Adipocyte "Fatty Acid Binding Protein" Gene Polymorphisms (rs1054135, rs16909196 and rs16909187) in Jordanians with Obesity and Type 2 Diabetes Mellitus.

Background: Obesity, type 2 diabetes mellitus (T2DM), and dyslipidemia may result from the interactions of genetic and environmental factors. There are controversial reports concerning the association of polymorphisms (rs1054135, rs16909196 and rs16909187) in the gene of adipocyte fatty acid binding protein (FABP4) with obesity and T2DM. Therefore, we designed this study to determine the association of these polymorphisms with obesity, T2DM, and dyslipidemia among Jordanian subjects. Methods: The study was approved by the National Center for Diabetes, Endocrinology, and Genetics (NCDEG) Institutional Review Board (IRB). A total of 397 subjects were enrolled in the study and divided into four groups as described in materials and methods section. The fatty acid binding protein 4 (FABP4) gene containing (rs1054135, rs16909196 and rs16909187) single nucleotide polymorphisms (SNP) was amplified by polymerase chain reaction (PCR) followed by Sanger DNA sequencing of the PCR product. Results: None of the three SNPs were associated with T2DM (p > 0.05). The rs16909187 and rs16909196 were significantly associated with obesity. The wild type (CC) of rs16909187 was significantly higher among the overweight and obese group compared with normal weight controls (OD = 2.17, 95% CI = 1.18 - 3.96, p =0.01). The wild type of rs16909196 (AA) was significantly higher among the overweight and obese group compared to controls, (OD = 2.26, 95% CI = 1.24 - 4.14, p = 0.01). These results may indicate that the wild-type may be a risk factor for obesity.Only the rs1054135 SNP was significantly associated with increased low density lipoprotein (LDL) levels in the overweight and obese group compared with the controls (p = 0.03). Conclusions: The wild-type genotypes of rs16909196 and rs16909187 may be risk factors for obesity but not T2DM. None of the three SNPs was associated with T2DM.

Pharmacokinetics of vancomycin in neonates admitted to the neonatology unit at the Jordan University Hospital.

BACKGROUND: Vancomycin is used in neonatal intensive care units to treat nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) or coagulase-negative staphylococci. Current dosing regimens are not adequate, producing trough concentrations below the target range. PATIENTS AND METHODS: 151 neonates who received vancomycin and had vancomycin peak and trough concentration measurements as part of regular therapeutic drug monitoring were utilized. The patients were divided into three groups according to gestational age; less than 28 weeks, 28 to less than 34 weeks and 34 weeks to term. Neonates were given vancomycin doses as per guidelines. The pharmacokinetic parameters, elimination rate constant (K), elimination half-life (t1/2), volume of distribution (VD) and clearance (CL), were calculated. RESULTS: Peak vancomycin concentrations ranged from 9.4 to 52.8 mg/l, while troughs ranged from 0.0 to 16.6 mg/l. One third of the trough concentrations were below 5 mg/l and are thus, subtherapeutic. There were no statistically significant differences between the three groups in regard to elimination rate constant and half-life. However, there was a statistically significant difference in volume of distribution between the three groups (p < 0.05), and in clearance between the first group and the other two (p < 0.05), using Kruskal-Wallis statistical test. CONCLUSIONS: The empirical dosing method used was inadequate in one third of patients. Individualization of vancomycin dosing in the neonatal critical care unit at The Jordan University Hospital seems necessary.

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.

Compliance with good practice in prescription writing at outpatient clinics in Saudi Arabia.

A sample of prescription orders received from outpatient departments by a hospital pharmacy in Asir, Saudi Arabia, were analysed over 1 year for the essential elements of prescriptions. The prescriber's name, address and signature were on 83.3%, 9.6% and 81.9% of prescriptions respecti-vely. The patient's name, age and sex were on 94.6%, 77.3% and 51.3%. No prescription contained the patient's address and weight. Generic drug names were used in only 15.1% and strength of medication and dose units were included in 26.6% and 55.6% of prescriptions. Most prescriptions (94.0%) had no quantity indicated and had only partial instructions for patient use (90.7%); the diagnosis was included in about two-thirds. The prescriber's handwriting was illegible in 64.3% of prescriptions. Measures to improve the situation are suggested.

Compliance with good practice in prescription writing at outpatient clinics in Saudi Arabia

A sample of prescription orders received from outpatient departments by a hospital pharmacy in Asir, Saudi Arabia, were analysed over 1 year for the essential elements of prescriptions. The prescriber's name, address and signature were on 83.3%, 9.6% and 81.9% of prescriptions respectively. The patient's name, age and sex were on 94.6%, 77.3% and 51.3%. No prescription contained the patient's address and weight. Generic drug names were used in only 15.1% and strength of medication and dose units were included in 26.6% and 55.6% of prescriptions. Most prescriptions [94.0%] had no quantity indicated and had only partial instructions for patient use [90.7%]; the diagnosis was included in about two-thirds. The prescriber's handwriting was illegible in 64.3% of prescriptions. Measures to improve the situation are suggested

Evaluation of therapeutic drug monitoring of antiepileptic drugs.

Results of the therapeutic drug monitoring (TDM) of the concentration of antiepileptic drugs (AEDs), performed at Aseer Central Hospital over a 1-year period were evaluated. Most of the requests were for phenytoin (PHT) determination followed by carbamazepine (CBZ), valproic acid (VPA) and phenobarbital (PB). Serum concentrations of PB, CBZ, VPA and PHT within the presumed therapeutic range constituted 87%, 73%, 45% and 33%, respectively. Valproic acid exhibited age differences in the proportion of concentrations below the presumed therapeutic range, such that subtherapeutic concentrations increased while therapeutic concentrations decreased with age. When the requests were related to particular patients, 71% of patients were on monotherapy with PHT as the most commonly used single drug and PB the least. Patients using 2 AEDs were found to constitute 23.5% of all patients with "PHT + CBZ" and "CBZ + VPA" being the most commonly prescribed 2 drugs combination. The frequency of concentrations within the therapeutic ranges decreased when 1 or 2 more drugs were used with either PHT or VPA. In addition, combination with PHT was associated with a reduction in mean CBZ concentration, while combination with CBZ was associated with a reduction in mean VPA concentration.

Variability of coumarin 7- and 3-hydroxylation in a Jordanian population is suggestive of a functional polymorphism in cytochrome P450 CYP2A6.

OBJECTIVE: To determine the variability of coumarin 7- and 3-hydroxylation in a human population and to evaluate the evidence for the existence of genetic polymorphism in these pathways. 7-Hydroxylation of coumarin is considered to be a detoxication pathway, whilst 3-hydroxylation, which predominates in rats, leads to hepatotoxicity in the rat. Coumarin metabolic phenotypes could aid in refining the risk evaluation for humans of dietary and environmental exposure to coumarin and for the chronic use of coumarin in high doses as a drug to treat lymphoedema and certain cancers. METHODS: Healthy male and female Jordanian volunteers (n = 103) were administered 2 mg coumarin by mouth and collected their 0-8-h urines. These, together with pre-dose blank urines, were analysed by selected-ion monitoring gas chromatography mass spectrometry for their content of the coumarin metabolites 7-hydroxycoumarin (70HC) and 2-hydroxyphenylacetic acid (2OHPAA), the latter arising from the 3-hydroxylation pathway. RESULTS: After coumarin administration, excretion of both 70HC and 2OHPAA was highly variable. A coumarin metabolic ratio (2OHPAA/7OHC) was suggestive of polymorphism. At least one subject had a metabolic response similar to an individual known to be both phenotypically and genotypically (CYP2A6 gene) 7-hydroxylation-deficient. CONCLUSION: In the light of the finding of high variability and possible polymorphism in both the 7- and 3-hydroxylation of coumarin in a human population. we recommend a reappraisal of the risk evaluation of human exposure to coumarin, particularly in pharmaceutical doses.

Comparative pharmacokinetics of two nifedipine products in capsule form following single oral administration in healthy volunteers.

The pharmacokinetic parameters (AUC, Cmax, Tmax, and t1/2) of nifedipine following single oral administration of a 10 mg capsule of test product were compared to those of the same amount of a reference product. The two products in capsule form were administered according to a randomized two-way crossover design in 22 healthy male volunteers. Nifedipine plasma concentrations were determined using a rapid, sensitive and precise high performance liquid chromatography (HPLC) method with ultraviolet (UV) detection at 235 nm. The parametric 90% confidence intervals of the mean value of the ratio [Myogard (test product) /Adalat (reference product)] for pharmacokinetic parameters were 0.90-1.08, 0.80-1.07, and 0.93-1.12 for AUC0-->infinity, Cmax and t1/2, respectively. In each case, values were within the acceptable bioequivalence range of 0.8-1.25. Distribution free point estimate for the difference in expected medians of Tmax of the two products (Myogard-Adalat) was 0.00 h with a 90% confidence interval of 0.00-0.13 which is greater than the accepted bioequivalence of +/- 0.12. The kinetic parameters were comparable to those reported for nifedipine, and no statistically significant differences were found in any of them when comparing the two products by analysis of variance (ANOVA) on log-transformed data. Thus, the two products could be considered bioequivalent regarding absorption rate (Cmax and Tmax), extent of absorption (Cmax and AUC) and elimination (t1/2).

Dextromethorphan metabolism in Jordanians: dissociation of dextromethorphan O-demethylation from debrisoquine 4-hydroxylation.

The concentrations of dextromethorphan (DM) and its metabolites dextrorphan (DRP), 3-methoxymorphinan (MM) and 3-hydroxymorphinan (HM) were measured in 8 h urine samples from 266 unrelated healthy Jordanian subjects following oral administration of 30 mg dextromethorphan hydrobromide and using a rapid, sensitive and precise HPLC method with fluorometric detection. The frequency of the 'poor' metabolizer status of DM-O-demethylation as judged by log DM/DRP was found to be 6.8% with a 95% confidence interval of 3.8-9.8%. There was a strong correlation between log DM/DRP and log total non-O-demethylated compounds (NODM)/total O-demethylated metabolites (ODM) metabolic ratios (r = 0.96, P < 0.01). However, one subject with log DM/DRP of 0.05 that classifies him as a poor metabolizer was found to have a log NODM/ODM of -0.73 which is in the range of extensive metabolizer status suggesting the presence of another cytochrome P450 isoenzyme involved in dextromethorphan O-demethylation. Dextromethorphan N-demethylation to 3-methoxymorphinan was detected in 55.3% of individuals. Furthermore, a dissociation between dextromethorphan O-demethylation and debrisoquine (D) 4-hydroxylation has been observed. Among the 116 subjects phenotyped with both dextromethorphan and debrisoquine, 7 were poor metabolizers of both, three were poor metabolizers of debrisoquine and extensive metabolizers of dextromethorphan whilst 4 were poor metabolizers of dextromethorphan and extensive metabolizers of debrisoquine, one of whom was reclassified as an extensive metabolizer of dextromethorphan using log NODM/ODM to characterize dextromethorphan metabolizer status.

Comparative pharmacokinetics of two brands of atenolol following a single oral administration.

The pharmacokinetic parameters (Cmax, Tmax, t1/2, AUC0-30h, AUC0-infinity) of following a single oral administration of 100 mg of a test product (Tenolol, The United Pharmaceutical Manufacturing Company, Amman, Jordan) were compared to those of a reference product (Tenormin, ICI Pharmaceuticals). The 2 products were administered according to a randomized 2-way crossover design to 24 healthy male volunteers. After drug administration, serial blood samples were collected over a period of 30 hours. Atenolol plasma concentrations were measured using an HPLC technique with fluorometric detection at an excitation and an emission wavelengths of 222 nm and 300 nm, respectively. The parametric 90% confidence intervals of the mean value of the ratio (Tenolol/Tenormin) of pharmacokinetic parameters were 0.90-1.12, 0.92-1.12, 0.88-1.14, and 0.91-1.09 for AUC0-30h, AUC0-infinity, Cmax, and t1/2. In each case values were within the acceptable bioequivalence range of 0.8-1.25. Point estimates of these parameters were 1.01, 1.02, 1.01, and 1.0. The parametric point estimate of the mean difference of Tmax between the 2 formulations (Tenolol-Tenormin) was 0.19 hours with a 90% confidence interval of -0.47-0.84, which overlaps with the stipulated bioequivalence range of +/- 0.64. Thus, the 2 products could be considered bioequivalent regarding rate of absorption (Cmax and Tmax), extent of absorption (Cmax and AUC), and elimination (t1/2).

Metabolic interactions of putative cytochrome P4503A substrates with alternative pathways of dapsone metabolism in human liver microsomes.

The cytochrome P4503A (CYP3A) subfamily of enzymes are responsible for the metabolism of a large number of endogenous and exogenous compounds, and activation of some procarcinogens; but the activity is not well understood. N-Hydroxylation of dapsone in human liver microsomes has been shown to be mediated largely by CYP3A4. We have also observed the formation of an as yet unidentified metabolite of dapsone, whose formation is inhibited by antibody to CYP3A4, by these microsomes. This study investigated the influence of various (22) CYP3A putative substrates on the formation of both metabolites of dapsone in human liver microsomes. The compounds fall into four different categories on the basis of the pattern of their inhibitory interaction with the formation of both metabolites: those that inhibited both metabolites; those that inhibited N-hydroxylamine alone; those that inhibited the unidentified metabolite alone; and those with no significant effect on either metabolite. Some others were stimulatory. These results are consistent with two alternative but not mutually exclusive hypotheses: 1) different isoforms of CYP3A are involved in the formation of the alternative metabolites and the pattern of interaction observed was caused by the particular isoform(s) that each compound interacted with; or 2) formation of the alternative metabolites is a result of dapsone's interaction with and orientation at the enzyme's active site and the pattern of interaction observed is a consequence of changes in orientation caused by these compounds. This study provides relevant observations that must be considered in understanding mechanisms of CYP3A-mediated metabolism.

S-mephenytoin hydroxylation phenotypes in a Jordanian population.

We tested the ability of 194 unrelated, healthy Jordanian volunteers to metabolize S-mephenytoin. Mephenytoin (100 mg) was coadministered with debrisoquin (10 mg) orally and urine was collected for 8 hours. Mephenytoin metabolism was tested according to three measures: the amount of 4-hydroxymephenytoin, the S/R enantiomeric ratio, and the presence of a polar, acid-labile metabolite in urine collected for 8 hours after the dose. The S/R ratio and the presence of the acid-labile metabolite were determined in the urine of 16 patients who had low amounts of 4-hydroxymephenytoin (log hydroxylation index > or = 1). On examination of these three parameters of oxidation status, nine subjects were found to be poor metabolizers of mephenytoin by all three parameters. Thus 4.6% (95% confidence interval of 1.6% to 7.6%) of Jordanian subjects studied were poor metabolizers of mephenytoin. According to the Hardy-Weinberg Law, the frequency of the recessive autosomal gene controlling the poor metabolizer status of mephenytoin was predicted to be 0.215% (95% confidence interval of 0.146% to 0.283%). These results are on the same order of magnitude as those determined in European white populations and constitute the first report in Arab populations.

Comparative pharmacokinetics of 2 brands of cefuroxime following a single intramuscular injection.

The pharmacokinetic parameters (AUC0-8h, AUC0-infinity, Cmax, tmax, t1/2, Ke) of cefuroxime following a single intramuscular injection of 750 mg of a test product (Maxil, Hikma Pharmaceuticals, Amman, Jordan) were compared to those of a reference product (Zinacef, Glaxo, UK). The 2 products were administered according to a randomized 2-way crossover design to 26 healthy male volunteers. Cefuroxime plasma concentrations were determined using a rapid, sensitive and precise HPLC method with UV detection at 280 nm. The means of the ratios AUC0-infinity Maxil/AUC0-infinity Zinacef and Cmax Maxil/Cmax Zinacef were close to 1 and their 90% confidence intervals included 1. The mean pharmacokinetic parameters of the 2 products were not different and their 90% confidence intervals overlapped. The 2 products were not statistically different with respect to both rate and extent of absorption as demonstrated by statistical analysis on Cmax, tmax, AUC0-8h and AUC0-infinity. The 2 products were also similar regarding t1/2 and Ke. The ANOVA analysis showed no differences in the pharmacokinetic parameters of the 2 products in relation to treatment, sequence of product administration or the interaction term. Pharmacokinetic parameters of cefuroxime were comparable to reported values. We conclude that the 2 products of cefuroxime (Maxil and Zinacef) are bioequivalent.

The N-oxidation of trimethylamine in a Jordanian population.

The ability to oxidise trimethylamine (TMA) to trimethylamine N-oxide (TMAO) is distributed polymorphically within a British white population with the majority of individuals excreting greater than 90% of total urinary TMA as TMAO. The opposite extreme is characterised by a rare inborn error of TMA N-oxidation known as the fish-odour syndrome. However there is a lack of information regarding inter-individual variability in the N-oxidation of TMA in other ethnic groups. In this study the urinary excretion of TMA and TMAO was determined over a period of 24 h in 82 Jordanian subjects. A frequency distribution histogram of % of total urinary TMA excreted as TMAO revealed that the majority of subjects excreted greater than 80% of the total urinary TMA as TMAO, however eight subjects (9.7%) excreted less than 80% of the total TMA as TMAO. In a previous study of 169 white British subjects only one (0.6%) excreted less than 80% of the total TMA as TMAO. The results suggest that the prevalence of compromised ability to N-oxidise TMA may be higher in a Jordanian population than in a British population.

Metoprolol alpha-hydroxylation is a poor probe for debrizoquine oxidation (CYP2D6) polymorphism in Jordanians.

The frequency distribution of the 8-h urinary ratio of log metoprolol/alpha-hydroxymetoprolol was assessed in 65 healthy, unrelated Jordanian volunteers. There was no apparent bimodality in the frequency distribution of this ratio among the subjects studied. The frequency of the poor metabolizer phenotype of metoprolol alpha-hydroxylation was 1.5% (one subject). There was a significant correlation (r = 0.61, P < 0.05, n = 39) between the log metoprolol/alpha-hydroxymetoprolol and the log debrisoquine/4-hydroxydebrisoquine ratios. However, the frequency of poor metabolizer status of debrisoquine among the 39 subjects was 7.7% (three subjects). Only one of the poor metabolizer of metoprolol alpha-hydroxylation. These findings indicate that metoprolol alpha-hydroxylation by CYP2D6 represents a poor probe for studying debrisoquine polymorphism in Jordanians.

Monoacetyldapsone inhibition of dapsone N-hydroxylation by human and rat liver microsomes.

Dapsone (DDS) is metabolized by N-hydroxylation and N-acetylation to DDS hydroxylamine (DDS-NOH) and monoacetyldapsone (MAD), respectively. The activities of these two alternative and independent reactions vary widely between individuals and show an inverse relationship during chronic DDS therapy. Toxicity observed during DDS therapy has been attributed to DDS-NOH. The observation of reduced toxicity in rapid acetylators, who are also poor hydroxylators, therefore, raised the possibility that MAD may be inhibiting DDS-NOH formation. This hypothesis was tested in human and rat liver microsomes. Human liver microsomes hydroxylated DDS with a lower affinity (KM 2-fold greater) and lower maximal catalytic activity (Vmax 12-fold lower) than that of the rat. The relative catalytic activity (Vmax/KM) was 22-fold higher in rat compared with human liver microsomes. Furthermore, MAD was a potent inhibitor of DDS N-hydroxylation by rat liver microsomes (52% inhibition at 0.01 mM MAD) compared with human liver microsomes (23% inhibition at 0.4 mM MAD). Human, but not rat, liver microsomes deacetylated MAD to DDS by an NADPH independent mechanism. These results show that substantial differences exist in DDS N-hydroxylase between rats and humans, with respect to substrate affinity, enzyme activity, and susceptibility to inhibition, such that information obtained from the rat should not be extrapolated to humans. We conclude that MAD is a potent inhibitor of DDS-NOH formation in rat liver microsomes. The degree of inhibition in human microsomes, however, suggest that MAD is unlikely to be a significant modulator of enzyme activity in vivo.

Gastrointestinal dialysis of digoxin using cholestyramine.

The pharmacokinetic parameters of digoxin given intravenously (0.075 mg/kg) alone and following treatment with oral cholestyramine (8 gm in 50 ml water) were studied in rabbits. Pretreatment with cholestyramine produced a significant decrease in the serum concentration of digoxin and significantly enhances its systemic clearance as indicated by a statistically significant decrease in the area under the concentration-time curve (AUC), half time of elimination (t 1/2), and mean residence time (MRT). These findings indicate that the idea of gastrointestinal dialysis, known with activated charcoal, could be extended to ion-exchange resins that could be a potentially useful adjunctive measure in the management of drug overdose especially with commonly used drugs with a low therapeutic index like digoxin.

Dextromethorphan O-demethylation polymorphism in Jordanians.

The O-demethylation of dextromethorphan (DMT) to dextrorphan (DRP) was studied in 241 unrelated, healthy Jordanian volunteers (171 males, 70 females). Urine was collected for 8 h following a single oral dose of DMT bromhydrate 30 mg. A thin-layer chromatographic (TLC) technique was used to identify the metaboliser phenotype. The frequency of the poor metaboliser phenotype was found to be 2.9% (approximate 95% confidence interval 0.8-5.0%). Applying the Hardy-Weinberg Law, the frequency of the recessive autosomal gene controlling poor metabolism was 0.17 (95% confidence interval 0.108-0.232).

Acetylation of dapsone by human whole blood.

We studied the acetylation of dapsone (DDS) in vitro by whole blood taken from subjects with known acetylator phenotype. The acetylation of DDS by whole blood was both incubation time- and DDS concentration-dependent. Thus, it is highly recommended to separate plasma immediately after blood withdrawal during acetylation phenotyping using DDS. para-aminobenzoic acid (PABA) substantially inhibited the acetylation of DDS by whole blood taken from both slow and rapid acetylators, while procainamide (PAD) significantly inhibited DDS acetylation by whole blood taken from slow acetylators. At the highest PAD concentration used (208 microM), DDS acetylation by whole blood taken from rapid acetylators was also inhibited. In contrast, sulphanilamide (SAD) failed to produce any significant inhibition of the acetylation of DDS by whole blood taken from either slow or rapid acetylators. Furthermore, there was no correlation between DDS acetylation by whole blood in vitro and the acetylator status of the subject. It is therefore not possible to predict the acetylator phenotype by studying DDS acetylation by human whole blood. These results indicate that the DDS N-acetyltransferase of human whole blood is most probably of the monomorphic type.