I just want to ask if how do I take metathione, because from what I know I just need to take it twice daily with vit. c? And my other question is what is the dosage of vit c and for what is that. Thanks!

I know that this is not a direct answer to your question, and someone else may have it. But, I found a couple of sites that may be of help to you. I hope that they are. Vitamin C is mentioned on both of them.

Skin whitening - skin care guide

Skin Lightening

Here's another links that are on this site.

https://www.askmehelpdesk.com/advice/t-22499.html