INTRODUCTION:
Liposomes vesicles were prepared in the early years of their history from various lipid classes identical to those present in most biological membranes. liposomes were discovered in the mid of 1960’s and originally studied as cell membrane model Paul Ehrlich coined the term “magic bullet” in 20th century where carrier system was proposed to simply carry the drug to its of action and releasing its selectively while non – target sits should absolutely be example from drug effect.1-4
To pursue optimal drug action, functional molecules could be transported by a carrier to the site of action and released to perform their task, for which the carrier itself should be non-toxic, biodegradable, and of suitable shape and size to accommodate …show more content…
Encapsulation efficiency: Liposome formulation of a drug could only be developed if the encapsulation efficiency is such that therapeutic doses could be delivered in a reasonable amount of lipid. Since lipids in high doses may be toxic and also cause non-linear (saturable) pharmacokinetics of liposomal drug formulation. Some new approaches that provide high encapsulation efficiencies for hydrophilic drugs have been developed. For instance, active loading of the amphipathic weak acidic or basic drugs in empty liposomes can be used to increase the encapsulation efficiency. However, active loading is not suitable for hydrophobic drugs such as paclitaxel for which encapsulation efficiency is < 3mole% mainly due to the low affinity of drug for the lipid bilayers.91, 95-97
4. Lysosomal degradation: One of the major limitations of active targeting using ligand-directed immunoliposomes has been their rapid clearance due to non-specific uptake by the cells of RES. The ligand (antibodies) conjugated with liposomes may increase the liposome size and reduce extravasation and thus could limit targeting to intravascular targets. Moreover, immunoliposome enter the cells by endocytosis and if liposome contents are not released from the endosome they would ultimately be degraded in the
Liposomes vesicles were prepared in the early years of their history from various lipid classes identical to those present in most biological membranes. liposomes were discovered in the mid of 1960’s and originally studied as cell membrane model Paul Ehrlich coined the term “magic bullet” in 20th century where carrier system was proposed to simply carry the drug to its of action and releasing its selectively while non – target sits should absolutely be example from drug effect.1-4
To pursue optimal drug action, functional molecules could be transported by a carrier to the site of action and released to perform their task, for which the carrier itself should be non-toxic, biodegradable, and of suitable shape and size to accommodate …show more content…
Encapsulation efficiency: Liposome formulation of a drug could only be developed if the encapsulation efficiency is such that therapeutic doses could be delivered in a reasonable amount of lipid. Since lipids in high doses may be toxic and also cause non-linear (saturable) pharmacokinetics of liposomal drug formulation. Some new approaches that provide high encapsulation efficiencies for hydrophilic drugs have been developed. For instance, active loading of the amphipathic weak acidic or basic drugs in empty liposomes can be used to increase the encapsulation efficiency. However, active loading is not suitable for hydrophobic drugs such as paclitaxel for which encapsulation efficiency is < 3mole% mainly due to the low affinity of drug for the lipid bilayers.91, 95-97
4. Lysosomal degradation: One of the major limitations of active targeting using ligand-directed immunoliposomes has been their rapid clearance due to non-specific uptake by the cells of RES. The ligand (antibodies) conjugated with liposomes may increase the liposome size and reduce extravasation and thus could limit targeting to intravascular targets. Moreover, immunoliposome enter the cells by endocytosis and if liposome contents are not released from the endosome they would ultimately be degraded in the