drug formualtuion Flashcards
what does hypoxia do
helps the tumour to grow and esacpe treatembts
what are the advantages of liposomes
they are easy and cheap to produce
what are the quailites of tumour vessles
- far apart
- serpertine formation
- variable blood flow
what are the factors in the microenviroment that affect the drug uptake and effectiveness in tumours
- angiogensis
-nutrients and oxygen uptake
-heterogeneicity of tumours
-cell prolifertaion rate
-intersistail fluid poressure
what factor is induced in low o2 levels
HIF-1, hypoxia inducible factor 1
what are the levels of O2 in hypoxic tumours
around 0.3%
what does hypoxa selecetd pressures increase
intrinsic resistance to antitumour immunity, or immunosupression and can increase therapuetic reistance
what is shunting
the blocking of the atrial part of into the venous part of the blood system without feeding the tissue properluy
what are the qualities of hypoxic cancer cells
- high HIF-1
-increased genetic instabilty
-influence ECM remodellinh
-altered angiogensis
-less suspectible to chemo and radiation
what biological marker is red and what does it do
Pimondazole - exogenous hypoxia marker
what biological marker is brown and what does it
BrdU- marker of DNA proliferation incorporates itslef into the DNA
What biological marker is blue and what does it do
Hoechst - blood perfusion marker, diffuses out of blood cells
how is HIF activated
through the stabilisation of the alpha subunit
how does HIF normally work
HIFa-> proline hydrolysis -> VHL mediated degradation
what is the startergy to expolit tumour hypoxia
exlpoit the reductuve enviorment by using drugs that are reduced to cytoxic speices in the hypoxic regions if tumours
what are the three main classes of hypoxia drugs
quinone antiboitics
nitroaramtics
di-N-oxides
what is an examamnple of a di-N-oxide drug and how dies it work
AQ4N
in healthy cells just stays in the cytoplasm and has a low tocixity
if hypoxic cells then AQ4N is taken up and converted to AQ4 which is highly toxic and has stroing binding to DNA
what does the upregualtion of EMT do
allows the tumour cells to be more plastic
how do you create hypoxic cells
leave them for 24-48 hrs in low o2 anymore and they will die
what cell culture can be used to look at hypoxia gradiatnets
spheirical
what do carbinaic anhydrases 9 and 12 do
upregulated by hypoxia
- involved in intracellular pH regualtion
-indirect cells extracellular acidification
what were the disadvatges of small molecule inhibitors for carbonic anhydrases
- weren’t specific enough
- had off target affects
what features do carbonic anhydrases inhibitors have
- zinc binding group- binds to the enzymatic domain
- tail creates more elctivity
- linker which spaces the zinc deep into the enzyamtic cleft
what is an example of a carbonic anhydrase inhibitor and what is its disadvangte
s4 and the disadvatge is it has a low uptake into the cells
how do you make CAi more affective for the isotopes
by changing the variable region
what are exmaples of nanoaprticles
liposomes
what are the advatges of liposomes
- increased stability via encapsulation
- can trap lipophilic and hydrophilic drugs
- less toxic to snesnitive tissues
-increased effficacy and theraputic affect - have flexibilty to couple with site spefic ligands to achieve active binding
- tehy are non toxic, biodegradeable, biocompatible and non immunogenic
what are the disadvantages of liposomes
- cost
- not all will be stable
- short half life
- somtimes lipids undergo oxidation or hydrolysis like reactions
- leakage and fusion of encapsulated drug
what are lipsomes made out of
cholestrol and phosphloplids
what is pahse transition tempertaure
the temperature required to change from a ordered gel phase to the disordered cystatline phase
what isthe major draw back from using liposomes more often
their instabilty
what are the stabilty asepcts of liposomes
- polar head
- chain length
- cholsterol: phospho lipid ratio
- PEGlated
- fatty acid chains
- degree of unsaturation
what does fatty acid chains do to help stabilty of lipsomes
reduces compactness
what does PEGlation do for liposome stabilty
stops recognition from the immune system
how does the chol: phospho lipid ratio help liposome stabilty
higher chol to phoso stabilises
how does the degree of saturation help with liposome stabilty
lipids with unsaturated acyls are suspectebible to degradation
what is passive intergration of drug to liposome
drug and liposomes are mixed together to get passive intergration and then gel filtration to get rid of the unbound inhibitor
how does the drug get intregrated into liposome with hydration
this is passive
- test the levels of chol:phopho
- mix them togetehr and let the solvent evaporate
- then hydrate with buffer for intergration
- extrude
- filtration chromotograhy
what size do you want the liposomes
between large unilamer vesicles and small unilamer
what is extrusion
when the lipsome suspension is passed through a membrane filter with a defined pore size. mikes liposomes smaller and more uniform
what extruder would you use in a lab
high pressure commerical extruder
what is active loading of the drugs
- liposomes are added to citrate buffer
- then Na2Co3 added and exchanged for the buffer this creates a proton gradinet
- then drig is added and exchanged into the liposome
what is the differnce between active and passive loading
passive laoding is during the fomration of the vesicle
passive loading is for hydrophlic or lipophilic drugs
active is a after the formation of the vesicle
active is for weakly acidic or wekaly alkaline drugs
what features are looked at with liposome characterissation
- size
- surface charge
- drug encapsulation percentage
- phase transition tempreature
- lipid phase transisiton
how is the size of liposome measured
static and dynamic light scattering
how is the drug encapsulation percentage measured
spectrophometry or flourecsnt spectroscopy
how is the surface charge measured
photon correlalation spectrascopy
how is phase transition tenmpreatyre measured
diiferential scanning calorimetry
how is lipid pahse transiiton measured
x-ray diffraction
factors affecting the passive uptake of liposmes
- vascualr permabilty
- level of angiogensis
- size of the nanoparticle
- physsiochemical properties
- intersistal fluid pressure
- lymphatic drainage
what does active uptake of nanoparticle increase
- accumulation
- specificty
- drug uptake
waht drug is 10 fld higher conc in liposome
daunoXone -> daunorubicin
what liposome incorporates doxicrubin
doxcil and myocet allows greater accumulationof doxirubicn with reduced cardiomyopathy
what is an example of a fucntionaliseed nanoparticle
liposome with retinoic acid loaded in them there is a greater uptake
