Band 32, Heft 3

Background: Haloperidol is used for the treatment of alcohol use disorders in patients with signs of alcohol-related psychosis. Haloperidol therapy poses a high risk of adverse drug reactions (ADR). Contradictory data, which include the effects of genetic polymorphisms in genes encoding the elements of haloperidol biotransformation system on haloperidol metabolism rate and plasma drug concentration ratio, are described in patients with different genotypes. The primary objective of this study was to investigate the effects of CYP2D6 and CYP3A5 genetic polymorphisms on haloperidol equilibrium concentration in patients with alcohol use disorder. Methods: The study included 69 male patients with alcohol use disorder. Genotyping was performed using the allele-specific real-time PCR. CYP2D6 and CYP3A were phenotyped with HPLC-MS using the concentration of endogenous substrate of the enzyme and its urinary metabolites [6-hydroxy-1,2,3,4-tetrahydro-β-carboline(6-HO-THBC) to pinoline ratio for CYP2D6 and 6-β-hydroxycortisol to cortisol ratio for CYP3A ]. The equilibrium plasma concentration was determined using LC-MS-MS. Results: Results indicated that both C/D indexes and equilibrium concentration levels depend on CYP2D6 genetic polymorphism, but only in patients receiving haloperidol intramuscular injections [0.26 (0.09; 0.48) vs. 0.54 (0.44; 0.74), p=0.037]. Conclusions: The study demonstrates that CYP2D6 genetic polymorphism ( 1846G>A ) can affect haloperidol concentration levels in patients with alcohol use disorder.

Background: Tramadol is prone to be abused alone, or in combination with 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy). It was reported that 95% of people with a history of substance abuse in the United States used tramadol in 2004. According to the WHO report in 2016, there was a growing number of tramadol abusers alone or in combination with psychoactive substances such as MDMA in particular in some Middle East countries. Higher concentrations of tramadol in plasma may lead to adverse drug reactions or lethal intoxication. In this study, the effect of MDMA on the pharmacokinetics of tramadol was examined in male rats. Methods: The effect of MDMA on T max , C max , area under the curve, elimination rate, and half-life of tramadol and its metabolites was examined. Two control and two treatment groups were designed. The treatment groups received MDMA 18 h before the administration of tramadol. Jugular vein blood samples were analyzed by high-performance liquid chromatography with fluorescent detector to determine the concentrations of tramadol and its metabolites. Independent-sample t-test was used to define the differences between pharmacokinetic parameters of control and treatment groups. Results: When tramadol administered intraperitoneally, the absorption rate of this drug was reduced, and a lower C max (40%) with longer T max (eight-fold) was achieved. MDMA exerted greater inhibitory effects on cytochrome P450 3A4 (CYP3A4) than on cytochrome P450 2D6 (CYP2D6). The M 2 metabolite ratio was reduced by half, and because of the inhibition of M 2 production, the M 1 plasma concentration slightly increased. Conclusions: According to the obtained data, MDMA treatment affected the absorption, distribution and metabolism phases of tramadol. This treatment increased the concentration of tramadol if administered intravenously and can latent the absorption of tramadol in oral route. However, MDMA was introduced as CYP2D6 inhibitor; in this study, MDMA inhibited CYP3A4 isoenzymes as well. This finding is important for the compounds that are metabolized through CYP3A4. It can be proposed that in abusers of MDMA who only receive tramadol for medical or nonmedical purposes in short intervals, the dangers of the intravenous administration of tramadol should be considered, and if tramadol is administered orally, the desired effect may not be achieved at the routine dose.

Background: As imatinib gained a lot of attention in the field of medicine, appropriate methods are needed for drug analysis. LC-MS/MS combined with complex sample preparation and column enrichment is usually the method of choice when high sensitivity is necessary. The application of LC-MS 3 in imatinib quantification has not been discussed in the literature. Methods: An LC-MS 3 imatinib quantification method was developed and validated in human serum. The sample preparation was based on the liquid-liquid extraction of 50 μL human serum. Chromatographic separation was performed using a Luna 5 μm C18 (2) 100 A, 150 mm×2 mm column and the elution was done using a mobile phase consisting of A (H 2 O/methanol=95/5, v/v) and B (H 2 O/methanol=3/97, v/v), both with 10 mM ammonium acetate and 0.1% acetic acid. Results: The conditions applied resulted in a limit of detection/quantification value of 0.14/0.45 ng/mL reached without a sophisticated sample preparation technique or enrichment column application. It could be demonstrated that MS 3 detection is a very effective way of sensitive imatinib quantification. Further, it could be stated that the strategy presented can be very useful for a sensitive analysis of other protein kinase inhibitors, because their molecule structure is appropriate for MS 3 detection. Conclusions: The presented analytical strategy is an effective way of protein kinase inhibitor analysis in human serum.

Background: Therapeutic drug monitoring is essential for both phenytoin and phenobarbital therapy given their narrow therapeutic indexes. Nevertheless, the measurement of either phenytoin or phenobarbital concentrations might not be available in some rural hospitals. Information assisting individualized phenytoin and phenobarbital combination therapy is important. This study’s objective was to determine the relationship between the maximum rate of metabolism of phenytoin (V max ) and phenobarbital clearance (CL PB ), which can serve as a guide to individualized drug therapy. Methods: Data on phenytoin and phenobarbital concentrations of 19 epileptic patients concurrently receiving both drugs were obtained from medical records. Phenytoin and phenobarbital pharmacokinetic parameters were studied at steady-state conditions. The relationship between the elimination parameters of both drugs was determined using simple linear regression. Results: A high correlation coefficient between V max and CL PB was found [r=0.744; p<0.001 for V max (mg/kg/day) vs. CL PB (L/kg/day)]. Such a relatively strong linear relationship between the elimination parameters of both drugs indicates that V max might be predicted from CL PB and vice versa . Conclusions: Regression equations were established for estimating V max from CL PB , and vice versa in patients treated with combination of phenytoin and phenobarbital. These proposed equations can be of use in aiding individualized drug therapy.

Background: Human response to the antidiabetic metformin is influenced by some factors, such as genetic variants in the SLC22A genes. This study aimed to determine the frequency of main SLC22A1 and SLC22A3 genetic variants and their influence on metformin pharmacokinetics among healthy unrelated Arab Jordanians. Patients and methods: The SLC22A1 and SLC22A3 genes were genotyped by DNA sequencing of exons 1, 3, 7, and 9 in the SLC22A1 gene and exons 6, 7, and 9 in the SLC22A3 gene. Then, a clinical pharmacokinetic study was conducted on 26 healthy volunteers. The pharmacokinetic parameters were calculated using non-compartmental model analysis. The study was an open-label, randomized study with single 1000 mg metformin administration. Results: Results showed that volunteers with SLC22A3 rs8187722 variant had higher (χ 2 , p<0.05) metformin C max and AUC values than the wild SLC22A3 volunteers, whereas T½ and K el were not affected. In addition, volunteers with the heterozygote SLC22A3 rs2292334 variant had significantly higher (χ 2 , p<0.05) metformin C max and AUC and lower K el values than the wild-type SLC22A3 genotype. Conclusions: The SLC22A3 rs8187722 and rs2292334 genetic variants affected metformin pharmacokinetics among a clinical sample of Jordanians. The findings may increase our understanding of the inter-individual and inter-ethnic variations in metformin response.

The carboxylesterase 1 gene ( CES1) encodes a hydrolase implicated in the metabolism of commonly used drugs. CES1A2 , a hybrid of CES1 and a CES1 -like pseudogene, has a promoter that is weak in most individuals. However, some individuals harbor a promoter haplotype of this gene with two overlapping Sp1 sites that confer significantly increased transcription potentially leading to rapid drug metabolism. This CES1A2 haplotype has previously been reported to be common among Asians. Using polymerase chain reaction followed by sequencing, the present study examined variation in the promoter and 5′ untranslated region of CES1A2 in 120 Han Chinese and 120 Japanese people enrolled in the 1000 Genomes Project. We identified 11 single nucleotide variations, two of which were novel, in 145 of the individuals who were found to carry CES1A2 . Alignment analysis indicated that the CES1A2 haplotype with the overlapping Sp1 sites has been generated by incorporation of a segment of CES1 . All minor allele frequencies were equal to or below 0.022 and the frequencies of the minor haplotypes were up to 40-fold lower than previously reported, including that of the haplotype with the overlapping Sp1 sites. This information is novel and suggests that the pharmacogenetic relevance of CES1A2 is limited in Asians.

Methylenetetrahydrofolate reductase (MTHFR) mutations have been linked to many diseases. Evidence has been provided to prove that we need to perform pharmacogenetic studies regarding the prevalence of MTHFR mutations and diseases, risks, and the impact on folate requirement in general, but little has been published about Puerto Ricans. A multi center cross-sectional retrospective review study or a prospective pharmacogenetic study of valid genotypes and phenotypes of MTHFR mutations within the different populations of Puerto Ricans and Hispanics are recommended, because differences within them and within the general population are expected.