The short version
Only one company currently supplies this market — there is no backup if it stumbles. The price has fallen 31% in a year, to $2.76 per unit — and generics that get this cheap tend to get abandoned rather than defended. It is in shortage right now — FDA lists the reason as “shortage of an active ingredient”. Put together: this is a fragile supply — if anything else goes wrong, there is very little slack to absorb it.
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