Correlations between the enantio- and regio-selective metabolisms of warfarin.

Aim: To clarify whether the activities of multiple CYPs associated with warfarin metabolism would be correlated with each other.

Methods: Oral clearances (CLpo) of warfarin enantiomers were estimated in 378 Chinese, Caucasians and African-Americans. The partial metabolic clearances (CLm) for 7-hydroxywarfarin enantiomers were also measured.

CYP2C19*17 affects R-warfarin plasma clearance and warfarin INR/dose ratio in patients on stable warfarin maintenance therapy.

Purpose: We aimed to assess the influence of CYP2C19*17 on R-warfarin clearance as well as the effect of CYP2C19, CYP2C8, CYP2C9, and VKORC1 polymorphisms together with non-genetic factors on warfarin international normalized ratio (INR)/daily dose.

Methods: One hundred fifty Caucasian Italian outpatients with data on steady-state plasma concentrations of S- and R-warfarin were genotyped for CYP2C19 (*2, *3, *4, *17), CYP2C9 (*2, *3), CYP2C8*3, and VKORC1*2. The statistical analysis was performed on the effect of genotypes/haplotypes, age, sex, and body weight on the clearance of warfarin enantiomers and dose-normalized INR.

Pharmacogenetics of drug-metabolizing enzymes in Italian populations.

Drug-metabolizing enzymes play a major role in the biotransformation and subsequent elimination of most drugs and xenobiotics from the body. Both phase I and phase II enzymes are highly polymorphic. Inter-individual differences in genes coding for drug-metabolizing enzymes are important for understanding variability in drug response and for individualization of drug prescription.

Mild hypoglycaemic attacks induced by sulphonylureas related to CYP2C9, CYP2C19 and CYP2C8 polymorphisms in routine clinical setting.

Aim: To evaluate the impact of polymorphisms in the cytochrome P450 (CYP) 2C9, 2C19 and 2C8 genes on the risk of mild hypoglycaemic attacks in patients treated with sulphonylureas.

Methods: One hundred and eight type 2 diabetic patients (50 men, 58 women), treated with oral antidiabetics, including at least one from the sulphonylurea group (glimepiride n = 50, gliclazide n = 46, or glipizide n = 12) for 3 months or longer, were included in the study. Symptoms of hypoglycaemia (sweating, tremor, anxiety and palpitations) during a 3 month period were recorded and confirmed by home glucose measurements.

Do CYP3A and ABCB1 genotypes influence the plasma concentration and clinical outcome of donepezil treatment?

Purpose: The aim of our study was to evaluate the impact of CYP3A4, CYP3A5, and ABCB1 polymorphisms on donepezil disposition and clinical outcome.

Methods: Fifty-four Italian patients diagnosed with probable mild to moderate Alzheimer's disease, treated with donepezil (37 patients 5 mg/day, 17 patients 10 mg/day) were genotyped for CYP3A4 (*1B, *3, and *4), CYP3A5 (*2, *3, and *6) and ABCB1 (3435C>T, 2677G>T/A, and 1236C>T) polymorphisms. All patients were evaluated for the degree of cognitive impairment with Mini Mental State Examination (MMSE) screening test at baseline (before treatment) and after at least 3 months of donepezil treatment at stable dose, when the drug plasma levels were measured.

Biological definition of multiple chemical sensitivity from redox state and cytokine profiling and not from polymorphisms of xenobiotic-metabolizing enzymes.

Background: Multiple chemical sensitivity (MCS) is a poorly clinically and biologically defined environment-associated syndrome. Although dysfunctions of phase I/phase II metabolizing enzymes and redox imbalance have been hypothesized, corresponding genetic and metabolic parameters in MCS have not been systematically examined.

Objectives: We sought for genetic, immunological, and metabolic markers in MCS.

Flavin-containing monooxygenase 3 polymorphisms in 13 ethnic populations from Europe, East Asia and sub-Saharan Africa: frequency and linkage analysis.

Aims: To investigate intra- and inter-ethnic differences in three widespread (E158K, V257M and E308G) and two African-specific (D132H and L360P) flavin-containing monooxygenase 3 (FMO3) polymorphisms.

Materials & Methods: Allele frequencies were determined by TaqMan allelic discrimination assay in 2152 healthy volunteers from Europe (Swedes, Italians and Turks), East Asia (Japanese) and sub-Saharan Africa (nine ethnic groups covering eastern, southern and western regions), followed by haplotype and linkage analysis.

Results: Significant subpopulation differences (p < 0.

Association between HTR2C and HTR2A polymorphisms and metabolic abnormalities in patients treated with olanzapine or clozapine.

Serotonin 2C and 2A receptor (5-HT2C and 5-HT2A) antagonisms are hypothesized to play a role in the metabolic adverse effects induced by olanzapine and clozapine. Associations between polymorphisms in 5-HT2C and 5-HT2A receptor coding genes, HTR2C and HTR2A, with antipsychotic-induced weight gain have been reported. The impact of HTR2C and HTR2A polymorphisms on body mass index (BMI), glucose-insulin homeostasis, and blood lipid levels was evaluated in 46 patients with schizophrenia or schizoaffective disorder and treated with olanzapine (n = 28) or clozapine (n = 18) for at least 6 months.

ABCB1 polymorphisms influence steady-state plasma levels of 9-hydroxyrisperidone and risperidone active moiety.

Risperidone is metabolized to its active metabolite, 9-hydroxyrisperidone, mainly by the cytochrome P450 enzymes CYP2D6 and 3A4. Its antipsychotic effect is assumed to be related to the active moiety, that is, the sum of risperidone and 9-hydroxyrisperidone. Both risperidone and 9-hydroxyrisperidone are substrates of P-glycoprotein (P-gp), a transport protein involved in drug absorption, distribution, and elimination.

Role of CYP3A5 in abnormal clearance of methadone.

Objective: To report a case of unusually low concentrations of methadone in a polydrug abuser during maintenance treatment with methadone.

Case Summary: A 25-year-old man (weight 55 kg, height 165 cm) with a 12-year history of polydrug abuse was admitted to an opiates withdrawal methadone program. At the time of our observation, he was using both cannabinoids and heroin; no other medical conditions were discovered.

Further evidence for the association between 5-HT2C receptor gene polymorphisms and extrapyramidal side effects in male schizophrenic patients.

Rationale: Antipsychotic-induced extrapyramidal side effects (EPS) are still a major problem in the treatment of schizophrenia. Serotonin 2C receptors (5-HT(2C)) have regulatory effects on dopaminergic pathways in brain regions involved with EPS. Polymorphisms in the 5-HT(2C) gene (HTR2C) have been suggested to be associated with the risk of developing EPS.

Antipsychotic-induced extrapyramidal symptoms in patients with schizophrenia: associations with dopamine and serotonin receptor and transporter polymorphisms.

Background: Little is known about the influence of polymorphisms of the dopamine and serotonin system on the risk for extrapyramidal symptoms (EPS) during treatment with antipsychotic drugs.

Methods: Of 119 subjects with schizophrenia treated with antipsychotics, 63 had current or previous EPS (acute dystonia, parkinsonism, tardive dyskinesia), and 56 had no such symptoms. All subjects were genotyped for a total of eight dopamine and serotonin receptor and transporter polymorphisms: the Taq1A polymorphism of the dopamine D(2) receptor (DRD2) gene, the Msc1 polymorphism of the dopamine D(3) receptor (DRD3) gene, the variable number of tandem repeat (VNTR) polymorphism of the dopamine transporter (DAT1) gene, four polymorphisms (102T/C, His452Tyr, 516 C/T, and Thr25Asn) of the serotonin 5-HT(2A) receptor (5HTR2A) gene, and the 5HTTLPR polymorphism of the serotonin transporter (5HTT) gene.

Serotonin and dopamine receptor gene polymorphisms and the risk of extrapyramidal side effects in perphenazine-treated schizophrenic patients.

Rationale: Perphenazine, a classical antipsychotic drug, has the potential to induce extrapyramidal side effects (EPS). Dopaminergic and serotonergic pathways are involved in the therapeutic and adverse effects of the drug.

Objectives: To evaluate the impact of polymorphisms in the dopamine D(2) and D(3) and serotonin 2A and 2C receptor genes (DRD2, DRD3, HTR2A, and HTR2C) on short-term effects of perphenazine monotherapy in schizophrenic patients.

Impact of the CYP2D6 polymorphism on steady-state plasma concentrations and clinical outcome of donepezil in Alzheimer's disease patients.

Objective: The aims of this study were to evaluate the impact of the CYP2D6 polymorphism on both the steady-state plasma concentrations (Cp) and the clinical outcome of donepezil, a selective acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease (AD).

Methods: Forty-two patients of Caucasian ethnicity affected by probable AD were included in the study. All had been receiving therapy with donepezil for at least 3 months: 31 patients with 5 mg/day and 11 patients with 10 mg/day.

Different contributions of polymorphisms in VKORC1 and CYP2C9 to intra- and inter-population differences in maintenance dose of warfarin in Japanese, Caucasians and African-Americans.

Objective: To investigate pharmacokinetic and pharmacodynamic factors associated with population differences in warfarin doses needed to achieve anticoagulation, in particular the possible involvement of genetic variability in vitamin K epoxide reductase (VKOR) and CYP2C9.

Methods: Warfarin maintenance dose, unbound plasma S-warfarin concentration [Cu(S)] and INR were determined in 157 Caucasians, 172 Japanese, and 36 African-Americans stably anticoagulated patients. In a subset (n = 166), fully carboxylated plasma normal prothrombin levels (NPT) were also measured.

No association between CYP2D6 polymorphism and Alzheimer's disease in an Italian population.

Allelic variation at the CYP2D6 gene has been suggested to be associated with CNS disorders, including Parkinson's disease and Lewy body dementia. In order to elucidate whether a relationship exists between CYP2D6 polymorphism and the risk of developing Alzheimer's disease (AD), CYP2D6 allele and genotype frequencies have been evaluated in 94 patients from Southern Italy (29 men and 65 women, aged 74+/-8 years) with AD, and in 350 healthy controls (204 men, 146 women, aged 33+/-9 years) from the same geographical region. Allele frequencies among AD patients were not significantly different from those in healthy controls.

Influence of CYP2C9, 2C19 and 2D6 genetic polymorphisms on the steady-state plasma concentrations of the enantiomers of fluoxetine and norfluoxetine.

The antidepressant fluoxetine is administered as racemic mixture of two enantiomers (S- and R-fluoxetine). While S- and R-fluoxetine are equipotent in blocking serotonin reuptake, the enantiomers of the demethylated metabolite, norfluoxetine, show marked differences in pharmacological activity, S-norfluoxetine being about 20 times as potent as R- norfluoxetine as a serotonin reuptake inhibitor. In vitro and in vivo data suggest that the metabolism of fluoxetine to norfluoxetine is stereoselective and mediated, at least in part, by the polymorphic cytochrome P450 (CYP) isoenzymes CYP2D6, CYP2C9 and CYP2C19.

Allele and genotype frequencies of CYP2C9, CYP2C19 and CYP2D6 in an Italian population.

The polymorphic cytochrome P450 isoenzymes (CYPs) 2C9, 2C19 and 2D6 metabolise many important drugs, as well as other xenobiotics. Their polymorphism gives rise to important interindividual and interethnic variability in the metabolism and disposition of several therapeutic agents and may cause differences in the clinical response to these drugs. In this study, we determined the genotype profile of a random Italian population in order to compare the CYP2C9, CYP2C19 and CYP2D6 allele frequencies among Italians with previous findings in other Caucasian populations.

Enantioselective analysis of citalopram and its metabolites in postmortem blood and genotyping for CYD2D6 and CYP2C19.

Citalopram, a selective serotonin reuptake inhibitor, is one of the most commonly found drugs in Swedish forensic autopsy cases. Citalopram is a racemic drug with 50:50 of the S- and R- enantiomers. Enantioselective analysis of citalopram and its metabolites desmethylcitalopram and didesmethylcitalopram were performed in femoral blood from 53 autopsy cases by a chiral high-performance liquid chromatography (HPLC) method.

Metabolic drug interactions with new psychotropic agents.

New psychotropic drugs introduced in clinical practice in recent years include new antidepressants, such as selective serotonin reuptake inhibitors (SSRI) and 'third generation' antidepressants, and atypical antipsychotics, i.e. clozapine, risperidone, olanzapine, quetiapine, ziprasidone and amisulpride.

Influence of CYP2C9 and CYP2C19 genetic polymorphisms on warfarin maintenance dose and metabolic clearance.

Objective: Our objective was to determine the influence of cytochrome P450 (CYP) 2C9 and CYP2C19 genetic polymorphisms on warfarin dose requirement and metabolic clearance.

Methods: The study population consisted of 93 Italian outpatients receiving long-term warfarin anticoagulant therapy (international normalized ratio values, 2-3), divided into 3 dose groups: low (<26.25 mg/wk; n = 37), medium (26.