Lithium

Lithium Side Effects:  Lithium is an unusual medication in that it is simply an element, rather than a compound molecule.  Lithium is usually used as a medication as lithium carbonate, and is available in 150 mg, 300 mg and 600 mg immediate release tablets or capsules, and as 300 mg and 450 mg extended release capsules.  Brand name products include Eskalith and Lithobid.  Lithium therapy is indicated for the treatment of bipolar disorder, especially bipolar disorder with mania, for acute mania and for schizoaffective disorder.  The usual starting dose is 600-900 mg daily as divided doses, and the maximum recommended dose is 2400 mg daily.  Monitoring of lithium levels is important to avoid lithium toxicity.  One of the difficult aspects of lithium therapy is that the therapeutic margin of lithium is narrow, meaning that the therapeutic blood levels are very close to the toxic levels.

Black Box Warnings:  Lithium toxicity is directly related to lithium levels, and lithium should only be used when access to accurate and timely lithium levels is available.  The narrow therapeutic window for lithium makes monitoring of blood levels very important.

Common Lithium Side Effects:  Tremor is probably the most common of the common lithium side effects.  Blurred vision, dry mouth, fatigue, cardiac arrhythmias, polyuria and muscle weakness are additional common lithium side effects.  Gastrointestinal common lithium side effects include anorexia, diarrhea, vomiting, and nausea.

Serious Lithium Side Effects:  Seizures, coma, ventricular arrhythmias, severe bradycardia, diabetes insipitus, and Raynaud’s phenomenon are among the serious lithium side effects.  Thyroid toxicity including goiter, hypothyroidism, as well as hyperparathyroidism are also noted.  Syncope is also among the potential serious lithium side effects.

Cautions and Drug Interactions: Lithium is excreted in the urine, so significant renal impairment is a major caution to lithium use. Lithium is contraindicated in pregnancy, as well as when patients would be unable to access resources to monitor lithium levels.  In cases of dehydration, lithium levels need to be watched closely, as excretion may be severely diminished.  Caution is also advised at the extremes of age, in the elderly and in children under 12 years of age. Caution is also advised in coronary heart disease. Lithium is relatively contraindicated for use with diuretics, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, with many calcium channel blockers, with the phenothiazines, and with vasopressin.  The list of additional cautions and drug interactions is extensive, and readers should consult the manufacturer’s prescriber guidelines or their pharmacist for more detailed specifics.  Some of the more commonly used drugs where monitoring or modification of dosing may be needed include caffeine, antacids, bismuth containing compounds, methyldopa, metronidazole, non-steroidal anti-inflammatory drugs, phenytoin, potassium supplements, and topiramate.  Use with the SSRI and SNRI drugs requires caution, though their concurrent use is fairly common in psychiatric patients who need both drugs’ effects.

Pregnancy and Lactation: Lithium is pregnancy category D, with confirmed evidence of fetal risk with maternal use in pregnancy. Lithium is felt possibly unsafe for use by breast feeding mothers.

Unusual Lithium Side Effects:  The most common of the lithium side effects is also among the more unusual, namely tremor.  Many, if not most, patients on lithium will develop tremor, and the degree of tremor may be related to the serum lithium levels in some patients, though this is not meant to be a suggestion that watching for tremor is an adequate way to watch for lithium toxicity.  Also unusual is the critical importance of monitoring lithium levels for safe and successful lithium therapy.

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