Biomedical subjects

David J Edwards

Publications and source records attributed to David J Edwards.

16 recordsLinked to original sources

PubMed2006

Pharmacokinetics of buspirone in autistic children.

Buspirone is used to treat generalized anxiety disorder in children and may be useful in developmental disorders in which brain serotonin synthesis is altered. Autistic children (13 boys, 7 girls) were given a single oral dose of 2.5 mg (2-3 years) or 5.0 mg (4-6 years). Blood was collected for 8 hours, and plasma was assayed for buspirone and its metabolite 1-pyrimidinylpiperazine (1-PP). The peak concentration of buspirone averaged 1141 +/- 748 pg/mL with a time to maximum concentration of 0.8 hours. Half-life was 1.6 +/- 0.3 hours. Peak concentrations of 1-PP were 4.5-fold higher than for buspirone. Girls had higher peak concentrations (1876 vs 746 pg/mL) for buspirone and a lower peak 1-PP/buspirone concentration ratio. These results suggest that buspirone is rapidly absorbed and eliminated in young children with extensive metabolism to 1-PP. Plasma concentrations with 2.5- to 5.0-mg doses were similar to those observed in older children receiving 7.5- to 15-mg doses.

Anti-Anxiety Agents↗

PubMed2005

Fine-tuning of biaryl dihedral angles: structural characterization of five homologous three-atom bridged biphenyls by X-ray crystallography.

The homologous series of three-atom bridged biaryls comprising 5,7-dihydro-1,2,3,9,10,11-hexamethoxydibenzo[c,e]oxepine, 6,7-dihydro-1,2,3,9,10,11-hexamethoxy-6-methyl-5H-dibenzo[c,e]azepinium chloride, 5,7-dihydro-1,2,3,9,10,11-hexamethoxydibenzo[c,e]thiepine, and the 6-oxide and 6,6-dioxide derivatives of the latter have been characterized by X-ray crystal structure analysis. Within this series the endocyclic and exocyclic biaryl dihedral angles vary over 10 degrees ranges, reflecting the changing balance of intramolecular (steric, geometric) and intermolecular (crystal packing) forces, the former being potential control elements for fine-tuning the helicity of the biaryl system.

Biphenyl Compounds↗

PubMed2005

Challenges of target/compound data integration from disease to chemistry: a case study of dihydrofolate reductase inhibitors.

Despite the improvements in informatics associated with initiatives in the structure-based design and genomics fields, no straight-forward links are available between a given disease class and drug chemistry. This involves effective linking of disease to protein targets, and then mapping these targets to drug chemistry. In practice, protein-ligand structural analyses and high-throughput screening experiments generate the links between targets implicated in disease and chemical leads. Additionally, large volumes of relevant data are also being produced by high-throughput X-ray crystallography and in-silico docking initiatives. Each of these efforts takes a distinctly different approach to how data is managed and mined, resulting in difficulties in sharing data across each area. This review discusses the diverse approaches taken to data management in these areas, and the challenges associated with the construction of a data warehouse that meets all of the needs of each data type. Using the current work available for dihydrofolate reductase inhibitors, we demonstrate the challenges and opportunities associated with data mining from disease to drug chemistry.

Animals↗

PubMed2004

Synthesis of cinnamic acids and related isosteres as potent and selective alpha v beta 3 receptor antagonists.

We describe a series of conformationally-restricted cinnamic acid peptidomimetics as well as several cinnamic acid isosteres, including 3-phenylpropionic acids, 2-amino-3-phenylpropionic acids, phenoxyacetic acids and 2-phenylcyclopropylcarboxylic acids. Several analogues demonstrated low to sub-nanomolar potencies against alpha(v)beta(3) and greater than 200-fold selectivity against the other beta(3) integrin alpha(IIb)beta(3). In whole 293 cells, many of these analogues also showed modest selectivity against other alpha(v) integrins such as alpha(v)beta(1) and alpha(v)beta(5). These compounds were synthesized from readily available starting materials using either Heck or Mitsunobu coupling conditions.

Cinnamates↗

PubMed2004

In vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmetto.

OBJECTIVES: Phytochemical-mediated modulation of cytochrome P450 (CYP) activity may underlie many herb-drug interactions. Single-time point phenotypic metabolic ratios were used to determine whether long-term supplementation of Citrus aurantium , Echinacea purpurea , milk thistle (Silybum marianum), or saw palmetto (Serenoa repens) extracts affected CYP1A2, CYP2D6, CYP2E1, or CYP3A4 activity. METHODS: Twelve healthy volunteers (6 women, 6 men) were randomly assigned to receive C aurantium , E purpurea , milk thistle, or saw palmetto for 28 days. For each subject, a 30-day washout period was interposed between each supplementation phase. Probe drug cocktails of midazolam and caffeine, followed 24 hours later by chlorzoxazone and debrisoquin (INN, debrisoquine), were administered before (baseline) and at the end of supplementation. Presupplementation and postsupplementation phenotypic trait measurements were determined for CYP3A4, CYP1A2, CYP2E1, and CYP2D6 by use of 1-hydroxymidazolam/midazolam serum ratios (1-hour sample), paraxanthine/caffeine serum ratios (6-hour sample), 6-hydroxychlorzoxazone/chlorzoxazone serum ratios (2-hour sample), and debrisoquin urinary recovery ratios (8-hour collection), respectively. The content of purported "active" phytochemicals was determined for each supplement. RESULTS: Comparisons of presupplementation and postsupplementation phenotypic ratios suggested that these particular supplements had no significant effect on CYP1A2, CYP2D6, CYP2E1, or CYP3A4 activity. Phytochemical profiles indicated that C aurantium was devoid of the CYP3A4 inhibitor 6',7'-dihydroxybergamottin. Quantities of fatty acids, flavonolignans, and cichoric acid were consistent with label claims for saw palmetto, milk thistle, and E purpurea , respectively. CONCLUSIONS: Botanical supplements containing C aurantium , milk thistle, or saw palmetto extracts appear to pose a minimal risk for CYP-mediated herb-drug interactions in humans. Although the effects of E purpurea on CYP activity were minor, further study into the interaction potential of this botanical is merited.

Adrenergic Agents↗

PubMed2004

Optimal delivery of minocycline to the brain: implication for human studies of acute neuroprotection.

Minocycline is currently under development as a neuroprotective agent in many different brain diseases. In more than a dozen experimental investigations in various models of brain injury, high doses of minocycline have been administered intraperitoneally. This report details new concerns with this route of administration and makes a case for intravenous dosing in experimental animals, particularly for acute neuroprotection, to optimize delivery to the brain and facilitate translation to human studies.

Animals↗

PubMed2004

Long-term improvement of quality of life during growth hormone (GH) replacement therapy in adults with GH deficiency, as measured by questions on life satisfaction-hypopituitarism (QLS-H).

Questions on Life Satisfaction-Hypopituitarism (QLS-H) is a new quality-of-life (QoL) questionnaire developed for adults with hypopituitarism. To determine the effects of long-term GH treatment on QoL, we evaluated QLS-H Z-scores in 576 adult patients with GH deficiency (GHD) enrolled in HypoCCS, an international observational study, using data from five countries in which comparative QLS-H data from the general population were available. Baseline QLS-H Z-scores were significantly lower in GH-deficient patients than in the general population of the same age, gender, and nationality. Z-scores were also significantly lower in female patients vs. males (P = 0.006) and in adult-onset vs. childhood-onset GHD (P = 0.002). Multivariate analysis associated female gender, multiple pituitary hormone deficiencies, low serum IGF-I values (<75 micro g/liter), and concomitant antidepressant medication with low baseline Z-scores. QLS-H Z-scores increased from -1.02 +/- 1.43 (SD) at baseline to -0.25 +/- 1.34 (SD) after 1 yr of GH treatment (P < 0.001) and were no longer significantly different from the general population after 4 yr of treatment. There was no correlation between change in Z-score and GH dose or changes in IGF-I and IGF binding protein-3 during treatment. This study demonstrates that 1) improvements in QoL, as measured by the QLS-H, are maintained during long-term GH replacement therapy of adults with GHD, and 2) the QLS-H is a useful tool for evaluating QoL in hypopituitary patients treated in clinical practice. The authors suggest that evaluation of QoL should be a part of the routine clinical management of adult GH-deficient patients, complementing the measurement of surrogate biological markers or other clinical end points.

Adult↗

PubMed2004

Pharmacokinetics of rofecoxib in children with sickle cell hemoglobinopathy.

Rofecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor approved for the treatment of pain and arthritis in adults. It is available as a suspension, but there are no published pediatric pharmacokinetic data. This study characterized the disposition of rofecoxib in children with sickle cell hemoglobinopathy in a single-oral-dose, intensive pharmacokinetic study. Eight subjects aged 3 to 14 years (mean 8.9 years, 5 boys and 3 girls) received a single oral dose of rofecoxib (1 mg/kg, maximum 50 mg) as a suspension. Blood samples were collected over 72 hours following drug administration and plasma was assayed for rofecoxib using high-performance liquid chromatography (HPLC). Pharmacokinetic parameters (peak concentration [Cmax], time to reach peak concentration [tmax], area under the curve [AUC], oral clearance [Cl/F], elimination half-life [t1/2]) were calculated using standard noncompartmental methods. The mean dose was 35.6 mg (range 15-50 mg). Cmax averaged 582 +/- 129 ng/mL, with a median tmax of 4.0 hours. Secondary peaks were observed in two subjects. Two subjects were discharged at 12 hours, preventing characterization of elimination. In the remaining six subjects, Cl/F averaged 1.34 +/- 0.32 mL/min/kg, with a t1/2 of 14.8 +/- 4.5 hours. No significant adverse events were observed. The disposition of rofecoxib in children appears to be similar to that in adults, with comparable values for Cmax, tmax, t1/2, and Cl/F.

Administration, Oral↗

PubMed2003

Influence of goldenseal root on the pharmacokinetics of indinavir.

Goldenseal root was identified as the most potent inhibitor of CYP3A4 in a study that tested 21 popular herbal products for in vitro inhibitory activity. The purpose of this investigation was to examine the influence of goldenseal root on the disposition of the CYP3A4 substrate indinavir in humans. Using a crossover study design, the pharmacokinetics of indinavir were characterized in 10 healthy volunteers before and after 14 days of treatment with goldenseal root (1140 mg twice daily). Indinavir was given as a single 800-mg oral dose, and blood samples were collected for 8 hours following the dose. No statistically significant differences in peak concentration (11.6 vs. 11.9 mg/L) or oral clearance (26.8 vs. 23.9 mg*h/L) were observed following treatment with goldenseal root. Half-life and time to reach peak concentration were also unchanged by goldenseal. These results suggest that patients being treated with indinavir can safely take goldenseal root and that interactions with other drugs metabolized by CYP3A4 in the liver are unlikely.

Adult↗

PubMed2003

Decreased quality of life in adult patients with growth hormone deficiency compared with general populations using the new, validated, self-weighted questionnaire, questions on life satisfaction hypopituitarism module.

To develop reference ranges for the Questions on Life Satisfaction Hypopituitarism Module (QLS-H), a new quality of life questionnaire for patients with hypopituitarism, data from 8177 adults were collected in France, Germany, Italy, The Netherlands, Spain, the United Kingdom, and the United States QLS-H scores declined with age, were lower in females than males, and differed significantly among countries. From these reference ranges we derived equations for z-scores, which adjust for age, gender, and country. QLS-H results from 957 adults with GH deficiency (GHD) participating in clinical trials were analyzed. At baseline, QLS-H scores were lower in females and differed significantly among countries. QLS-H scores significantly increased after GH treatment (6-8 months), but differences by country persisted. Calculating z-scores for patients eliminated all gender and most country differences. Pooled z-scores (mean +/- SD) from all patients increased from -0.99 +/- 1.39 at baseline to -0.14 +/- 1.30 after GH treatment. Quality of life assessment in adults with GHD requires the use of z-scores to correct for age, gender, and country differences. This approach allows pooling of data from different cohorts and comparison with general populations. QLS-H scores in adults with GHD were significantly decreased at baseline and were almost normalized after 6-8 months of GH therapy.

Adult↗

PubMed2003

Proteomic informatics: in silico methods lead to data management challenges.

Proteomics, which identifies proteins and analyzes their function in cells, is foreseen as the next challenge in biomedicine as diseases in the body are most easily recognized through the function of their proteins. Achieving this recognition is more difficult than pure gene analysis: it is estimated that 35,000 genes are present in human DNA, encoding more than 1 million proteins. A myriad of in vitro and in silico technologies now exist for studying proteins and their biological function. This review focuses on the vast array of in silico proteomic analysis methods, highlights public and commercial repositories for this data, and discusses the challenges associated with resolving and integrating the knowledge originating from this data.

Amino Acid Sequence↗

PubMed2002

The effect of grapefruit juice and seville orange juice on the pharmacokinetics of dextromethorphan: the role of gut CYP3A and P-glycoprotein.

The objective of this study was to determine the effects of grapefruit juice and seville orange juice on dextromethorphan (DM) pharmacokinetics. Eleven healthy volunteers were studied over a 3-week period consisting of 5 study days each separated by a three-day washout. All subjects refrained from drinking caffeine containing beverages (coffee, soda, etc.) 8 h before orally taking DM (30 mg) with 200 ml water, 200 ml grapefruit juice, 200 ml water, 200 ml seville orange juice, and 200 ml water on Study Days 1 to 5. Aliquots of urine samples were assayed and analysed for DM, and the DM metabolites dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan using a validated HPLC method employing a phenyl column and a fluorescence detection. Results suggests that DM could provide some useful information on P-glycoprotein or related membrane efflux protein activity in the human gastro-intestinal tract. Bioavailability (F) of DM increased significantly with grapefruit and seville orange juice, but only returned to half the baseline value after three days of washout. This confirms that grapefruit and seville orange juice are long-lasting and perhaps irreversible inhibitors of gut CYP3A/P-glycoprotein. Grapefruit and seville orange juice appeared to have the same overall effect on DM pharmacokinetics. In addition, this paper presents a novel method of phenotyping for CYP2D6, CYP3A and P-glycoprotein using DM as a probe.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Functional annotation of proteomic sequences based on consensus of sequence and structural analysis.

To maximise the assignment of function of the proteins encoded by a genome and to aid the search for novel drug targets, there is an emerging need for sensitive methods of predicting protein function on a genome-wide basis. GeneAtlas is an automated, high-throughput pipeline for the prediction of protein structure and function using sequence similarity detection, homology modelling and fold recognition methods. GeneAtlas is described in detail here. To test GeneAtlas, a 'virtual' genome was used, a subset of PDB structures from the SCOP database, in which the functional relationships are known. GeneAtlas detects additional relationships by building 3D models in comparison with the sequence searching method PSI-BLAST. Functionally related proteins with sequence identity below the twilight zone can be recognised correctly.

Consensus Sequence↗

PubMed2002

Pioglitazone: effect on CYP3A4 activity.

Clinical studies demonstrate CYP3A4 enzyme induction with troglitazone, a thiazolidinedione derivative structurally related to pioglitazone. The objective of this prospective, open-label study conducted in healthy volunteers was to evaluate the influence of multiple-dose pioglitazone therapy on the urinary excretion ratio of 6-beta-hydroxycortisol to cortisol, an endogenous marker of CYP3A4 activity. Twelve subjects were given pioglitazone hydrochloride 45 mg daily for 14 days. Urine was collected over a 24-hour period before pioglitazone and after administration of the last tablet. Baseline and posttreatment CYP3A4 activity was assessed with the urinary 6-beta-hydroxycortisol/cortisol ratio. The mean +/- SD 6-beta-hydroxycortisol/cortisol ratios before and after treatment were 8.3 +/- 4.4 and 9.4 +/- 4.0, respectively (p = 0.29). The mean change from baseline was a nonsignificant 20.2%. Nine subjects had a small increase and 3 subjects had a reduction in the ratio. Using the ratio as a marker of CYP3A4 activity, the data support a lack of inductive effect on CYP3A4 by multiple-dose pioglitazone therapy. Thus, administration of pioglitazone should not result in clinically significant effects on the pharmacokinetics of other CYP3A4 substrates.

Adult↗

PubMed2002

Effect of Seville orange juice and grapefruit juice on indinavir pharmacokinetics.

Considerable interpatient variability in indinavir pharmacokinetics, possibly due in part to variable metabolism of the drug through intestinal cytochrome P450 (CYP) 3A4, may contribute to poor virologic response in certain individuals with HIV infection. The purpose of this study was to characterize the influence of intestinal CYP3A4 modulation with grapefruit juice and Seville orange juice on indinavir pharmacokinetics. In an open-label, three-period crossover study, 13 healthy volunteers received indinavir 800 mg every 8 hours for 1 day and a single 800 mg dose the next morning. The last two indinavir doses were taken with 8 ounces of Seville orange juice, single-strength grapefruit juice, or water (control). Plasma samples were collected at time 0 (predose) and at 0.5, 1, 2, 3, 4, and 5 hours after the last indinavir dose. Concentration-time data were analyzed using noncompartmental methods. Coadministration of Seville orange juice and indinavir resulted in a statistically significant increase in indinavir t(max) (1.87 [1.65-2.22] vs. 1.25 [1.03-1.60] h; p < 0.05) without altering other pharmacokinetic parameter values. Grapefruit juice administration did not result in any changes in indinavir pharmacokinetics. Modulation of intestinal CYP3A4 by grapefruit juice and Seville orange juice did not alter the systemic availability of indinavir. The contribution of presystemic metabolism to indinavir interpatient variability appears to be small.

Adult↗

PubMedDate not supplied

Variations in alkaloid content of herbal products containing goldenseal.

OBJECTIVE: To determine the concentration of hydrastine and berberine, the primary alkaloids in herbal products containing goldenseal. DESIGN: Descriptive comparison of 20 products purchased at local pharmacies or health food stores; 17 products were labeled as containing goldenseal root and 3 products contained goldenseal herb as the sole active herbal ingredient. SETTING: Laboratory assessment of alkaloid content using high-performance liquid chromatography. MAIN OUTCOME MEASURES: Comparisons of hydrastine and berberine concentration, alkaloid ratio, and total alkaloid content among products. RESULTS: Hydrastine concentration in products labeled as containing goldenseal root ranged from 0 to 2.93%, whereas berberine concentration varied from 0.82% to 5.86%. Median total alkaloid concentration was 5.30%. Only 10 of 17 products met proposed United States Pharmacopeia (USP) standards for the hydrastine and berberine content of goldenseal root. Five products contained little or no hydrastine, unusual berberine:hydrastine ratios, and additional peaks not observed with other products. Alkaloid content in goldenseal root products was about fourfold higher than in products labeled as containing goldenseal herb. CONCLUSION: Alkaloid content of goldenseal products varies widely, with many products failing to meet proposed USP standards. In addition, the chromatographic pattern and alkaloid ratio for several products were atypical for goldenseal. Given the current absence of regulation of the quality of herbal products, pharmacists should take extra care to ensure that substandard goldenseal products are not sold in their pharmacies.

Alkaloids↗