There are a number of psychiatrists (quite a few English speaking) in Capital Federal who can prescribe different forms of prescription antidepressants. As someone from the US, where mental health care is pretty much non-existent and frighteningly expensive, is that a key factor to keep in mind here is even without medical insurance (obra social), medications here are considerably more affordable, and in many cases, generic equivilants are available.
For what it's worth, I have also lived abroad in South Korea, where it was a scandalous taboo to seek any form of psychiatric/psychological help (online forums encouraged anyone living there to seek help only if absolutely necessary far from where you lived and worked, and never to use the insurance provided by your employer... which was an unhealthy situation for many reasons). Thankfully, here such a damning stigma is not the case.
Moreover, I do not know all the circumstances of your situation (each case is totally different), but it is also worth mentioning that many psychiatrists are also certified as psychologists (there are several fields of expertise), or they can recommend an additional therapist for talk-therapy. If you plan on being here for any length of time, speaking from persoal experience, you can't fly on one wing, and even the most effective medication in the world will not be as helpful if you don't have the opportunity to address any potential underlying issues.
Suerte!