Don't panic!
An API is what is known as the "Active Pharmaceutical Ingredient" ie Sofosbuvir or Ledipasvir.
If you take Gilead as an example the APIs for Harvoni are made in Jordan.
This chemical powder is then shipped to Ireland where the two parts are mixed with glue, lactose (milk sugar), fibre, disintegrant, sand, wax and pressed into tablets.
The extra bits are called excipients and can be used to control rate of release but in the case of Harvoni it's a fast release instant dissolution.
Harvoni Excipients:
- Copovidone (glue)
- Lactose monohydrate (sugar)
- Microcrystalline cellulose (fibre)
- Croscarmellose sodium (disintegrant)
- Colloidal anhydrous silica (sand)
- Magnesium stearate (wax)
What you have is the APIs mixed with Microcrystaline cellulose in a capsule that, like Harvoni releases the API rapidly. The other parts of the tablet are only used to make the table stick together, and then dissolve in your stomach. It's cheaper to make a tablet than a capsule which is why they are commonly used.
There are now hundreds of people now have taken Sofosbuvir/Ledipasvir in this form and are at viral load zero.
The APIs in both Twinvir and your medication came from China (different large scale factories). They are chemically identical the the APIs in Harvoni and you can read the testing reports about that here:
Testing Provisions Patient Safety
.