I think one of the major factors to determine whether a new derivative is to be made oral or parentaral dosage form, is its solubility. If the drug is lipophilic, it is better that it is made oral and if it is hydrophilic, it is better that it is made in the IV form.
Is the drug suitable for oral administration (pharmacology and therapeutic use)? If so, you can check solubility and permability from molecular descriptors. See an approximation in the attached file (it is still in Spanish).