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Why Are Statins Taken at Night?

posted Jul 6, 2016, 4:52 PM by Mike Mi   [ updated Jul 6, 2016, 5:00 PM ]
Welcome to the inaugural post of the editor's blog for the bidwiki, where we tackle random questions that keep yours truly up at night.

Of all the medications that we prescribe in the hospital, few default automatically to "QHS," in particular are the HMG-CoA reductase inhibitors (of course there's Flomax, but that one seems obvious...).

A patient once asked me why he should take his statins at night rather than with his other morning medications, and I thought to myself, "huh, I did not learn that one in medical school..." It turns out, the short answer is that more cholesterol is produced by the liver at night than during the day, therefore, maximizing the effect of statins.

In one study looking at the difference between morning vs. evening drug administration of simvastatin, there was a mean difference of 15 mg/dL decrease in LDL depending on the time when it was taken.

What's interesting is that this effect seems to be limited to statins with short half-lives. According to the FDA drug information sheet for simvastatin (I only now discovered these treasure troves of information, where you can find out that Chinese patients have a higher risk of myopathy when taking concurrently simvastatin and >1 gram per day of niacin), simvastatin level drops to 10% of peak 12 hours after administration. Consequently, the FDA recommends taking simvastatin at night. The same applies to lovastatin, pravastatin, and fluvastatin. On the other hand, longer half-life agents such as atorvastatin and rosuvastatin can be taken at any time during the day, with or without food.

Well, it seems that as always, answers to questions in medicine often come down to, "it depends...." For statins, most should be taken at night to maximize their effects, but exceptions can be made for atorvastatin and rosuvastatin. Of course, there's the theoretical risk of drinking a lot of grapefruit juice in the morning along with taking one's statin, which can cause CYP P450 interactions, but we should probably be advising people to avoid grapefruit juice with all medications.

One last wrinkle though! A study looking at atorvastatin found that while the timing did not change LDL level, night time dosing may decrease rate of revascularization, unstable angina, and MI in patients who underwent PCI. This study perhaps once more demonstrates the pleiotropic effect of statins on more than just LDL cholesterol level.

Ok, I guess we'll stick to taking our statins at night then.
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