Afro-Americans have a poorer response to citalopram compared to Caucasians.
There were overall significant differences (unadjusted data) between Caucasian (self-identied as US 'white) and Afro-Americans (self-identied as US 'blacks') participants with nonpsychotic depressive disorder who achieved remission on the clinician-rated HRSD17 (Caucasian remission rate = 30.1%; Afro-American remission rate = 18.6%; p<0.0001) and the participant-rated QIDS-SR16 (Caucasian remission rate = 36.1%; Afro-American remission rate = 22.2%; p<0.0001).
After adjustment (see note 1) the differences in remission between Caucasians and Afro-Americans disappeared in the HRSD17 but remained in the QIDS-SR16 (odds ratio Caucasian = 1; odds Afro-American = 0.698; p=0.0183).

note 1:
Adjusted for:
regional center, gender, education, employment, income, medical insurance, marital status, illness onset age and duration, n episodes, family history of mood disorder and substance abuse, current episode duration, HRSD17 or QIDS-SR16, anxious and melancholic subtype features, SF12, Q-LES-Q, WSAS, specialty care setting, CIRS ratings sum, and n psychiatric disorders.

(N=2348; Caucasian = 1853; Afro-American = 495)

(Lesser, 2007)

Afro-Americans may be more susceptible to the side effects associated with lithium treatment. The sample was divided into 22 Caucasians and 12 African-Americans. Afro-Americans (n=12) had higher Lithium 'RedBloodCount/plasma' ratio (LR) and increased reports of side effects (p < 0.05). Strickland et al. 1995.

Afro-Americans might have a higher clearance of olanzapine, due to a high prevalence of a SNP of CYP3A43. Olanzapine clearance was associated with measures of clinical response: Patients with greater clearance had higher symptom ratings and were more likely to discontinue treatment due to an inadequate response. In the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) (n=336, 60% Caucasian, 36% African American) the authors identified a single nucleotide polymorphism in the drug metabolizing enzyme, cytochrome P450 3A43 that highly significantly predicted olanzapine clearance. At standard antipsychotic doses, 50% of individuals with the high clearance genotype (AA) have trough blood levels below the therapeutic range. A much higher proportion of African Americans (67%) carry the A allele compared with Caucasians (14%). After accounting for CYP3A43 genotype, race is no longer a significant predictor of olanzapine clearance. The authors identified a genetic mechanism for variation in olanzapine response and demonstrate that blood level monitoring of olanzapine treatment is advisable (Bigos et al., 2011).

Pharmacokinetics USA Afro-Americans

Afro-Americans (n=12) had increased reports of side effects compared to Caucasians (p < 0.05).
Afro-Americans (n=12) had higher Lithium 'RedBloodCount/plasma' ratio (LR) compared to Caucasians (p < 0.05).