P9: Nanocarrier Systems Flashcards
what is the stratum corneum
the outermost layer of the epidermis
the location of barrier within the skin largely resided in the stratum corneum, prevents the entry of both toxic and topical agents
what are nanoparticles
solid colloidal particles ranging from 1-1000nm; consists of macromolecular materials, can be used as drug carriers in which the active principle is dissolved, entrapped or encapsulated, or to which the active principle is absorbed or attached
what is nanomedicine
application of technologies on the scale of 1-500nm to diagnose and treat diseases; increases drug penetration and stability, too small to be detected by immune system, deliver the drug in the target organ using lower doses to reduce side effects
what are vesicle based lisosomes
lipid bilyer structures made of phospholipids and cholesterol
hydrophilic drugs are entrapped in the aqueous layer of the liposomes, while hydrophobic drugs are incorporated in the lipid bilayers
what are the advantages of liposomes
biocompatibility, low toxicity, targeted delivery of drugs to the site of action
what are the limitations of topical drug delivery
limited penetrating ability (confined to upper layers of stratum corneum), chemically and physically unstable
what are transfersomes
ultra-deformable liposomes composed of phospholipids and additional surfactant/emulsifier
edge activators that destabalise the lipid bilayers of the stratum corneum and increase in deformability by lowering interfacial tension of lipid bilayers
what are the advantages of transfersomes
elastic vesicles capeable of permeating intact skin, by squeezing themselves along the intracellular sealing lipid of the stratum corneum, the drug penetrating ability increases; localised at higher concentration in the deep layers of the skin than liposomes
what are the disadvantages of transfersomes
edge activators must be highly pure to avoid skin irritation and toxicity
what are ethosomes
soft lipid vesicles composed of phospholipids, water and ethanol in relatively high concentrations
what are the advantages of ethosomes
more effective transdermal delivery than classic liposomes, smaller and higher entrapment efficiency liposomes, interferes with lipid bilayers of the stratum corneum due to fluidising effect of alcohol, shows better skin permeation and stability than classical liposomes, alcohol also enhances deformability of vesicles
what are the disadvantages of ethosomes
skin irritation due to high concentration of alcohol
what are binary ethosomes
developed by adding another type of alcohol to the classical ethosomes, most commonly used alcohols are propylene glycol and isopropyl alcohol
what are transethosomes
new generation of ethosomal systems
contains basic components of classical ethosomes and an additional surfactant
developed in an attempt to combine the advantages of classical ethosomes and deformable liposomes
entrap drugs with MW ranging from 130Da to 200-325Da
what is celecoxib
NSAID COX-2 inhibitor
prevents skin cancer development and increases effectiveness of anticancer drugs
what does SLN stand for
solid lipid nanoparticles
what does NLC stand for
nanostructured lipid carriers
what are the three SLN types
- homogenous matrix model (release from 1-14 days)
- drug-enriched shell model (fast compound delivery)
- drug-enriched core model (slow controlled release of the active)
what are the disadvantages of SLN
decreased loading capacity, expulsion of drug during storage
what are some advantages of NLC
overcome the limits of SLN, different matrix structure
what are the three types of NLC
- imperfect type (blend of solid lipids and liquid lipids with different molecular structures)
- amorphous type (lipid solid matrix in the amorphous state)
- multiple type or O/F/W (drug solubility in oils is higher than in solid lipids)
what are the shared characteristics of SLN and NLC
adhesive films formed on the skin -> occlusive effect -> increased skin hydration
what are the advantages of lipid nanoparticle carriers
low toxicity, small particle size, increased skin hydration -> occlusive effect, enhance the stability of liable compounds, physical sunscreen on their own, reduce skin irritation
what are niosomes
surfactant/vesicle based
bilayered structures made of non-ionic surfactant and cholesterol
what are the advantages of niosomes
able to entrap wide range of chemicals (both hydrophilic and hydrophobic), less toxic than carriers with ionic surfactant
what are the disadvantages of niosomes
limited shelf-life, time-consuming and specialised required for the preparation process
what is 5-FU (5-fluorouracil)
first topical therapy for the treatment of superficial basal cell carcinoma approved by the FDA
topical administration, poor percutaneous permeation due to its hydrophilic properties
what are nanoemulsions
isotropic dispersed systems of two immiscible liquids (o/w or w/o)
what are the advantages of nanoemulsions
both hydrophilic and hydrophobic drugs can be applied
solubilisation/extraction of stratum corneum lipids, thereby decreasing resistance for drug transport
greater and extended cellular penetration
raised efficacy due to increasing surface-to-folume ratios
non-toxic and non-irritant
kinetically stable
what are the disadvantages of nanoemulsions
stability problems
