Advanced Drug Delivery Flashcards
What does drug delivery/ targeting mean?
Delivery of a drug to its precise site of action at the right concentration for the right time
What are conventional dosage forms?
Drug release/ drug plasma levels depend on the physicochemical properties of the active ingredient
What are non-conventional dosage forms?
Drug release/ drug plasma levels are determined by the technological characteristics of the formulation (e.g. modified release)
What type of dosage form is ‘modified-release’?
Non-conventional
Can dopamine cross the blood brain barrier?
No
In what terms can a drug be ‘modified’?
(1) Rate
(2) Time
(3) Space
Why can L-DOPA cross the blood brain barrier where dopamine cannot?
Carboxylic acid group has been added
Is an amino acid
What are some ways in which ‘rate’ of a drug release can be changed?
(1) Very fast release
(2) Sustained release
How may ‘time’ of a drug release be changed?
When release starts after a certain time following administration
How may ‘space’ of a drug release be changed?
Occurs in specific areas/ tissues
Targeting
Who is Paul Ehrlich?
Nobel prize winner for medicine in 1908
Worked in field of immunity
What is the objective of drug targeting?
Localise and concentrate drugs to the desired therapeutic site, avoiding all other tissues in the body
i.e. pharmacological response without the side-effects
What is first order drug targeting?
Organ/ tissue specificity
What is second order drug targeting?
Certain type of cell specificity
e.g. tumour cells
What is third order drug targetting?
Intracellular compartment specificity
e.g. lysosomes
What are three approaches to drug targeting?
(1) Magic bullet
(2) Prodrug
(3) Macromolecular carrier
What is the ‘magic bullet’ approach to drug targeting?
API is potent + selective
What is the ‘prodrug’ approach to drug targeting?
Inactive prodrug
Activated to drug in site of action
What is the ‘macromolecular carrier’ approach to drug targeting?
Carrier transports the drug to desired site of action
What drug targeting approach do monoclonal antibodies largely align with?
(1) Magic bullet
(2) Macromolecular carrier
When were monoclonal antibodies first introduced?
1975
What types of monoclonal antibody are commercially available?
(1) Diagnostic agents
(2) Therapeutic agents
Why is drug targeting of bacterial cells easier than that of cancer cells?
Bacterial cells have many differences to human cells
Cancer cells are very similar
Who coined the phrase ‘magic bullet’?
Paul Ehrlich
Medicine nobel prize winner
What is the difference between a polyclonal antibody and a monoclonal antibody?
Polyclonal: Multiple antigen targets
Monoclonal: Single antigen target
What was the first monoclonal antibody to reach the market?
OKT3
Anti-CD3 antibody
What is OKT3 used for?
Prevent rejection of kidney transplants
What is abciximab?
Monoclonal antibody
Used for prevention of cardiac ishaemic complications
What is trastuzumab?
Monoclonal antibody
HER-2 positive breast carcinoma
What is Herceptin?
Trastuzumab monoclonal antibody
What is ReoPro?
Abciximab monoclonal antibody
What is the principle of monoclonal antibodies as imaging agents?
mABs against tumour-associated antigens have been developed
mABs are conjugated with a diagnostic imaging agent
What are some available commercial products of monoclonal antibodies as imaging agents?
(1) Oncoscint
(2) Prostascint
(3) Myoscint
What is oncoscint?
Monoclonal antibody
For imaging of colon and ovarian cancer
What is prostascint?
Monoclonal antibody
For imaging of prostate cancer
What is myoscint?
Monoclonal antibody
Cardiac imaging
What is an antibody?
Protein
Produced by the body
As a result of exposure to an antigen
What is a prodrug?
Chemically/ pharmacologically inactive derivative of the drug
Undergo action at the target site
How many chains are there in an antibody?
4 chains
2 light
2 heavy
How are the chains of an antibody connected?
Disulfide bonds
What happens to a prodrug when it reaches the target site?
- Chemically activated
- Physically activated
- Enzymatically activated
Why are prodrugs used?
(1) Improve permeability through biological membranes
(2) Site-specific administration
(3) Increase duration of drug action
(4) Decrease toxicity and side-effects
(5) Improve the formulation
(6) Improve organoleptic properties
- Effects on organs
What does ‘organoleptic’ mean?
Action/ effects on organs
What are macromolecular carriers?
Biologically inert macromolecules
Used to deliver the drug to the site of action
What are macromolecular carriers generally composed of?
Polymers
What types of macromolecular carrier are there?
(1) Particulate carrier system
(2) Soluble macromolecular carrier
How can a drug be in a macromolecular carrier?
(1) Entrapped in the carrier via physical bonds
(2) Covalently conjugated via covalent bonds
In a macromolecular carrier, what does the distribution of the drug depend on?
The characteristics of the carrier
What are the types of targeting in macromolecular carriers?
(1) Active targeting
(2) Passive targeting
(3) Physical targeting
- Apply physical stimulus to promote API release in a certain area
How does ‘passive targeting’ work in macromolecular carriers?
Exploits the natural (passive) distribution pattern of a drug carrier
What type(s) of drug targeting technologies are associated with monoclonal antibodies?
(1) Magic bullet
(2) Macromolecular carriers
What type(s) of drug targeting technologies are associated with liposomes?
Macromolecular carriers
What type(s) of drug targeting technologies are associated with microparticles?
Macromolecular carriers
What type(s) of drug targeting technologies are associated with nanoparticles?
Macromolecular carriers
What type(s) of drug targeting technologies are associated with micelles?
Macromolecular carriers
What type(s) of drug targeting technologies are associated with polymer therapeutics?
Macromolecular carriers
From smallest to largest, list the sizes of general drug delivery systems and carriers.
(1) Monoclonal antibodies
(2) Nanoparticles
(3) Microparticles
(4) Macrodevices
- e.g. implantable devices
What is needed for a drug to have a therapeutic effect?
(1) Pharmacologically active
(2) To arrive at the right place at the right time
What is levodopa?
Modified dopamine, can cross BBB
Prodrug
How can drug release be modified?
(1) Rate
- very fast/ sustained release
(2) Time
- when release starts after a certain time following administration
(3) Space
- specific tissues (targeting)
What is 1st order targeting?
Organ/ tissue
e.g. liver
What is 2nd order targeting?
Certain type of cell
e.g. tumour cells
What is 3rd order targeting?
Intracellular compartment
e.g. lysosomes
What are some different targeting approaches?
(1) Magic bullet
(2) Prodrug
(3) Macromolecular carrier
What is magic bullet?
Targeting approach
Active ingredient is active and selective
What is prodrug targeting?
Targeting approach
Inactive prodrug - activated at site of action
What is macromolecular targeting?
Targeting approach
Carrier transports drug to site of action
What type(s) of activation can prodrugs undergo at the target site?
Chemical/ physical/ enzymatic activation
Why do we use prodrugs?
(1) Improve permeability through membranes
(2) Site-specific administration
(3) Increase duration of drug action
(4) Decrease toxicity + side effects
(5) Improve formulation
(7) Improve organoleptic properties
Define organoleptic properties.
Taste/ sight/ smell/ touch of drug
What are macromolecular carriers generally composed of?
Polymer
What are the two mechanisms by which a macromolecular carrier can deliver a drug?
(1) Entrapped in the carrier
- physical bonds
(2) Covalently conjugated
- covalent bonds