Since liposomes have a similar structure to cell membrane, they were used to study the structure and function of biofilms in the early stage. In the late 1960s, Rahman et al. firstly applied liposomes as drug carriers. In recent years, liposome preparation technology gradually gets to be improved and liposome mechanisms to be further clarified. It has the advantages of easy in vivo degradation, low toxicity, and low immunogenicity, especially a lot of experimental data verifying that liposome as a drug carriers can increase therapeutic index, reduce side effects of drugs, decrease dosage, etc. Therefore, the research of liposomes as drug carrier has been paid more attention in the pharmaceutical industry.
Liposome drugs already on the market or in development
At present, there are 14 companies conducting liposome research and developing related drugs. And there are three major classes of liposome drugs or vaccines under development: chemotherapy drugs, vaccines, and nucleic acid drugs.
Research progress of liposomes for drug delivery
1. Anti-cancer and anti-tumor drug carrier
Cytotoxic drugs have no selectivity to normal tissues and pathological sites of the body, so it is difficult to clinically apply them. Researchers have been considering making the drugs directly reach the pathological sites. Several studies have shown that the toxicity of adriamycin encapsulated by liposome is 50%-70%, lower than that of free drugs, while the anti-cancer activity of liposome drugs is much higher than that of free drugs. Multiple treatments with adriamycin liposome can increase the survival time of tumor-bearing animals, which is not prolonged when using free drugs. Many drugs such as actinomycin D, mitomycin, methotrexate, bleomycin, and cisplatin have been wrapped by liposomes. And the US FDA has approved doxorubicin liposome TLCD99, amphotericin B, and daunorubicin liposome into clinical trials.
As carriers of anti-cancer drugs, liposomes have the characteristics of increasing affinity with cancer cells, overcoming drug resistance, raising drug intake of cancer cells, reducing drug dose, improving efficacy, and reducing toxic or side effects.
2. Anti-parasitic and anti-fungal drug carrier
After intravenous injection, liposomes can be rapidly ingested by the reticuloendothelial system, where some parasites such as Leishmania and Plasmodium live. Therefore, liposome can be used to wrap drugs against parasites. For example, pentavalent antimony treatment has a high level of drug toxicity that its therapeutic dose and toxic dose are equal. When wrapped by liposomes, the treatment of experimental Leishmaniasis is safe and effective with the therapeutic dose greatly reduced. Researchers have applied the characteristics of fucose-fructose receptors on the surface of macrophages to synthesize fucose liposomes wrapping the antimony compounds. The treatment results of hamsters infected with 30d Leishmaniawith show that the efficacy of liposome drugs is reinforced (inhibition rate 55%). And the effect of liposome containing fucose is even more obvious (inhibition rate 72%). Instead, the inhibition rate of drugs without liposomes is only 26%.
3. Liposomes for peptide and enzyme drugs
Both peptides and enzymes are biological macromolecules, which have a common characteristic of being unstable in organisms and easy to be degraded by proteolytic enzymes, so their half-life in organisms is short and most of them are not conducive to oral administration. Superoxide dismutase (SOD) can remove excess superoxide anion radicals in vivo, but it is easily destroyed by protease hydrolysis. When coated with liposomes, its half-life in organisms is significantly increased, and the uptake of SOD by cells is also added, thus better protecting cells from free radical damage. Studies have shown that the half-life of subcutaneous injection of free IL-2 is only 6min, while that of liposome-coated IL-2 is 68min, and the distribution and pharmacokinetics of liposome-coated IL-2 are greatly changed. After oral administration of insulin, due to the destruction by gastric enzymes and acids, the bioavailability of insulin is very low. However, if encapsulated with liposomes, these shortcomings can be overcome, and the blood glucose of animals decreases significantly after oral administration.
4. Hormone drug carrier
Anti-inflammatory alcohols hormone encapsulated into liposomes have great superiority. Its concentration on inflammation is easy to be swallowed up by the phagocytes, avoiding the interaction of free drugs with plasma proteins. Once arriving at the inflammation parts, it can be internalized, and released after the fusion. It can work at lower doses, thus reducing the complications and side effects caused by high doses of steroidal hormones.
Insulin is already used with liposome carriers to improve bioavailability and patient compliance. However, there are still problems of low encapsulation rate and inactivation of drugs in the gastrointestinal tract, which needs further improvement.
5. Vaccine carrier
Childers et al. made glucosyltransferase liposomes of streptococcus mutants into enteric-soluble capsules, and gave them to 7 healthy adults orally with 500ug per person per day for 3 days, and then increased doses 28 days later. The results showed that the levels of IgA1 and IgA2 against GTF in human parotid secretion were augmented, and reached a peak on the 35th day, indicating that liposome vaccine can induce the production of secretory IgA antibodies and enhance humoral and cellular immunity simultaneously.
6. Antidote carrier
EDTA or EDPA can dissolve metal and treat metal storage diseases. However, the inability of these chelates to pass through the cell membrane affects their in vivo effect. If the chelates are made into liposomes, they can be transported to the cells that store metals.
7. Liposomes used in immunodiagnosis
Alkaline phosphatase is packed into immune liposomes while enzyme substrates are outside liposomes. After the binding of immune liposome and the antigen, liposome membrane permeability is changed to release AP. Then AP reacts with the substrate to develop colors. This method can be used for qualitative or quantitative analysis, for instance in the diagnosis of lupus erythematosus, syphilis, hepatitis b, etc.
Related Products:
| Name | CAS | Synonyms | Description |
| Adriamycin | 23214-92-8 | doxorubicin; Doxil; Adriablastin | Doxorubicin(Adriamycin) is an antibiotic agent that inhibits DNA topoisomerase II and induces DNA damage and apoptosis. |
| Actinomycin D | 50-76-0 | Actinomycin; Cosmegen; Cosmegen Lyovac; Dactinomycin; Lyovac Cosmegen | Actinomycin D is a chromopeptide antineoplastic antibiotic that exhibits high antibacterial and antitumor activity. |
| Methotrexate | 59-05-2 | WR19039; CL14377; WR 19039; WR-19039; CL 14377; CL-14377 | Methotrexate can interfere with the growth of certain cells of the body, especially cells that reproduce quickly, such as cancer cells, bone marrow cells, and skin cells. |
| Bleomycin | 11056-06-7 | Bleocin;Blenoxane;Pingyangmyvin A2;Blanoxan | Bleomycin is a medication used to treat cancer, including Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, testicular cancer, ovarian cancer, and cervical cancer among others. |
| Cisplatin | 15663-27-1 | (SP-4-2)-diamminedichloro-platinum | Cisplatin induces cytotoxic by interaction with DNA to form DNA adducts which activate several signal transduction pathways. |
| Amphotericin B | 1397-89-3 | amphotericin b; Amfotericina B; Amphotericinum B; AMPH-B; Fungizone; Liposomal Amphotericin B; Amphotericine B; Ambisome; Amphozone; Fungilin; NSC 527017 | Amphotericin B is an important antifungal drug, especially for deep fungal infection. |
| Insulin | 9004-10-8 | Insulin recombinant; Endopancrine; Decurvon; Dermulin; Exubera | Insulin is a pancreatic hormone that regulates glucose metabolism, cellular uptake, as well as the storage of glucose, amino acids and fatty acids. |