Tuesday, February 2, 2010

Bipolar Disorder Part 6

Today I will continue to talk about medications to treat bipolar disorder. We have discussed lithium and the antiepileptic drugs and today we will review the third class of medications, the second generation antipsychotics which include some of the newer medications available to treat bipolar disorder.

The second generation antipsychotics are referred to as such in that although they initially came out to treat schizophrenia and partially work like previous antpsychotics in terms of blocking the neurotransmitter dopamine they have some different properties as well which sets them apart from the older antipsychotics or the "first generation". They have some action at serotonin type 1 and serotonin type 2 receptors as well as at dopamine receptors and they bind more at dopamine type 4 receptors and are less active at dopamine 2 receptors resulting in a much reduced tendency for neuromuscular side effects than our older drugs.

These medications include risperidone(Risperdal),quetapine(Seroquel),olanzapine(Zyprexa),ziprasidone(Geodon),Aripiprazole(Abilify), and the newest one paliperidol(Invega). They are very effective antimanic medications, we believe prevent mania and depression to some degree and unlike the other bipolar medications treat depression as well. These medications all have some different properties but tend to have the same set of side effects and risks so I will talk about them as a group.

The main side effects are neuromuscular side effects and metabolic effects. Like the older antipsychotics there is a small risk for a life threatening condition, neuroleptic malignant syndrome, as well as for tardive dyskinesias which are potentially irreversible abnormal involuntary muscle movements. The other much more common and troubling side effects are metabolic. They cause weight gain, increased triglycerides and increased blood sugar leading to possible cardiovascular disease and diabetes.They are not associated with birth defects if used during pregnancy though there is a national registry to monitor this. Geodon and Abilify have much less tendency than the others to cause this metabolic triad. So why use the others? Some people will not respond to Abilify or Geodon and do respond to the others. In fact I have never seen a patient whose acute mania did not respond to Zyprexa. Because of the least amount of side effects and risks I tend to use Abilify as first line treatment because if it works there are not the problems the more severe problems we have with lithium the, aniepileptic drugs s and the other second generation antipsychotics. Geodon could also be a first line treatment for the same reasons but tens in some people to cause sedation.

So, lithium, the antiepileptic drugs and the second generation antipsychotics are what we have available to treat bipolar disorder. I hope that there will be continued development of medications with greater effectiveness and lower side effects. Tomorrow I will talk about some of the non pharmacological treatments that are helpful in bipolar disorder.

Thought for the day

"He whose heart is in the smallest degree set upon goodness will dislike no one".

Ancient Chinese

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