The stuff below should help ...

www.nps.org.au/australian-prescriber/articles/pharmacokinetics-made-easy-11-designing-dose-regimens

www.sciencedirect.com/topics/medicine-and-dentistry/oral-drug-administration

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Can liquid dosage form be used for oral administration?

Both liquid dosage form and solid dosage form, such as powder, tablet, pellet, capsule, and film can be utilized in oral administration. The prepared liquid nanosuspensions can be directly utilized in liquid dosage form for oral administration. Allan McI. Mowat, ... Howard L. Weiner, in Mucosal Immunology (Third Edition), 2005

Oral Drug Administration - an overview | ScienceDirect Topics

www.sciencedirect.com/topics/medicine-and-dentistry/or…

What ' s The difference between oral and Parenteral Drug Administration?

In comparison to various forms of parenteral administration, oral dosing results in a relative low peak drug level in plasma. In addition, more uncertainty exists in regard to the time when the maximum plasma level is reached because this value varies for different drugs over a wider range after oral than after parenteral application.

Oral Drug Administration - an overview | ScienceDirect Topics

www.sciencedirect.com/topics/medicine-and-dentistry/or…

Which is more absorbed orally or parenterally?

Some drugs that are particularly well absorbed by the gastrointestinal mucosa may have bio-availability comparable with that of an IV dose, for example the antibiotic ciprofloxacin. However, most drugs do not have this level of availability by the oral route so the dose given orally is usually higher than that given parenterally.

Administration of drugs 1: oral route | Nursing Times

www.nursingtimes.net/archive/administration-of-drugs-1-…

What is the most effective route of Drug Administration?

This is the most frequently used route of drug administration and is the most convenient and cost-effective. Although solid-dose forms such as tablets and capsules have a high degree of drug stability and provide accurate dosage, the oral route is problematic because of the unpredictable nature of gastrointestinal absorption.

Administration of drugs 1: oral route | Nursing Times

www.nursingtimes.net/archive/administration-of-drugs-1-…

Len Leonid Mizrah

Thank you for the great resources!

Please correct me if I am wrong, but these are mostly focused on "converting" parenteral/injected doses to an oral/systemic doses, correct?

I am looking for a conversion between topical concentrations - given through a locally applied cream on the skin - to an oral dose.

Will these resources/equations still be applicable for me?

Thanks again!

The portal has its own search engine, and there's "Contact us" section as well. Use them to explore farther. It's a pharma metrology specific question.