Hi there and welcome to MedHelp. So, Pristiq is a SNRI. That drug doesn't really have a generalized anxiety disorder indication but is often used (off label . . . many medications are used this way). Some doctors do feel it is effective. The labeling information on it by the FDA states that there is no therapeutic benefit above 50 mg. You are already on 75 mg. Did your doctor take you up to that dose because you weren't getting a good therapeutic effect at 50 mg? And are you wanting to up the dose further for that same reason? It may just not be a great fit for what you are trying to treat. Tell us more and we'll definitely try to help. :>)
That class of meds isn't the first choice for anxiety treatment. By the way, it makes no difference whatsoever if a drug got an indication as a treatment for anxiety or not. None of the antidepressants had an indication for anxiety treatment until years after they were commonly used for that -- they were all originally and only approved to treat depression. Some of them went back and got new certification to be used for certain types of anxiety to extend patent protection and some didn't, but they were used for it anyway. But this class of drug can be very stimulating, as it intentionally works on norepinephrine, also called noradrenaline, as well as serotonin. This doesn't mean it won't work for anxiety, but it also causes it in many people who never had it. The catch is, many of us anxiety sufferers are also depression sufferers, and if you tamp down the depression you often also tamp down the anxiety. I can tell you that my current psychiatrist, who is a psychopharmacologist, does not use this class for those with really bad anxiety problems, as in her experience it is too stimulating. But others do use it. This drug is basically a newer version of Effexor. Normally, if you don't have depression and are mainly an anxiety sufferer you will be put on either a tricyclic antidepressant or an ssri to start with. But if it doesn't work, you try anything until you do find something that works. Bottom line, though, if a drug isn't working, it isn't the right drug. As for dosage, individuals vary. Some need more because they don't absorb meds very well. Most will fit the recommendations of the manufacturer. Talk to your psychiatrist and see what he or she feels about it, but if it isn't working you need to try something else. Make sure if you do stop this drug, do it slowly and safely. Best of luck.