6.4 Mood Stabilizers

Mood stabilizers are used primarily to treat bipolar disorder. They are also used to treat depression (usually in combination with an antidepressant), schizoaffective disorder, and disorders of impulse control. Lithium is an example of a mood stabilizer. Anticonvulsant medications are also used as mood stabilizers.^[1] Antipsychotics, antianxiety, and antidepressants may also be used to treat bipolar disorders.

Lithium

Lithium was the first agent used to treat bipolar disorder and remains a first-line mainstay, particularly for the mania phase of the disorder. Lithium reduces excitatory neurotransmission (dopamine and glutamate) and increases inhibitory neurotransmission (GABA). As a positively charged ion, it also alters sodium transport in nerve and muscle cells and causes a shift in metabolism of catecholamines. When administered to a client experiencing a manic episode, lithium may reduce symptoms within one to three weeks. It possesses unique anti-suicidal properties that sets it apart from antidepressants.

However, lithium comes with numerous nursing concerns. Lithium has a narrow therapeutic window, meaning that the effective dose is close to the toxic dose. Patients taking lithium medications must have regular bloodwork to monitor the level of medication. Patients need to be instructed to keep a stable intake of salt and water. Adverse effects include dermatological changes, hair loss, weight gain, sedation, and a fine tremor. Laboratory studies that monitor renal and thyroid function must be monitored regularly.^[2],[3]

Lithium effects, adverse effects, and patient teaching are further explored in Chapter 8.

Anticonvulsants

Medications used for seizures are called anticonvulsants or anti-seizure drugs. Anti-seizure drugs stabilize cell membranes and suppress the abnormal electric impulses in the cerebral cortex. Because of this ability to suppress neuron excitability, many agents are also useful in the management of bipolar disorder and mood instability.

Valproate/valproic acid: Valproate (Depakote) is an anticonvulsant drug that functions as a mood stabilizer and antiepileptic agent by enhancing the inhibitory effect of gamma aminobutyric-acid (GABA). This therapy reduces repetitive neuronal firing and can reduce inhibition and excitation within neuronal networks. This medication is recommended for manic episodes in particular. Like lithium, it has adverse effects of sedation, tremor, and weight gain but its therapeutic window is much wider thus lessening toxicity concerns.  Monitoring blood levels is required, however, and bloodwork includes liver function tests (LFTs) and complete blood counts (CBC) as liver failure is one of the serious adverse effects.  Valproate is avoided during pregnancy due to potential birth defects in the developing fetus.  Female patients should have a pregnancy test prior to starting valproate. Nurses need to monitor patients for improving manic symptoms as well as adverse effects.^[4]

Carbamazepine: Carbamazepine (Tegretol) is considered to be a second-line treatment for bipolar disorder. Like other anticonvulsants, it slows neuronal transmission by reducing activity in the sodium channels of the cells. While effective for mania and mixed states, it is a powerful inducer of the liver enzyme P450 3A4, which breaks down many medications, notably antipsychotics. Higher doses of medications are then needed to be efficacious. Adverse effects include dizziness, somnolence, GI effects, and blurred vision. Serious adverse effects include bone marrow suppression and toxic epidermal necrolysis.^[5]

Lamotrigine: Lamotrigine (Lamictal), like valproate, is an anticonvulsant. Its mechanism of action involves reducing only the frequency (and not amplitude) of excitatory postsynaptic currents in the CNS, causing a decrease in glutamate release while causing a concomitant increase in frequency and amplitude of inhibitory postsynaptic currents, which enhances GABA release. Therefore, lamotrigine causes opposite effects on glutamate and GABA transmission, downregulating glutamate release and increasing GABA release. Primary side effects are dizziness, headache, nausea, and visual complaints. Serious adverse effects include epidermal necrolysis syndrome. However, most patients tolerate lamotrigine well and no blood draws are required.^[6]