Dose Tailoring of Vancomycin Through Population Pharmacokinetic Modeling Among Surgical Patients in Pakistan.

Background: Vancomycin is a narrow therapeutic agent, and it is necessary to optimize the dose to achieve safe therapeutic outcomes. The purpose of this study was to identify the significant covariates for vancomycin clearance and to optimize the dose among surgical patients in Pakistan. Methods: Plasma concentration data of 176 samples collected from 58 surgical patients treated with vancomycin were used in this study. A population pharmacokinetic model was developed on NONMEM® using plasma concentration-time data. The effect of all available covariates was evaluated on the pharmacokinetic parameters of vancomycin by stepwise covariate modeling. The final model was evaluated using bootstrap, goodness-of-fit plots, and visual predictive checks. Results: The pharmacokinetics of vancomycin followed a one-compartment model with first-order elimination. The vancomycin clearance (CL) and volume of distribution (Vd) were 2.45 L/h and 22.6 l, respectively. Vancomycin CL was influenced by creatinine clearance (CRCL) and body weight of the patients; however, no covariate was significant for its effect on the volume of distribution. Dose tailoring was performed by simulating dosage regimens at a steady state based on the CRCL of the patients. The tailored doses were 400, 600, 800, and 1,000 mg for patients with a CRCL of 20, 60, 100, and 140 ml/min, respectively. Conclusion: Vancomycin CL is influenced by CRCL and body weight of the patient. This model can be helpful for the dose tailoring of vancomycin based on renal status in Pakistani patients.

Taro-corms mucilage-alginate microspheres for the sustained release of pregabalin: In vitro &in vivo evaluation.

Taro corms mucilage (TCM)-alginate microspheres had been prepared using TCM and alginate as blend and coated form in various ratios through inotropic gelation approach. The prepared microspheres have been of sphere-formed having coarse surface with average particle size within the range 498 µm ±â€¯0.17 to 715 µm ±â€¯0.34. The drug entrapment efficiency was 74.33 ±â€¯0.04% to 89.63 ±â€¯0.01% and swelling of microspheres followed the pattern (blended >coated >plain). FTIR research showed that there had been no interactions among pregabalin and polymers used; these microspheres were further characterized by DSC and XRD. The in vitro drug release followed sustained release (Korsmeyer-Peppas model) pattern (R2 = 0.9552-0.9906) and value of n > 1 showed that drug released by means of anomalous (non-Fickian) diffusion. The in vivo research established that there were highly significant difference with p < 0.001 within the pharmacokinetic parameters (Cmax, t½, AUC0-∞, Ke), while pregabalin microspheres in comparison to pure drug. Therefore, it is concluded that blended microspheres has greater bioavailability for pregabalin with sustained release effect. This evolved that TCM has been proved to be emerging potential pharmaceutical excipient for sustained release drug delivery systems.

Evaluation of gender difference in pharmacokinetics of Candesartan cilexetil in the fasted state by RP-HPLC: A single dose comparative study.

To compare the pharmacokinetics of candesartan cilexetil in healthy male and female volunteers in order to identify possible influence of gender and to improve therapeutic outcomes, an HPLC method for the quantification of candesartan cilexetil was developed and validated. Total of 16 volunteers (8 male and 8 female) were registered. Candesartan cilexetil 16 mg was administered orally to all the volunteers and blood samples were collected at different time intervals between 0-72 hours. Plasma was separated and analysed by HPLC method. Pharmacokinetic parameters were calculated by using APO software MW/PHARM version 3.02 and compared in male and female volunteers. The developed HPLC method fulfils the criteria for linearity, accuracy and precision described in EMA guideline. The values for absorption rate constant (Ka), maximum plasma concentration (Cmax), volume of distribution (Vd) and Clearance (CL) were similar in male and female volunteers. No influence of gender was observed on overall pharmacokinetics of candesartan cilexetil. Therefore, no need for dose optimization while administering candesartan cilexetil in male and female patients was found based on the results of this study.

Isocratic High Performance Liquid Chromatography Assay for Quantification of Ceftiofur Hydrochloride in Bubaline Plasma.

We optimized and validated an isocratic high-performance liquid chromatography (HPLC) assay for quantification of ceftiofur hydrochloride in bubaline plasma. Ceftiofur, its metabolic products and protein-bound residues were cleaved, derivatized into desfuroylceftiofur acetamide and injected into HPLC system. The mobile phase comprising of sodium dihydrogen phosphate (0.025 M, pH 7) and acetonitrile (34:66, v/v), was driven at a flow rate of 1 mL/min, and separation was achieved using C18 column. Isocratic elution was performed with an injection volume of 45 µL and analyte was scanned at 310 nm. The linearity range, limit of detection and limit of quantification were 0.1-10 µg/mL, 0.03 µg/mL and 0.11 µg/mL respectively. Moreover, the accuracy, precision and recovery remained within the acceptable limits. The assay was effectively applied for determining the concentration of ceftiofur in plasma samples collected from ceftiofur-treated buffalo calves.

Polymeric microspheres of okra mucilage and alginate for the controlled release of oxcarbazepine: In vitro &in vivo evaluation.

Oxcarbazepine-loaded alginate/okra pods mucilage microspheres were prepared through inotropic gelation technique for the sustained release of oxcarbazepine. The drug encapsulating efficiency of these microspheres was found 76.22 ±â€¯0.01% to 90.57 ±â€¯0.02% and their average particle sizes were 496 µm ±â€¯0.41 to 692 µm ±â€¯0.22. These microspheres were characterized in terms of swelling capacity, FTIR, DSC and SEM analysis. The in vitro drug release from these microspheres was followed sustained release (Korsemeyer - Peppas model) pattern (R2 = 0.9552-0.9906) and value of n > 1 showed that drug released by anomalous (non-Fickian) diffusion. The in vivo studies showed that there were highly significant difference with p < 0.001 in the pharmacokinetic parameters (Cmax, t½, AUC0-∞, Ke), when oxcarbazepine was formulated in form of polymeric microspheres as compared to pure drug.

Phytoremediation of organochlorine and pyrethroid pesticides by aquatic macrophytes and algae in freshwater systems.

Extensive use of Pesticides in agriculture and its surface runoff in river water is a major environmental concern. The present study evaluated the phytoremediation potential of Eichornia crassipes, Pistia strateotes and algae (Chaetomorpha sutoria, Sirogonium sticticum and Zygnema sp.) for organochlorine and pyrethroid pesticides. Water and plant samples were extracted by liquid phase and solid phase extraction respectively and analyzed by high-performance liquid chromatography. Eleven treatments (T1-T11) with and without plants were used for phytoremediation of organochlorine and pyrethroid pesticides. During the experiment, P. strateotes, E. crassipes and algae (C. sutoria, S. sticticum and Zygnema sp.) showed the highest removal efficiency with 62 (71% root, 29% shoot), 60 (67% root, 33% shoot), and 58% respectively for organochlorine and 76 (76% root, 24% shoot), 68 (69% root, 31% shoot), and 70% respectively for pyrethroids for the respective aquatic plants. Dissipation rate constant of treatments with plants (T2, T3, T5, T6, T8, and T9) was significantly higher (p < 0.05) as compared to that of treatments without plants (T10 and T11, control) for both organochlorine and pyrethroid. The bioconcentration factor of pyrethroid treatments (T3, T6, and T9) was significantly higher (p < 0.05) as compared to that of organochlorine treatments (T2, T5 and T8). The removal efficiency of E. crassipes, P. strateotes and algae (C. sutoria, S. sticticum and Zygnema sp.) for pyrethroids was significantly higher (p < 0.01) as compared to that of organochlorine.

Quantitative Scrutinization of Aflatoxins in Different Spices from Pakistan.

The current research work aimed to access the contamination level of aflatoxins B1, B2, G1, and G2 in the household spices that are widely consumed in huge amounts. 200 different spice samples, 100 packed and 100 unpacked, were analyzed for the aflatoxins profile by HPLC with an incidence of 61.5% contamination out of which 53.66% samples exceed the EU limit. The results disclosed that the unpacked samples are more contaminated as compared to the packed samples except for white cumin seeds. Among packed and unpacked samples of spices, the maximum value of aflatoxins was detected in fennel, that is, 27.93 µg/kg and 67.04 µg/kg, respectively. The lowest concentration of aflatoxin was detected in cinnamon in packed form (0.79 µg/kg) and in the unpacked samples of white cumin seeds which is 1.75 µg/kg. Caraway seeds and coriander in its unpacked form showed positive results whereas black pepper (packed and unpacked) was found free from aflatoxins. This is the first report on the occurrence of aflatoxins in packed and unpacked samples of spices from Pakistan. To ensure safe consumption of spices, there should be constant monitoring of aflatoxin and more studies need to be executed with the intention of preventing mycotoxin accretion in this commodity.

Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts.

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 µg L(-1) and AFB2; 50 µg L(-1)) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82-87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins.

Toxicity Appraisal of Untreated Dyeing Industry Wastewater Based on Chemical Characterization and Short Term Bioassays.

Characterizing wastewaters only on a chemical basis may be insufficient owing to their complex nature. The purpose of this study was to assess toxicity of textile dyeing wastewater based on analytical techniques and short term toxicity based bioassays. In this study, screening of the fractionated wastewater through GC-MS showed the presence of phenols, phthalic acid derivatives and chlorpyrifos. Metal analysis revealed that chromium, arsenic and mercury were present in amounts higher than the wastewater discharge limits. Textile dyeing wastewater was found to be highly mutagenic in the Ames test. DNA damage in sheep lymphocytes decreased linearly with an increase in the dilution of wastewater. MTT assay showed that 8.3 percent v/v wastewater decreased cell survival percentage to 50 %. It can be concluded from this study that short term toxicity tests such as Ames test, in vitro comet assay, and cytotoxicity assays may serve as useful indicators of wastewater pollution along with their organic and inorganic chemical characterizations.

Determination of S- and R-warfarin enantiomers by using modified HPLC method.

Warfarin is a commonly prescribed anticoagulant existing in two enantiomeric forms S- and R-warfarin. Many techniques have been used to analyze warfarin in plasma but less frequently for enantiomeric analysis. One of the HPLC method employed was further simplified and made economical. Method was validated according to ICH guidelines and was found to be sensitive, reliable and less time consuming. For both enantiomers, LLOQ was 12.5 ng/mL. The CV% and accuracy for method were in the range of 0.8-14.6% and 92-107% respectively. The recoveries for both enantiomers were in the range of 86-103.8%. Blood samples were collected from 170 stable patients taking warfarin and S- and R-warfarin levels were determined by this method. Majority of subjects were found to have S/R-warfarin ratio of about 1:2 as reported in previous studies due to rapid clearance of S-enantiomer than R-enantiomer. However individual subjects data was suggestive of presence of slow metabolizers of S-warfarin leading to altered S/R ratio. Previous studies have also pointed out CYP2C9 polymorphism being responsible for such inter-individual differences in S-warfarin metabolism. So plasma warfarin S/R ratio may serve as a useful phenotypic test for CYP2C9 polymorphism.

Assessment of sex differences in Pharmacokinetics of carvedilol in human.

Carvedilol is an anti-hypertensive agent capable of blocking both alph (α) and beta (ß) receptors used to preclude cardiac arrhythmias and angina. The study was designed to evaluate the Pharmacokinetics of carvedilol in human male and female volunteers. Healthy male and female (twenty each) volunteers were finalized for the study after preliminarily clinical examination. Blood samples were collected at specific time intervals after giving an oral dose of 12.5mg carvedilol, separated the plasma and placed at -80°C until analysis. Estimation of carvedilol in human plasma was accomplished by High performance liquid chromatographic (HPLC) method using fluorescent detector. Plasma concentration-time curve was used for calculation of pharmacokinetic parameters using two-compartment open model. Mean (SD) values of AUC and Cmax 0.076±0.021ßg.h/ml and 0.024±0.005ßg/mL, respectively) in male differ significantly (P<0.05) from the female 0.197±0.042ßg.h/ml and 0.048±0.02ßg/mL, respectively). Overall, bioavailability of carvedilol was somewhat higher in females than in males, but these differences could be expounded by the lower body weight of female. Conversely, no significant differences were found for tmax, clearance and half-life in male and female. Moreover the ethnicity had significant impact on the Pharmacokinetics of carvedilol in human.

Aflatoxins and ochratoxin A in maize of Punjab, Pakistan.

Aflatoxin and ochratoxin levels were determined in maize samples collected from store houses of 15 districts belonging to three agro-ecological zones of Punjab, Pakistan. Toxins were extracted by Aflaochra immunoaffinity columns and analysed by high-performance liquid chromatography (HPLC). Mean moisture content of maize kernels was recorded above the safe storage level of 15%. Results indicated that aflatoxin B1 and B2 contamination was found in 97.3% and 78.9% of the collected samples, respectively. Aflatoxin G1, aflatoxin G2 and ochratoxin A were not detected in any sample. Among positive samples, 77.3% contained aflatoxin B1 and 28% aflatoxin B2, exceeding the legal limits as set by the European Union (EU) and the United States Food and Drug Administration (USFDA). It was concluded that a significant number of samples contained aflatoxin B1 and B2 above the legal limits.

Bioequivalence study of montelukast tablets in healthy Pakistani volunteers.

Montelukast is a leukotrien receptor antagonist used for asthma treatment. Objective of this study was to evaluate the bioequivalence of two montelukast 10mg tablets, Innovator drug (Singulair) as reference and other locally manufactured drug (Montiget) in 12 healthy volunteers. It was randomized, single dose, two-period crossover study with 1 week washout period. Blood samples (4-5 ml) were collected before and after drug administration and plasma was separated for analysis. Concentrations of montelukast at different time intervals were determined by validated UV-HPLC method at 345nm wavelength. Bioequivalence was assessed by using non compartmental approach and also calculated the 90% confidence interval of the least-squared pharmacokinetic parameters (Cmax, AUC0-t and AUC0-OO). On average, Cmax, AUC0-t, AUC0-inf, was 2.35µg/mL, 1.28µg.h./ml, 1.67µg.h./ml, for innovator drug and 2.53µg/mL, 1.53µg.h./ml, 1.96µg.h./ml, for test drug, respectively. Confidence interval (90%) for Cmax, AUC0-t and AUC0-inf was 89-97%, 85-91% and 81-98% respectively. No statistical difference was found between the Cmax and AUC values of test and reference drugs. The confidence intervals for Cmax, AUC0-t and AUC0-OO are fully laid within the acceptable range of FDA (80-125%), thus two formulations are considered to be bioequivalent.