Formulations with improved stability

A formulation comprising:

• a compound having a structure:
• or a pharmaceutically acceptable salt thereof;
• and
• a lipophilic vehicle comprising at least one lipid excipient and at least one surfactant,
• wherein the compound, or the pharmaceutically acceptable salt thereof, is soluble in the lipophilic vehicle,
• wherein the lipophilic vehicle comprises at least two selected from the group consisting of PEG-200, PEG-300, PEG-400, a PEG castor oil, a lauroyl PEG glyceride, a stearoyl PEG glyceride, an oleoyl PEG glyceride, a caprylocapryl PEG glyceride, a PEG-20 glyceryl stearate, a glycerol oleate, a glycerol linoleate, a glycerol stearate, propylene glycol monocaprylate, polyglyceryl-3 dioleate, diethylene glycol monoethyl ether, d-alpha-tocopheryl polyethylene glycol 1000 succinate, polyoxyethylene (20) sorbitan monooleate, and polyoxyethylene (20) sorbitan monolaurate, and
• wherein the formulation is suitable for oral administration.