Reader seeks best dosing schedule

Dear Dr. Roach: My doctor invariably prescribes four 200 mg Advils (ibuprofen), to be taken three times every 24 hours for a few days. I suspect this will create useful peaks, but also create unwanted troughs, compared to taking a smaller dose more frequently that results in the same aggregate dose every 24 hours.

My suspicion is that they are changing the optimal dosing schedule in order to achieve adherence. Whenever I tell them that I promise I will follow a better schedule if one exists, they don’t want to talk about it.

Please sort out peaks versus troughs for me.

R.A.

Answer: Ibuprofen reaches its maximum level in the body about two hours after taking a tablet and will begin going down in the body afterward, due to the liver inactivating the medication. Every two hours or so, half of the dose is metabolized. So, four hours after taking the dose, there’s about half the maximum; while at six hours, there is 1/4 of the maximum level. By the time you take another dose, only 1/8 of the medicine is left in the body.

Taking smaller doses more frequently will reduce the difference between the peak level and the lowest level, the trough, which occurs just before you take the next dose. So, if you took 600 mg four times a day, the ibuprofen level in your body would not get below half the maximum during the day.

With some drugs, it is critically important to minimize the difference between peaks and troughs, but not so with ibuprofen, because it is effective at a very wide range of levels in the blood. It is not particularly toxic, however, it should be used at the lowest effective dose for the shortest amount of time necessary.

For ibuprofen, either 800 mg three times a day or 600 mg four times a day (or even 400 mg six times a day) all are likely to provide similar relief of pain and inflammation without a high risk of toxicity. But the shorter dosing intervals will probably have a small benefit in effectiveness.