| The reasons are numerous. Initially, a drug may be under dosed or initially administered in a lower than usual dose and slowly titrated to its full therapeutic effect. Perhaps that initial lower dosage did not allow the interaction to manifest quickly or perhaps allowed the precipitant and the interacting drug to equilibrate during the dosage titration. Additionally, a patient may only be on an agent for a short period of time, such as with antibiotics. However, if the interaction with the antibiotic is P-450 enzyme inhibition, the interaction may manifest within 24 hours of adding the offending agent to the patient’s drug regimen. Finally, the manifestation of the interaction may take a long time to reach full effect. For example, enzyme induction may take up to 1 month in certain scenarios to fully manifest. |
| “Why Don’t We Always See the Interactions?” |
 | |  | |  | |  | |  | |  |