Business case

1 in 50 have a drug error

One in 50 (or more) consume at least 10 drugs on a regular basis. We have analyzed a number of these, and in 75% Drug GPS can identify an error, so that it can be fixed afterwards by adjusting the dose or pick another drug.

So approx. 1 in 50 have an error that Drug GPS can identify (and suggest how to fix).

Types of medication errors caught by Drug GPS

WHO (UN) estimates that the cost of drug errors is 1% of the total health budget. This corresponds to a saving of at least USD 10 per person per year. The error types that Drug GPS screens for and identifies are in the following categories:

Overdose of a Risk Class

Risk Classes are e.g. Anticoagulants, Opioids, Psychotropics, NSAIDs, Methotrexate, and Potassium. Most often the collective impact of several drugs create an over dose situation, even though each one of them is correctly dosed. We catch these situations as the only system that does it, because we compute the amount of Active Substances par 24 hours and then compute a weighted sum for each Risk Class of the Active Substances that contribute to this class.

Most of the serious errors including most fatal errors are in this category. And Drug GPS is the only system to identify them.

Overdose of a single Active Substance

We use the Daily Defined Dose (DDD) of WHO, which is defined by ATC code. We find the ATC of the drug, that has the Active Substance as a mono-ingredient and thus calculate "the ATC of the Active Substance".

Since DDDs are often ignored as thresholds, we report only the following:

  • More than 33% past the DDD: Then the drug is in all cases strongly dosed, and it must be assured that it can be tolerated.
  • More than 100% past the DDD (more than double dose): Then the drug is probably over dosed.

Allergies towards drugs

Certain allergy classes may mean allergy towards a drug that yo do not expect. Thus we see the drug is taken, despite the allergy towards it (towards the Active Substance).

A frequent example is Sulfanomide allergy (which is frequent among people that have received a lot of anti biotics), and people despite that have a drug containing Furesumide (which is a Sulfa drug and a frequent diuretic used against high bloog pressure). People in this situation suffer allergic reactions, typically not feeling well, every day.


The most interactions are "dosis correction" or "certain precautions" interactions, marked as "yellow". Some are "red", which means they should be avoided (one of the drugs in the interaction discontinued). We report them as they come from trying all Active Substances in the Danish Interactions Database (which we have taken a copy of in our database).

These interactions are rarely important (most of them being "yellow"), and they have created an "alert fatigue" among doctors and other health care professionals. We differ in the reporting of these - only the "red" interactions are real errors.

The need for reporting of too much af a Risk Class and the inability to compute that correctly has led to the creation of interactions between e.g. some Anticoagulant drugs - where there is in fact no interaction, but the doctor must be alerted to the fact that the patient may be overdosed, if both drugs are on the list. This is a wrong use of interactions (but the only means available to most), it leads to the reporting of situations that are not an error (if two drugs are indeed combined, but they do not lead to an over dose situation of the Risk Class), and it is inadequate in that not all combinations inside all Risk Classes are there.

Genes affecting metabolization

Some Active Substances, many of them frequent like the Statins, are metabolized by an enzyme the effectivity of which isn't known unless genes are known, and the drug is therefore not correctly dosed, until a pharmacological gene test is undertaken.

The pro-drugs are not active unless metabolized once, and therefore these drugs may not at all work, if this metabolization is inefficient. This goes for Tamoxifene, given to ER positive breast cancers, and all male breast cancers. It is a pro-drug, and 15% of the population has no effect from it, because (as revealed by a gene test) they do not metabolize it.

For each medication list reported to Drug GPS, the list of Active Substances that warrant a gene test is given. So you can see how important it is to get the gene test.

Several Active Substances in one class

The main example of this situation is several diuretics, because they are used in several combination drugs, e.g. blood pressure drugs. We have seen examples, where people had several diuretics by error, and were therefore de-hydrated etc.

Some errors may be identified by this happening, so we report it for all classes, including for the broader Risk Classes.

Contra indications and warnings from the Package Inserts

Since we have digitized the Package Inserts (for the top sellers of drugs, so we get them digitized more and more, starting with the most frequent Active Substances) we can report if any of them are violated. A violated contra indication is a drug error - and often a non-handled violation of a precaution is also a drug error.

We make sure to ask all the questions required by the Package Inserts in order to be able to perform the checking.

Package Inserts also report which "Other drugs" you should tell your doctor about. We check them off, since we assume we know of all drugs taken. It can be seen as a supplement of the Interactions, and we do not view this part as a source of error (although it could be, if it isn't caught by the Interactions).

Required measurements

Like we derive what questions we need to ask, we also derive the measurements that must be monitored, when you take certain drugs. E.g.

  • INR for many blood thinners,
  • QTc (a heart beat value) for many psychotropics,
  • eGFR when important metabolization happens in the kidneys etc.

In some cases the output values of these measurements must be taken into account when correctly calculating the threshold doses.

Drug GPS for Clinicians

This document (click to open) explains in detail what the errors are and what knowledge the solution consists of. It goes through an example.