u/C17H27NO2_

Male 30, caucasian.

I take lamotrigine for mood swings because I have borderline personality disorder.

I've been using lamictal for a decade. When I changed to 400 mg my blood levels of s-lamotrigine only got to 12 µmol/L. So I started 500 mg and it increased to 15 µmol/L which my psychiatrist said was inside the 15–50 window I needed, which I was to be expected to be inside taking only 200 mg. I take 500 mg and have that level.. So the dosage is beyond recommended.

I don't understand why the blood level of s-lamotrigine is so low. The therapeutic range is 10–50 µmol/L.

I split the dosage, so the blood was drawn at 12 hrs since last dose.

I take no other medication that induce the metabolism of lamotrigine by UGT1A4 and UGT2B7, like birth control or valproate. My BMI is only 18.5 so distribution volume is low. I do however take 450 mg of bupropion. My TSH level is normal range, and my FT4 level is 26 pmol/L which is a little bit high. I take levothyroxine.

My question is why the level is so low? Is there even a point for me to take lamotrigine if the levels are so low, dosage so high, maybe I only get side effects and no benefits?

I also had my s-bupropion level checked (sum of bupropion and hydroxybupropion I guess) and at 450 mg it was only about 1200 nmol/L which is low as well because the therapeutic window according to the lab is 1000–5000 nmol/L. Is my body just super quick, or is this expected?

Hi.

I've been using lamictal for a decade. When I changed to 400 mg my blood levels of s-lamotrigine only got to 12µmol/L. So I started 500 mg and it increased to 15 µmol/L which my psychiatrist said was a level which was to be expected taking only 200 mg. I take 500 mg and have that level..

I don't understand why the blood level of s-lamotrigine is so low. The therapeutic range is 10 – 50 µmol/L.

I split the dosage, so the blood was drawn at 12 hrs since last dose.

I take no other medication that induce the metabolism of lamotrigine by UGT1A4 and UGT2B7, like birth control or valproate. My BMI is only 18.5.

Anyone else have very low levels lamotrigine despite high dosage?

Hi.

I've been using lamictal for a decade. When I changed to 400 mg my blood levels of s-lamotrigine only got to 12µmol/L. So I started 500 mg and it increased to 15 µmol/L which my psychiatrist said was a level which was to be expected taking only 200 mg. I take 500 mg and have that level..

I don't understand why the blood level of s-lamotrigine is so low. The therapeutic range is 10 – 50 µmol/L.

I split the dosage, so the blood was drawn at 12 hrs since last dose.

I take no other medication that induce the metabolism of lamotrigine by UGT1A4 and UGT2B7, like birth control or valproate. My BMI is only 18.5.

Anyone else have very low levels lamotrigine despite high dosage?