Absorption kinetics vary between ingestion and injection. Ingested substances are never absorbed 100%, whereas injection ensures full absorption. Absorption through the gut takes longer than with a water suspension, leading to a concentrated spike. Oil-based substances provide a more stable release, even without an ester, as muscle tissue absorbs oil more slowly. Liver toxicity increases slightly with more substance entering the system. Although it bypasses the first-pass effect, eventual metabolism still occurs in the liver. Additionally I’d note injectable oral steroids are gonna lead to a higher concentration in the body as again it’s absorbed 100% IM.