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Biomedical subjects

J McElnay

Publications and source records attributed to J McElnay.

10 recordsLinked to original sources
PubMed2007

A cross-sectional study evaluating the relationship between cortisol suppression and asthma control in patients with difficult asthma.

AIM: To examine the relationship between cortisol suppression and asthma symptoms in patients with difficult asthma. METHODS: Patients, referred to a specialist difficult asthma service and who fulfilled the criteria for difficult asthma, were recruited to the study in a sequential, unselected manner. At each clinic visit, all patients completed a validated asthma control questionnaire. For measuring cortisol suppression, early morning urinary cortisol [corrected for creatinine to give urinary cortisol creatinine ratio (UCC ratio)] was used. The urine samples were collected and stored at -70 degrees C until ready for analysis. Urinary cortisol was extracted (solid-phase extraction) and analysed using high-performance liquid chromatography. The Pearson correlation coefficient was used for correlation analysis while t-tests were used for between-group differences for normally distributed data. If the data were not normally distributed, nonparametric statistics were used. A P-value < 0.05 was considered statistically significant. RESULTS: During the study period all the patients who attended the difficult asthma clinic and fulfilled the criteria for difficult asthma (n = 66) agreed to take part in the study. There were moderate to strong and significant associations between several measures of asthma control and UCC ratio. The correlation coefficient with five indicators of asthma control ranged between 0.3 and 0.5 (P < 0.05). CONCLUSIONS: We have demonstrated a relationship between cortisol suppression and asthma control in difficult asthmatics on high-dose steroid therapy. We have proposed a model based on the relationship between symptom control and cortisol suppression, whereby both adherence and therapeutic adjustments could potentially be made. A properly controlled prospective clinical trial should examine the utility of this approach in clinical practice.

Adult↗
PubMed2006

Dried blood spot liquid chromatography assay for therapeutic drug monitoring of metformin.

The use of blood spot collection cards is a simple way to obtain specimens for analysis of drugs for the purpose of therapeutic drug monitoring, assessing adherence to medications and preventing toxicity in routine clinical setting. We describe the development and validation of a microanalytical technique for the determination of metformin from dried blood spots. The method is based on reversed phase high-performance liquid chromatography with ultraviolet detection. Drug recovery in the developed method was found to be more than 84%. The limits of detection and quantification were calculated to be to be 90 and 150 ng/ml, respectively. The intraday and interday precision (measured by CV%) was always less than 9%. The accuracy (measured by relative error, %) was always less than 12%. Stability analysis showed that metformin is stable for at least 2 months when stored at -70 degrees C. The small volume of blood required (10 microL), combined with the simplicity of the analytical technique makes this a useful procedure for monitoring metformin concentrations in routine clinical settings. The method is currently being applied to the analysis of blood spots taken from diabetic patients to assess adherence to medications and relationship between metformin level and metabolic control of diabetes.

Drug Monitoring↗
PubMed2005

The development and validation of liquid chromatography method for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma.

This article describes the development of SPE and HPLC methods for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma. Several extraction and HPLC methods have been described previously for the determination of each of these analytes in plasma separately. The simultaneous determination of these analytes is important for the routine monitoring of diabetic patients who take combination medications and for studying the pharmacokinetics of the combined dosage forms. In addition this developed method can serve as a standard method for the plasma determination of these analytes therefore saving time, effort and money. The recoveries of the developed methods were found to be between 76.3% and 101.9%. The limits of quantification were between 5 and 22.5 ng/ml. The intraday and interday precision (measured by coefficient of variation, CV%) was always less than 9%. The accuracy (measured by relative error %) was always less than 12%. Stability analysis showed that all analytes are stable for at least 3 months when stored at -70 degrees C.

Chromatography, High Pressure Liquid↗
PubMed2005

Relationship between lung function and asthma symptoms in patients with difficult to control asthma.

Several studies have demonstrated a poor relationship between measures of asthma control and lung function in patients with asthma. We sought to examine this relationship in a cohort of difficult to control asthmatics attending a hospital outpatient clinic. FEV1 % and asthma control scores (ACSs) were measured at the first clinic visit and at a follow-up visit. A total of 59 patients took part in the study. At the initial visit, FEV1 % correlated with limitation of activity (p = 0.002), shortness of breath (p = 0.02), wheezing (p = 0.029), and ACS (p = 0.014). However, at follow-up, there was no correlation between FEV1 % and any measured index of asthma control. When patients with severe fixed airflow obstruction were excluded from the analysis (n = 16), FEV1 % at follow-up became significantly correlated with night waking (p = 0.02), wheezing (p = 0.05), and ACS (p = 0.036). The improvement in asthma control score at follow-up was significantly and strongly associated (r = 0.51 for total asthma control, p < 0.001) with the improvement in lung function in patients without severe fixed airflow obstruction. Lung function was not associated with any measure of asthma control in patients with severe fixed airflow obstruction. FEV1 % correlates well with asthma symptoms in difficult asthma patients with poor control but not when control improves. This loss of relationship is due to subjects with severe fixed airflow obstruction where good subjective control does not exclude the presence of significant obstruction. How severe fixed airflow obstruction should be prevented, delayed, or managed in asthma requires further research.

Adult↗
PubMed2003

Determination of metformin in plasma using a new ion pair solid phase extraction technique and ion pair liquid chromatography.

This article describes the development of the first ion pair solid phase extraction technique (IPSPE), which has been applied to the extraction of metformin from plasma samples. In addition an ion pair chromatographic method was developed for the specific HPLC determination of metformin. Several extraction and HPLC methods have been described previously for metformin, however, most of them did not solve the problems associated with the high polarity of this drug. Drug recovery in the developed method was found to be more than 98%. The limit of detection and limit of quantification was 3 and 5 ng/ml, respectively. The intraday and interday precision (measured by coefficient of variation, CV%) was always less than 9%. The accuracy (measured by relative error, R.E.%) was always less than 6.9%. Stability analysis showed that metformin is stable for at least 3 months when stored at -70 degrees C. The method has been applied to 150 patient samples as part of a medication adherence study.

Chromatography, High Pressure Liquid↗
PubMed2003

Simple liquid chromatography method for the rapid simultaneous determination of prednisolone and cortisol in plasma and urine using hydrophilic lipophilic balanced solid phase extraction cartridges.

This article describes the development and validation of a simple solid phase extraction (SPE) and HPLC method for the extraction and the specific determination of prednisolone and hydrocortisone (cortisol) in both plasma and urine using one washing step with Oasis hydrophilic lipophilic balanced (HLB) cartridges (1 ml/30 mg, 30 microm). Recoveries of prednisolone and cortisol from plasma and urine exceeded 82%. The limit of quantification (LOQ) in plasma and urine was 9.9 and 6.7 ng/ml for cortisol, respectively, and 11.6 and 8.0 ng/ml for prednisolone, respectively. The intraday and interday precision (measured by CV%) for both prednisolone and cortisol in both plasma and urine was always less than 7%. The accuracy (measured by relative error %) for both prednisolone and cortisol in both plasma and urine was always less than 8%. The advantages of the developed method are the use of a one step washing SPE utilising HLB cartridges which do not suffer the drying out problems of conventional SPE cartridges and the time saving when compared with solvent extraction (SE), in addition to the simultaneous determination of prednisolone and cortisol in both plasma and urine.

Chromatography, High Pressure Liquid↗
PubMed2001

Improving the well-being of elderly patients via community pharmacy-based provision of pharmaceutical care: a multicentre study in seven European countries.

OBJECTIVE: This study aimed to measure the outcomes of a harmonised, structured pharmaceutical care programme provided to elderly patients (> or =65 years of age) by community pharmacists in a multicentre international study performed in 7 European countries. DESIGN AND SETTING: The study was a randomised, controlled, longitudinal, clinical trial with repeated measures performed over an 18-month period. A total of 104 intervention and 86 control pharmacy sites participated in the research and 1290 intervention patients and 1164 control patients were recruited into the study. MAIN OUTCOME MEASURES AND RESULTS: A general decline in health-related quality of life over time was observed in the pooled data; however, significant improvements were achieved in patients involved in the pharmaceutical care programme in some countries. Intervention patients reported better control of their medical conditions as a result of the study and cost savings associated with pharmaceutical care provision were observed in most countries. The new structured service was well accepted by intervention patients and patient satisfaction with the services improved during the study. The pharmacists involved in providing pharmaceutical care had a positive opinion on the new approach, as did the majority of general practitioners surveyed. The positive effects appear to have been achieved via social and psychosocial aspects of the intervention, such as the increased support provided by community pharmacists, rather than via biomedical mechanisms. CONCLUSIONS: This study is the first large-scale, multicentre study to investigate the effects of pharmaceutical care provision by community pharmacists to elderly patients. Future research methodology and implementation will be informed by the experience gained from this challenging trial.

Aged↗
PubMed1994

Effect of exercise on the nasal transmucosal potential difference in patients with cystic fibrosis and normal subjects.

BACKGROUND: Normal subjects have a negative nasal transmucosal potential difference (TPD) at rest which becomes more negative with exercise. Patients with cystic fibrosis have a more negative resting nasal TPD than controls. The present study was designed to determine the effects of exercise on the TPD of patients with cystic fibrosis. METHODS: Seven subjects with cystic fibrosis and seven control subjects had their usual TPD measured at rest, and during and after a 12 minute period on an exercise bicycle designed to produce a pulse rate of 80% of their maximum predicted value. RESULTS: The normal subjects developed a more negative nasal TPD during exercise which returned towards normal at the completion of the rest period. The patients with cystic fibrosis had higher resting values which became less negative during exercise. At the end of the exercise period there was no difference between the two groups. At the end of the recovery period the results for the patients with cystic fibrosis had returned to their resting values. CONCLUSIONS: Exercise reduces the abnormally high resting values for nasal TPD in patients with cystic fibrosis. Elucidation of the mechanism for this change may help to produce functional improvement for patients with this disease.

Adolescent↗