Lithium African Americans

Lithium presents yet another model of ethnic variation in side effects and response. It is well established that African Americans show a higher red blood cell (RBC) to plasma ratio of lithium concentration when compared to Asians and... 

The clinical significance of this ethnic difference for psychiatry was found later. A study examining lithium tolerability found more side effects in African American patients with high RBC/plasma ratio even when the lithium levels were in the therapeutic range (Strickland etal., 1995). It is not known whether African Americans require lower doses and will respond with lower plasma levels. We do know that African Americans with mood disorders are less likely to be prescribed lithium either as primary treatment or adjunctive therapy (Valenstein etal., 2006 Kilbourne 8c Pincus, 2006). It is unknown as to whether the lack of tolerability at usual therapeutic doses is a factor. 

Strickland, T. L., Lin, K. M., Fu, P., Anderson, D. et al. (1995). Comparison of lithium ratio between African-American and Caucasian bipolar patients. Biol. Psychiatry, 37, 325-30. 

Relatively recent studies suggest that African Americans handle lithium differently than do other ethnic groups. A higher red blood cell-to-plasma ratio of lithium has been consistently found... 

These findings have important implications for the treatment of bipolar affective disorder. Some agents used to treat partial-complex seizures such as carbamazepine and various valproate formulations have been found to be effective in bipolar affective disorder (Bowden 1995). One such agent, divalproex, is now the most commonly prescribed antimanic agent. These agents may be more effective in subtypes of mania that are not lithium responsive. As noted earlier, African Americans are more often prescribed antipsychotics. Poor tolerance of lithium maybe a factor. Improving access to alternatives to lithium may reduce the need for antipsychotics in some African Americans with mania. 

Strickland TL, Lawson WB, Lin K-M Interethnic variation in response to lithium therapy among African-American and Asian-American populations, in Psychopharmacology and Psychobiology of Ethnicity. Edited by Lin K-M, Poland RE, Nakasaki G. Washington, DC, American Psychiatric Press, 1993, pp 107-123... 

Another example of PD differences is that of reports on lithium in the manic phase of bipolar depression. Asian patients, including Japanese, are reported to have therapeutic blood levels at 0.5-0.8 m.eg/1 compared to required levels in US Caucasian patients of 0.8-1.2 m.eg/1 (Takahashi, 1979 Jefferson et al., 1987 Yang, 1987) these findings, however, are disputed by Chang et al. (1985). African-Americans require less drug, but this is because of higher levels due to a slower clearance rate than Caucasians (Lin et al., 1986 Jefferson et al., 1987). 

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