Try kegel exercise to improve blood flow to your penis.
Exercise is most important to improve your blood circulation.
Supplements to improve your testosterone level ,take zinc and magnesium (normally they come together )

Try google citric q, all result came out are from product selling website.

What is the US company that producing this drug/supplements?

Read more on FDA approved drugs
https://www.livestrong.com/article/421353-w...u-look-younger/

"Federal law classifies vitamins as a dietary supplement, which places them under the general category of food and not drugs. As a dietary supplement, the FDA has no duty or authority to "authorize" a vitamin for sale. A vitamin manufacturer has the duty to ensure the vitamins it sells are safe before entering the market, but the FDA does not have to authorize or approve the vitamin before the manufacturer sells it"