Pharmaceutics Flashcards
What are the 3 Solid Lipid Nanoparticles (SLN) types?
Homogenous Matrix –> A release form from day 1
Drug Enriched Shell –> A fast compound delivery system (due to the particles being at the edge)
Drug Enriched Core –> A slow, controlled released form (as the drug is in the middle)
What are the 3 forms of Nanostructured Lipid Carriers (NLCs)
Imperfect –> A blend of solid and liquid lipids with different molecular structures
Amorphous –> Lipid solid matrix in the amorphous state
Multiple Type (O/F/W) –> The drug solubility in oils (liquid lipids) is greater than in solid lipids
What does cross-linking do in hydrogels?
Increases the hydrophobicity of the gel
Decreases the diffusion rate of the drug
What is one of the main disadvantages with in using natural polymers in wound healing?
Batch to batch variability
How can we easily get drugs to the brain?
Via the nose
The olfactory epithelium is an area in which the BBB is not present, so drugs can move through this and into the brain via paracellular diffusion (eg, cocaine)
What are niosomes?
Bilayered structures that are made of non-ionic surfactant, and cholesterol
These are able to entap a wide range of chemicals
What are pericytes?
Cells that can migrate from the vasculature and into the wound site
They contract and deposit down collagen
Similar to myofibroblasts
What are the negatives of SLNs?
And how do Nanostructured Lipid Carriers (NLCs) fix these?
The crystalline structure causes little space for the actual drug, with it becoming more ordered time goes along (to go to its lowest energy form), expelling the drug!
NLCs have a more diverse matrix structure, so there is more room for the active compound
What affects the rigidity/fluidity of liposomes?
And what does this cause?
The alkyl-chain length and degree of unsaturation (saturation = rigid)
Cholesterol –> Makes it more rigid
The more rigid the structure the more stable it is, and so the longer the encapsualted drug will stay inside of the liposome (prolonged release)
What are…
Organogels
Xerogel
Jelly
Organogels –> Organic liquid containing (eg, petrolatum)
Xerogel –> When the liquid is removed, and so only the matrix remains (eg, gelatin sheets)
Jelly –> When the matrix is rich in liquid (ephedrine sulphate jelly)
What are the advantages of Lipid Nanoparticle Carriers?
Low toxicity
Small particle size
Increase skin hydration
Reduce skin irritation
Act as a sunscreen
What are the 3 types of closed wounds?
Contusions (Bruises) –> Blunt force trauma causing tissue damage under the skin
Hematoma –> Damage to the blood vessles under the skin, causing blood accumulation
Crushing Injuries –> Blunt force causing a pressure injury over a long period of time
What are nanomedicines?
The application of technologies on the scale of 1-500nm to diagnose and treat diseases
They are too small to be detected by the immune system
Allow the drug to be delivered to the site of action with smaller doses… so less side effects
Increased drug penetration and stability
What is a big problem when giving drugs inter-otically, to the middle ear, to children?
Childrens membranes may be more permeable than adults, causing an increase in absorption…..and so possibly more side effects!!
Explain macromolecular compound gels
Either formed with covalent bonds (thermally irreversible) or phyisical interactions (thermally reversible)
Type 1 –> 3D network formed with covalent bonds between the macromolecules (thermally irreversible)
Formed by the polymersiation of monomers of water soluble polymers (in the presence of an X-linker)
Type 2 –> Held together by weak intermolecular bonds (thermally reversible)
When cooled below point T, PVA is formed….which are viscous in water –> Allowing for use in topical applications
In nasal drug delivery, when would a drug be absorbed via the paracellular route?
When hydrophillic and a MW less than 1kDa
Explain the 3 phases of the wound healing process
Inflammatory Phase –> Bleeding occurs to remove toxins before vasoconstriction occurs
The clotting mechanism then kicks in, along with inflammatory mediators much as histamine release. Vasodialation happens allowing phagocytes to enter the wound
Proliferative Phase –> Granulation occurs, which is the effect of fibroblasts and macrophages stimulating the production of fibrous tissue
Fibroplasia creates a new collagen bed, pulling the wound edges together…. whilst new capillaries are formed (angiogenesis)
The Remodelling Phase –> Fibroblasts create collagen to increase tensile strength. As the collagen matures it X-links
What are the main characteristics of liposomes?
Biodegradable
Biologically inert –> So weakly immunogenic and has a low toxicity
Can alter tissue distribution of the drug they are carrying
What is a wound?
Any defect, or damage, to the skin as a result of physical/chemical/thermal factors, or as a result of an infectious disease
Explain what occurs as the concentration of ampiphille increases
Phospholipids become ordered into vesicles
Then into a hexagonal columnar phase (middle soap phase)
Then into a lamella phase (neat soap phase) –> where sheets of ampiphilles are seperates by water
Describe what hydrogels are, and how drugs are released from them
They can retain large quantities of water (100x their dry weight) but are still water insoluble
Highly hydrated –> Diffusion occurs through pores
Low Hydration –> Drug is dissolved in the polymer, and is transported between the chains
Hydrogels can also swell and cause the drug to be released…dependent on Heat/pH/Application/Electrical current
What is the difference between an incision and a laceration?
Incision –> A regular wound thats caused by a clean sharp-edged object
Laceration –> A rough irregular wound caused by crushing or ripping forces
What’s the difference between Unilamellar and Multilamellar liposomes?
Unilamellar –> One bilayer surrounds an aqueous core
Multilamellar –> A multitude of concentrically orientated bilayers surronding the aqueous core
What are the 3 types of ethosome?
Classical –> Soft-liquid vesicles composed of phospholipids, water and ethanol (in high concs)
Binary –> The addition of another type of alcohol (PG or isopropyl alcohol (IPA))
Transethosomes –> The addition of a penetration enhancer or surfactant (edge activator) to a classical ethosome
Which type of drugs/molecules are suited to nasal delivery?
Acid sensitive drugs
Polar drugs with low BA
Small lipophillic drugs
What are the 4 types of classification of liposomes?
Conventional –> Neutral or negatively charged, and used for targetting of the cells of the mononucelur phagocyte systems (MPS). Contain mainly phospholipids and/or cholesterol
Sterically Stabilised (‘Stealth’) –> Has hydrophobic coatings (commonly PEG) to prolong circulation times
Immunoliposomes (‘Antibody-targeted’) –> These can be conventional or sterically stabilised. Specific antibodies on their surface to enhance target site binding
Cationic –> Positively charged, used for transporting genetic material. These can cause complement to be activated
What is the definiation of a Gel?
Viscoelastic, solid-like materials comprised of an elastic cross-linked network and a solvent
Mainly composed of the solvent
Relatively unaffected by thermal motion
What are physical/supramolecular gels?
Gels that are derived from low molecular mass compounds
Formed through self-aggregation of small gelator molecules to form Self-Assembled Fibrillar Networks (SAFINs)
These SAFINs are formed via many non-covalent interactions, so they are thermally reversible
What is the intial hurdle in nasal drug delivery?
Drug deposition in the nasal cavity
Name 4 ways that we can improve nasal drug delivery
Alter the mucous layer
Increase the contact time with the nasal epithelium (using mucoadhesives)
Use of penetration enhansers
Specialised devices
What are always added to nasal sprays?
Very small amounts of co-solvents –> to improve solubility
Viscosity-modifying agents
Preservatives
Anti-oxidants
Name 3 characteristic features of water soluble gels
Large increase in viscosity above gel point (critical polymer concentration)
Appearance of rubber-like elasiticty
The gel retains shape under low stress, but will deform at higher stress
When will dry phospholipids spontaneously swell?
When in water above Tm
What are transfersomes?
Ultra-deformable liposomes, composed of phospholipids and additional surfactant/emulsifier (‘edge activator’)
Elastic vesicles that can permeate in-tact skin
Localised at higher concentrations (in the SC)
Can cause some irritation if the edge activators aren’t very pure
