Today, we were discussing optical activity in class and our teacher said that some drugs are kept in dark coloured bottles to avoid direct exposure to sunlight. Same is the case with some other drugs in which it's written that the direct exposure to sunlight should be avoided.
The reason he gave for the above was that the one form of isomer can get converted to other form in direct sunlight. But as far as i know, photolytic decomposition can happen. Is the conversion of d to l isomer and vice versa possible in sunlight?