Liposomes are a novel drug delivery system (DDS). They are bimolecular vesicles that form spontaneously when phospholipids are dispersed in water. Liposomes vary in size, composition and charge and can be used as carriers for a wide range of drug molecules, such as chemotherapeutic agents, antimicrobial and antiviral drugs, antiparasitic drugs, genetic material, vaccines, therapeutic proteins, and anti-inflammatory agents. Liposomal formulations have unique advantages in both safety and efficacy, so they are one of the most rapidly developing formulations in recent years. In the past 30 years, research in the field of liposomes has made great progress. Various types of liposomes, such as liposomes with different particle sizes, the composition of phospholipids, and suitable additives to meet clinical needs, have been applied in various therapeutics.
Protect the drug from degradation
The lipids used in the liposomal formulation are sufficiently resistant to enzymatic degradation to allow the liposomes to protect the encapsulated drug during circulation. When the liposome enters the cell, the encapsulated drug is released by membrane diffusion or by lysosomal degradation of the lipid membrane. Liposomes can also protect their encapsulated drugs in the gastrointestinal environment and facilitate the gastrointestinal transport of a variety of substances. Due to their advantages of biodegradability and non-toxicity, liposomes can be used as vaccine delivery vehicles. The protective effect of loaded molecules makes liposomes a good candidate carrier for oral vaccines.
It has been reported that the main factors affecting the stability of oral drugs include bile, pH values and pancreatic enzymes in the gastrointestinal environment. Microemulsions are prepared by using liposomes as suspensions or solubilizers for highly insoluble or lipophilic drugs, and further made into soft capsules for oral delivery can protect drugs from the gastrointestinal environment and improve the oral bioavailability of drugs. In addition, oral administration of liposome-antigen formulations may enhance antigen delivery to antigen-presenting cells.
Topical drug administration
Liposomes can reduce the side effects of topical drugs because they require only small doses when used as topical formulations. Furthermore, they increase the permeability of the skin to the loaded drug. Liposomes are also important in skincare and cosmetic applications. The enhanced skin transport of drugs is attributed to the lipid properties of the vesicles as drug carriers.
Many drugs such as peptides and proteins are highly unstable and degrade in a poor gastrointestinal environment. Pulmonary administration is an ideal and suitable route of administration for such sensitive drugs. As pulmonary drug delivery vehicles, liposomal formulations have advantages over non-encapsulated drug aerosols. Pulmonary administration of drug-loaded liposomes can prolong the topical and systemic therapeutic effects of drugs. Similarly, liposomal DDS facilitates intracellular drug delivery, especially in epithelial cells, alveolar macrophages, and tumor cells. This DDS also prevents topical stimulation of lung tissue and reduces drug toxicity. Using surface-bound ligands or antibodies, the most significant advantage of liposome formulations for pulmonary administration application is the targeting of specific cell populations.
Enhance antibiotic efficacy and safety
Many factors hinder the effective therapeutic effects of antibiotics. Enzymatic degradation of antibiotics is an important factor. Cephalosporin and penicillin are highly susceptible to degradation by β-lactamases, resulting in poor clinical outcomes. Encapsulation of antibiotics by liposomes is a key method to avoid such degradation. Similarly, liposomal delivery of antibiotics increases the cellular uptake of drugs, reduces their required effective dose, and reduces the development of dose-dependent toxicity.
The use of liposomes for drug delivery reduces cardiotoxicity and skin toxicity. In animal experiments, the survival rate of animals in the liposomal DDS group was higher than that in the free anticancer drug molecule group. Similar studies have also found that drug-loaded liposomes can increase the concentration of drugs in tumor tissue. Compared with free drug molecules, liposome-delivered drugs have superior antitumor effects on solid tumors. The liposomal targeting of anticancer drugs can be further improved by targeting specific ligands to antigens expressed on malignant cells for selective delivery. The approach not only improves treatment effects, but also reduces the side effects associated with chemotherapy.
CD Formulation is a leading provider of contract research services for pharmaceutical formulation development. Driven by the latest science and technology, it has grown to be a company that provides drug delivery system development services for pharmaceutical industries. Always at the forefront of innovation, CD Formulation aims to address the challenges arising from pharmaceutical formulation, and in a much broad sense, hopes to advance the global medical business.
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