Dose range ethnic differences

A small, flexible dose study of citalopram (dosage range = 10-40 mg/day) in 14 Hispanic and 6 non-Hispanic (non-White) depressed HIV-positive patients conducted in Miami also showed no differences in response rate or effective dose between ethnicities (Currier etal., 2004). In addition, Hispanic patients did not have a significantly higher attrition rate compared to non-Hispanics. 

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. 

Foreign clinical results are acceptable except in areas where there are immunological and ethnic differences between Japanese and foreigners. The ethnic factors are divided into two components intrinsic factors such as racial factors and physiological differences and extrinsic factors, which include cultural and environmental issues. In these cases, the MHLW may require that some bridging comparative clinical trials be performed with dose ranging protocols. This will enable absorption, distribution, metabolism, and excretion studies to be carried out on Japanese individuals and provide better dosage and indication for the Japanese people. The MHLW also requires that application be accompanied by one year of real-time stability data and that sterility test results be included. 

The reported incidence of liver injury in this report is higher (at 1.2%) than in previous reports, perhaps reflecting patient selection or ethnic differences in study populations. An association with propylthiouracil in the six cases described was supported by the temporal association with the start of therapy and recovery after withdrawal. This complication is likely to be a hypersusceptibility reaction, given the lack of dose association within the therapeutic range, the unpredictable... 

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