Ketamine in Psychiatry

Ketamine is a drug which has been used in general anesthesia for decades.  It is a so-called "dissociative anesthetic," which means that it causes an altered state of sensory perception without loss of consciousness.  It is a blocker of NMDA receptors;  this blockade in turn boosts glutamate release through reduced presynaptic inhition.  From there the increased glutamate increases stimulation of AMPA receptors.  These effects occur only for a few hours after a dose.  The significance of these changes would be of some debate among neuroscientists, but the bottom line is that there is a brief but marked acute alteration in one of the core aspects of the brain's dynamics and metabolism, including those aspects responsible for the management of memory, learning, and emotional processing.   

Ketamine is used illictly as a recreational drug, a fact which might bias many of us against considering its potential benefit in medicine.  

The exciting news about ketamine recently is that a single dose can lead to a dramatic improvement in symptoms of depression, even in patients who have severe, chronic, treatment-refractory mood disorders.  Aside from these case reports, there have been a number of larger studies coming out, all of which look very promising. 

Here is my literature review on ketamine, I've selected what I have thought are the best or most representative articles:

I. studies showing effects in mood disorders

http://www.ncbi.nlm.nih.gov/pubmed/22297150
bipolar depressed patients randomized to get IV ketamine 0.5 mg/kg or placebo, 2 infusions, 2 weeks apart. Around 70-80% response rates and 30% remission rates, with effects lasting several days on average. The placebo group had a 0% response rate.

http://www.ncbi.nlm.nih.gov/pubmed/22840761
ketamine 0.5 mg/kg IV 3 times per week x 2 weeks, in 24 patients with refractory depression. About 70% (17/ 24) of patients had a large, substantial improvement in depressive symptoms; improvement lasted an average of about 2-3 weeks.

http://www.ncbi.nlm.nih.gov/pubmed/20679587
Archives study, randomized add on of IV ketamine for bipolar depression. 13 of 17 patients in the ketamine group completed the study, vs. 15 of 16 patients in the placebo group. The patients were hospitalized, and had not responded to a mood stabilizer and antidepressant. Only 2 infusions, 2 weeks apart. But 50-60% response rates, 20-30% remission rates, lasting for 3-4 days, with a very large difference from placebo. Dissociative side effects occurred only acutely, for a few hours.

http://www.ncbi.nlm.nih.gov/pubmed/22297150
A similar study replicating the results of the above study.

http://www.ncbi.nlm.nih.gov/pubmed/23200737
ketamine 30-120 mg intranasally, used for severely symptomatic male bipolar patients, ages 6-17, every 3-7 days.  Marked symptom improvement in multiple domains, lasting 3-4 days after each dose.  side effects diminished with subsequent doses.  but still good clinical improvement.  Average of 20 weeks duration.  But this was a retrospective chart review.  Side effects such as transient dizziness etc. but no severe side effect problems. 

http://www.ncbi.nlm.nih.gov/pubmed/23182590
case series of 3 patients, treated with ketamine 0.5 mg/kg IV, every 1-2 weeks or so.  These patients had long complex histories of severe treatment-refractory depressions with comorbidities & axis II problems.  Varied response, one of the patients had marked improvement, the others had some benefit but not nearly so compelling. 

http://www.ncbi.nlm.nih.gov/pubmed/22854933
case series, 50-70 mg IM  ketamine q4 days for bipolar depression, marked improvement in one patient, slight improvement in another.  In these patients intranasal and/or oral ketamine did not help. 
Side effects of headache and irritability. 

http://www.ncbi.nlm.nih.gov/pubmed/23145560
bipolar depressed patients with a positive family history of alcoholism had better responses to ketamine.

http://www.ncbi.nlm.nih.gov/pubmed/20636166
a couple of cases of using oral ketamine 0.5 mg/kg to successfully treat anxiety and depressive symptoms in palliative care patients. Once again, good symptom improvement lasting about about a week. This study stands out for using oral ketamine, which would be much more convenient to use for outpatients.

II. effect on other psychiatric symptoms

http://www.ncbi.nlm.nih.gov/pubmed/22784486
no improvement in OCD symptoms with IV ketamine.

http://www.ncbi.nlm.nih.gov/pubmed/23245747
no exacerbation of PTSD symptoms in patients with trauma history exposed to a ketamine dose

III. use for treating pain disorders on an outpatient basis

http://www.ncbi.nlm.nih.gov/pubmed/22833771
a chart review showing that transdermal ketamine can be useful for treating neuropathic pain.  I include this here to show that a transdermal route is possible, and also to show evidence of safety in other areas of outpatient medicine. 

http://www.ncbi.nlm.nih.gov/pubmed/21939497
another study looking at outpatient ketamine to treat chronic pain successfully. It was a 5-year retrospective study.    Here they used infusions, generally at a higher dose than the psychiatric studies (0.5-1 mg/kg), repeated every 3-4 weeks.   The treatments were successful and generally well-tolerated with no severe side effect problems.

This article (**) discusses ketamine use in palliative care, according to the authors' experience. In this population they suggest a starting oral dose of about 25 mg, up to 4 times daily, increasing if necessary to a maximum of 200 mg 4 times daily. As the first reference of my post suggests, it may be that IM ketamine is more effective than oral or nasal ketamine. 

http://www.ncbi.nlm.nih.gov/pubmed/20648208
a negative study, showing that adding ketamine to high-dose opioids for pain patients was not particularly useful in the long-term, in terms of reducing long-term high-dose opioid dose requirement. 

IV. toxicity & risks

http://www.ncbi.nlm.nih.gov/pubmed/19919593
This 1-year longitudinal study shows substantial cognitive and functional impairment in heavy users of ketamine (many of whom using 20 doses per month).

http://www.ncbi.nlm.nih.gov/pubmed/23145560
this study found that daily 1 mg/kg doses of IV ketamine caused signs of neurotoxicity after 6 months in monkeys.

V. Pharmacology (from the Monograph)**

Ketamine comes in 10, 50, or 100 mg/ mL solutions (the 100 mg/mL needs to be diluted for IV).
Parenteral use does not impair pharyngeal reflexes, therefore is safe for airway management. With IV administration, redistribution & metabolism causes duration of action of 45 minutes, and a half life of 10-15 minutes; a partially active metabolite has a half life of 2.5 hours.

There is a possible acute elevation in blood pressure with a rapid parenteral dose. Overall, it has a wide margin of safety in anesthesia.  There is respiratory depression only with rapid high-dose IV doses.

A dose of 2 mg/kg IV produces surgical anesthesia in 30 sec, lasting 5-10 minutes.  Doses of 9-13 mg/kg IM produce surgical anesthesia within 3-4 minutes, lasting 12-25 minutes. In surgery, low dose IV diazepam (under 20 mg) is used with the ketamine.

The LD50 in rats is about 20 times the equivalent human IM surgical dose.   

VI. Mode of Administration   **

Oral ketamine has about 20% the bioavailability of IV, but leads to equal bioavailability of the active metabolite.  So overall it would be conservative practice to start with the same dose orally as parenterally, and adjust (probably upwards) from there. An oral dose might need to be 3-4 times higher than a parenteral dose, to cause the same effect.  But an oral dose is likely to have an acute effect which lasts about twice as long as parenteral (approximately 4 hours of acute effects instead of 2 hours).   The qualitative difference of oral vs. parenteral effects may be due to the difference in levels of the metabolites.  The reference shown above suggest that IV doses may work better to treat mood symptoms, compared to non-parenteral dosing.   

Possible routes of administration include oral, intravenous (IV), intramuscular (IM), subcutaneous (SC), intranasal (nasal spray),  transdermal (skin creams or patches), and rectal. 


Some of the questions I have about ketamine use in psychiatry are:

1) how safe or useful is it in patients with strong histories of psychotic symptoms? 

2) to what degree does the environmental setting during the dose impact its effectiveness?  I wonder if the environment in the moment might act as a catalyst for its effects.  I suspect that a very positive, peaceful, meaningful environmental setting would consolidate the experience of symptom relief much more positively than exposure to the drug without any regard to the external situation.  This would be akin, I am thinking, to temporarily relieving a physical disability (as a prelude to working towards permanent improvement) being much more effective if the resources were in place during that temporary relief, to fully enjoy and appreciate the regained function in the moment.  This is why I suspect that the recreational use of agents such as ketamine in socially desolate or agitated settings (e.g. on the street, in a marginalized or socially impoverished situation, or in noisy parties, etc.) could have an emotionally harmful effect rather than any sustained benefit. 

3) if the ketamine is effective, what is the best long-term dosing interval?  (current studies suggest every 1-4 weeks, but not enough data to be sure)   My reading of the evidence suggests weekly dosing, with diminished frequency or dose  if symptoms remain stable.  Also, what is the role of other antidepressant therapies, including other antidepressants, in patients having ketamine treatments?  (some of the articles quoted above suggest that some drugs such as benzodiazepines may reduce ketamine's effects--I wonder if this is true for other drugs such as mood stabilizers)

4) if it is effective, does it remain effective for very long-term followup (over many years).  And if there is repeated use over this time, are there emergent side effect risks not appreciated in the present short-term studies?   

5) given that this is a new and exciting area of research, should this not warrant intense widespread research scrutiny, including large multicentre trials?  A new SSRI trial may well be more easy to fund and organize, due to the present funding and political structure of the research system, but perhaps a ketamine trial would be of greater good for patients. 

6) Ketamine has been used so far only in treatment-resistant severely ill patients.  Could ketamine have a role as a first-line agent for less severe cases? 

7) Could ketamine be useful as a component of therapy for other problems (e.g. personality disorders, eating disorders, relational disorders, etc.)

8) Because part of ketamine treatment is very immediate and acute (an effect lasting hours), could there be some type of psychotherapeutic activity during this time which might optimize its effect?

9) What is the legal status of physicians prescribing ketamine on an off-label basis?

So, in conclusion, a very promising new area to be researched further.   I will be curious to find out more answers to these questions. 

Lamotrigine review: bipolar depression, unipolar depression, borderline personality, OCD

Lamotrigine is a novel anticonvulsant.  Clearly it is useful for treating epilepsy, in terms of reducing seizure frequency in difficult cases, with a better side-effect profile than many other anti-seizure medications. 

It has been used in psychiatry for over 10 years, mainly to treat bipolar depression.  Initial studies were quite encouraging.  More recent studies have been a bit more mixed. 

Here are a few recent references:

http://www.ncbi.nlm.nih.gov/pubmed/21367355 
this was a large study of using lamotrigine as an augmentation to treat unipolar depression.  It did not show that lamotrigine was useful overall.  But it appeared much more effective in a subgroup of  patients with much more severe depression.  Average doses were about 200 mg/d, maximum 400 mg. 

http://www.ncbi.nlm.nih.gov/pubmed/19636254
this study showed improvements in affective lability with lamotrigine vs. placebo, in patients with borderline personality, using a flexible dose (average about 100 mg/day).

http://www.ncbi.nlm.nih.gov/pubmed/19200421  200 mg/d lamotrigine  helpful for bipolar depression as add-on with lithium x 8 wks

http://www.ncbi.nlm.nih.gov/pubmed/23107222
no difference in depression scores with lamotrigine vs placebo  as add on for bipolar patients 

http://www.ncbi.nlm.nih.gov/pubmed/22351381  adding lamotrigine 100 mg to an SSRI improved symptoms (about 30% reduction in YBOCS score) in OCD patients, compared to placebo, after 16 weeks.

In conclusion, I think lamotrigine is in the "why not give it a try" category for a variety of problems.  It might possibly help for treating depression in bipolar patients, or even as an augmentation in unipolar depression.  It might be useful in OCD patients, and in borderline personality.  It may be one of those agents which helps some individuals very well, even though the average effect for a group of similarly afflicted individuals may be unremarkable.  Another possibility is that it could help with certain symptom domains, such as obsessionality, ruminativeness, etc. which could occur more prominently in some but not all patients with mood or personality disorders. 

I think the big advantage of lamotrigine is that it is quite well-tolerated, with a benign side-effect profile, except for a small risk of a dangerous rash and a few other rare serious problems, which just need to be watched for carefully. 

N-acetylcysteine for OCD

I've written a post about N-acetylcysteine before (http://garthkroeker.blogspot.ca/2009/09/n-acetylcysteine-for-treatment-of.html), which suggested that it could be useful in treating compulsive behaviour disorders such as skin-picking. 

A recent 2012 study by Afshar et al. has shown that NAC is useful for treating obsessive-compulsive disorder (OCD).  Here's the reference: http://www.ncbi.nlm.nih.gov/pubmed/23131885

In this study, 48 patients with OCD who had not responded to an SSRI were given NAC up to 2400 mg/day or placebo, in addition to a continued dose of the same SSRI, for 12 weeks. 

The NAC group had about a 40% reduction in YBOCS score (a quantitative measure of OCD symptoms) after 12 weeks, compared to a 20% reduction in the placebo group.  This is a good, clinically relevant symptom change especially for a treatment-resistant group. 

Mild gastrointestinal complaints were more common in the NAC group, but there was not a big difference in drop-out rates between placebo and NAC. 

NAC works as as a glutamate-modulating agent, with possible anti-inflammatory effects.  It is metabolized to the amino acid cystine after entering the brain. 

So it appears that NAC could be a simple, low-risk, effective adjunct, or even a primary treatment modality, for obsessive-compulsive disorder. 

I would be curious to see more research looking at NAC for other anxiety disorders, or for ruminative depression. 

Long-term clonazepam for panic disorder

The treatment of anxiety disorders, particularly panic disorder, should emphasize behavioural and cognitive therapy, exercise, lifestyle factors, etc. 

But medication treatments can often be very helpful if these other therapies are not helping.  The trend of thinking on this matter over the past few decades has been to preferentially use SSRI antidepressants, and to minimize the use of benzodiazepines such as clonazepam, due to concerns about side effects and dependence. 

This study challenges that notion:  http://www.ncbi.nlm.nih.gov/pubmed/22198456   It is a 3 year followup study (an excellent duration for a psychiatric study!) -- and compares paroxetine 40 mg/d with clonazepam 2 mg/d (all doses taken at bedtime) for treatment of panic disorder. 

The clonazepam alone group did very similarly well to the paroxetine group, with even a slight edge of superiority over paroxetine.  And there were fewer side effect complaints in the clonazepam group compared to paroxetine.  There was no advantage to combined therapy (clonazepam + paroxetine). 

While I still remain concerned about dependency and abuse problems with benzodiazepines, this type of study affirms that long-term benzodiazepine use may be helpful--and possibly superior to antidepressants--for some patients. 

Interesting Augmentations 2: L-methylfolate

L-methylfolate is an active form of folic acid which enters the brain.  Folic acid supplementation has been considered for decades in treating depression, with varying results (generally mildly positive).  The mechanism in the brain is generally as an indirect enhancer of the production of neurotransmitters, through its involvement in the metabolic pathway. 

Here are some recent studies looking at l-methylfolate as an augmentation:

http://www.ncbi.nlm.nih.gov/pubmed/21311704
Here, a dose of 15 mg/day of l-methylfolate (but not 7.5 mg) added to an SSRI led to a doubling of the response rate for depressed patients, after 30 days (about 30% vs. 15%).   These patients had previously been on the same SSRI alone without response.   There were no side effect problems. 

http://www.ncbi.nlm.nih.gov/pubmed/23212058
Another positive study from 2011.  Again showing a significant improvement in response rate with l-methylfolate augmentation, with no side effect problems (probably fewer side effects in the folate group).  But this is a much weaker study due to it being retrospective. 

As I look further at this I see some controversy about whether there may be bias here, as the methylfolate is quite an expensive product.  I would want to see a comparison study between methylfolate and the much more inexpensive ordinary folic acid.    In discussions I've looked at pertaining to this issue, the argument is made that the dose of ordinary folic acid would be very high to match 15 mg of l-methylfolate.  Maybe so--but it would be very simple to do a comparison study, since if there is no clinical superiority of one over the other, then the more affordable product should be recommended.