I accidentally left my depression/anxiety medication in the car overnight. The coldest it got was -6 with a wind chill of -12 (Celsius). The medication in question are tablets, not liquid or gel capsules. There is no condensation on the bottle, or anything as such amiss that I can see inside the bottle or on the pills themselves. Everything look normal. Would they still be okay to take?
Drug shelf life is usually measured at 25 deg C but accelerated testing for stability is done at higher temperatures as this adds energy to the system degrading the drugs faster. So, storing drugs at lower temperatures increases shelf life.
When a new drug product is being formulated, it is desirable to determine the stability of the drug entity in the drug product so that a shelf life or expiration date may be assigned to the product. The shelf-life is the length of time required for the product potency to be reduced to some percentage of its original value. For most products, this is the T90 or time at which the product retains 90% of its original potency. Although the drug's stability at room temperature is of primary interest, a stability study at room temperature would take too long to be useful as a screening procedure for new formulations. Therefore, such screening studies are conducted at elevated temperatures in accordance with the Arrhenius equation: