Hello. 1. If not exposed to light, it will help you to live longer. If stored in a cool place will help to live longer but cannot assess whether how many months Because it depends on the different elements of the formula. If it is a formula developed for sale Members must test their stability before being released. such as placing it in soft light according to the actual packaging that will be sold or put it into the incubator (
Incubator ) at different temperatures To see how long it lasts 2. Because
Vitamin A will Soluble in oil, substance
Antioxidant that will suit
Vitamin A should also be oil-soluble. As for UV protection or
สารกันแดด if it's an oil-in-water formula, you can choose to use it. Soluble UV Because it will cover the
Vitamin A , another permitted form of drug use only), but the use of Retinol at an exorbitant rate It can irritate the skin. The recommended usage rate of 2% is as specified by the manufacturer.