I don't dispute that ketamine may perhaps have some clinical relevance for humans, but unfortunately it wreaks too much havoc on the kidneys for me to consider it as a viable option for treatment of depression.
Those points seemed already covered in the article, but somehow it must have been unclear.
First of all, it's unlikely to ever have ketamine as a first-line treatment for a depression. Probably more somewhere near electroconvulsive therapy. ECT also has adverse effects which can't be considered as minor (e.g. severe memory loss). However, at the same time it's recognized as a life-saver for certain population of patients.
As I have understood from this research and previous ones, it's hoped that the effect of ketamine would be long-lasting: at least up to months. Not so-called daily anti-depressant pill. The adverse effects of ECT would also be more severe if it would be administered on a daily basis. As it was mentioned, some patients relapsed within days, some were free from depression for up to three months.
According to animal research[1], it's prolonged not acute ketamine use that has shown signs of renal and bladder damage. In a review of ketamine-induced vesicopathy[2] it's also noted that 'Very little is known regarding the pathogenesis of its effects on the urinary tract.' I'm not claiming that it doesn't cause any damage, but that it needs more research and currently there's no indication of "renal havoc" after few doses.
In light of this, I can't even imagine how someone could call possibility of using ketamine for treatment of depression not viable. However, it may be because I know how disabling severe or even moderate depression is and how much damage it causes to person's life.
Each person reacts very differently to anti-depressants and there's large amount of people with treatment resistant depression. It's not like there's silver bullet and because of that we need as many as possible different treatment methods. Depression is life-threatening condition and thus all of those methods can't (and don't need to) be 100% safe. A lot of approved drugs have serious side-effects. Basically it's all about assessing the benefit:risk ratio of a drug. It's not rational to cross any treatment out, just because it may have side-effects. Especially if there's not reasonable amount research done - like with ketamine.
When we have more data, then it may show that certain population would need additional doses of ketamine after 1-3 months and the damage to organs is minor or non-existent in such case. Or it may show something else. It's just unthinkable to call it as "not viable" option, yet.
[1] Yeung, LY, Rudd JA, Lam WP, Mak YT, Yew DT. (2009) Mice are prone to kidney pathology after prolonged ketamine addiction. Toxicol Lett. 2009 Dec 15;191(2-3):275-8. doi: 10.1016/j.toxlet.2009.09.006. Epub 2009 Sep 17.
[2] Middela, S., Pearce, I. (2010) Ketamine-induced vesicopathy: a literature review. Int J Clin Pract. 2011 Jan;65(1):27-30. doi: 10.1111/j.1742-1241.2010.02502.x.
