The relationship between dopamine D-2 receptor polymorphism at the Taq1 A locus and therapeutic response to nemonapride, a selective dopamine antagonist, in schizophrenic patients
A. Suzuki et al., The relationship between dopamine D-2 receptor polymorphism at the Taq1 A locus and therapeutic response to nemonapride, a selective dopamine antagonist, in schizophrenic patients, PHARMACOGEN, 10(4), 2000, pp. 335-341
Previous studies have demonstrated that subjects with one or two Al alleles
of dopamine D-2 receptor (DRD2) polymorphism at the Taq1 A locus have lowe
r DRD2 density than those with no A1 allele. The present study aimed to exa
mine whether the Taq1 A DRD2 genotypes are related to therapeutic response
to nemonapride, a selective dopamine antagonist, in schizophrenic patients,
The subjects were 25 acutely exacerbated schizophrenic inpatients who had
received no medication for at least 1 month before the study. The fixed dos
e (18 mg/day) of nemonapride was administered to each patient for 3 weeks,
The clinical status was prospectively monitored by the Brief Psychiatric Ra
ting Scale (BPRS) before, and 3 weeks after, the treatment. The Taq1 A geno
types (A1 and A2 alleles) were determined by the polymerase chain reaction
method. Three patients were homozygous for the Al allele, 11 were heterozyg
ous for the A1 and A2 alleles, and 11 were homozygous for the A2 allele. Th
e patients with one or two A1 alleles (n = 14) showed significantly higher
percentage improvement in total BPRS and positive symptoms than those with
no A1 allele (n = 11) after 3-week treatment while the percentage improveme
nt in other subgrouped symptoms (negative, anxiety-depression, excitement a
nd cognitive symptoms) was similar between the two genotype groups. The pre
sent results suggest that the Taq1 A DRD2 polymorphism is related to early
therapeutic response to nemonapride in schizophrenic patients, possibly by
modifying the efficiency of DRD2 antagonism of the drug in the central nerv
ous system. Pharmacogenetics 10:335-341 (C) 2000 Lippincott Williams & Wilk
ins.