One of the leading companies in the world that manufacturers deer antler spray is called Nutronics Labs. According to information posted on their website, they have been making deer antler supplements for two decades. They state that their deer antler products range in concentration/strength from about 25,000ng (nanograms)–200,000ng of IGF-1. According to studies done by Nutronics Labs, deer antler powders appear to be less concentrated with IGF-1. They also may be poorly absorbed compared to deer antler extract.
Deer antler velvet may help to increase macrophage activity. Macrophages are a type of white blood cell (immunity cell) that digests cellular debris, foreign substances, cancer cells, and other microorganisms. Macrophages help to stimulate defense mechanisms in the body by recruiting immune cells such as lymphocytes. With this increased number of white blood cells, your immunity system becomes strengthened and will have a better chance at fighting off a sickness or infection.
A systemic review on human interventions makes note of a study conducted on patients of osteoarthritis (Edelman et al. 2000; cannot be located online) which found improvements in joint pain symptoms relative to baseline in the Velvet Antler group and not placebo, although a lack of information on blinding and randomization precludes results that can be drawn from this study.