Two Phases: Phase I and Phase II. During phase I, the liver makes lipophilic molecules into more polar molecules. This may increase, decrease, or not change the drug's activity. This phase may be enough to eliminate the drug via the kidney. Phase II: Conjugation of the drug by adding a molecule to it that makes the drug much more polar and hydrophilic, allowing for elimination by the kidneys. Most often, these drugs are inactive after conjugation. Usually Phase I comes before Phase II, but sometimes it's in reverse order.