Creating liposomal pills may by theory be more bioavailable than traditional pill structure.
You can certainly deliver peptides and other medications (especially small molecule drugs) with liposomal nanoparticles. But you will have to either coat individual particles or clusters of them in enteric coating (usually polymeric, ie. Eudragit). Liposome will degrade in the stomach otherwise. An example of one way to go about it would be:
(1) make the drug-loaded liposomes, *optionally lyophilize them (make sure the drug remains active and you still get the desired release profile when resuspended) to increase shelf life,
(2) coat groups of lyophilized particles with enteric coatings (or you can even buy capsules that are already coated) to prevent degradation and premature drug release in the acidic stomach. Depending on whether you want small intestine release or colon release, you will have to select different pH-sensitive enteric coatings (ie. Eudragit L100 vs. S100).
There are other ways of controlling release without resorting to pH-sensitive polymers, such as using enzyme-cleavable linkers. In any case, you will have to rationalize the use of liposomes, since you can always just pack drugs in a capsule and coat the capsule with the polymer.
I presume that you are specifically interested in the oral route of delivery and will provide few thoughts with the oral route in mind.
According to the biopharmaceutical classification system (BCS), peptides and proteins are classified (mainly) as class III compounds. i.e. their oral bioavailability is limited by their membrane permeability. Whilst this may sound as an over simplification of the problem but in reality that is what limits oral absorption of such compounds. Research on developing an oral formulation of insulin is well over 4 decades old and up to this day, insulin is still not available as an oral dosage form, although there has been some break-throughs with other routes of delivery:
https://afrezza.com/
Vaccines and their oral delivery is another area where formulations scientists are challenged (in some cases) to deliver peptides / proteins via the oral route.
Liposomes (theoretically) would improve oral absorption of such compounds, simply because they are lipid vesicles and as such are more capable of permeating through GI tract wall. The problem though, is uploading liposomes with clinically meaningful amounts of water-soluble drugs which is rather limited.
The other important aspect that needs to be considered when thinking about oral delivery of proteins and peptides is their vulnerability and susceptibility to degradation in the GI tract. This mainly due to effect pH (the answer above addresses how this could be overcome using pH-responsive polymers) or due to enzymatic degradation (amidases, peptidases, proteases etc).
A combination of coating with pH-responsive polymers, incorporation into lipid based systems (such as SMEDDS, liposomes or Nano / microemulsions) along with using appropriate enzyme inhibitors could work.
Professor,
I am humbled by your answer. Hopefully these questions will lead to life saving medications. I believe that this may be possible, and I at this point do not carry the expertise the facilitate such technology.
Perhaps you do, professor.
With gratitude,
Tyler Ekern
Perhaps constructing a pill made of small liposomes could bypass the GI tract. Creating a time release could perhaps solve another issue. Considering this, perhaps the medicine could flow through blood vessels and capillaries. From what I understand of liposomes, the medicine could bypass the blood brain barrier. Theoretical perhaps, but this is the nature of science at times. Critique?
I am humbled your time, both of you.
Thank you,
Tyler
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