A recent study found what we have seen in the office here in Beverly Hills:  When men receive anti-wrinkle treatment, they need larger doses than women.  This is in keeping for all plastic surgery procedures:  men are just plain different than women.  This holds for facial aesthetics and liposuction and everything in between.  Here is a summary of the article—

There has recently become a growing interest in cosmetic procedures by men. Although most practices see a majority of women, the number of male patients who seek treatment is slowly increasing.

Men often require more units of Botox than women which may be because men have a greater muscle mass than women. Similarly, it has been a common clinical observation that larger, stronger men need more units per treatment area than slender, small-boned men. The most common cause of inadequate results in male patients is under-dosing, which may lead to men requiring additional Botox injections.

“Various areas of the male face can be treated with Botox and injections need to keep in mind the greater muscle mass in men,” the author notes.