A therapeutic index

What is a therapeutic index and why should I care?

 

If you take any drugs, you need to know what this means. In simple terms, the therapeutic index is the window in which the drug is reaching its targeted amount in the bloodstream to treat whatever it is designed for. That is my simpleton explanation from my standpoint. You can read about therapeutic index here  http://en.wikipedia.org/wiki/Therapeutic_index  or in medical journals, etc.

 

Dilantin/Phenytoin (generic) has a therapeutic index of 10 to 20 mcg/mL. Many drugs do not have such a small window meaning that there is less leeway with Dilantin. Other drugs are more forgiving—the target isn’t so small. This particular one is used for seizure control. It was the “go to” drug of choice back when I was diagnosed in the early 1970s but there are probably better drugs today with fewer side effects. Each of us is different and we react to medicines in varying ways so many times it becomes a tradeoff.

 

I personally am at my best when the serum Dilantin level is about 17 mcg/mL—on the high end. It doesn’t take much to make it swing one way or the other but at 17, my seizures were well-controlled. To measure how much is in my system, a blood test is performed. Usually this is done twice a year when I show no problems and more if I have issues. There have been times where my level went down to 0.02 (yes, below 1). That is when I would pass out because I was not getting oxygen to my brain. That’s not a fun time either.

 

Anything ranging outside the bubble (so to say) is bad 🙂 . Anything above 20 is considered toxic. Toxic doesn’t necessarily mean lethal. Lethal doses are usually not referred to in the literature quite so much with humans but lethal means dead if you get my drift. Dead is definitely bad news (humor for the moment). So… toxic is an indicator that something is wrong and in my case it had nothing to do with changes of dosage—not in 2014.

 

Back in graduate school, my serum Dilantin level dropped and had to be reregulated…it had to be readjusted to get it back between 10 and 20. Sometimes it is hit and miss until you get it right and many times it takes a while. With me, I do better with a larger dose in the morning and smaller one at night but there are so many factors that can affect the level. Over the years I have learned what works and what doesn’t—well, usually I know when it is off.

One of my many counselor experiences during graduate school.

 

All this basically boils down to is how the liver breaks down the drugs. We really should treat our livers better but that’s another story, too. The highest level I ever had measured until this year was 40 mcg/mL and that was hell, to put it lightly. My gums turned white and I could not tell you who I was basically. I could not walk/balance—a host of problems. That was the graduate school lesson and the only time I ever knew when I was toxic.

 

If you take medication, even illegal drugs, you need to know what you are doing to your body. There is a consequence for everything we do. Choose wisely, please.

 

Next:  “Mom, I’m broken.”