Do Automated Screening Systems for Drug Interactions Adequately Protect You?

Computerized drug interaction screening systems are insufficient to catch all important drug interactions, and are not an adequate replacement for conversations with your prescribing physician and pharmacist.

Although most of these systems detect the majority of important drug interactions, the systems have so many flaws that clinically important drug interactions often get lost in the shuffle.

In this article, we highlight some of the major flaws associated with these screening systems.

Too many unimportant interactions listed 

Experts who have looked at these systems generally agree that the most damaging flaw of these screening systems is the inclusion of too many unimportant drug interactions. This causes the truly important drug interactions to become obscured by all of the less-important ones.

For a number of reasons, removing the drug interactions of minor importance from these systems is a more complicated task than it might seem at first glance.

First, vendors of these systems may be reluctant to remove drug interactions for fear of liability. By putting all drug interactions on their system that have even a small chance of causing harm, they transfer any liability to the healthcare provider using their product.

Second, the scientific data on drug interactions consists primarily of case reports and small studies in healthy subjects, rather than large studies in actual patients. So, in some cases, it is difficult to tell how often a particular drug interaction would actually cause adverse outcomes.

Despite the suboptimal nature of these reports, it is clear that many of the drug interactions on these systems do not belong there.

There are some initial efforts to make these systems "leaner" and thus more useful. Ultimately, a national database of some sort may be necessary to promote a rational approach to the problem, which would reduce the overriding influence of perceived liability on the part of the vendors. A national database (not necessarily governmental — perhaps a non-profit) that all vendors could use could compete on the basis of cost, ease of use, value added features, etc.

Missing drug interactions

This is not nearly as much of a problem as the issue of too many interactions described above, but it can be dangerous if the missing interaction is life-threatening.

Consider the colchicine drug interactions described in the December 2008 Worst Pills, Best Pills News, in which very high levels of colchicine in the blood can lead to fever, vomiting, diarrhea, abdominal pain and muscle pains. This drug interaction should be on computerized drug interaction screening systems, but a review of many of these systems shows that several do not contain the full information on these serious colchicine interactions and thus fail to adequately warn people about this potentially fatal problem.

Lack of some useful details 

Most computerized drug interaction screening systems describe the drug interaction, but specific (and important) details are often missing.

It is important to know, for example, if the interaction is based on actual clinical studies or only on theoretical considerations, although many systems do not include this information.

Also the likely severity and time course of the interaction is helpful to know, but frequently missing.

Moreover, most systems do not describe under what circumstances the interaction is not likely to be important. Often no adverse interaction will occur, for example, if the medication dose is below a certain level or the medication is given only for a short period of time.

Lack of management advice 

Very few drug interaction systems give adequate advice to the prescriber or pharmacist about the best way to handle the drug interaction.

There are a few ways to manage a drug interaction. For instance, sometimes another drug can be substituted for one of the interacting drugs to circumvent the interaction.

Other times, separating the administration of the interacting drugs by a certain amount of time can mitigate the interaction. Advice on how to monitor for interactions is also important. When it is necessary to give the interacting drugs together, it is important for both the patient and the health professional to know what symptoms to look for so that the interaction can be detected early before things get out of hand. However, many systems do not provide this.

What You Can Do

Until the screening systems are improved, some common sense precautions are in order:

• Take as few drugs as possible. Many interactions involve drugs, at least one of which was not necessary in the first place.

• Inform your primary physician of all medications you are taking, including prescription, non-prescription and herbal medications and periodically go over with her/him the reasons for taking each. This process can draw attention to marginally, if at all useful drugs.

• Read up on the drugs you are taking. Reading Worst Pills, Best Pills News is a good start, and you would do well to also read the product information for all of the drugs you take.

• Pay attention to your body, especially if you have recently started a new medication. If you think you may be having an adverse drug interaction, contact your prescriber to get advice. Remember rule seven of our 10 Rules for Safer Drug Use: assume that any new symptom you develop after starting a new drug may be caused by the drug. If you have a new symptom, report it to your doctor.

• If possible, try to get all of your medications at one place. Even the best system cannot detect an interaction with a drug recorded only in another computerized system at another pharmacy.