Battle of the retins: AVAGE versus Renova
The active ingredient in AVAGE is tazarotene. This is a tretinoin, or member of the vitamin A family, which are also known as retinoids or retinols. My research efforts failed to find anything that describes tazarotene as anything other than another retinol. It doesn't seem to be differentiated by being more stable or powerful than its siblings.
Nevertheless, in a clinical trial, it has been proven to outperform Renova. 349 people with moderate photodamage were randomly given tazarotene, Renova or a control. After two weeks, both active groups were looking better than the controls. In the end, although tazarotene did slightly better than Renova, there wasn't that much in it. Treatment success, defined as improvement in photodamage of at least 50%, was achieved by 67% of the tazarotene group, 52% of the Renova group.
There are a couple of problems, however. The trial was sponsored by Allergan. And, secondly, tazarotene was used at twice the concentration (1%) as the tretinoin in Renova. This may explain why 59% of subjects reported mild-to-moderate peeling, itching, dryness, redness, or burning.
It is worth noting that AVAGE has a 1% dose of tazarotene and Renova is in a moisturizing base, which means it is generally considered to be a little milder and less drying than its prescription cousin, Retin A.