(b) I have no sympathy for patients in news stories that cry wolf. They lie too much, and conceal critical facts that are in favor of pharmaceutical companies. Plus journalists, such as this one, often do not do homework, taking those patients at face value.
(i) First and foremost, even taking Kuvan a PKU patient still has to limit intake of protein containing phenylalanine, which means almost all protein.
(ii) Before I introduce you to PKU, I will talk about the drug Kuvan.
(iii) No miracle drug, Kuvan is the trade name for an ordinary chemical, which our body already produces. See tetrahydrobiopterin
https://en.wikipedia.org/wiki/Tetrahydrobiopterin
("(BH4) also known as sapropterin, is a cofactor;" section 6 Biosynthesis and recycling)
(A) At the top of this Wiki page, you see the chemical structure of tetrahydrobiopterin, whose difference with biopterin
https://en.wikipedia.org/wiki/Biopterin
is the addition of four hydrogen atoms in right aromatic ring. The fourth hydrogen atom is not shown, as is the practice in chemistry. (By definition, in chemistry addition of (at least) one hydrogen atom is reduction 还原.)
(B) pterin
https://en.wikipedia.org/wiki/Pterin
("Pterins were first discovered in the pigments of butterfly wings (hence the origin of their name, from the Greek pteron (πτερόν), wing) and perform many roles in coloration in the biological world") (citations omitted)
pterin
https://www.merriam-webster.com/dictionary/pterin
(pronunciation)
shows p is silent.
(C) cofactor (biochemistry)
https://en.wikipedia.org/wiki/Cofactor_(biochemistry)
Many vitamins belong to this category of chemicals. These chemicals are vitamins because out (human) body can not make it, such as vitamin C.
(iv)
(A) Chemically, Kuvan is simply sapropterin dihydrochloride. The "dihydrochloride" merely means the resulting salt after adding two "HCl" per sapropterin.
(B) BH4. Schircks Laboratories (based in Bauma (20-mile air distance east of Zurich), Switzerland), Jan 26, 2016
www.schircks.ch/pteridines/data/11209_11214_11215_BH4.pdf
("It [BH4] reacts with oxygen especially in neutral and alkaline solutions [this explains why 2HCl was added, to make the solution acidic (before a patient drinks the solution, but this is a chemical company whose product is not sterile]. * * * Dry powder has different stability depending on conditions, as described in the table below ['in ampoules: RT [room temperature] several months, or -20°C several years'])
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