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Name : Tawfiq Abdel Raheem Arafat

Academic Rank: Professor

Administrative Position : Dean

Office 8313       Ext No 209

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Specialization: advanced instrumental analysis

Graduate Of: Wales

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    United Kingdom

  • Journal Paper

      Enas 1. Hasan', Bass, " Assessment of a controlled release hydrophilic matrix formulation for metocIopramide Hel " , "",Vol.,No., , , 01/01/2003 Abstract:
      Melocloprall1ide HCI showed controlled release hehavior when ell1hedded in a hydrophilic matrix of chitosan and sodiull1 a1t!inate, TIll' in \itro release data was found to he first order accordint! to the HiguL'lli mechanism, An in vi\o e\aluation of the Il1L'tocloprall1idL' controlled release ll1atrix on six male \olunteers was carried oul. The plasma samples were analyzed using a high-perforll1allL'e liquid L'lmlillatography (HPLC) method usint! a ll10hile phase of aCclonitrile:acetic acid (30:70). \\ ith the pH adjusted to -1,7. a rnCJ'se phase lIypnsil BDS Phell\ I L'!llull1ll (-I /J-Ill. 250 X -I mill) and the detection \\ Download

      Ghadeer A. R. Y. Sua, " Synthetic approaches to peptides containing the L-Gln-L-Val-D(S)-Dmt motif " , "",Vol.,No., , , 01/01/2007 Abstract:
      The p.lcudoprolines S-Omo (5.5-dimethyl-4-oxaproline) and R-Omt (5.5-dimethyl-4-thiaproline) have been used to study the effects of forcing a fully cis conformation in peptides. Synthesis of peptides containing these (which havc the samc configuration as I.-Pro) is straightforward. However. synthesis of peptides containing S-Dmt is dil1icult. owing to the rapid cyclisatioll of I -Aaa-S¬Omt amides and esters to form the corresponding diketopiperazines (OKP); thus the intermediacy of t-Aaa-S-Omt amides and esters must be avoided in the synthetic sequence. Peptides containing the I.-G]n-t-Val-O(S)-Dmt motif are particularly dil1icult. owing to the insolubility of coupling partners containing Gin. Introduction of Gin as N-Boc-pyroglutamate overcame the latter ditllculty and thc dipeptide active ester BocPygValOCoF, coupled in good yield with S-OmtOIl. BocPygVal-S¬DmtNH(CH:,),Cr,H-lNO:, was converted quantitatively to BocGlnVal-S-OmtNH(CH:,):,Cr,H-lNO:, with ammonia. demonstrating the utility of this approach. Two peptide derivatives (CbzSerLysLeuGlnVal-S-OmtNH(CH:,hC"H.jNO:, and CbzSerSerLysLeuGln¬Val-,)'- DmtN H(CH,j,C(,H.jNO,) were assembled. using these new methods of coupling a dipeptide acid active ester with S-OmtOIl and introduction of Gin as Pyg. followed by conventional peptide couplings. The presence of the Val caused these peptides to be cleaved very slowly by prostate-specific antigen (PSA) at Leu] GIn. rather than the expected Gin 1 Val. © ~()()7 Elsevier Ltd. All rights reserved.

      Nancy Hakooz, Rana A, " A Trend of Lo\v Serum Vitamin B12 in Jordanian Adults from Two Ethnic Groups in Amman " , "",Vol.,No., , , 01/01/2005 Abstract:
      The plasma Bl2 level was measured in 290 subjects (124 men, ] 66 women, aged ] 6-72) from two ethnic groups; Circassians and Arabs. These participants were recruited by simple random sampling from both communities from June 2004 to March 2005. Results: The prevalence of vitamin B]2 deficiency (B]2 level lower than 200 pg/ ml) was 50.8 and 46.9% in Arab and Circassians, respectively. No ~ignificant differences in the plasma B 12 level were found between the different age groups in Arabs and Circassians and between the same age groups of the hvo populations. One notable exception was the subjects \vho are older than 60 years in Circassians. Their plasma B]2 levels were significantly lower than those in the other age groups in Circassians and the same age group in Arab (P<0.05). There were differences in the plasma BI2 level according to gender; the plasma Bl2 levels for men were lower than those obtained for women in both groups. This difference was significant (P

      Adnan BADWAN , Mayas, " Enhancement of oral bioavailability of insulin in humans " , "",Vol.,No., , , 01/01/2009 Abstract:
      OBJECTIVE: The purpose of this study is to investigate oral absorption of I, 2 and 3 U/kg oral insulin five test products with different particle sizes in comparison with 0.1 U/kg subcutaneous reference formulation. METHODS: Twenty five healthy volunteers participated in five studies using a two-phase, two-sequence crossover design with washout period of one day. Mean disposition kinetics was determined by non-compartmental analysis using Kinetica program. Absorption kinetics of insulin products were then determined using SIMCYP simulator utilizing ADAM model. RESULTS & CONCLUSIONS: Dimensional analysis results showed the superiority of formula 4: 2 U/kg oral dose with 57 nm particle size over other oral formulations when compared with subcutaneous route. Optimized intestinal permeability coefficients (x 10-4) of insulin best test and reference formulations were 0.084 and 0.179 cm/ sec respectively. Total fraction of insulin dose absorbed (Fa) for the test and reference products were 3.0% and 19% respectively. Subcuta¬neous product exhibited higher absorption rate and extent than oral insulin. Yet that was compensated by the increase in other factors such as Fa *, Peff* and oral dose, leading to similar insulin plasma levels and similar effect on glucose infu¬sion rates. Oral insulin bioavailability was shown promising for the development of oral insulin product. Download

      Ashok K. Shakya a.*,, " Validated liquid chromatographic-ultraviolet method for the quantitation of tadalafil in human plasma using liquid-liquid extraction " , "",Vol.,No., , , 01/01/2007 Abstract:
      A highly selective. sensitive amJ rapid IIPLC method has heen developed and validated to Ljuantify tadalafil in human plasma. The tadalatil and internal standard (ioratadine, LS,) were extracted hy liLjuid-liquid extraction technique followed hy an aqueous back-extraction allowing injection of an aqueous solvent in the HPLC system, The chromatographic separation was performed on a reverse phase BOS Hypersil C-I K column (250 mm x 4,6 mm, 5 fun. Thermo Separation Co., USA) with a mobile phase of acetonitrile and aqueous solution containing 0,012 M triethylamine + 0,020 M orthophosphoric acid (50/50, v/v), The analytes were detected at 225 nm. The assay exhibited a linear range of5-600 ng/mL for tadalat11 in human plasma, The lower limit of quantitation (LLOQ) was 5 ng/mL The within- and between hatch precision (expressed as codticient of variation, CV) did not exceed 10,Y,if, and the accuracy was within -7,6% deviation of the nominal concentration, The recovery of tadalalil from plasma was greater than 66,] 'iL Stability of tadalalil in plasma was excellent with no evidence of degradation during sample processing (auto-sampler) and 30 days storage in a freezer. This validated method is applied for the clinical study of the tadalatil in human volunteers, Download

      Nancv Hakoozl, Tawfi, " Genetic Analysis of Thiopurine Methyltransferase Polymorphism in Jordanian Population " , "",Vol.,No., , , 01/01/2009 Abstract:
      Thioflurinc mcthyltranskrase (TPMT) catalyscs the .'I-methylation of thiopurine drugs such as 6-mercaptopurinc. 6-thioguanine. and azathiopurine. These drugs have a \Iell-established role as immunosuflpressive agents in a variety of chronic inflammator) conditions. haematological neoplasia and in transplant rejection. lP,IfT polymorphisms are the m,\ior determinants of interindividual differcnces in thc se\erc to"\icity or emcacy of 6-mercaptopurine. The Irequencies of /llur (TPMl* 2, lPMT*3A. TPMT*38 and lPMT*3(') variants \Iere investigated in the Jordanian floflulation. The difkrences in TPMT activity results from single nucleotide polymorph isms (SNPs). rhe wild-IYflc allele is designated as lPI/T*1 and to date. at least 23 variant alleles of TP.\IT gene have heen identified. Four alleles (1I'.lfl*2. *3.1. *313 and *3(') account t(lr XO-95% of inherited TPMT deliciency and 10\\ enzyme activity. Several studics have investigated the flrevalence of these mutations in different flopulations. From the Illllr mutations mentioned earlier. the most rare mutation is the fj',lfT* 313. The most frequent allele mutation in Caucasians is lPMl*3A while the Il'Ml*3(' is the most flrelalent allele mutations in African and Asian floflulations. Download

      A.-M" Youscf* PhD, T, " Smoking behaviour modulates pharmacokinetics of orally administered clopidogrel " , "",Vol.,No., , , 01/01/2008 Abstract:
      Backgrolllld alld objectives: Clopidogrel is an important antiplatelet drug that is effective in preventing thrombotic events, especially for patients undergoing percutaneous coronary intervention. The therapeutic usefulness of clop-idogrel has been limited by documented inter¬individual heterogeneity in platelet inhibition, which may be attributable to known clopidogrel pharmacokinetic variability. The objective of this study was to assess the influence of smoking cigarettes and abnormal body weight on the pharmacokinetics of clopidogrel. Methods: Seventy-six healthy adult male volun¬teers were selected randomly. Each subject received a single 75 mg oral dose of clopidogrel after overnight fast. Clopidogrel carboxylate plasma levels were measured and non-compart-mental analysis was used to determine peak plasma concentration (Cmax), time to peak plasma concentration (T max), elimination half-life (tV2e) , and area under the curve (AVCo ---> _). T~eslllts: One-third of volunteers were smokers (II = 27) and one-half had abnormal body weight (1/ = 39). Smokers had lower AVCo ---> _ (smokers: 6'24 ± 2•32 ~g/h/m L vs. non-smokers: 8,93 ± 3'80 ~g/h/mL, I' < 0'(01) and shorter half-life (smokers: 5,46 ± 2'99 vs. non-smokers: 8,43 ± 4'26, l' = 0.(01). Smoking behaviour had no influence on Cnax (I' = 0'3) and Tmax (I' = 0'7). There was no statistically significant difference in Cmax, ;\ UCa ---> _, Tmax and tl/Ze between volunteers with abnormal body weight and normal body weight. However the difference in body weight of the Download

      Ghadeer A. R. Y. Sua, " Effects of steric bulk and stereochemistry on the rates of diketopiperazine formation from N-aminoacyl¬2,2-dimethylthiazolidine-4-carboxamides (Dmt dipeptide ami des )-a model for a new prodrug linker system " , "",Vol.,No., , , 01/01/2006 Abstract:
      A peptide-like self-immolative molecular clip is required for release of active drugs from prodrugs hy endopeptidases. Upon cleavage from the carrier, this clip must collapse and release the drug rapidly. A series of aminoacyl-5,S-dimethylthiaproline (Aaa-Dmt) N-(2-(4-nitrophenyl)ethyl)amides were designed. Boc-L-aminoacyl Ouorides were coupled with R-DmtOH to give Boc-L-Aaa-R-DmtOH. which were converted to the Boe-L-Aaa-R-Dmt N-(2-(4-nitrophenyl)ethyl)amides. The L.S diastereomeric series was prepared by thc reaction of Boc-Aaa PFP esters with S-DmtOH. The L-Aaa-Dmt N-(2-(4-nitrophenyl)ethyl)amides were allowed to cyclise to diketopiperalines (DKPsj in aqueous bufkrs. expelling 2-(4-nitrophenyl)ethylamine as a model for amine-containing drugs. Reaction rates were dependant on pH. In the L,R diastereomeric series, increasing steric bulk of the Aaa side-chain (Gly, Ala. Phe, Val, led to decrease in the reaction rate. 110\\¬ever. in the L,S series, the greatest rate of reaction was observed for the most bulky amino-acid (Val), with t./, = 15 min at pH R.O. The ellects of sterie bulk and stereochemistry are rationalised through conformational analysis (NMR and X-ray crystallography) of the starting dipeptide amides. the product dikctopiperazines and key analogues. Since the dipeptides are (almost) exclusively in the cis-amide conformation. tram¬cis interconversion is not relevant. The data suggest that steric interactions in the reacting conformations of the dipeptide amides. as they form the tetrahedral intermediates, are the controlling factors. Thus, L-Aaa-S-Dmt amides are shown to be excellent candidates for incorporation into the design of novel prodrugs.

      Ibraheem D. AI-Deebl, " The Effect of Licorice Drink on the Systemic Exposure of Verapamil In Rabbits " , "",Vol.,No., , , 01/01/2010 Abstract:
      The effect of licorice root drink (aqueous extract of Glycyrrhiza glabra Fabaceae) on plasma concentration of verapamil, using rabbits as animal model, was investigated. Two groups of locally inbred Newzeland male rabbits were used. The first group was given a single dose of licorice drink (4 mUkg body weight) concomitantly with 30 mg/kg vera¬pamil, and the second group was given a daily dose of licorice drink (4 ml/kg body \Ieight) for two weeks, with single doses ofverapamil on days, 7 and 14. Single dose treatment resulted in a nonsignificant decrease in mean Cmax by 33.2% (P = 0.41), but in a significant decrease of AUCO.24 and AUCo-oo by 60.5% and 63.6%, respectively (P = 0.0 I). First period of multiple dose treatment study (7 days), resulted in a significant reduction in mean Cma" AUCO.24 and AUCo-oo by 55.0%, 47.0% and 45.7%, respectively (P = 0.02,0.03 and 0.03, respectively). A more pronounced effect was seen at second pe¬riod of multiple dose treatment study (14 days), where the corresponding decrease was, 85.4%, 76.8% and 73.3%, respec¬tively (P < 0.0 I). Mean T max was significantly increased 4.2-fold over control period at day 14 of multiple dose study (1' = 0.02). In conclusion, licorice root drink decreased verapamil systemic exposure both after single dose and after daily doses for 14 days. Download

      Ashok K. Shakyaa", T, " Simultaneous determination of triprolidine and pseudoephedrine in human plasma by liquid chromatography-ion trap mass spectrometry " , "",Vol.,No., , , 01/01/2009 Abstract:
      1\ highly efflcient, selective and specinc method for simultaneous quantitation of triprolidille and pseu-doephedrine in human plasma by liquid chromatography-ion trap-tandem mass spectronwtry coupled with electro spray ionization (LC-ESI-ion trap-tandem MS) has been validated and successfully applied to a clinical pharmacokinetic study. Both targeted compounds together with the internal standard (gabapentin) were extracted from the plasma by direct protein precipitation. Chromatographic separation was achieved on a C,X ACE'" column (50.0 mm x 2.1 mm, 5/-1In, Advance Chromatography Technologies, Aberdeen, UK), using an isocratic mobile phase, consisting of water, methanol and formic ,1CId (55:45 :0.5, v/vjv), at a flow-rate ofO.3mL/min. The transition monitored (positive mode) was mlz 27<)1 -. mlz 20Kl for triprolidine, mlz 165.9 . mlz 148.0 for pseudoephedrine and mlz 172.0 . mlz 154.0 for gdbapentin (IS). This method had d chromatographic run time of 5.0 min and a linear calibration curves ranged from 0.2 to 20.0 ng/mL for triprolidine and 5.0-500.0 ng/mL for pseudoephedrine. The within- ,1Ild betweell¬batch accuracy and precision (expressed as coefncient of variation, %C.V.) evaludted at four quality control levels were within 94.3-106.3% and 1.0-9.6% respectively. The mean recoveries of tnprolidine, pseudoephedrine and gabapentin were 93.6, 76.3 and 82.0?!, respectively. Stability of triprolidine ,1Ild pseudoephedrine was assessed under different storage conditions. The validated method was success¬fully employed for the bioequivalence study oftriprolidine and pseudoephedrine formuldtion in twenty six volunteers under fasting conditions. Download
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