Liposomes as a delivery system

Liposomes contain bioactive compounds with health-promoting effects. These compounds are encapsulated in liposomes to enable them to overcome serious hurdles they would otherwise encounter in the gastrointestinal (GI) tract upon oral intake [1,2]. Liposomes are particularly useful for the delivery of bioactive compounds with a molecular structure that is hydrophobic (i.e. ‘water fearing’). Their hydrophobic nature is the reason why such compounds are poorly soluble in aqueous media including GI fluids, making low solubility the first hurdle which must be overcome. Also, prior to absorption into the bloodstream, hydrophobic bioactives must resist degradation processes potentially imposed on them by the harsh conditions existing in the GI tract. Finally, they face the low permeability of the GI tract wall.

Liposome technology

Despite most marketing claims, these problematic factors make it unlikely for many nutraceuticals to provide their full benefit to the body without proper delivery. LIPOSOMA’s solution is to exploit liposomal technology for this delivery purpose. LIPOSOMA’s well-developed and well-characterized liposomal technology allows for stable encapsulation and optimal delivery, maximizing the chance of achieving the intended physiological effects and health benefits.

Innocuous nature & structural versatility

Over the years, a large variety of delivery systems have been devised. Of these, most excitement has been engendered by the liposome system [3,4]. Liposomes are very small (usually smaller than 1 micrometer) spherical vesicles made of phospholipid bilayers enclosing an aqueous interior. Liposomes are suitable for loading poorly water-soluble compounds (within the bilayer membranes) as well as water-soluble compounds (within the internal aqueous phase). Phospholipids are also naturally occurring as major components of cell membranes in the human body. They render liposomes biodegradable and safe for oral and parenteral use by humans. Structural versatility in terms of size, charge and lipid composition is another important feature of a liposomal formulation allowing optimal tailoring to the type of bioactive that needs to be incorporated. Due to their structure, liposomes also have the potential for delivering more than one bioactive compound via co-encapsulation.

Solubilization of poorly water-soluble bioactive compounds

Many natural bioactive compounds are poorly water soluble (often termed as hydrophobic meaning ‘water fearing’). This property is usually strongly limiting their administration and in the case of oral administration their absorption into the bloodstream, with inferior bioactivity as a consequence. Liposomes offer the opportunity to solubilize such compounds in their phospholipid bilayers and to enhance their transport over the GI tract wall so that they reach the blood circulation in higher amounts [5]. Once trapped in this hydrophobic bilayer environment, they are well accommodated by the liposomes as they fear the water molecules in the surrounding aqueous medium.

Protection of encapsulated bioactive compounds

Bioactive compounds may be metabolized by different enzymes or undergo chemical degradation (e.g. hydrolysis and oxidation) during their passage through the GI tract before reaching the epithelium cells in the GI tract wall [1]. Obviously, the occurrence of such processes translates into a loss of the amount of the nutraceutical which can be absorbed into the bloodstream. Encapsulation in liposomes can protect bioactive compounds against such detrimental processes [2-5].

Robust liposome production technology

Liposomes have matured as a delivery system for therapeutic agents, as evidenced by the availability in the clinic of quite some pharmaceutical liposome products in important disease areas [7]. Currently, we see a wave of new liposomal products entering the field of nutraceuticals and food supplements. Despite this progress, it is important to realize that the production of liposomal nutraceuticals is certainly not without challenges [8]. Solidly grounded in scientific research and with broad expertise in manufacturing and quality control, LIPOSOMA is the optimal partner for anyone with the ambition to investigate, develop and/or produce liposomal health products.

Enhanced bioavailability

The above mentioned hurdles can strongly limit the entry of the orally administered nutraceutical in the blood circulation. Poor absorption from the GI tract lumen results in low bioavailability (i.e. the amount reaching the bloodstream) of and therefore low bioactivity. It is well documented that liposome encapsulation can increase the bioavailability of bioactive compounds with low water solubility [2,5]. Liposomal oral delivery can also improve the body distribution of a lipophilic active molecule after the process of intestinal uptake, by locally stimulating the production of so-called chylomicrons (small fat particles) that enter the lymphatic system instead of the blood circulation. This way, rapid deactivation of the bioactive by the liver can be avoided [6].

This graph outlines the results of an example study in which a liposomal drug product is compared with the drug formulated as a conventional suspension. The results show that with specially engineered liposomal formulations improved drug levels and thus better bioavailability can be achieved in specific cases [22].

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