Liposomes (FINAL) Flashcards
What are liposomes?
Colloidal, vesicular structures composed of self-assembled lipid bilayers surrounding an internal aqueous compartment.
What is the most commonly lipid in liposomes?
Phospholipid.
What are the 3 types of lipids found in liposomes?
Neutral lipids, anionic lipids, cationic lipids.
What are examples of a neutral lipid?
Distearoyl phosphatidylethanolamine (DSPE), cholesterol, Distearoylphosphatidylcholine (DSPC).
What is an example of a cationic lipid?
Dioleoyltrimethylammonium propane (DOTAP) or Dioctadecyldimethylammonium bromide (DODAB).
What is an example of an anionic lipid?
Dimyristoylphosphatidylglycerol (DMPG).
What are the two important regions of a lipid that form from the bilayer structure?
Hydrophilic head (polar) and hydrophobic tail (nonpolar).
How do liposomes serve as drug carriers?
They can encapsulate both hydrophilic drugs in the aqueous core and hydrophobic drugs in the bilayer structure.
What are conventional liposomes?
Liposomes made of phospholipids and/or cholesterol that are used traditionally as drug carriers.
What are some advantages of liposomes as drug carriers?
Low toxicity profile, ability to incorporate various drugs, protection from inactivation, variability in size, and controlled delivery.
What is a limitation of conventional liposomes?
They are quickly taken up by phagocytic cells, leading to localization primarily in the liver and spleen.
What is an example of a drug formulated in conventional liposomes?
AmBisome (Amphotericin B).
What distinguishes long-circulating liposomes from conventional liposomes?
They are modified with hydrophilic polymers (like PEG) to increase circulation time in the bloodstream.
What is Doxil?
A pegylated liposomal formulation of doxoorubicin used for cancer treatment.
What are immunoliposomes?
Liposomes coated with antibodies or antibody fragments for targeted drug delivery.
What are the two types of immunoliposomes?
Non-stealth immunoliposomes and stealth immunoliposomes.
What are cationic liposomes primarily used for?
Gene delivery due to their ability to interact with negatively charged drugs or DNA.
What are pH-sensitive liposomes?
Liposomes that release their content at acidic pH, typically used to enhance drug delivery into cells.
What are non stealth immunoliposomes?
Antibody-conjugated liposomes that do NOT have long circulating properties (may be conventional liposomes coated/engrafted with antibodies).
What are stealth immunoliposomes?
Antibody-coated liposomes that have long circulating properties (can be conjugated either to the surface of pegylated liposomes or attached distally to PEG.
