Final answer:
The best administration route for a drug that irritates tissues is the parenteral route, often through intravenous or intramuscular injection, to avoid GI irritation and achieve higher plasma levels more quickly.
Step-by-step explanation:
The best route of administration for a drug that is irritating to tissues would be a parenteral route, such as intravenous or intramuscular injection. This method is preferred because it avoids direct contact with the gastrointestinal (GI) tract where irritation can occur.
Drugs administered intravenously can reach higher plasma levels compared to oral or intramuscular administration, which is especially important for treating systemic infections. When administered parenterally, drugs bypass GI absorption and potential tissue irritation, leading to a more direct entry into the bloodstream and a quicker therapeutic effect.
This practice, however, is generally reserved for health-care settings because it requires professional skill to administer.