... neuralgia for 13 yrs. About 7 months ago, my dosage was switched from 600mg/4xday capsules to 800mg/3xday tablets. Same amount, just tablets instead of capsules... now here's the complication... Since that time, or sometime soon thereafter, I began having very bad constipation. The tablets are QUITE "chalky" and will rub off even on my hand while taking them. I've contacted pharmacist and he said "research with the pharmacutical company that makes them". Gastro is just searching for anything that might be causing this, it might even be another one of my meds