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John Newton

Publications and source records attributed to John Newton.

6 recordsLinked to original sources
PubMed2003

Practice based, longitudinal, qualitative interview study of computerised evidence based guidelines in primary care.

OBJECTIVE: To understand the factors influencing the adoption of a computerised clinical decision support system for two chronic diseases in general practice. DESIGN: Practice based, longitudinal, qualitative interview study. SETTING: Five general practices in north east England. PARTICIPANTS: 13 respondents (two practice managers, three nurses, and eight general practitioners) gave a total of 19 semistructured interviews. 40 people in practices included in the randomised controlled trial (34 doctors, three nurses) and interview study (three doctors, one previously interviewed) gave feedback. RESULTS: Negative comments about the decision support system significantly outweighed the positive or neutral comments. Three main areas of concern among clinicians emerged: timing of the guideline trigger, ease of use of the system, and helpfulness of the content. Respondents did not feel that the system fitted well within the general practice context. Experience of "on-demand" information sources, which were generally more positively viewed, informed the comments about the system. Some general practitioners suggested that nurses might find the guideline content more clinically useful and might be more prepared to use a computerised decision support system, but lack of feedback from nurses who had experienced the system limited the ability to assess this. CONCLUSIONS: Significant barriers exist to the use of complex clinical decision support systems for chronic disease by general practitioners. Key issues include the relevance and accuracy of messages and the flexibility to respond to other factors influencing decision making in primary care.

Attitude of Health Personnel↗
PubMed2002

Fondaparinux sodium is not metabolised in mammalian liver fractions and does not inhibit cytochrome P450-mediated metabolism of concomitant drugs.

OBJECTIVE: To investigate the in vitro metabolism of the antithrombotic agent fondaparinux sodium in mammalian liver fractions and to evaluate its potential inhibitory effect on human cytochrome P450 (CYP)-mediated metabolism of other drugs. METHODS: Metabolism was evaluated by incubating radioisotope-labelled fondaparinux sodium with postmitochondrial liver fractions of rat, rabbit, monkey or human origin (three subjects). Human liver microsomal preparations and an NADPH-generating system were incubated with phenacetin, coumarin, tolbutamide, S-mephenytoin, bufuralol, chlorzoxazone or nifedipine. These are selectively metabolised by CYP isoforms: CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 or CYP3A4, respectively. Experiments were designed to determine apparent K(i) (inhibitory constant) values for fondaparinux sodium against each CYP isoform, by varying concentrations of fondaparinux sodium and the selective substrate. Each experiment included control reaction mixtures containing an isoform-selective inhibitor. After incubation, the mixtures were analysed by LC-MS/MS or with fluorometric detection. RESULTS: All liver fractions were enzymatically active, as demonstrated by degradation of [(14)C]testosterone. No metabolism of fondaparinux sodium was detectable in postmitochondrial liver fractions. Apparent K(i) values for fondaparinux sodium against the CYP isoforms could not be determined because the oxidative metabolism of the isoform-selective CYP substrates was not significantly inhibited in pooled microsomal reaction mixtures. In the presence of selective CYP inhibitors, metabolism of each substrate was significantly reduced, confirming that inhibition could be observed in these assays. CONCLUSION: The demonstrated lack of mammalian hepatic metabolism of fondaparinux sodium is consistent with animal and human studies. The absence of inhibition of the human CYP isoforms commonly involved in the metabolism of drugs suggests that clinical treatment with fondaparinux sodium is unlikely to interfere with the pharmacokinetics and metabolism of a wide range of other drugs which are associated with CYP inhibition.

Adult↗