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Biomedical subjects

R O Day

Publications and source records attributed to R O Day.

At least 19 recordsLinked to original sources
PubMed2003

Pharmacokinetics of estradiol, progesterone, testosterone and dehydroepiandrosterone after transbuccal administration to postmenopausal women.

OBJECTIVE: To evaluate the pharmacokinetic profiles of estradiol, progesterone, testosterone and dehydroepiandrosterone in postmenopausal women following single and multiple dosing using a troche and the transbuccal route of administration. METHODS: Each troche contained estradiol (0.5 mg), progesterone (200 mg), testosterone (2.0 mg) and dehydroepiandrosterone (10 mg). A half troche was administered to each of six women and the plasma concentration-time profiles determined over 24 h. Thereafter, a one-half troche was taken twice daily for 2 weeks and concentrations determined over a dosage interval (12 h). Blood and saliva samples were collected at specified time intervals on the first day and again after 2 weeks. RESULTS: Each of the hormones was readily absorbed via the buccal mucous membrane. Peak plasma concentrations of estradiol and progesterone were comparable to those found normally in young menstruating women. CONCLUSION: The transbuccal route is a novel approach to provide therapy for the management of menopause-related symptoms of postmenopausal women without the need to resort to conjugated or synthesized hormones, and may overcome the poor or erratic systemic availability associated with other routes of administration.

Administration, Buccal↗
PubMed2001

Coordination of carbonyl and carboxyl oxygen atoms with phosphorus in the presence of hydrogen bonding. P-O donor action.

A series of phosphorus compounds 1-5 containing carbonyl or carboxyl groups was obtained and subjected to X-ray analysis. Syntheses of the phosphoranes 1 and 5 were effected by oxidation reactions using potassium permaganate, while the phosphine oxide 2 was obtained by oxidation with hydrogen peroxide. The readily available phosphines 3 and 4 were included in the study. The structures revealed that P-O coordination occurred for 1-3 in the presence of extensive hydrogen bonding and led to trigonal bipyramidal geometries. A similar structure was observed for 4 in the absence of hydrogen bonding. (31)P chemical shifts indicate retention of the basic coordination geometries in solution. Consideration of the chirality of the phosphoranes 1 and 5 leads to a pair of mirror images that are possible in solution but exist in preferred isomeric forms in the crystalline state. Evaluation of the energies of two competing bonding types indicated a range for P-O coordination above and below the hydrogen bond energy. The results suggest that phosphoryl transfer enzyme mechanisms should benefit by taking into account donor interactions to phosphorus by residues at active sites in addition to the inclusion of hydrogen bonding interactions.

Journal Article↗
PubMed2001

Pharmacotherapeutics: what a difference five decades makes!

Our ability to prevent, cure or modify disease, as compared with relieving symptoms, has changed beyond recognition in the past half century. With the completion of the Human Genome Project and rapid advances in understanding of molecular biology and in technologies, our ability to target disease mechanisms and optimise an individual's responses will improve exponentially.

Drug Therapy↗
PubMed2001

Patient based method of assessing adverse events in clinical trials in rheumatology: the revised Stanford Toxicity Index.

We describe the progress towards developing a patient rated toxicity index that meets all of the patient-important attributes defined by the OMERACT Drug Safety Working Party. These attributes are frequency, severity, importance to patient, importance to the clinician, impact on economics, impact on activities, and integration of adverse effects with benefits. The Stanford Toxicity Index (STI) has been revised to collect all attributes with the exception of impact on activities. However, since the STI is a part of the Health Assessment Questionnaire (HAQ), impact on activities is collected by the HAQ. In particular, a new question asks patients to rate overall satisfaction, taking into consideration both benefits and adverse effects. The next step in the development of this tool is to ensure that the STI meets the OMERACT filter of truth, discrimination, and feasibility. Although truth and feasibility have been confirmed by comparisons within the ARAMIS database, discrimination needs to be assessed in clinical trials.

Adverse Drug Reaction Reporting Systems↗
PubMed2000

Synthesis and structure of cyclic phosphate, phosphoramidate, phosphonates, and phosphonium salts. Phosphatrane formation.

Reaction of tris(2-hydroxy-3,5-dimethylbenzyl)amine (6) with phosphorus reagents led to the formation of the phosphoramidate, N[CH2(Me2C6H2)O]2PO (1), the phosphate N[CH2(Me2C6H2)O]2[CH2(Me2C6H2)OH]P(O)(OPh) (2), the phosphonium salts N[CH2(Me2C6H2)O]3PMe+I- (3A) and N[CH2(Me2C6H2)O]3PMe+I3- (3B), and the phosphonates N[CH2(Me2C6H2)O]2[CH2(Me2C6H2)OH]P(O)Me (4) and N[CH2(Me2C6H2)O]2[CH2(Me2C6H2)OSiMe3]P(O)Me (5). X-ray analysis provided molecular structures for all of the compounds. The solid-state structural representations were supported in solution by an analysis of the NCH2 proton NMR patterns. The structures of 3A and 3B show the presence of phosphatranes with weak P-N donor interactions. These represent the first phosphatranes containing all six-membered rings. Variable temperature analysis of the 1H NMR spectra of 3A indicates fluxional behavior whereby a racemic mixture of the chiral phosphonium salt rapidly intraconverts at room temperature. The activation energy for the enantiomeric conversion of the clockwise and anticlockwise orientations of the propeller-like phosphatrane is 11.2 kcal/mol, which is compared to that of the isoelectronic silatrane N[CH2(Me2C6H2)O]3SiMe (E), 10.3 kcal/mol.

Journal Article↗
PubMed2000

COX-2 inhibitors.

Cyclooxygenase-2 (COX-2) inhibitors constitute a new group of non-steroidal anti-inflammatory drugs (NSAIDs) which, at recommended doses, block prostaglandin production by cyclooxygenase-2, but not by cyclooxygenase-1. Two COX-2 inhibitors are currently available in Australia--celecoxib, which is taken twice daily, and rofecoxib, which is taken once daily. Both drugs act rapidly in providing pain relief and their anti-inflammatory analgesic effect in osteoarthritis and rheumatoid arthritis is equivalent to standard doses of non-selective NSAIDs. Celecoxib and rofecoxib show significantly lower incidences of gastrotoxicity (as measured by endoscopic studies and gastrointestinal ulcers and bleeds) than non-selective NSAIDs. There is Level 2 evidence that COX-2 inhibitors: reduce pain in classic pain models--third-molar extraction, dysmenorrhoea and after orthopaedic surgery; reduce pain and disability in osteoarthritis of the hip and knee; and reduce pain and disability in rheumatoid arthritis. Other adverse effects, such as interference with antihypertensive agents and the potential to produce renal dysfunction in patients with compromised renal function by COX-2 inhibitors, seem similar to those of non-selective NSAIDs.

Algorithms↗
PubMed2000

Anabolic-androgenic steroids: medical assessment of present, past and potential users.

OBJECTIVE: To document adverse effects of anabolic-androgenic steroid (AAS) use in community-based users attending a medical clinic. DESIGN AND SETTING: Prospective recruitment, questionnaire-based interview, physical examination and investigations, with follow-up, of people who attended, anonymously, an inner-city hospital clinic established specifically to examine AAS use. PARTICIPANTS: 58 men, comprising 27 past AAS users, 14 present users and 17 potential users (who formed the control group). MAIN OUTCOME MEASURE: Clinical adverse effects and abnormal laboratory findings. RESULTS: Cyclical use of oral and intramuscular, human and veterinary AASs were reported. The most commonly reported source of AASs was friends (59%), gymnasiums (25%) and doctors (14%). The most common reported adverse effects were alterations in libido (61%), changes in mood (48%), reduced testis volume (46%) and acne (43%). Although mean systolic and diastolic blood pressure was not significantly different between groups, five present (29%), 10 past (37%) and one potential user (8%) were hypertensive. Gynaecomastia was found in 10 past users (37%; P<0.01 v. potential users), two present users (12%) and no potential users. Mean testis volume was significantly smaller in present users (18 mL; P<0.02) than in the other groups. Twenty past users (83%), eight present users (62%) and five potential users (71%) had abnormal liver function test results (P=0.5). After discussion of test results, only 11 participants (19%) reported they would not use AASs in the future. CONCLUSIONS: Adverse effects were reported by or detected in most of the AAS users who attended the clinic. Despite awareness of adverse consequences, most participants planned future use of AASs.

Administration, Oral↗
PubMed2000

Clinical pharmacokinetics and pharmacodynamics of celecoxib: a selective cyclo-oxygenase-2 inhibitor.

Celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), is the first specific inhibitor of cyclo-oxygenase-2 (COX-2) approved to treat patients with rheumatism and osteoarthritis. Preliminary data suggest that celecoxib also has analgesic and anticancer properties. The selective inhibition of COX-2 is thought to lead to a reduction in the unwanted effects of NSAIDs. Upper gastrointestinal complication rates in clinical trials are significantly lower for celecoxib than for traditional nonselective NSAIDs (e.g. naproxen, ibuprofen and diclofenac). The rate of absorption of celexocib is moderate when given orally (peak plasma drug concentration occurs after 2 to 4 hours), although the extent of absorption is not known. Celexocib is extensively protein bound, primarily to plasma albumin, and has an apparent volume of distribution of 455+/-166L in humans. The area under the plasma concentration-time curve (AUC) of celecoxib increases in proportion to increasing oral doses between 100 and 800mg. Celecoxib is eliminated following biotransformation to carboxylic acid and glucuronide metabolites that are excreted in urine and faeces, with little drug (2%) being eliminated unchanged in the urine. Celecoxib is metabolised primarily by the cytochrome P450 (CYP) 2C9 isoenzyme and has an elimination half-life of about 11 hours in healthy individuals. Racial differences in drug disposition and pharmacokinetic changes in the elderly have been reported for celecoxib. Plasma concentrations (AUC) of celecoxib appear to be 43% lower in patients with chronic renal insufficiency [glomerular filtration rate 2.1 to 3.6 L/h (35 to 60 ml/min)] compared with individuals with healthy renal function, with a 47% increase in apparent clearance. Compared with healthy controls, it has been reported that the steady-state AUC is increased by approximately 40% and 180% in patients with mild and moderate hepatic impairment, respectively. Celecoxib does not appear to interact with warfarin, ketoconazole or methotrexate; however, clinically significant drug interactions with fluconazole and lithium have been documented. As celecoxib is metabolised by CYP2C9, increased clinical vigilance is required during the coadministration of other substrates or inhibitors of this enzyme.

Administration, Oral↗
PubMed2000

Concentration-effect relationship of hydroxychloroquine in patients with rheumatoid arthritis--a prospective, dose ranging study.

OBJECTIVE: A 6 month prospective randomized double blind study was conducted to investigate hydroxychloroquine dose concentration-effect relationships in people with rheumatoid arthritis. METHODS: Patients were randomized in 2 groups: one group received 200 mg hydroxychloroquine sulfate daily (A) and one group received 400 mg daily (B). Each month, 8 disease variables were assessed, adverse events recorded, and hydroxychloroquine blood concentrations determined. RESULTS: Twenty-three patients were included: 10 in group A and 13 in group B. After 6 months of therapy, a significant improvement in disease activity was noted for 6 criteria with no statistical differences between groups: pain (assessed by a visual analog scale), joint scores (swelling and tenderness), impairment in daily living activity (18 activities graded 0 to 8), patient assessment of disease state, and erythrocyte sedimentation rate. Hydroxychloroquine steady-state blood concentrations (Month 6) were significantly different between groups (mean +/- SD): 450.6 +/- 285.3 ng/ml (A) vs 870.3 +/- 329.3 ng/ml (B) (p = 0.0001). Steady-state concentrations were correlated with the daily dose (r = 0.63, p = 0.005), the improvement in activity of daily living (r = 0.49, p = 0.03), and the improvement in joint tenderness score (r = 0.47, p = 0.038). CONCLUSION: The data indicate that hydroxychloroquine is an effective therapy, but there were no further improvements observed in the group receiving 400 mg daily compared to those receiving 200 mg. There were some correlations between hydroxychloroquine steady-state blood concentrations and effects.

Adult↗
PubMed1999

Stereoselective and substrate-dependent inhibition of hepatic mitochondria beta-oxidation and oxidative phosphorylation by the non-steroidal anti-inflammatory drugs ibuprofen, flurbiprofen, and ketorolac.

Non-steroidal anti-inflammatory drugs (NSAIDs) cause a range of adverse effects, some of which have been associated with perturbances of lipid metabolic pathways. Previous data demonstrating stereoselective formation of the CoA thioester of R-ibuprofen in particular were suggestive of possible stereoselective effects on lipid metabolism. Our aim was to characterise the relative stereoselectivity of the effects of ibuprofen, flurbiprofen, and ketorolac (0.01-1.0 mM) on both the beta-oxidation of palmitate and oxidative phosphorylation in rat hepatic mitochondria as a means of dissecting prostaglandin related from non-prostaglandin-related events. Beta-oxidation was inhibited stereoselectively by R-ibuprofen (P = 0.015), non-stereoselectively by R- and S-flurbiprofen (P = 0.002 and P = 0.004, respectively), and was essentially unaffected by either enantiomer of ketorolac. At 0.25 mM, inhibition by R-ibuprofen and both flurbiprofen enantiomers was partially reversed by increasing CoA concentrations (0-200 microM). Mitochondrial respiration was moderately inhibited by both enantiomers of ibuprofen and flurbiprofen (P < 0.01), but only by high concentrations (> or = 1 mM) of the enantiomers of ketorolac (P < 0.01). Uncoupling of oxidative phosphorylation measured as stimulation of State 4 respiration contributed to these effects. The data support interactions involving both stereoselective CoA-dependent and non-CoA-dependent mechanisms. The plasma drug concentrations required to achieve these effects are not likely to be attained in the majority of patients, although these concentrations are achievable in the gastrointestinal tract and may contribute to the well-known spectrum of adverse effects in this organ. Some patients do experience systemic adverse events which may be mediated by these mechanisms.

Animals↗
PubMed1999

Towards the safer use of non-steroidal anti-inflammatory drugs.

Musculoskeletal conditions afflict most of us at some time in our lives, and we all have relatives and friends who suffer the pain and disability sometimes associated with conditions such as back or neck pain, fibrositis and osteoarthritis. The goal of those of us who try to help individuals with these conditions is to achieve effective, but also safe, management of their musculoskeletal disorders, the commonest symptom of which is pain. This goal can be achieved by better diagnosis and problem formulation (allowing better selection of treatment options); informed selection of non-drug and drug therapeutic options, based on relative cost-benefit considerations; and the judicious, appropriate and safe use of drugs, particularly non-steroidal anti-inflammatory drugs (NSAID). Setting realistic goals and maintaining regular surveillance of patients are also important considerations. Finally, the active involvement of the patient in their own management is associated with better and safer outcomes.

Aged↗
PubMed1999

Pharmacokinetics of nonsteroidal anti-inflammatory drugs in synovial fluid.

The major site of action for nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of rheumatic diseases is probably within the synovial compartment. There has been little work on the disposition of NSAIDs in the synovium and most studies have involved the measurement of their concentrations in synovial fluid. The concentrations of NSAIDs are more sustained in synovial fluid than in plasma, the difference being particularly noted with NSAIDs with short elimination half-lives. The more sustained concentrations may contribute to the prolonged effect of the short half-life NSAIDs, which are usually administered at intervals longer than their half-lives in plasma. The most widely used method of kinetic analysis of NSAIDs in synovial fluid is a compartmental model in which synovial fluid is a peripheral compartment of distribution of the drug. Repeated samples of synovial fluid from individual patients are difficult to collect, but even 1 sample of synovial fluid and plasma from each patient can provide useful data when analysed using the population approach to pharmacokinetic analysis. According to the compartmental model, the mean half-lives of efflux of the NSAIDs from synovial fluid range from 1.5 to 7 hours. The mean partition coefficient of most NSAIDs between synovial fluid and plasma is approximately 0.6. The NSAIDs are highly protein-bound, and the lower mean concentrations in synovial fluid are largely because of the lower concentrations of the binding protein, albumin. The NSAIDs diffuse into and out of synovial fluid in their unbound forms, but there is some diffusion in the protein-bound forms, particularly out of synovial fluid. The mean rates of diffusion of NSAIDs into and out of skin blisters in humans are similar to the rates of influx and efflux in the synovial fluid of the knee, but there is considerable variation between the pharmacokinetics of transfer at the 2 sites in individual patients. NSAIDs decrease the synthesis of prostaglandins in synovial fluid, but there are few data on the relationship between the kinetics of NSAIDs in synovial fluid and the effects on prostaglandin synthesis.

Animals↗
PubMed1998

The death of a healthy volunteer in a human research project: implications for Australian clinical research.

A healthy 19-year-old United States college student volunteer in a clinical research program underwent a bronchoscopy and died as a result of acute lignocaine toxicity. The major contributing factor in the tragedy was that the research protocol failed to specify an upper dose limit for lignocaine spray, although previous versions of the protocol had done so. We look at the implications of this case for Australian institutional ethics committees.

Adult↗
PubMed1998

Indicators for drug and therapeutics committees.

AIMS: This study describes development and field testing of a set of indicators for drug and therapeutics committees (DTCs) in hospitals. It was intended that these indicators should be accessible, useful and relevant in the Australian setting. METHODS: Candidate indicators were written following consultation and data collection. A framework of outcome, impact and process indicators was based on DTC goals, objectives and strategies. The candidate indicators were field tested over a 2 month period in teaching, city non-teaching, rural and private hospitals. The field tests provided response data for each indicator and evaluation of the indicators against criteria for accessibility, relevance, usefulness, clarity and resource utilisation. Consensus on which indicators to accept, modify or reject was reached at a workshop of stakeholders and experts, taking account of the field test results. RESULTS: Thirty-five candidate indicators were tested in 16 hospitals. Twenty-two had a response from >80% of sites, 23 had a mean relevance rating >3.5, 19 had a mean usefulness rating >3.5, 27 were correctly interpreted by > 90% of sites and 25 could be collected in an acceptable time. The most acceptable indicators required least data collection or provided data deemed useful for purposes other than the field test. At the consensus workshop 13 indicators were accepted with no or minor change, nine were accepted after major modification and eight were discarded. It was recommended that a further five indicators should be merged or subsumed into one indicator. CONCLUSIONS: This study has developed and field tested a set of indicators for DTCs in Australia. The indicators have been taken up enthusiastically as a first attempt to monitor DTC performance but require ongoing validation and development to ensure continuing relevance and usefulness.

Australia↗
PubMed1998

The application of adverse drug reaction data to drug choice decisions made by pharmacy and therapeutics committees. An Australian perspective.

Pharmacy and Therapeutics (P&T) committees undertake policy, regulatory and educational activities to promote rational use of medicines in their institutions with the aim of improving the quality of health and economic outcomes at these institutions. Formulary management is an important part of the P&T committees' activities and making drug choices is one of the committees' most difficult tasks. The 3 types of information most commonly identified by P&T committees as necessary for making drug choices are effectiveness, safety and cost data; usually in this order of importance. There is some evidence, however, that safety data are not considered by all committees when they make decisions about adding a new drug to a formulary. The role of adverse drug reaction (ADR) data in formulary decision-making (for registered drugs) occurs at several levels. First, ADR data obtained from pre-marketing studies of the drug are important and enable the committee to make an assessment of the risk of toxicity that should be anticipated for the drug. However, the limited nature of this information makes an absolute assessment impossible. Secondly, comparative safety information is necessary when deciding the place in therapy of a particular drug. Weighing up the comparative risks and benefits is a complex task which is a routine activity for most P&T committees whatever level of sophistication is applied. Thirdly, ADR data are an important ingredient of any economic assessment considered by a P&T committee. Calculation of the costs and consequences associated with the adverse effects of treatment demand careful assessment. Finally, aggregated adverse drug event reports which collate not only the consequences of adverse drug reactions but also medication incidents (medication errors) and which have been reported locally can be a useful quality assurance process for a P&T committee. This information will contribute to the identification of drugs for deletion from the formulary and less commonly in making decisions about additions to the formulary. As formulary management forms only part of a P&T committee's work, so the committee's interest in ADR is broader than the use of these data in making drug choices. The P&T committee may also be involved in promoting ADR reporting to either a central database or primary carers. Although often of limited availability, ADR information has an important role in the formulary management process of P&T committees.

Adverse Drug Reaction Reporting Systems↗
PubMed1998

Effect of clofibrate on the chiral disposition of ibuprofen in rats.

A potentially clinically important interaction has been described between clofibrate and ibuprofen in vitro. To determine whether this in vitro interaction is paralleled by a change in pharmacokinetics of ibuprofen in vivo two groups of rats were treated orally with clofibrate (n = 8, 280 mg/kg/day) or vehicle (n = 7) for 3 days. On day 3, 2 hr after the last dose of clofibrate, the rats were given an i.v. dose of pseudoracemic ibuprofen (20 mg/kg, 10 mg R-ibuprofen, 10 mg 13C-S-ibuprofen). Plasma concentrations of the enantiomers were monitored by a stereospecific gas chromatography mass spectrometry assay. The clearance of R-ibuprofen more than doubled in the clofibrate-treated group (mean +/- S.E.M.; 29.4 +/- 4.0 ml/min) as compared to control rats (13.0 +/- 1.4 ml/min; P = .003). This increase was similarly reflected in the clearance by inversion (treated, 23.2 +/- 3.2 ml/min, untreated, 10.0 +/- 1.2 ml/min; P = .003) and there was also an increase in the rate of inversion (treated, t1/2 inversion, 8.3 +/- 1.6 min; untreated, 13.9 +/- 1.4 min; P = .029). By contrast, the estimates of fractional chiral inversion were not affected by clofibrate and were in close agreement whether estimated by the area under the plasma concentration-time curve approach (treated, 0.79 +/- 0.02; untreated, 0.72 +/- 0.02) or by deconvolution (treated, 0.78 +/- 0.02; untreated, 0.73 +/- 0.02). There was a significant increase in volume of distribution at steady-state (treated, 4.42 +/- 1.12 liter/kg; untreated, 1.03 +/- 0.30 liter/kg; P = .017) observed for the R-enantiomer but not the S-enantiomer (treated, 1.04 +/- 0.13 liter/kg; untreated, 1.10 +/- 0.21 liter/kg). Pretreatment of rats with clofibrate significantly increased the concentrations of ibuprofen in fat, lung, brain and liver tissue. With respect to the protein levels of two key enzymes involved in chiral inversion, clofibrate pretreatment significantly induced expression of long chain acyl-coenzyme A synthetase, although the expression of the epimerase was unaltered. It is concluded, that clofibrate may increase the proportion of R-ibuprofen incorporated into long-lived lipid ("hybrid" lipid) stores.

Animals↗