Excipients used in API

Question

In detail can someone outline the following points in relation to Porous silica

1. History
2. Properties
3. Safety and hazards
4. Applications and uses

Answer 1

Hi Emily M.,

You are probably referring to fumed silica, a common enough excipient in pharma, especially as a mixing agent in powders to be compressed into tablets. Silica gel (which is porous, but is beads, not a powder) wouldn't be used in a tablet, but might be in a desiccant packet in a bottle of tablets.

It is not an API, nor "in API". API == the pure drug (active pharmaceutical ingredient), which usually needs help from excipients to make a durable, nicely-sized, air-stable, etc. tablet.

You could easily look lots of this info up, either in manufacturer product info sheets, or in a pharmaceutical textbook, such as Goodman and Gilman.

In general, you don't want to inhale particulate silica (or asbestos, or anything else inorganic and insoluble!). Additionally, I note that even coarse (beach size) sand for heating baths,etc. comes with extraordinary amounts of hazard labeling. More hazard warnings than on dioxin bottles, if you can imagine. And this is cleaner stuff than you would find on an ocean beach, anyway. Go figure.

There are also some chemical requirements for use in pharma products, see the USP (United States Pharmacopoeia) and NF (National Formulary) entries for Silica. The pH value, especially, can be a troublesome issue. If you want to get technical, comment back and I'll assist if I can.

-- Cheers, --Mr. d.