Doxycycline - Why would drug companies put Titanium dioxide (TiO2) and Sodium lauryl sulfate?

All solid oral dosage products (tablets or capsules) consist of an “active” ingredient or drug. It is rare to find a solid oral dosage product consisting of drug alone. To produce a final product that is not only practical and convenient to handle but also facilitates patient compliance, the drug substance needs to be processed with other excipients. These drug “fillers” or excipients serve many roles in the formulation. Some examples are binders, fillers (or diluents), disintegrants, lubricants, colorants, buffering agents and coatings.

Food dyes are added to make them "look pretty".
TiO2 is added for its whiteness and opacity.
Sodium lauryl sulphate is added because of its lubricant properties and aids the manufacture process (stops tablets sticking to tablet punches).

Expand this post...

Have a chat with your pharmacist. There are many doxycycline versions on the market but most will have a variety of excipients added . A suggestion is to open a capsule and take the contents... it would taste terrible but you would avoid swallowing some of the additives.