Hi PJ-
Primidone was the second drug I took for my epilepsy nearly 20 years ago. I was on it for several years. Right from the start it made me sleepy and caused me to stumble around. I had to hang on to the furniture and walls just to make it across the room. It took me weeks to get used to it, but eventually I became tolerant to the side effects and was nearly normal, except for being somewhat drowsy. My dosage was 250mg at night, but I felt sleepy most of the day. The only time I felt really alert was in the evening right before my next dose.
Luckily, it eliminated my seizures for the several years I was on it. The reason I was taken off it was that I became pregnant and had to go off it. Back then, there wasn't the variety of choices of anticonvulsants as today, and it must have been used a lot more. I hardly ever hear of anyone on it today.
Hope that helps, Glenda 