Protonix is a relatively common drug prescribed for those with acid reflux, erosive esophagitis, and Zollinger-Ellison syndrome.  The reason I am writing about the drug is because I was prescribed it.

The purpose of the following illustration of this drug is to share with you the common principle that all drugs work by a molecular mechanism of action.  This understanding is fundamental to the broader understanding of molecular-based medicine — where medicine is moving from a “trial-by-error” approach to a much more knowledge-based, molecularly descriptive approach.

Sources:

1. http://bidd.nus.edu.sg/group/cjttd/ZFTTDDRUG.asp?ID=DAP000724
2. http://www.rxlist.com/protonix-iv-drug.htm (page 6)
3. http://www.webmd.com/drugs/drug-18142-Protonix+Oral.aspx?drugid=18142&drugname=Protonix+Oral

Protonix’ Mechanism of Action:

Covalently binds to Potassium-transporting ATPase alpha chain 1 (H+, K+ ATPase enzyme) at the secretory surface of gastric parietal cells.  What this means for your stomach is, a longer than 24 hour inhibition of the final step of gastric acid production (Source 2)

Metabolism

Protonix is metabolized (broken down) in the body through the Cytochrome P450 System – by a few enzymes (i.e., CYP2C19 and CYP3A4).  The reason this is important is because a recent case with Plavix suggests it is not good to combine Plavix with CYP2C19 inhibitors (read more here); moreover, people with variations in this C19 gene are more likely to have major to severe adverse side effects (read more here).

What this means?

What this means as far as Protonix’ mechanism of action is that it works by inhibiting molecule X (ATPase…) by covalently binding to it, therefore inhibiting gastric acid production and subsequently decreasing your acid reflux.  Additionally, based on Plavix’s recent studies, it can be inferred that gene variations in the enzymes which break down Protonix MAY increase the chance of Protonix’ adverse side effects.

In the Future (or now, if you want)

In the future (or now), you can test your metabolic genes — of which countless correlations between variations in these genes and adverse side effects / variations in therapeutic effectiveness will likely be discovered.  The value of these tests will be to effectively dose the drug for your body (genes), as well to select the drug which is right for your genes / molecular profile.  To-date, I am not sure about insurance coverage of such tests; however, genome-wide sequencing and genome-wide profiling is becoming cheaper by the day.  Eventually the cost of looking at an entire genome and/or molecular profile will be the same as the cost to test one gene.

The price to test only variants of CYP2C19 are currently between an estimated $200 and $375 (Source A, Source B, Source C).  See Quest Diagnostics or other services for more.

The price to test a slew of genes through 23 and Me (including CYP2C19 variants) is $500 it appears.  (Source D and Source E)

What choice will your doctor make? Likely, your physician will chose the more expensive tests — because, currently it appears to be law that 23 and Me’s test cannot be used for medical purposes.  If this is the case, and physicians cannot legally use the results of 23andMe’s test to aid in clinical decisions, the physicians will likely steer away from it because, if the physician did get sued after using 23 and Me’s test results to aid in making a clinical decision (i.e., not prescribe you Plavix or Protonix because of a genetic variant), the physician would lose because 23 and Me’s test cannot be used for medical purposes.  This is the same for any gene 23 and Me tests, including the BRCA1 and 2 genes (very important genes for predicting the likelihood of developing breast cancer).  Read about this issue on M.D., Beralano Mesko’s blog post.

As always, we welcome your thoughts.