Yacoub M. Irshaid

Association of MDR1 C3435T and RFC1 G80A polymorphisms with methotrexate toxicity and response in Jordanian rheumatoid arthritis patients.

OBJECTIVES Methotrexate (MTX) is the most commonly used disease-modifying antirheumatic drug for the treatment of rheumatoid arthritis (RA). Genetic polymorphisms of reduced folate carrier (RFC1 G80A) and multi-drug resistance-1 (MDR1 C3435T) might affect MTX response and/or toxicity. The aim of this study was to find out if there is an association between those polymorphisms and MTX toxicity and/or response in Jordanian RA patients. METHOD A genotyping approach was used to determine the studied polymorphisms in 159 RA patients. RESULTS There was an association between RFC1 G80A and MDR1 C3435T polymorphisms with MTX toxicity. Patients with RFC1 80GG genotype were at higher risk for gastrointestinal toxicity (p = 0.036). Patients carrying at least one MDR1 3435T variant allele were at higher risk for MTX overall toxicity (p = 0.04), especially hepatotoxicity (p = 0.028). Furthermore, the distribution of RFC1 G80A polymorphism between males and females was significantly different. The variant genotype 80AA was found to be more in males than in females (60% vs. 31%) (p = 0.011). CONCLUSIONS Our results suggest that genetic polymorphisms in methotrexate transporters affect the toxicity but not the response of MTX treatment. Further studies should be performed to have more conclusive results.

N-Acetyltransferase-2 (NAT2) genotype frequency among Jordanian volunteers.

OBJECTIVE To determine the frequency of major NAT2 alleles and genotypes among the Jordanian population. METHODS DNA samples from 150 healthy Jordanian volunteers were analyzed by polymerase chain reaction followed by restriction fragment length polymorphism assays (PCR-RFLP) to determine the frequency of four major alleles: NAT2*4, NAT2*5, NAT2*6 and NAT2*7. RESULTS The frequency (95% confidence interval) of NAT2*4, NAT2*5, NAT2*6 and NAT2*7 alleles was 0.247 (0.198 - 0.296), 0.373 (0.318 - 0.428), 0.347. 0.293 - 0.401) and 0.033 (0.013 - 0.053), respectively. The most prevalent genotypes are those which encode slow acetylation phenotype. Around 58.7%, 33.3% and 8% of volunteers carried the slow, the intermediate and the fast-encoding genotypes, respectively. CONCLUSION NAT2 genotype profile among Jordanians is similar to Caucasians. However, NAT2*6 allele is slightly high in comparison with Arab Middle Eastern populations.

Frequency of Certain Single-Nucleotide Polymorphisms and Duplication of CYP2D6 in the Jordanian Population

The CYP2D6 isozymes are responsible for metabolism of 7-10% of clinically available drugs. Genetic polymorphism in CYP2D6 may have an impact on drug efficacy and toxicity. The aim of this study was to determine the allelic frequency of CYP2D6*4, *10, and *17 and CYP2D6*2×N duplication allele in 192 healthy unrelated male and female Jordanian volunteers. Polymerase chain reaction (PCR)-restriction fragment length polymorphism-based methods were used to identify the CYP2D6*4, *10, and *17 genotypes; and allele-specific long PCR was used to determine the CYP2D6*2×N allelic frequency. The CYP2D6*10 allele was the most frequent mutant allele in Jordanians (14.8%) followed by CYP2D6*4 and *17 at 12.8%, and 8.3%, respectively. The duplication allele was found in 13.5% of the studied sample. The CYP2D6*4 G-A heterozygote genotype frequency was 20.3%, and the homozygous mutant genotype was 2.6%. In case of CYP2D6*10 C-T and CYP2D6*17 G-C heterozygote genotypes, the frequencies were 21.4% and 12.5%, respectively, while the homozygous mutant genotype frequencies of T-T and C-C were 4.2% and 2.1%, respectively. In conclusion, the allelic distributions of the CYP2D6 gene among Jordanians are different from other Mediterranean groups, especially the *10 and *17 single-nucleotide polymorphisms, and more importantly the CYP2D6*2×N duplication allele, which seems to follow a gradient reduction in prevalence from Ethiopia to Northern Europe.

Effect of Mint Drink on Metabolism of Nicotine as Measured by Nicotine to Cotinine Ratio in Urine of Jordanian Smoking Volunteers

INTRODUCTION Variation in nicotine metabolism may be due to genetic alterations in CYP 2A6, environmental factors, and diet. The purpose of this research was to evaluate mint drink effect on nicotine metabolism as judged by nicotine/cotinine ratio in urine of Jordanian smokers. METHODS Twenty-four Jordanian smoker volunteers were allocated randomly into two groups. They either received mint drink 3 times a day for 1 week during the mint drink period or avoided menthol-containing products and mint drink for 1 week during the off-menthol period. One group treatment sequence was mint drink, off-menthol, while the other group treatment was off-menthol, mint drink. Early morning urine samples were collected at baseline and at the end of each period. Samples were analyzed by liquid chromatography-mass spectrometry for the nicotine and cotinine concentrations. Nicotine/cotinine ratio was calculated and compared among the different periods for each participant using the paired t test. RESULTS All participants showed a consistent pattern of higher nicotine/cotinine ratios during mint drink compared with off-menthol periods, although to a variable extent. Mean nicotine/cotinine ratio during mint drink for all participants (1.327 ± 0.707) was higher than that during off-menthol (0.993 ± 0.547). Paired t test statistical analysis revealed a p < .0001. The mean difference in nicotine/cotinine ratio between the two periods was (-0.335), and the 95% confidence interval of the mean difference was (-0.451) - (-0.219). CONCLUSION Mint drink increased nicotine/cotinine ratio in urine, suggesting a reduction in conversion of nicotine to cotinine.

N-acetyltransferase-2 genotypes among patients with rheumatoid arthritis attending Jordan University Hospital.

AIM To determine the frequency of major N-acetyltransferase (NAT2) alleles and genotypes among Jordanian patients with rheumatoid arthritis (RA). METHODS The study was approved by the IRB of the Jordan University Hospital. An informed consent was signed by every patient. DNA samples from 150 healthy volunteers and 108 patients with RA were analyzed by polymerase chain reaction followed by a restriction fragment length polymorphism assay (PCR-RFLP) to determine the frequency of four major alleles: NAT2*4, NAT2*5, NAT2*6, and NAT2*7. RESULTS The most prevalent genotypes are those that encode the slow acetylation phenotype. About 59.3% of the patients with RA carried the slow, 33.3% the intermediate, and 7.4% the fast-encoding genotypes. The frequency of NAT2 alleles was 0.241 (95% confidence interval [CI] 0.184-0.298) for NAT2*4, 0.449 (95% CI 0.383-0.515) for NAT2*5, 0.273 (95% CI 0.214-0.332) for NAT2*6, and 0.037 (95% CI 0.012-0.062) for NAT2*7 allele. The overall frequency of the slow acetylation genotype in patients with RA is similar to that in healthy Jordanian volunteers. However, the NAT2*5/7 genotype was found in seven patients (6.5%) with RA and was absent in Jordanian volunteers, and the z test revealed that the difference was statistically significant. This genotype constituted 10.9% of the genotypes encoding slow acetylation. CONCLUSION The overall acetylator genotype in RA is similar to that in healthy volunteers. The overall slow acetylator genotypes do not seem to be a genetic risk factor for RA among Jordanians. However, the NAT2*5/7 genotype seems to be related to RA. The nature of this relationship needs further clarification.

Discrepancies between elderly patient’s self-reported and prescribed medications: a social investigation

AIMS To study some characteristics of the elderly people attending the family practice clinic at the Jordan University Hospital (JUH) and to evaluate their knowledge of the prescribed drugs. METHODS A total of 400 elderly people (180 men and 220 women) aged 71 ± 5.8 years were studied regarding sociodemographic characteristics and the use of medicinal and nonmedicinal remedies. In addition, agreement between self-reported drug information and information taken from the medical records was also evaluated. FINDINGS Almost one-third of the patients had full agreement between their knowledge of total number of drugs they take and the numbers found in the medical records, whereas 43.4% underestimated and 21.8% overestimated these numbers. Five drugs/classes were accurately estimated by the patient (methyldopa, ezetimibe, warfarin, statins and antigout drugs). Underestimation was noticed in 17 drugs/classes and overestimation in 14. The significantly underestimated drug classes were biphoshponates, proton pump inhibitors, sulfonylureas and antiepileptic drugs. CONCLUSION Some aspects of elderly people were evaluated regarding their medication knowledge. Almost two-third of the patients did not take their drugs in the proper way. The results of the study highlight the importance of taking several actions by all healthcare workers and by the community to optimise health care provided for elderly people.

Thiopurine S-methytransferase Gene Polymorphism in Rheumatoid Arthritis

BACKGROUND AND AIMS Thiopurine S-methyltransferase (TPMT) is responsible for inactivation of thiopurine drugs which are commonly used in leukemia, organ transplantation and autoimmune diseases. The gene encoding TPMT is polymorphic, and both phenotyping and genotyping studies have shown ethnic variations in gene sequence and enzyme activity worldwide. The aim of this study is to identify the most common genetic polymorphisms of TPMT in healthy Jordanian volunteers and patients with rheumatoid arthritis (RA). METHODS A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to identify the frequency of TPMT (*2, *3A, *3B, and *3C) polymorphisms in 250 healthy Jordanian volunteers and 110 RA patients. RESULTS Only four healthy subjects (1.6%) and one RA patient (0.9%) with variant alleles were identified in this study. Two healthy subjects had the TPMT*3A allele and the other two had the TPMT*3B allele, whereas the one RA patient had the TPMT*3A allele. No homozygous polymorphisms were detected and all genotypes detected were heterozygous (*1/*3A) (*1/*3B). None of the subjects had TPMT*2 or TPMT*3C variant alleles. CONCLUSIONS Mutant alleles identified in this study have a low frequency. TPMT (*3A and *3B) were the only detected heterozygous alleles. No homozygous variant allele was detected. Further studies are necessary to identify other variant alleles that might uniquely occur in Jordanians.

The Effect of Ethyl Acetate Extract of Pomelo Mix on Systemic Exposure of Verapamil in Rabbits

The effect of ethyl acetate extract of pomelo fruit on systemic exposure of verapamil was explored in rabbits. Two groups each of 8 locally-inbred New Zealand male rabbits were used. The first group was used for single-dose treatment (both verapamil and pomelo extract). The second group was used for multiple-dose treatment, pomelo extract (once daily for 14 days) and verapamil single doses (at days 7 and 14). A verapamil dose of 30 mg/kg and a pomelo extract dose of 45 mg/kg were used. Single-dose treatment with pomelo extract resulted in a minor change in mean C(max) of verapamil in plasma, while a decrease of 37.8% in AUC(0-24) and 28.3% in AUC(0-∞) was observed but did not reach statistical significance. After the first period of multiple dose treatment (pomelo extract for 7 days), the combination increased the concentration of verapamil in plasma with a significant increase in mean C(max), AUC(0-24) and AUC(0-∞) by 461.9%, 299.7%, and 261.1%, respectively (p values were 0.005, 0.002, and 0.006, respectively). In contrast, after the second period (day 14 of pomelo extract use), the combination decreased the concentration of verapamil in the plasma with a substantial decrease in mean C(max), AUC(0-24), and AUC(0-∞), by 68.2%, 69.7% and 58.3%, respectively. This decrease did not reach statistical significance (p values were 0.073, 0.081 and 0.083, respectively). The T(max) was not affected significantly in both studies. The study illustrates a complex time-dependent interaction between verapamil and the ethyl acetate extract of pomelo mix. More intensive studies are needed to further understand the nature of the interaction.