I suppose you intend to dose the compounds orally? If the compounds are very lipofilic/have a low solubility, you might consider chemically modifying the compounds towards less lipofilicty, while retaining target specificity. You may also adress the issue from a formulation point of view, like salt formation, amorphism etc. see
Various factors influence the bioavailability of the drug. in order to answer your question please let me know following parameters
1. which extra-vascular route the material being administered.
2. distribution coefficient of the compound estimated using octonol/water system.(degree of lipophilicty)
3. whether the compound is crude or isolated and its state like solid or liquid.
4. most of natural lipophilc compounds exhibit tissue binding in G.I. preventing systemic absorption. i.e. need to check free drug concentration at site of admin.
5. whether the compound exhibit First pass effect?
6. solubility category such as poorly soluble or practically insoluble etc
7. permeability coefficient .
if these parameters are known we can technically funnel the reasons for poor bioavailabilityand accordingly address the problem.
Both of above scientists explained in a very fantastic ways. Along with the above suggestions, you can also try to enhance the solubility of the compounds by mechanochemical activation (Co-grinding) technique and other established solubility enhancement approaches. This can help you to intern enhance the bioavailablity of your intended natural compounds. Hope you will become success in this.
Thanks for suggestion. Its intended for oral route. Its natural compound and in nutraceutical industry we don't have luxury to salt forms. The compound is insoluble.
Our compound is isolated with the percentage of more than 80%. It is insoluble in water. We also try to put natural PGP inhibitor to enhance bioavailabiliy. Other than salt form what can be done for improve bioavailability.