Both oral as well as intramuscular administration of haloperidol leads to higher serum haloperidol concentrations and more prominent prolactin responses in Asians than Caucasians (haloperidol 1 mg p.o. as well as 0.5 mg i.m.). No significant differences were found between foreign-born and US-born Asians. Results suggest that any differences in lifestyles between US-born and foreign born Asians influences responses to haloperidol only minimally. Details: 34 healthy volunteers: 12 Caucasian males, 11 US-born Asians (subcultural background: 5 Filipino, 3 Chinese, 2 Japanese, 1 Korean), 11 foreign-born Asians (5 Filipino, 3 Chinese, 1 Japanese, 2 Koreans). Lin et al,1988.

Haloperidol plasma concentrations after equal oral dose administration are 40 to 50% higher in Chinese patients compared to Caucasian, Afro-American and Hispanic Americans. Likewise: to achieve similar haloperidol plasma levels the Chinese patients required lower doses (40-50% less) compared to Caucasians and Afro-American patients (Jann, 1992)