Hi, I don't understand concepts well enough, so appreciate if you can correct my understandings below, appreciate it.
a) I read somewhere that you use for transdermal drug delivery, cationic polymers (i.e. positive charge polymers) as skin and hair are negatively charged, so these polymers bind to the skin, and in that process, the product gets a chance to permeate through the skin barrier.
b) so while the above is merely one component (i.e. binding to skin) of topical delivery science, another would be to force the product to actually enter the skin. I can see 2 methods: 1. diffusion, 2. transport. What factors help diffusion and transport?
c) Diffusion: I can think of pH of product solution as helping with diffusion?. Transport: As for transport, maybe mixing an ingredient that has a skin transporter present? What would be transporter ingredient?
d) so what happens if you combine cationic polymers (such as chitosan, guar gum) with anionic (such as xanthan gum). You end up with a Polyelectrolyte Complex. 1. Would that be not suitable for Transdermal use? 2. Would the application be for oral delivery instead?
e) Can you comment on this topical formulation with least ingredients but still sufficient to penetrate at least in epidermal, but preferably in dermis as well:
Active ingredients (safe even if goes into systemic circulation): x (hard to dissolve, lipophilic product), y (hydrophilic product)
Solvents: 1. try to dissolve in healthiest oils first. 2 If fail, Glycerin, 3. If fail Propylene glycol
Polymers: For max skin absorption: what do you think about: Gum arabic vs Guar gum vs Chitosan vs Xanthan gum vs Sodium Hyaluronate. How would each fare for dermal vs epidermal absorption?
Short-term stability/preservation: citric acid, edta
f) Is there something lacking in above. How do you think about adding sunflower lecithin to the above?
Thanks a lot, sorry for this being long.