IDM Flashcards
How long could drug discovery and design and development take for one new drug ?
10-15 years
involves looking at 5000 - 10,000 compounds
costs 2B
What is the chronological order of developing a new drug and bringing it into the market ?
1) Pre- discovery
2) Drug discovery
3) Pre-clinical
4) Clinical trials
5) FDA review
6) scale-up MFG
7) Post- marketing surveillance
How long does each stage in the drug development process actually take ?
Drug discovery and preclinical is 3-6 years
Clinical trials is 6-7 years
FDA review and scale up to MFG is 0.5-2 years
Post marketing surveillance is indefinite.
How many phases are clinical trials made of ?
4 phases
if ya include PMS
how many volunteers in phase 1 clinical trials
20-100
how many volunteers in phase 2 clinical trials
100-500
how many volunteers in phase 3 clinical trials
1000-5000
how many compounds in drug discovery ?
5000-10000 compounds
how many of the compounds from “drug discovery” stage, go into “pre clinical” stage ?
250
How many compounds from the pre clinical stage, make it into clinical trials ?
5
How does disease tend to occur ?
When process in the body has stopped working
or when function is not normal
or when the body has become overactive
Hit molecule identification via
High throughput screening:
where many many compounds are held in these “compound banks” usually in pharmaceutical companies.
compounds are assayed against target to see if there might be a potential match.
Hit molecule identification via
“natural products” :
involves
organic compounds isolated from natural sources, that are produced by primary or secondary metabolism.
- no biological responsibilities in the host
- may lead to enhanced survival traits
What are the 5 “natural sources” :
Plant kingdom (plants)
microorganisms
Marine sources (aquatic life)
Animal sources
venoms and toxins
hit molecule identification via
“natural ligands”:
Molecules that already interact well with protein
can be chemically altered to generate “new hits” ( new matches)
For example, adrenaline and nor adrenaline helped with the development of salbutamol, dobutamine, xamoterol.
why might you have to modify exiting drugs even if they work well ?
For example,
If you would like for them to be consumed in a form that reduces toxic effects.
For example you may have a compound that is great at oral absorption, but intend for your drug to be an inhalation drugs, as this would be more effective at reducing toxicity.
One advantage of mustard gases ?
Mustard gases were further optimised to treat leukaemia
( condition where number of white blood cells increases rapidly)
What does “SAR’s” stand for ?
Structure activity relationships.
Whats the next stage after hit molecule identification ?
Lead molecule optimisation
Result of this is identity of 5 molecules with desired properties,
But not perfect.
Whats after lead molecule optimisation ?
Candidate selection stage
Brief description of “candidate selection” stage ?
This is where a molecule is selected for the “pre-clinical” stage
The main focus is to investigate toxicity
What does “candidate selection” stage involve ?
- in vitro tests on cells and in-vivo tests on animals
to investigate whether the compound has any effect on reproduction
and to identify potential carcinogens which would prevent any further development of the candidate.
- toxicity testing ( Acute toxicity and Long term toxicity testing)
Administering large doses to find out what the toxicity level is.
What is a “prodrug” ?
When a drug is “in-active” but after intake is METABOLISED into a pharmologically active drug.
( when metabolite formed is more active than the parent compound)
What’s another thing that is considered at the candidate selection stage ?
Formulation of the drug
combination of API
and
excipients
What is an “excipient” ?
An inactive substance that serves as the vehicle or medium for a drug or other active substance.
What are the 3 main regulatory bodies with regards to regulatory affairs ?
FDA USA ( Food and Drug Administration)
EMEA ( European Agency For the Evaluation of Medicinal Products).
MHRA (Medicines and Healthcare products Regulatory Agency)
Whats an “IND” ?
Investigational exemption to a New Drug application
Whats an NDA with relation to drug development process ?
NDA ( New Drug Application)
NDA will go to FDA
But an MAA ( Marketing authorisation application) will go to the EMEA.
( Large document with all the research)
What kinda drug tends to fly through drug development process ?
Orphan drugs
What is an orphan drug ?
New drugs that can treat diseases, that have never been able to be treated before.
What’s the final step for a medicine in the UK which has been successfully licensed and put on the market ?
Cost vs Benefit analysis
carried out by “ NICE”
national Institute for Health and Clinical Excellence.
- they decide whether the NHS should pay for novel drugs
- and decide if they are fine to be prescribed to patients or not.
What’s a novel drug ?
A drug that is molecularly distinct from prior drugs.
What is the general chronological order for “cheminformatics” ?
1) Candidate Drug library
2) Molecular modelling
3) Property profiles generated
4) Computational screening: to see if there or how much toxicity there is.
Advantages of cheminformatics ?
Fast
Low cost
Reduces animal testing
unsuitable cadidates ( too toxic) can be identified and rejected.
Can handle huge amounts of data
Disadvantages of cheminformatics ?
Predictions may sometimes be inaccurate
Need to develop/buy a arsenal of predictive models
complex software interface may put people off
Cheminformatics is not a “stand-alone” approach.
What is “repositioning” ?
Finding new uses for existing drug compounds
What is “orbital hybridisation” ?
When atoms hybridise ( Mix) in order to optimise geometry
And minimise the energy ( this is a good thing)
And produce orbitals with same energy level.
what are the 3 types of hybridisation states ?
sp, sp^2 , sp^3
Easy way to find out the hybridisation state of an atom ?
sp ^ (3-n)
Where “n” is the number of pi bonds associated with the atom.
what shape is 4sp^3 orbital ? (Hybridisation)
Tetrahedral shape 109.5 degrees
This shape allows the orbitals to be far apart from each other and therefore have the lowest possible energy.
What are sigma bonds ?
Single bonds
Are free to rotate
What are pi bonds
Double bonds
not free to rotate
What shape is 3sp^2 (Hybridisation)
Flat triangular shape
90 degrees
What shape is 2sp ( Hybridisation)
Linear
180 degrees
Briefly describe the structure of benzene ?
3 double bonds
3 single bonds
flat hexagonal shape
each bond in the same length
What is the hybridisation type of each carbon in benzene ?
sp^2
Is it good if the electrons are far apart from each other as possible ?
yeahhhhhhhhhhhhhhhhhhhhhhhhhhh
what is VSEPR theory ?
All it means is
Repulsion.
Resulting in electrons being far apart from each other as possible.
With regards to bond length, what does more “pi bond” mean ?
Decreased bond length.
more pi bond also tends to mean more “bond energy”.
What is “bond order” ?
The NUMBER of bonds between atoms.
What has greater bond angle, double bonds or single bonds ?
Double bonds.
due to greater repulsion
What are “structural isomers” ?
Different compounds with same molecular formula but different structural arrangement.
Stereoisomerism def ?
Same structural formula, different spatial arrangement.
What are the two types of stereo-isomers ?
1) Enantiomers
2) Diastereoisomers
Enantiomers def :
Non super imposable mirror images stereoisomers.
Is wedge line towards/away from you ?
WEDGE= TOWARDS
WEDGES COME TOWARDS US TO BE EATEN
Is dashed line towards/away from you ?
Away from you
What’s a “racemic mixture” ?
Contains 50% of each enantiomer
optically inactive
as they cant rotate plane polarised light.
What are a “pair of enantiomers” known as ?
Optical isomers
as they can rotate plane polarised light.
clock wise ppl rotation =
D enantiomer (+)
Anti-clockwise ppl rotation =
L enantiomer (-)
A sample that only contains ONE ENANTIOMER is known as what ?
homochiral / enantiomerically pure
what is a conformer ?
A compound that uses thermal energy to rotate it’s single bonds.
To visualise conformers we use New mans projection.
Difference between “conformation” and “configuration” ?
conformation is rotation of bonds
configuration is the breaking of covalent bonds.
What are the 2 different types of receptors that acetylcholine acts as ?
Nicotinic
and
Muscarinic receptors
how many conformers does cyclopropane have ?
ONE
chair vs boat (conformers) :
chair ( hydrogen more staggered/spread out)
boat ( hydrogens more eclipsed)
what are the 2 types of amino acids ?
L- amino ( Naturally occurring and are present in proteins, formed during translation in the ribosome)
D-amino ( rare and only found in some proteins by enzyme posttranslational modifications)
What are diasteroisomers ?
steroisomers that are not enantiomers
they idffer in physcial properties
How to find the maximum number of stereoisomers a compound can have ?
2n
where “n” is the number of chiral centres.
Solution def ?
A one phase system which consist of solute molecules dissolved in a solvent vehicle.
Solute def ?
A substance which is dissolved in solution.
Less solute than solvent present.
Solvent def ?
A substance that is used to dissolve a solute
Dissolution def ?
Mixing of solute and solvent to get solution.
What is an “amorphous solid” ?
Non - crystalline solid
- lacks order
If a substance is soluble in water, is it polar or non-polar ?
Polar
What is maximum solubility / equilibrium solubility ?
The maximum amount of solute that can be dissolved in a solvent under specific conditions.
Difference between molarity and molality ?
(solubility expressions)
Molarity: Number of moles of solute in one litre
Molality: Number of moles of solute in one kg
How does water get it’s polarity ?
The high electronegativity of oxygen compared to hydrogen, means that electrons are unequally shared, causing partial charges
giving water its polarity
How many “lone pairs” does water have ?
2
How many lone pairs on water are actually “available” ?
ONLY ONE
Non polar solvents:
Contain bonds between atoms with similar electronegativities
What are the 9 different factors that affect solubility :
1) Temperature
2) Kinetic energy
3) Pressure
4) Melting point
5) Molecular shape and symmetry
6) Molecular weight
7) Hydrogen bonding
8) Types of functional groups (Polar/non polar)
9) pH
How does an increase in temperature affect solubility ?
increases it
How does increase in kinetic energy affect solubility ?
increases it
By causing solute dispersion to increase and exposing solute to fresh solvent faster.
How does increasing pressure affect solubility ?
NO EFFECT, for solid and liquid systems
but there is for gases.
What does high melting point with relation to solubility ?
Normally compounds with a high melting point have LOW solubility.
Are symmetrical molecules more or less soluble than un-symmetrical molecules ?
less
- molecules pack closer together with stronger intermolecular forces
this results in higher melting points
which results in low solubility.
How does an increase in molecular weight affect solubility ?
Decreases solubility
Increasing molecular weight increases “non-polar” nature.
In pharmaceutical industry with regards to molecular weight and its affect on solubility, what is the rule of thumb ?
Less than 500 Da is low solubility.
More than 1200 Da should be avoided.
1 Da = 1 g/mol
How does hydrogen bonding affect solubility ?
Increased hydrogen bonding = increased solubility
How do polar functional groups affect solubility ?
Increase it
How do non-polar functional groups affect solubility ?
decrease it
they increase hydrophobic nature and disrupt hydrogen bonding with water.
What is “intrinsic solubility” ?
Solubility of unionised solute.
What are “colligative properties” ?
Affects solubility due to the AMOUNT of solute present, rather than the nature of the solid.
What are some examples of colligative properties ?
1) Lowering of vapour pressure
2) Increasing Boiling point and Decreasing Freezing point.
Osmosis def ?
Net movement of water from an area of high water concentration to an area of low water concentration across a partially permeable membrane, down a water potential gradient.
What is osmotic pressure ?
Pressure needed to stop movement of water.
What is “tonicity” ?
Overall
osmotic pressure gradient of both sides of the membrane
Hypotonic vs hypertonic vs Isotonic solution ?
Hypotonic- water will enter the cell and cell will swell and burst
Hypertonic - water will leave the cell and it will shrink and shrivel.
Isotonic- equal amounts of water entering and leaving cell.
Partitioning coefficient formula ?
P = (Non polar - polar) / polar
Log P
- Partioning coefficient only valid for solutes that are not charged.
Apparent partition coefficient :
Is for when the solute of interest is likely to be ionised instead of unionised.
Apparent partition coefficient equation ?
D = P x Fu
D (P app) = Apparent partition coefficient
P = Partition coefficient
Fu = Fraction of unionised drug
What is “Bioavailability” ?
Ability of a drug to be absorbed and used in the body.
What is one method of Log p determination ?
Shake flask method
What is the shake flask method ?
octanol and water are left to equilibrate
a substance is added
flask is shaken mechanically for less than an hour
and left to settle.
concentration of the substance in one solvent is found usually via UV spectroscopy.
Why is Octanol used in Log P determination ?
- used as the non polar solvent
- used because its structure represents the structure of a amphiphilic phospholipid ( phallic head and phobic tail)
- Log P can indicate whether or not a substance can pass through the phospholipid bi layer.
Amphiphilic meaning ?
Contains both hydrophobic and hydrophilic nature
E.g. phospholipids
What is the range of the dose administered in therapeutic dose ?
50 - 500 mg of API per dose
What actually is “pharmaceutical formulation” ?
Combination of API’s and Excipients
What are “excipients” ?
Inert ingredients, that are used to give the final dosage form ( tablet, capsule, cream etc).
Or to control characteristics of performance of the drug.
4 ways a drug can be eliminated from the body ?
1) Urine
2) faeces
3) sweating
4) exhaled air
Oral administration goes through what type of tract ?
GI tract
3 Advantages of oral administration ?
1) convenient
2) less expensive than other forms
3) Can be modified for extended release
Disadvantages of oral administration ?
1) Not good for unconscious patients
2) requires time for absorption and distribution
3) May be unable to swallow
4) Absorption time may be affected by the food eaten prior.
Common types of excipients used :
Write definitions for each
Filler ( Diluent)- bulk up the tablet
Binder- to hold tablet together and prevent breakage
Disintegrant- promote tablet break down
Glidant- to improve powder flowability
Anti- adherent- provide non-sticking properties
Lubricant- to help in manufacturing
Colourant- make visually appealing
Flavouring agent- improve taste
Filler:
Can increase size of tablets
- Lactose is the most common “filler”
- Filler may not be necessary is the dose of the drug is high
What’s a suitable replacement for the filler Lactose ?
Engineered xylitol
- Great excipient
Has been proven to produce tablets with improved physiochemical and biopharmaceutical properties.
Binder:
E.g. starch paste
Binders help to promote granulation.
Disintegrant :
Helps the tablet to break down into small fragments, when ingested.
- Helps the medicine to dissolve and be taken up by the body so that it can act more quickly.
Glidant :
Improves the flowability of the tablet granules or the powder, by reducing the friction between particles.
Preventing the formation of lumps.
One of the most common is “Aerosil” (0.2 % by weight).
Anti-adherent :
Stop powder from sticking to equipment as the tablet is made.
Lubricant :
Ensures that the tablet has a smooth surface
Reduce friction
Colourant :
Colours recognise your tablet
( Product identification)
More visual appeal
Flavouring agent :
Improve taste of the tablet
For chewable tablets or tablets that dissolve in mouth
- masks the unpleasant taste of API
Advantages of Capsules over liquid dosage forms ?
Lower cost
More stable
Longer half life
Advantages of Capsules over solid dosage forms ?
More elegant
Improved bioavailability
Versatile
Easily prepared and protected from light ( Due to the opaque shell).
3 Advantages of solutions ?
1) Fast absorption
2) Less GI tract irritation
3) Phase separation is not a concern
3 Disadvantages of solutions ?
1) Susceptible to microbial contamination
2) Possible hydrolysis of API
3) Unpleasant taste
What are Suspensions used for ?
Useful for administering insoluble or pooly soluble drugs.
Syrups :
Mask bad taste
Mainly administered to kids.
Used for coughs - Their viscosity allows increased “contact time” with affected areas.
Elixir :
Similar to syrups
Strong
Clear
Sugary - to mask the taste
LInctus:
Coats a soothing film over mucous membrane
Increases production of secretions
sipped slowly
What is Parenteral Administration ?
Any route of administration except GI tract
- Usually injection.
- systemic
whole body distribution.
Advantages of Parenteral administration ?
1) Drug doesn’t pass through intestinal tract
2) fast drug action
3) Eliminates many factors that may affect absorption rates
4) Suitable for unconscious patients.
Disadvantages of parenteral administration ?
1) Invasive
2) May introduce bacteria into the system
3) Painful or scary
What is Injection Fibrosis ?
Complication that may occur if the injections are delivered with
great frequency or improper technique.
Subcutaneous Injection:
Under the skin
Great method of administering insulin
Intradermal injection:
Top layers of skin
not as deep as subcutaneous injection
Intra-articular injection ?
Injecting into a “joint”.
E.g. knee joints
Intraperitoneal injection ?
Injection into the abdominal cavity