Let’s start with the basics

 

Each medicinal substance (when we are talking about drugs) or nutritional (when we are talking about food supplements) must be in a pharmaceutical form so that it can be administered by an appropriate route, e.g. orally, parenterally or into the eye. A pharmaceutical form needs i.e. a certain type of a carrier for a given substance, for example, a tablet, a hard capsule (those that can be opened), a soft capsule (e.g. with oils), a suppository, eye drops, ear drops, solution for injection, suspension for subcutaneous administration, submicron emulsion and liposomes.

Liposomal technology. What are liposomes?

 

Liposomes are vesicles of various sizes from 50 nm – 50 µm, depending on the method of their preparation, built of one or more concentrically arranged double phospholipid layers the core of which is water.

Liposomes protect the transported substances from being broken down in the gastrointestinal tract.

What is the phenomenon of liposomes and liposomal technology?

 

Liposomes can transport both water-soluble and fat-soluble substances.

The phenomenon of liposomes is that they are an excellent carrier for both hydrophilic substances (i.e. those that like water) and lipophilic substances (that do not like water, e.g. oils), which in turn will be in the liposome’s liposome shell made of phospholipids (1 ).

 

Liposomes are made of phospholipids, which makes them biocompatible with the cells of the human body

A very important feature that distinguishes liposomes as carriers of transported substances in relation to other pharmaceutical forms (e.g. tablets or capsules) is the fact that they are made of phospholipids, i.e. the same substances that build all cells of our body, i.e. in the literature it is defined that liposomes are biocompatible with the human body.

Liposomes deliver substances directly to specific places in the body.

 

Liposomes are used parenterally (in the form of injection) in targeted therapies as vehicles delivering medicinal substances directly to specific places in the body. Thanks to that, if it is necessary to administer a medicinal substance, the side effect of which is a toxic effect, e.g. on the heart, the so-called cardiotoxicity, administration of this active substance in the form of a liposome will avoid adverse effects on the heart (2).

This is where the question arises: Why are not all substances produced and administered in the form of liposomes? Well, the technology of producing liposomes is much more complicated and expensive than tablets or capsules. When administered parenterally, it is required that the liposomes be very small so as not to obstruct the blood vessels in the lungs.

Liposomes are also used for the transdermal delivery of substances, e.g. in cosmetics. Liposomes are absorbed by the stratum corneum of the skin; next, fusion takes place, i.e. the connection of the phospholipid envelope of the liposome and the release of a substance that moves to the deeper layers of the skin (3).

Benefits of administering substances in the form of liposomes

  • Liposomes are made of the same components (phospholipids) as the cells of the human body, i.e. they are biocompatible. This means that thanks to liposomes, we can deliver a given substance without unnecessary fillers that are present in other forms, e.g. in tablets.
  • For the oral route, it is very important that the liposomes are not as small as for the parenteral route because they will degrade in the gastrointestinal tract before they reach their site of action (4). Orally administered liposomes can even be multilayered, so that the outer layer of the liposome can be digested in the gastrointestinal tract and thus protect the transported substance from degradation and safely deliver it to the site of absorption, i.e. the intestines (5). Summarizing, liposomes protect the transported substances against decomposition in the gastrointestinal tract.
  • The proper structure of the liposome enables much more of the transported substances to be absorbed and thus reach the site of action. It is reported in the literature that vitamin C administered in the form of tablets is absorbed in approx. 45%, while in the liposomal form – twice as much, which means that from a tablet containing 1000 mg of vitamin C, approx. 450 mg reaches our cells, while in the form of liposomal approximately 900 mg (6).
  • Liposomes not only protect the transported substance against decomposition in the gastrointestinal tract but also protect the gastrointestinal tract from the irritating effects of certain substances.

Literature

(1) Kanásová M and Nesměrák K. Systematic review of liposomes’ characterization methods. Monatshefte fur Chemie (2017) 148: 1581–1593.

(2) Verma NK and Roshan A. Liposomes: A Targeted Drug Delivery System- A Review. Acta Medica Sci. (2015) 2: 65–70.

(3) Tiwari R, Ansari VA, Singh S, Khalid M, and Akhtar J. Liposomes: the novel approach in cosmaceuticals. World J. Pharm. Pharm. Sci. (2015) 4: 1616–1640.

(4) He H, Lu Y, Qi J, Zhu Q, Chen Z, and Wu W. Adapting liposomes for oral drug delivery. Acta Pharm. Sin. B (2018) 9: 36–48.

(5) Alavi M, Karimi N, and Safaei M. Application of various types of liposomes in drug delivery systems. Adv. Pharm. Bull. (2017) 7: 3–9.

(6) Łukawski M, Dałek P, Borowik T, Foryś A, Langner M, Witkiewicz W, et al. New oral liposomal vitamin C formulation: properties and bioavailability. J. Liposome Res. (2020) 30: 227–234.