Thank you very much for the reply. Unfortunately, the chemical is not optional, and I can't find any other ways for my friend to buy it to avoid continuing progressive brain damage, among many other problems. It costs over $1,000 USD for 3 grams from US resellers from what I can tell, which is deliberately impossible to afford, $10 USD for 1,000 grams from a manufacturer.

Hello, I need to source an important chemical for a friend (sapropterin dihydrochloride), and I can only find one website that has it (made-in-china). If this is the wrong forum to ask for help with this, please help direct me toward a more appropriate one (I have cognitive issues). I am having difficulty because I don't know if that is the "right" website to order from, or how to select the right listing to manage risks of: contamination, toxic additives, resellers, the seller not actually sending it, seizure by US customs, impure / intended for further processing. There are very many companies with listings on this one site, and I can't find any others that have these kinds of chemicals (alibaba etc.). I don't even know if there's anything special I need to tell them for shipping to a US address. I have ordered other things overseas before, but it was a long time ago and it seems things have changed, many forum posts are outdated, and it was from a very different style of website. This is only manufactured in China from what I can tell. 1 kg would probably last years.

Most of all, is there any sanity check type of thing that I seem to be overtly missing, or anything special I need to do for delivery to a residential US address?