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Featured researches published by Wt Friesen.


Journal of Chromatography B: Biomedical Sciences and Applications | 1987

Rapid high-performance liquid chromatographic assay for the simultaneous analysis of non-steroidal antiinflammatory drugs in plasma

Susan G. Owen; Michael S. Roberts; Wt Friesen

Abstract A high-performance liquid chromatographic assay has been developed for the determination of a number of non-steroidal anti-inflammatory drugs in plasma. The samples were prepared by adding acetonitrile and perchloric acid to 200 μl of plasma. Diclofenac, fenoprofen, ketoprofen, naproxen, phenylbutazone, piroxicam and sulindac were quantified in the supernatant produced using a mobile phase of phosphoric acid 0.03% (pH 2.5) -acetonitrile and a detecting wavelength of 254 nm. The reproducibility, linearity, precision and specificity of the assay were determined and found to be satisfactory. Alteration of the detection wavelength to 229 nm also permitted accurate determination of ibuprofen concentration in plasma. While reduction of the organic solvent content of the mobile phase and alteration of wavelength to 313 nm produced a system capable of quantizing salicylate and its metabolites in plasma and by further reducing the detecting wavelength to 237 nm, aspirin also was quantifiable. These methods have been applied in a cross-sectional study of medication compliance among rheumatoid arthritis patients treated with non-steroidal anti-inflammatory drugs.


Journal of Pain and Symptom Management | 1995

An investigation of pain experience and management following gynecological day surgery: Differences between open and closed surgery

Bronwen L. Roberts; Gm Peterson; Wt Friesen; Warren G. Beckett

This study aimed to investigate the pain and activity levels of patients for a 5-day period following gynecological day surgery. Patients recorded their degree of pain and activity on visual analogue scales in a diary; completed diaries were returned by 54.9% of the patients approached (106 of 193). The median age of the women was 28.5 years (range, 15-55 years). Each procedure was classified as either open or closed surgery, depending upon whether an incision was necessary. Most (63.2%) of the patients required analgesics on the first morning after their surgery. Open surgery patients experienced significantly more pain for at least 3 postoperative days and were less active until the fifth day (P < 0.05 by Mann-Whitney tests). Drowsiness (47.2%), nausea (30.2%), and headache (30.2%) were the most common adverse effects experienced in the first postoperative morning. The incidence of adverse effects declined over the five days, but a minority of patients still suffered with headache (14.2%), drowsiness (9.4%), sore throat (7.5%), and nausea (5.3%) on the fifth day following surgery. The percentage of patients who experienced constipation peaked at 19.8% on the second day, most likely reflecting the consumption of codeine-containing analgesics on the first and second postoperative days. While day surgery has an important role in many forms of gynecological surgery, the potential discomfort and recovery time following day surgery should not be underestimated.


Annals of the Rheumatic Diseases | 1986

Functional capacity and treatment data from a community based study of patients with rheumatoid arthritis.

Susan G. Owen; Wt Friesen; Michael S. Roberts; H Francis; William Flux

A community based study of rheumatoid arthritis was undertaken to determine patient characteristics and the patterns of treatment. Three hundred and eighty subjects were visited in their homes throughout Tasmania (pop. 430 000) by a research team. The median age of the sample was 60 years (interquartile range (IR) 49-69), with a female predominance of 2.65 to 1. The average onset age was 41 years (IR 30-53). Prescribing data indicated that polypharmacy was not common in the community, and that the use of slow acting antirheumatic drugs (SAARDs) and oral corticosteroids was not widespread. At the time of the study 26% of subjects were assayed fully functional--class I of the American Rheumatism Associations (ARA) functional classifications. The functional capacity data provided evidence that the spectrum of rheumatoid arthritis found in the community differed from that found in specialist rheumatology clinics.


Journal of Clinical Pharmacy and Therapeutics | 1997

Case-controlled review of Clostridium difficile-associated diarrhoea in southern Tasmania.

H. A. Halim; Gm Peterson; Wt Friesen; A. K. Ott

Aim: While the incidence of Clostridium difficile‐associated diarrhoea (CDAD) has increased sharply over the last 15 years, its risk factors are still not well defined. The aim of this study was to review cases of CDAD at the major teaching hospital in Tasmania, Australia, to identify risk factors for CDAD and their association with prognosis.


Journal of Clinical Pharmacy and Therapeutics | 2000

Changes in the management of acute myocardial infarction in Southern Tasmania

Ks McNamara; Gm Peterson; Wt Friesen

Background: In recent years, the management of acute myocardial infarction (AMI) has been the subject of many clinical trials. These studies have clearly established the value of using pharmacological agents, including aspirin, β‐blockers, thrombolytics and angiotensin converting enzyme (ACE) inhibitors. There have been suggestions, however, that practice has been slow to change in light of the findings of these trials.


Journal of Clinical Pharmacy and Therapeutics | 1981

RECORD‐LINKED AUDIT OF DRUG UTILIZATION DATA IN A HOSPITAL: ANTIMICROBIAL USE ON A UROLOGY WARD

Y. A. Hekster; Wt Friesen; J. B. J. Boerema

Antimicrobial drug utilization patterns were studied on a urology ward with a view to establishing base‐line data and subsequently determining drug usage data during the implementation of antimicrobial prescribing guidelines.


Journal of Clinical Pharmacy and Therapeutics | 1984

AN AUDIT OF THERAPEUTIC DRUG MONITORING PROCEDURES—USE OF THEOPHYLLINE ASSAY SERVICES

C. A. D'Souza; Wt Friesen; R. J. Witt; G. R. Taylor; Michael S. Roberts

Monitoring therapy involving drugs exhibiting high intersubject variation and/or narrow therapeutic index has become more generally accepted in hospitals. This paper describes an audit conducted jointly by clinical pharmacists and clinical biochemists into the use and therapeutic value of a drug monitoring service in a general hospital using theophylline as a model. Assay values were categorized as ‘subtherapeutic’, ‘therapeutic’ or ‘potentially toxic’. The reporting procedures involving the two departments were evaluated along with action taken by the requesting clinicians. The study showed that 60% of the theophylline assay results fell within the therapeutic range at the time of sampling. However only 38% of samples were considered to have been taken under steady state conditions. There was a significant delay in relaying the results to the clinicians. Procedural changes involving sampling times, analytical techniques, recording and conveying results to clinicians and co‐operative policies between the departments of pharmacy and clinical chemistry have been implemented as a result of this study.


Rheumatology | 1985

DETERMINANTS OF COMPLIANCE IN RHEUMATOID ARTHRITIC PATIENTS ASSESSED IN THEIR HOME ENVIRONMENT

Susan G. Owen; Wt Friesen; Michael S. Roberts; William Flux


Journal of Clinical Pharmacy and Therapeutics | 1998

Review of antithrombotic drug usage in atrial fibrillation

Sy Ang; Gm Peterson; Wt Friesen; Jh Vial


British Journal of Clinical Pharmacology | 1989

Salicylate pharmacokinetics in patients with rheumatoid arthritis.

Susan G. Owen; Roberts; Wt Friesen; Hw Francis

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Gm Peterson

University of Tasmania

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Michael S. Roberts

University of South Australia

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Jh Vial

University of Tasmania

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Rh Rumble

University of Tasmania

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Sy Ang

Health Science University

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A. K. Ott

Royal Hobart Hospital

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