature ramp

HPLC solvent ramp

133
Q

What are the 3 ways of changing temp/ solvent?

A

Linear
Stepped
Convex/ concave

134
Q

What are the 2 characteristics of internal standard for HPLC?

A

Same chromophores

Similar chem structure

135
Q

Give examples for organic modifiers that can be mixed with water to give a solvent

A 
Methanol 
Ethanol
Propanol
MeCN
ACN- acetonitrile
136
Q

Explain what is SPE?

A

Solid phase extraction
Can be used to isolate analytes of interest from urine, blood, water
It uses the affinity of solutes in a liquid mobile phase and in solid stationary phase to separate a mixture into desired and undesired components
If the portion retained on the stationary phase includes the desired analyte they can be removed from stationary phase by rinsing it with an appropriate eluent

137
Q

What can b cyclodextrin also be used for?

A

Controlled release of drugs
Neural ph along the GIT
Constant release

138
Q

What does antioxidant do

A

Increase stability of drug. Oxidised in preference to drug protecting drug from decomposition

139
Q

Example of Preservatives

A

Benzoic acid and salts
Sorbic acid and salts
Alkyl ester is parahydroxybenzoic acid

Healthy Body (9 decks)

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