I am really confused at the selling prices in Retail Pharma

Hey,

When I started Pharma, I sold at 120g/unit but when restocked my pharma when 0 was left. No one bought it even though no change in competition. I had to put it at 109g/unit, and today I could put it as 125g/unit. I don’t understand, does the market demand change day by day just like in real life?