I've been to GNC and many Thai pharmacies for something called NAC, very common in US vitamins shops. It controls my OCD, though most people use it as an antioxidant. It suppresses the glutamate receptors, which suppresses obsessive thinking, my problem. 

Moved to main health forum.

Actually, I google thailand for this: nac site:th, and found a vitamin shop that stocks it called nanavitamins.com. I called to confirm. Apparently the shop is very far away from Nana area. And I couldn't get a straight answer about the location (language problems).

 

http://www.nanavitamins.com/category

NAC n-acetyl cysteine capsules are available in Thai drug stores. Sometimes I get tubes of NAC Long, more expensive, tablets that effervese in water.