Understanding Panic and Other Anxiety Disorders by Benjamin Root

Author:Benjamin Root
Language: eng
Format: epub
Publisher: University Press of Mississippi
Published: 2001-08-14T16:00:00+00:00

Mood Stabilizers

Certain medications that stabilize mood can also prove useful in the treatment of the anxiety disorders, including panic disorder. These include lithium, carbamazepine (Tegretol), valproic acid (Depakote), clonazepam (Klonopin), and gabapentin (Neurontin).

Lithium is a chemical element, compounds of which are used for disorders of mood instability (see chapter 2), and for mood stabilization in general, but its mechanism of action is still not clear, in spite of its being used now for many years. While most of the medications used in psychiatry work, in some fashion, through specific neurotransmitter systems, research done on lithium shows that it probably does not focus on any specific neurotransmitter system but instead works on a second-messenger system, probably triggered by its reaction with G-proteins in the membranes of nerve cells. In particular, its involvement with second-transmitter systems seems related to its inhibition of an enzyme involved in the phosphoinositide (PI) system. These second-messenger systems are quite pervasive, and would help to explain lithium’s far-reaching effects. Also, the involvement of second messenger systems contributes to the difficulty researchers have had in pinning down any particular neurotransmitter system associated with lithium, since the medication affects so many of them. Researchers feel that these second messengers are, in turn, affecting intracellular metabolism in complex ways. Pharmaceutical houses usually supply lithium as the salt lithium carbonate (see chapter 6).

Carbamazepine (Tegretol) first found its niche as an anticonvulsant medication, but it soon proved helpful in disorders of mood instability as well. It seems to work on peripheral benzodiazepine receptors. Valproic acid (Depakote, Depakene) is another medication that originally was used as an anti-convulsant but which soon found its way into the psychiatric area. It seems to more directly enhance the effect of GABA. Clonazepam (Klonopin) is a high-potency, long-acting benzodiazepine, also originally used as an anticonvulsant and now beneficial in the area of mood instability. A newer agent, yet another anticonvulsant, gabapentin (Neurontin), is showing promise in the treatment of mood instability, but its mechanism of action is not yet clear. Other newer anticonvulsants being studied are lamotrigine (Lamictal), felbamate (Felbatol), topiramate (Topamax), and fosphenytoin (Cerebyx), but their usefulness in mood instability is not yet clearly established.

When lithium, carbamazepine, and valproic acid are being used, periodic attention should be paid to blood levels. Patients who take lithium may sometimes develop trouble with their thyroid function (often becoming hypothyroid) or with untoward effects on their kidneys, but monitoring of such potential problems is fairly easy through blood and urine tests. Those using carbamazepine and valproic acid should have their livers checked occasionally, as well as having blood counts done, to head off any potential trouble with adverse effects on liver function or decreasing blood counts.

Carbamazepine can cause agranulocytosis or aplastic anemia, both serious problems with the production, respectively, of certain white blood cells and of red blood cells. Patients taking valproic acid need to be watched primarily for liver problems and for thrombocytopenia (a disorder involving platelet counts so low that the blood doesn’t clot as quickly as it should).

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