Term 2 Flashcards
the most important responsibility of the rxist with biotech products
patient counselling
how may pre filled syringes can you give out at a time and why
1 weeks worth, sterility issues
how long is reconstituted interferon stable for? CSF?
interferon for a month if refrigerated, CSF must be used within hours
how do you minimize biotech SEs
give 650mg acetamin 30 minutes before injection, and many symptoms will disappear. HS to sleep off effects also good
for product evaluation, to dtermie if the drugs are equivalent must determine the
type of host cell used to generate the rHu protein-will be needed to determine post translational modifications
the dose required to obtain therapeutic response may be different from the dose necessary for biologic response. This results in
SEs not commonly seen at physiologic concentrations
how do you provide information to co workers on new biotech
pharmacy in service programs, monthly newsletter or bulletin, continuing education
what is the shelf life of most biotech
doesn’t exceed 12-18 months, even less after reconstituted. Can be as low as 3 months (interferon)
what is the expiration date for reconstituted biotech
2-30 days range; may not contain preservatives and 8-72 hour dating may be necessary
how do you avoid biotech products adhering to packaging
coat with HSA (human serum albumin)- should be added to solution prior to drug
should use in line filters with biotech products
NO- significant loss of protein
how to add diluent into a vial
against the side no into the product
what does parenteral route include
IV, IM, SC, intraperitoneal
advantages of parenteral
avoid presystemic degradation ie first pass resulting in highest dose of protein in biological system
how to increase mean residence time of short half life proteins and what might occur
switch to IM or SC- but changes in disposition may occur (difference in exercise, massage, heat, state of tissue, blood flow), can also have enhanced exposure to degradation enzymes (can take lymphatic route), presystematic degradation, trauma from injection
when protein is given SC or IM, a fraction can enter the lymphatic system, this is determined by
molecular weight (size determines if its taken up by capillaries to enter circulation)
why is oral often preferred
patient friendly, no medical intervention to administer, cost effective
why does oral route have low F, when can we not use it
protein degradation in GI (endopeptidases) and poor permeability for passive transport (especially high MW) - can’t use when high or constant F is required
types of peptidases
pepsins (active between 3-5, lose activity at higher pH), those active at neutral pH (trpsin, chymotrypsin, elastase)
what is an exopeptidase? give an example
proteases degrading peptide chains at their ends, carboxypeptidase A and B (eXo carboXy)
methods to improve oral F
encapsulation with nanoparticles, chemically modifying AAs, coadministering protease inhibitors
for oral vaccines, why are hurdles of degradation and permeation not necessarily prohibitive
only a small fraction of the antigen has to reach its target to illicit an immune response (can use liposomes, modified live vectors, etc to help improve antigen delivery)
nasal route advantages, and issues
easily accessible, fast uptake, lower proteolytic activity vs GI, avoid first pass, spatial containment of absorption enhancers. Reproducibility and safety are issues, low F
which two methods are quite equivalent for F
lungs and IV
Buccal route advantages and disadvantage
A-accessible, lower proteolytic activity, avoids first pass, spatial containment of absorption enhancers, can remove D- low F
Rectal route advantages and dis
A- accessible, lower proteolytic activity, partially avoids first pass, spatial containment of absoprtion enhancers, d-low F
transdermal route A and D
A- acessible, avoids first pass, can remove, sustained/controlled possible, d-low F
which routes of administration avoid first pass
transdermal, IV, nasal, buccal, PARTIALLY rectal,pulmonary
which routes of admin can’t contain spatial containment of absorption enhancers
oral, pulmonary,
pulmonary route A and d
A- easy, fast, lower proteolytic, avoid first pass, D- reproducibility, safety
if systematic action is required, these routes have little clinical relevance especially if simple protein formulations without absorption enhancing technology are used
nasal, buccal, rectal, transdermal -F is just too low
mechanisms to enhance F of proteins to increasing permeability of absorption barrier:
add ons (Fa/phospholipids, bile salts, enamine derivatives of phenylglycine, ester and ether non ionic detergents, saponins, salicylate derivatives), iontophoresis, liposomes
mechanism to enhance F or proteins by decreasing peptidase activity at site of absorption and along absorption route
protease inhibitors, modify molecular structure to enhance resistance to degradation, prolong exposure time
iontophoresis (what it is and what it depends on)
transdermal electric current through two electrodes on two places on skin- ionized molecules migrate through skin. Depends on current (pulsed or direct), pH, ionic strength, charge, temperature
for iontophoresis, how should the protein be charged
over the full thickness of the skin
are there size restrictions for iontophoreses
not clear, we know it is primarily dependent on charge and only potent proteins will be successful candidates
what is the present flux through the skin for iontophoresis
10ug/cm2/hr
as a rule, proteins are administered in____, and only ______ are delivered as colloidal dispersions
aq solutions, recombinant vaccines such as insulin
what is a colloidal
chemical mixture in which one substance is dispersed evenly throughout another ex// milk
what is the only drug currently administered using controlled release system
insulin
what does addition of chemical moiety do to a drug? What is a common example of this
can change half life and tissue distribution, can limit side effects, be used for better targetting. PEGylation
what is PEGylation and what can it do
COVALENTLY attaching PEG to another molecule (or encapsulating it- shields it from immune system to prevent immune response), can increase solubilty in water, can add targeting molecules to the PEGylated drug as well, improves T1/2
controlled release systems for parenteral delivery are either
open loop (continusous infusion with pump or osmotically driven), closed loop (feedback system with a biosensor pump combo ad encapsulated secretory cells- primarily langerhan)
describe open loop systems
mechanically driven pumps for continusous infusions, can have pulsatile or variable rate delivery, can have flexible input rates
issues for selecting a proper pump
must deliver drug for extended length of time, be safe, convenient
what to consider when a pump must deliver for an extended amount of time
have wide range of delivery rates, ensure accurate and precise stable delivery, contain reliable pump and electrical components, drugs must be compatible with pump intervals and maintain stability, provide simple means to monitor status and performance of pump
factors to consider for pump safety
biocompatible exterior if implanted, fail safe mechanism, sterilized interiors and exterors (if implantable), show no leakage, have Overdose protection
for open loop osmotic delivery systems, how is rate determined? What should be special about the protein solution?
influx of water through a rigid, external semi permeable membrane; water empties drug reservoir and release rate depends on characteristics of semipermeable membrane and on osmotic pressure differences over the membrane. Solution must be compatible to pump parts its exposed to
for a pump to be convenient, it should
be reasonable small and inconspicuous, have a long reservoir life, easy to program
disadvantage of open loop
fixed release rate which is not always desired (specifically osmotic driven)
reasons to switch to an insulin open loop pump
less pain, fewer hassles, less life interference, convenient, more flexible, more control, more likely to maintain desired BG levels
potential problems with pumps
may fail because of energy, problems with syringe, accidental needle withdrawal, leakage of catheter, problems at injection or implantation site, long term stability of drug may be problem, pump still has to collect data to adjust rate (ie with insulin still must take BG), invasive sampling of body bluids on regular basis
what must a protein be stable at to be used in a pump
37 celsius or ambient temperature (internal and external respectively)
close loop delivery systems- why created
developed for goal of insulin injections based on current blood readings, doesn’t require patient to maintain proper BG, readings in real time and regulated totally internally
what must a closed loop delivery system contain
a known relationship between plasma level and pharmacological effect, biosensor (measure plasma level of protein), algorithm, (calculate required input rate), pump system to administer drug at required rate over prolonged periods, NOT biodegradable polymer
protein delivery by microencapsulated secretory cells- what has been a major goal
implant of Langerhan cells in diabetics to restore insulin production in biodfeedback fashion
what is needed for protein delivery by microencapsulated secretory cells
cells should be protected from body environment (avoid rejection) (also desirable to keep cells from migrating in all direction), thin walls, robust, biocompatible polymeric membranes (should ensure transport of nutrients from outside medium to inside cell to keep them physiologically healthy but prohibit induction of undesirable immune responses ie block Abs and immune system cells)
in the case of insulin, what must microencapsulated cells be permeable to
glucose and relatively small sized hormones that are essential for biofeedback process
what is a key ingredient in Alzet for continuous infusion?
osmotic agents
reasons why drugs fail
active compound never reaches target site (rapidly eliminated or inactivated), drug doesn’t enter cell (high MW or hydrophilic), only small fraction reaches target site (accumulation of drug at target site is the exception not rule)
we generally don’t and can’t inject directly to a target except
skin, bladder, peritoneal cavities
what is the goal of targeted drug therapy
maximize therapeutic effect and avoid toxic effects elsewhere by specific delivery to action site and keeping it there until it is inactivated and detoxified
progress in drug targeting can be attributed to
revealing nature of anatomic and physiologic barriers that hinder access to target sites, insights into pathophys of disease at cellular and molecular level (specific receptors and homing devices to target them ie Abs), more technology (liposomes, PEG, etc)
necrotic tissue can hamper access to tumor tissue
fact
two types of targeting
passive, active
describe passive targeting
natural disposition pattern of carrier system is utilized for site specific delivery- usually macrophages in contact with circulation and accumulate in liver (Kupffer cells) and Spleen
special cells in liver that can be targeted
Kupffer cells
describe active targeting
change device or homing principle to select one particular tissue or cell type
site specific delivery (active targeting) systems contain 3 units (what are they for)
active moiety (for therapeutic effect), carrier (protection and disposition), homing device (specificity, usually Abs, to target drug)
when to target drugs
high total clearance, site has low blood flow, increase in rate of elimination, toxic
to maximize target effect, release of drug from carrier should be restricted to
response compartment
examples of colloidal particulate carrier systems for targeted delivery of proteins
biodegradable polycyanoacrylate nanoparticles, polylactic acid microspheres, LDL, albumin microspheres, liposomes
in colloidal particulate carrier systems, what is the cut off size for permeation through batters
20 nm
what factors control fate of particulate colloidal carriers in vivo
size, charge, surface hydrophobicity, presence of homing devices
what happens to stable colloidal particulate systems with the cells of the mononuclear phagocyte system
if they are less than 5 um, they are recognized as foreign body like and phagocytosed
what happens to stable colloidal particulate systems when they are larger than 5um and IB injected
tend to form emboli in lung capillaries on first encounter with this organ
main component of liposome bilayer
phospatidylcholine
what can vary in liposomes (be specific)
siz (30nm-10um), charge (negative or positively charged lipids incorporated), bilayer rigidity (selecting different phospholipids or adding lipids like cholesterol)
when are homing devices not required to be covalently coupled to the outside bilayer leaflet of liposome? (and what is this phenomenon called)
if target tissue is liver (Kupffer cells), or spleen (macrophages) as this occurs by passive targeting
how to extend the normally short half life of liposomes in blood circulation to hours and even days and what happens to them
PEGylation chains grafted on surface and stable bilayer structures used- can escape macrophage uptake and are sequestered in organs other than liver and spleen alone
liposome encapsulated lymphokines (like interferon) and microbial products like MTP-PE can do what
activate macrophages and enable them to kill micrometastases or help stimulate immune reactions. Activating macrophages may also help fight macrophage located microbial/viral/bacterial disease
why do liposomes have poor access to targets outside blood after IV injection?
high resistance against penetration through endothelial lining and relatively short circulation time- we should use target sites in blood circulation or those in cavities so that we can locally administer it (bladder, peritoneal, etc)
advantages of liposomes as delivery systems
low toxicity, safe and experience, large aq core needed to stabilize many proteins, can manipulate their characteristics and control disposition by changing preparation techniques and bilayer constituents
examples of current liposome systems for delivery
amphotericin b, doxorubicin, daunorubicin
how to make monoconal Abs
start by immunizing mouse with antigen you want antibody to recognize, isolate antibodies from mouse spleen, fuse antibody forming cell with cancer cell to proliferate in culture (hybridomas), test to ensure specificity and efficiency
what can occur when cancer cell has been targeted by MAb
binding can illicit immune response (body kills cancer cells), drugs can be attached to antibody and delivered to cancer cell (resulting in cell death), binding to a receptor can prevent activation (turn off survival and growth signals to cell, block entrance or exit of specific molecules to prevent survival
what is the problem with mouse origin Abs? What can be done
can lead to problems in body such as production of HAMA (human anti mouse Abs) which may neutralize antigen binding site (prohibit further use of therapeutic MAbs). Can coadminister with immunosuppressant to minimize SEs, or use human MAb so no immune response (humanize mouse too)
what portion of the antibody does the human immune system recognize? What is this section needed for?
Fc (causes the problem and immune system responds), needed to kill the cell with an immune response so if you don’t use it must attach a mechanism to kill the cells or design to change cell metabolism
how to prevent production of HAMA
use only the Fab portion of antibody (but now must attach mechanism to kills cells or change cells metabolism), OR develop humanized or human MAbs
it is considered ethical to immunize humans and isolate spleens to prevent HAMA
no
how to make humanized Abs
build chimeric molecules with human Fc and mouse Fab, use human cells in culture to develop humanized Abs, completely human MAbs made my transfecting human antibody genes into mouse cells which will them produce human MAbs, transgenic mice can develop more humanized ABs
murine also means
mouse
chimeric means
partly human, partly murine
what is the in vivo target of liposome delivery
macrophages
which Ab recruits macrophages
Fc
how can liposomes be passively targetted to the liver
Kupffer cells
when can macrophages be activated to stimulate the immune system? (when liposome carriers are encapsulated with_____)
lymphokines
can liposomes be given orally
no
what is the FAB domain
antigen binding site, doesn’t cause HAMA
what is the Fc domain
complement cascade site, activates immune system, causes HAMA
why have bispecific antibodies been developed
enhance therapeutic potential of antibodies
what are bispecific antibodies
manufactured from two separate antibodies to create a molecule with two different binding sites; they bring target cells or tissue (one binding site) in contact with other structures (second antigen binding site)
what can the second antigen binding site on bispecific antibody do
bind to effector cells via cytotoxicity (triggers cytotoxicity) ex// T cell, NK cells, macrophages
what are autologous T lymphocytes
come from the same individual; cultured outside of body and expanded in presence of IL 2 (stimulated) and given back to patient
immunoconjugates- what are they and why are they used
combination between monoclonal antibody and active compound (usually drug known to kill cancer cells), developed because in many cases Ab or bispecific Ab alone lacks sufficient therapeutic activity. These are highly potent and toxic
what can go wrong with conjugating drugs to immunoconjugates
inactivate Ab (lose targeting specificity), cause worsening immune response, change PK profile or make toxic
what do immunoconjugates mainly focus on
cancer tx
what kind of drug need to be used for immunoconjugates to be successful
highly potent are needed to give sufficient therapeutic activity
not only existing drugs, but active drugs never used before because of toxicities should be reconsidered because of immunoconjugate technology
yes- we can conjugate them with Abs and make them more specific
examples of immunoconjugate toxins as chemo agents to treat cancer ie immunotoxins (and what they do)
ricin, abrin, diphteria- extremely toxic all block intracellular protein synthesis at ribosomal level
what does ricin bind to
it is an immunotoxin and it binds to galactose receptors
ricin has two chains- what are they and what are they responsible for
A chain blocks protein synthesis at ribosomes (ie is responsible for killing), B chain is important for cellular uptake of molecule (endocytosis) and intracellular trafficking)
how much ricin kills one cell
one molecule (minute quantities)
what is the main target for natural ricin, how much immuno conjugated ricin accumulates at tumor tissue, how do we fix this
-natural target is liver, only 1% accumulates in tumor, to minimize liver targeting block/remove/mask the ligands on the ricin for galactose receptors on hepatocytes
problems with immunoconjugates
covalent binding can change cytotoxic potential and decrease affinity of MAb for antigen, stability in vivo can be insufficient and fragmentation can lead to loss of activity and specificity, immunogenicity of MAb and toxicity of protein can change dramatically
factors that interfere with successful targeting of proteins to tumor cells
tumor heterogeneity, antigen shedding, antigen modulation
what is tumor heterogeneity and how do you overcome it
problem for successful targeting of proteins to tumor cells; hard to target because multiple receptors (make up of tumor cells is not constant) so not all tumor cells will react with one single targeted conjugate. Overcome by using cocktail of Mab or clone tumor to see what is exactly in it and design an antigen- but this is very expensive.
what are clone specific antigens
unique for the clone forming the tumor- problem when focusing on them is that each patient probably needs a tailor made MAb
what is antigen shedding and how do you overcome it
interferes with targeting of proteins to tumor cells; antigens are released form surface of tumor and can interact with circulating immunoconjugates outside the target area and form a complex which neutralizes homing potential of conjugates before target area has been reached. Target specificity is lost. Overcome- give Ab ahead of time by itself to bind to antigen shedding sites and saturate them, then give immunoconjugate (Ab with drug) and it will go to the tumor site
qhat is antigen modulation and how do you overcome it
interferes with targeting proteins to tumor cells; lose active receptors with time during treatment (surface antigen is not replenished); upon endocytosis of surface antigen immunoconjugate complex, some antigens aren’t exposed on the surface anymore an there is no replenishment, so immunoconjugate will no longer be recognized by tumor. overcome- look for a receptor that doesn’t undergo modulation
how to overcome problems related to tumor cell heterogeneity, shedding and modulation?
cocktail of MAbs, bystander approach induced (active part released from immunoconjugate after complex endocytosed and drug can be transported to neighboring cells), if shedding or modulation occurs choose different antigen/MAb combination, inject free MAb before immunoconjugate to neutralize free circulating antigen
why might not MAb conjugates pan out
tumor cell heterogeneity, poor access to tumors, immunogenicity
what two sites are recognized in bispecific Abs
tumor antigen, macrophages
ricin is taken up by endocytosis after binding receptors for
galactose
which organ is suitable for ex vivo gene therapy
liver
what is a glycoprotein
predominantly protein, and polysaccharide; a protein produced by an animal cell with a sugar moiety(s) attached
what is a preoteoglycan
predominantly polysaccharide (95%) and protein
what does glycoconjugate include
glycoproteins, glycolipids, and proteoglycans
bacteria can glycosylate
false- and non glycosylated proteins will often differ in their biological activity as compared to the active glycoprotein
why is there a huge amount of variability in glycobiology
the monosaccharide units can be coupled in so many ways- you don’t find this with AAs of proteins or nucleotides of DNA
there are ___(#) sugar commonly found in eukaryotes and they are
8: 4 alpha Ds (glucose, galactose, mannose, xylose), 1 alpha L (fucose), 3 N acetyl (alpha d glucosamine, alpha d galactosamine, alpha n acetlneuraminic acid aka sialic acid)
sucrose is a common monosaccharide found in eukaryotic glycoproteins
false- find fucose, galactose, glucose, n acetyl alpha glucose and galactose, xylose, mannose, and n acetylneruaminic acid (sialic acid)
for an oligmer with 10 bases (10 mer), how many linear oligomers that are structurally distinct are there for DNA, protein, and oligosaccharides
*6,13,18- DNA (4 possible bases) 1.04 x 10 6, protein (20 possible bases) 1.28 x 10 13, oligosaccarides (8 possible bases) 1.34 x 10 18
after the synthesis of glycans, what are they known as
secondary gene products
it is not possible to use recombinant glycan technology to produce large quantities of glycans for structural and functional studies
true
two types of glycans of glycoproteins (structurally)
O linked (aka mucins)(galactose), N linked (asparagine linked) (glucose)
o linked glycans structure
link between N acetylgalactosamine and hydroxyl group of either serine or threonine
n linked glycans structure
all are linked through N acetylglucosamine and the amide group of the amino acid asparagine. Asparagine (ASN)-any AA (not proline)- Serine or threonine
glycosylation does not affect biological activity
false- without these carbs attached, many don’t function therapeutically
what are glycoforms and what makes them different, give an example
variations in glycosylation patterns of a glycoprotein- may have different biochemical and physiochemical properties ex// erythropeoitin (one O link, 3 N linked)
what happens with the removal of terminal sugars at each site- what happens when you remove all sugar. What is the exception to this rule
terminal- destroys in vivo activity, all gives more rapid clearance and shorter T1/2. Exception= deglycosylation of hematopoietic cytokine granulocyte macrophage colony stimulating factor (GM-CSF)- removing carbs increasing specific activity 6 fold
what happens when you remove galatose residues from IgG
less effective binding to the first component of the complement cascade
n linked carbohydrates play an important role in what kinds of immunity
cellular and humoral
what is humoral immunity
immunity associated with circulating antibodies, vs cellular which in within the cell itself
sugars linked to proteins can help shield the surface of the glycoprotein from antibody recognition
true
what can sugars linked to proteins do
protect from antibody recognition, help recognize binding sites and binding of biomolecules
what is the name for the specific type of polysaccharide attached to proteoglycans
glycosaminoglycans (GAGs)
what can the GAG chain be made of
chondrotin 4 and 6 sulfates, dermatan sulfates, heparan sulfates, hyaluronic acids, keraton sulfates
what is the most abundant GAG and where is it found
chondroitin sulfate-cartilage, bone, and heart valves
where is dermatan sulfate found
skin, blood vessels, heart valves
what is a major component of the animal ECM
proteoglycans (it is the filler substance existing between cells in all organisms- they form large complexes with other proteoglycans, hyaluronan and fibrous matrix proteins such as collagen
what are proteoglycans involved in
major component of animal ECM, binding molecules and water, regulating movement of molecules through matrix, can affect activity and stability of proteins and signalling molecules in the matrix
what can individual functions of the proteoglycans be attributed to
protein core or the attached GAG chain
how are the protein core of proteoglycans made
synthesized by ribosomes within the cell, then moved to golgi to have glycon moieties added on, then secreted as the complete proteoglycan into ECM in vesicles
how many glycolipids (aa glycosphingolipids) have been isolated and identified from mammalian tissues
over 200
what are mucins generally linked to
serine and threonine residues
genetic variation or polymorphisms- what are they and how prevalent
variations in DNA sequences that occur in at least 1% of the population-most are due to single base differences
what are single base differences in DNA called, how often do they occur and what is most common
single nucleotide polymorphisms (SNPs), occur 1 per 300-1000 bps, 2/3 are cytosine to thymine
how many nucleotides does the human genome have- what does this mean for SNPs?
3 billion (about 3-10million SNPs are expected to exist between any two genomes)
what is SNP scoring
correlating the prescence of SNPs with disease etiology and drug response
what is a SNP map
cataloguing discovered SNPs within the human genome
what is the goal of pharmacogenomics
maximize drug response while minimizing adverse effects
give an example of a pharmacogenomic drug and what it is for
herceptin- used for metastatic breast cancer- give only to patients with HER2 (overexpressed in some tumors)- prescribing based on presence of this gene to predict drug efficacy (avoids giving to non responders and prevents exposure to life threatening SEs)
almost all of the hepatic CYP450 have genetic polymorphisms that influence ability to metabolize drugs
true
drugs affected by CYP2D6
BB (alter effect), antipsych (tardive dyskinesia), narcotics( SE), imipramine (change dose), tamoxifen (relapse breast cancer)
drugs affected by CYP2C9, 2C19
warfarin, omeprazole
who should you expose in clinical trials
least number of patients- more benefit decreased cost- limit it to those most likely to show response
what are benefits of pharmacogenomics to health care
more powerful medicines (facilitate drug discovery, more targeted, max benefit decrease damage, create drugs based on disease), better safer drugs the first time (speed recover, increase safety, AE risk eliminated), advanced screening for disease, decrease overall cost to healthcare (decrease AE/failed drug trials/time to get drug approved), more accurate methods of determining appropriate doses (base on genetics vs age and weight), improvements in drug discovery and approval processes (can revive previously failed candidates, target on people capable of responding)
