I'd like to add something to this thread about definitions and labeling of drugs.

Basically the FDA approves drugs to be used for certain purposes and this is based on studies presented to the panel there.
Anticonvulsants were initially approved for seizure control.

But their use has generalized into other categories now as well.

In this case, Lyrica was originally approved for seizures. (Pfizer tried to get an approval for anxiety use, but couldn't get their studies to show what the FDA wanted.) Instead they recently obtained approval for Fibromyaglia (pain). I am reading that an additional approval will be most likely be coming for anxiety after all..but we have to wait and see this time.

So as it stands now Lyrica is an anticonvulsant, but it is most commonly given for pain control. Many doctors prescribe it for nerve pain (off label) and also now for Fibro (approved). Approval basically results in insurance companies paying for the treatment with a diagnosis. The FDA has approved Lyrica for neuropathic pain associated with Diabetes. (it does not at this time have a global anti pain approval however.)

Many drugs may be used off label for other purposes.
For example, benzodiazepines like Klonopin and Valium may be used for seizure patients. Valium is commonly given after a seizure ends, in the post ictal phase. But Valium is approved for anxiety.
Further, chronic anxiety may lead to depression, according to some psychologists we know who took care of my son at one time. So treating anxiety may diminish the appearance of depression in some patients. Reducing pain may also reduce the depression that may accompany chronic pain. In in a very round about way, Lyrica may reduce depression, without having direct effects on the depression itself, but on its development.

So the bottom line is that drugs today are not all black and white and easily categorized. We use the rules in US from the FDA and insurance companies to get payment, but past that, drugs may have multiple actions and different people may use them for many purposes, other than their approval category.
In other words, many gray areas exist in actual treatment settings.

This thread has brought up many examples, of how we look at drugs. And as far as discussion goes, it is very interesting to read the responses.