nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
See here for more discussion.

Monday, November 8, 2010

The Logic Of "Drug Holidays"

No, drug holidays are not about getting stoned during Christmas.

Has your doctor ever recommended a holiday from one of the medicines you've been taking for a long time?  I read this note in the LA Times Health blog (Nov 8) about how patients may have a tough time accepting the need to stop their medicines for a while.

The blog post was referring to recent evidence that suggests it is potentially harmful to stay on certain drugs for osteoporosis, in particular the bisphosphonates (Boniva, Actonel, Reclast, and Fosamax).  These are very common drugs and some patients have been taking them for a decade or more.

So, how is it that a beneficial drug is not harmful in the short term, but can be so in the long term?

Our bodies adapt to continued exposure over long periods of time.  We know that some exposures are harmful from the beginning--like cigarette smoking--and don't have a problem accepting that in the long term other even more harmful things can occur.

But an agent that's good for us at first becoming harmful later is a bit harder to explain.

Most medicines have effects that are unrelated to the mechanism of action for which they are prescribed.  Aspirin was a great medicine for lowering fever, but it also interfered with the blood clotting mechanism...and is currently prescribed for that in low dose to prevent coronary occlusion and heart attacks.  It takes about a week off  aspirin for your blood clotting mechanism to return to normal.

In the case of the osteoporosis drugs, those patients who have been on the medicine for many years may be at a very slightly increased risk of esophageal cancer; the research is not complete on this.  However, there is a risk of hip fractures after long-term use which most studies seem to confirm.

Physicians have long recommended that most patients not stay on hormone replacement therapy for many years, with similar concerns for risk of cancer and vascular disease.

But drug holidays aren't just about hormones.  Non-steroidal anti-inflammatory drugs (NSAIDS)--used for degenerative arthritis and other pain conditions--that were designed to avoid the risk of GI bleeding accompanying some drugs of this type (like ibuprofen), have been shown to lose their protective effect after long-term use.  And doctors are recommending drug holidays for these (Celebrex, for instance).

It's important to note that most drugs don't need a holiday.  You should never stop insulin, digoxin, other heart medicines, and legions of other drugs without consulting your doctor.

But the theory is that a holiday will interrupt the process by which the risk is developing, and restore normal physiology, so the drug can be re-introduced.

How good is that theory?  It's hard to prove.  A risk that took years to become measurable may take years of study to know it's been averted. In most cases, we don't have a good test to tell when the risk is gone.  In some cases it may be that re-introducing the medicine puts you right back at the level of risk you were at when you stopped. 

Overall, the principle is one of caution.  And, occasionally, you find that a patient will go on a drug holiday only to learn that they don't need to take it any more.  That's a good thing; we sometimes end up taking too many medicines of dubious benefit.

The bottom line is, if your doctor recommends you go off treatment for a while, get the full story.  Weigh the risk against the benefit and make an informed decision.  Drug holidays have a place, and an underlying logic for why they can be important.

Doc D

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