What Is The Antiviral Drug Liposome?
Viruses are the smallest kind of pathogenic microorganisms. They reproduce in cells. The core is ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), and the outer shell is protein, which does not have a cell structure. The virus parasitizes in the host cell and relies on the host cell metabolic system for proliferation and replication. Statistics show that about 60% of epidemics are caused by viral infections. The research and development of antiviral drugs has naturally become a hot spot for investment in the pharmaceutical industry.
Until now, there is still a lack of specific drugs for the treatment of viral diseases. The clinically commonly used drugs mainly include the following categories: antiviral drugs that inhibit virus replication; immunomodulators that enhance the body’s immune function; for clinical symptoms Antitussive, analgesic, antipyretic and anti-inflammatory drugs; anti-infectives to prevent secondary infections; vaccines to prevent viral infections and disinfectants to block virus transmission. There are few types of antiviral drugs, no more than 50. Antiviral drugs are only viral inhibitors in a sense and cannot directly kill the virus and destroy the virion, otherwise it will damage the host cell. Therefore, the emergence of new antiviral drug liposomes brings hope to the treatment of viral infections.
Liposome bimolecular membranes are similar to biological membranes, are easily absorbed, and have little toxic and side effects to the body. After liposomes encapsulate antiviral drugs, they can reduce drug toxicity, reduce drug usage, and have sustained and controlled release effects. For example, the antiviral drugs ganciclovir and 5-fluorouridine have good sustained-release and controlled-release effects after being made into liposome preparations.
Ganciclovir is an effective drug for the treatment of human cytomegalovirus (CMV) infection and has broad-spectrum anti-herpes virus activity. It was first marketed in the UK in 1988, and four preparations (intravenous injections, capsules, intraocular implants and 0.15% eye ointment) have been approved for the treatment of CMV infections. Ganciclovir can be converted into ganciclovir triphosphate in the body, which inhibits the polymerase of herpes simplex virus and CMV by competitively inhibiting the insertion and extension of deoxyguanosine triphosphate. After ganciclovir triphosphate releases pyrophosphate, ganciclovir monophosphate is embedded at the end of the virus chain and can also slow down the replication of the virus. In addition, ganciclovir is also effective in preventing and treating hepatitis B.
Ganciclovir liposomes can be prepared by reverse phase evaporation. Dissolve cholesterol, lecithin, and polysorbate 80 in chloroform, mix with ganciclovir solution (pH 6.8 PBS solution), and ultrasonically form a homogeneous emulsion. Rotary evaporation to remove organic solvents in a 60 degree water bath to obtain a milky white mixture. The suspension was passed through a medium-speed filter paper and a 0.45 μm microporous membrane in turn to obtain ganciclovir liposomes with an encapsulation rate of 43.24% and a leakage rate of 1.02%. The liposomes are separated by a gel column, the drug content is determined by HPLC, and the ganciclovir liposomes are coated with hydrophilic polyvinyl alcohol to improve the stability of the ganciclovir liposomes. The polyvinyl alcohol solution and liposomes are directly mixed to prepare polyvinyl alcohol-coated liposomes. On the one hand, polyvinyl alcohol forms a layer on the surface of liposomes to protect the liposomes; on the other hand, there is no strong interaction between polyvinyl alcohol and phospholipids, and soft polyvinyl alcohol molecules entangle and accumulate on the surface of liposomes to form protective layer. After the liposomes are coated with polyvinyl alcohol, the encapsulation rate of liposomes is significantly increased and the leakage rate decreases, but when the concentration of polyvinyl alcohol exceeds 3 mg/mL, the encapsulation rate begins to decrease.