Drug-herb interaction: database of medicinal plants of the Caribbean, their indications, toxicities and possible interactions with conventional medication

OBJECTIVE

Healthcare professionals in the Caribbean today know very little about these drug-herb interactions of the popular West Indian medicinal herb practices linked to the immigrants from West Africa and India, and to the indigenous Amerindians. It is the intent of this project to produce a database which comprehensively summarizes indications and possible drug-herb interactions of these plants.

METHOD

Using the database programme Epi Info 3.5.1, one hundred and eighty-three herbs used in the Caribbean as medicine by locals have been entered into the West Indian Drug Herb Interaction Database version 0.06 (WIDHID 0.06).

RESULTS

A range of one to three common names have been entered with the family and scientific name of each herb, in addition to a range of one to six conditions/illnesses for which a particular plant was to be used as a medicinal herb. One to four bioactive compounds have been made to correlate with the typical herbal preparation methods and toxicity. Thirty of the most common and popular herbs have been researched for their drug herb interactions.

CONCLUSION

West Indian Drug Herb Interaction Database version 0.06 for the first time allows easy access to Caribbean ethno-medicinal plant cures with their possible drug-herb interactions reference sources, a feature often absent although so important. In addition, WIDHID 0.06 will support pharmaco-epidemiological studies in the field. It will also ensure future public access to ethno-medicinal information through developed web pages or programmes.

Health human resource planning in Barbados and the eastern Caribbean states: a matter of sustainability

Health and Human Resources (HHR) are very important issues to be considered in healthcare services. While various factors may be of greater significance in one area depending on resources, priorities and stage of economic development, a robust HHR plan is important in all cases. There are many factors such as demographic shifts, changing delivery models, consumer expectations, global shortages and financial restraints that must be considered in proper HHR planning. This manuscript summarizes some of the factors that should be considered and some of the short comings of current HHR planning approaches. Based on our review and experience, we developed a framework for HHR planning and apply the framework to Barbados to try to identify the existing challenges and issues and potential areas for staff and training investments.

TeleMedMail: free software to facilitate telemedicine in developing countries

Telemedicine offers the potential to alleviate the severe shortage of medical specialists in developing countries. However lack of equipment and poor network connections usually rule out video-conferencing systems. This paper describes a software application to facilitate store-and-forward telemedicine by email of images from digital cameras. TeleMedMail is written in Java and allows structured text entry, image processing, image and data compression, and data encryption. The design, implementation, and initial evaluation are described.

Research, health policies and health care in the Caribbean. The role of the University of the West Indies

The University of the West Indies has had a major impact on the provision of health care and the health of Caribbean nations over the last 50 years, through undergraduate, postgraduate and continuing medical education, research, outreach and public service. These roles are fully accepted, and the Faculties of Medical Sciences and School of Clinical Medicine and Research have provided most of the doctors now serving the English-speaking Caribbean, including academic leaders and chief medical officers. The design of a curriculum to produce doctors "designed" for the region has been a well-articulated goal, and the need to carry out relevant and essential national health research is now accepted. But the broader roles of ensuring translation of research into policy and practice, and developing effective ways of promoting on-going continuing training and behaviour change are far from understood or seriously attempted. Communication of research findings and evidence-based practice is crucial. The West Indian Medical Journal clearly has a valuable role to play here and this requires expansion and support. But a multi-faceted approach to communicating research findings and translating evidence into policy, planning and care is necessary. One possible approach would be a University Unit of Health Policy Research and Development.

Fifty years of clinical examinations at the University of the West Indies

The University of the West Indies was founded at Mona, Jamaica, in 1948. After fifty-two years, the format of the final Bachelor of Medicine clinical examination in Medicine and Therapeutics has been radically revised. The change from the traditional to an evidence-based, objective structured clinical examination (OSCE) was undertaken in November/December 2000. Assessment drives learning and both the methods chosen for assessment and the manner in which they are applied determine how students learn. The philosophical underpinnings of the change in format are discussed in this paper.

Elevated systemic concentrations of soluble ICAM-1 (sICAM) are not reflected in the gingival crevicular fluid of smokers with periodontitis

Raised serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) in smokers could have immunomodulatory effects in periodontitis. The aim of this study was to compare serum and gingival crevicular fluid (GCF) concentrations of sICAM-1 in smokers and non-smokers with periodontal disease. sICAM-1 in serum and GCF collected from age- and gender-matched smokers (n = 14) and non-smokers (n = 14) with periodontitis were measured by ELISA. Mean serum sICAM-1 concentrations were significantly elevated in smokers (331 ng mL(-1)), compared with non-smokers (238 ng mL(-1), p = 0.008). However, the concentration of sICAM-1 in the GCF was significantly lower in the smokers (83 ng mL(-1)), compared with non-smokers (212 ng mL(-1), p = 0.013). The difference between concentrations of sICAM-1 in GCF and serum was significant only in smokers (p < 0.001). Since GCF is a serum-derived tissue exudate, these results suggest that, in smokers, circulating sICAM-1 molecules are affected either in their passage from the periodontal microvasculature or within the periodontal tissues.

Using patient-reportable clinical history factors to predict myocardial infarction

Using a derivation data set of 1253 patients, we built several logistic regression and neural network models to estimate the likelihood of myocardial infarction based upon patient-reportable clinical history factors only. The best performing logistic regression model and neural network model had C-indices of 0.8444 and 0.8503, respectively, when validated on an independent data set of 500 patients. We conclude that both logistic regression and neural network models can be built that successfully predict the probability of myocardial infarction based on patient-reportable history factors alone. These models could have important utility in applications outside of a hospital setting when objective diagnostic test information is not yet be available.

New approaches to measuring the performance of programs that generate differential diagnoses using ROC curves and other metrics

INTRODUCTION

Evaluation of computer programs which generate multiple diagnoses can be hampered by a lack of effective, well recognized performance metrics. We have developed a method to calculate mean sensitivity and specificity for multiple diagnoses and generate ROC curves.

METHODS

Data came from a clinical evaluation of the Heart Disease Program (HDP). Sensitivity, specificity, positive and negative predictive value (PPV, NPV) were calculated for each diagnosis type in the study. A weighted mean of overall sensitivity and specificity was derived and used to create an ROC curve. Alternative metrics Comprehensiveness and Relevance were calculated for each case and compared to the other measures.

RESULTS

Weighted mean sensitivity closely matched Comprehensiveness and mean PPV matched Relevance. Plotting the Physician's sensitivity and specificity on the ROC curve showed that their discrimination was similar to the HDP but sensitivity was significantly lower.

CONCLUSIONS

These metrics give a clear picture of a program's diagnostic performance and allow straightforward comparison between different programs and different studies.

Neurological and neurosurgical referrals overseas from the Queen Elizabeth Hospital, Barbados, 1987-1996

This paper reports on neurological and neurosurgical referrals overseas from the Queen Elizabeth Hospital (QEH) for the period November 1987 to November 1996, and is a follow up to an earlier report for the period January 1984 to November 1987. It outlines the pattern of referral, diagnoses, referral centres and costs based on examination of the files of all QEH patients transferred overseas under a government aided scheme. There were 203 transfers of 191 patients (69 males, 122 females) including 10 patients who were transferred twice and one patient who was transferred three times. Patients' ages ranged from 1 to 80 years (mean 37 years). Twenty overseas centres were used during the period but most patients were transferred to Brooklyn Hospital, New York in 1988, Mount Sinai Medical Center, New York, between 1989 and 1994, and Hospital de Clinicas Caracas, Venezuela (1992 to 1996). 65% of the referrals were for neurosurgery and 25% were for magnetic resonance imaging scans for diagnosis. The largest diagnostic categories were central nervous system tumors (40%) and subarachnoid haemorrhage (25%). Estimated costs reached almost BDS$11 million, but the mean actual cost was BDS$63,916 based on information from 123 patient transfers. Thus, the actual total government expenditure was probably closer to BDS$13 million. This study demonstrates the urgent need to establish a neurosurgical service at the QEH and the cost effectiveness of doing so.

Improving machine learning performance by removing redundant cases in medical data sets

Neural network models and other machine learning methods have successfully been applied to several medical classification problems. These models can be periodically refined and retrained as new cases become available. Since training neural networks by backpropagation is time consuming, it is desirable that a minimum number of representative cases be kept in the training set (i.e., redundant cases should be removed). The removal of redundant cases should be carefully monitored so that classification performance is not significantly affected. We made experiments on data removal on a data set of 700 patients suspected of having myocardial infarction and show that there is no statistical difference in classification performance (measured by the differences in areas under the ROC curve on two previously unknown sets of 553 and 500 cases) when as many as 86% of the cases are randomly removed. A proportional reduction in the amount of time required to train the neural network model is achieved.

Using classification tree and logistic regression methods to diagnose myocardial infarction

Early and accurate diagnosis of myocardial infarction (MI) in patients who present to the Emergency Room (ER) complaining of chest pain is an important problem in emergency medicine. A number of decision aids have been developed to assist with this problem but have not achieved general use. Machine learning techniques, including classification tree and logistic regression (LR) methods, have the potential to create simple but accurate decision aids. Both a classification tree (FT Tree) and an LR model (FT LR) have been developed to predict the probability that a patient with chest pain is having an MI based solely upon data available at time of presentation to the ER. Training data came from a data set collected in Edinburgh, Scotland. Each model was then tested on a separate Edinburgh data set, as well as on a data set from a different hospital in Sheffield, England. Previously published models, the Goldman classification tree[1] and Kennedy LR equation[2], were evaluated on the same test data sets. On the Edinburgh test set, results showed that the FT Tree, FT LR, and Kennedy LR performed equally well, with ROC curve areas of 94.04%, 94.28%, and 94.30%, respectively, while the Goldman Tree's performance was significantly poorer, with an area of 84.03%. The difference in ROC areas between the first three models and the Goldman model is significant beyond the 0.0001 level. On the Sheffield test set, results showed that the FT Tree, FT LR, and Kennedy LR ROC areas were not significantly different (p > = 0.17), while the FT Tree again outperformed the Goldman Tree (p = 0.006). Unlike previous work[3], this study indicates that classification trees, which have certain advantages over LR models, may perform as well as LR models in the diagnosis of patients with MI.

Differential diagnoses of the heart disease program have better sensitivity than resident physicians

We describe a prospective clinical evaluation of a computer program to assist with the diagnosis of heart disease. The Heart Disease Program (HDP) is a large diagnostic program covering most areas of heart disease and some related areas of general medicine. The program's output is a set of differential diagnoses with explanations and it can be deployed in a clinical setting using a web interface. A framework for assessing the complex diagnostic summaries generated by the HDP was developed and the program's diagnostic accuracy in a clinical setting was assessed. The diagnoses used for comparison came from the physician entering the case, a "gold standard" assigned by review of patient charts and investigations, and the opinions of expert cardiologists. The data collection, methods of comparison, example analyses and results on 114 cases are presented here. The HDP had a significantly higher sensitivity for both the gold standard (60%) and the cardiologist's diagnoses (58%) than the physicians did (39%, 34%). These findings were consistent in the 2 collection cohorts and for the more serious diagnoses alone. The significance of these findings and the many challenges in comparing these different diagnoses and minimizing bias are discussed.

An artificial neural network system for diagnosis of acute myocardial infarction (AMI) in the accident and emergency department: evaluation and comparison with serum myoglobin measurements

Recent studies have confirmed that artificial neural networks (ANNs) are adept at recognising patterns in sets of clinical data. The diagnosis of acute myocardial infarction (AMI) in patients presenting with chest pain remains one of the greatest challenges in emergency medicine. The aim of this study was to evaluate the performance of an ANN trained to analyse clinical data from chest pain patients. The ANN was compared with serum myoglobin measurements--cardiac damage is associated with increased circulating myoglobin levels, and this is widely used as an early marker for evolving AMI. We used 39 items of clinical and ECG data from the time of presentation to derive 53 binary inputs to a back propagation network. On test data (200 cases), overall accuracy, sensitivity, specificity and positive predictive value (PPV) of the ANN were 91.8, 91.2, 90.2 and 84.9% respectively. Corresponding figures using linear discriminant analysis were 81.0, 77.9, 82.6 and 69.7% (P < 0.01). Using a further test set from a different centre (91 cases), the accuracy, sensitivity, specificity and PPV for the admitting physicians were 65.1, 28.5, 76.9 and 28.6% respectively compared with 73.6, 52.4, 80.0 and 44.0% for the ANN. Although myoglobin at presentation was highly specific, it was only 38.0% sensitive, compared with 85.7% at 3 h. Simple strategies to combine clinical opinion, ANN output and myoglobin at presentation could greatly improve sensitivity and specificity of AMI diagnosis. The ideal support for emergency room physicians may come from a combination of computer-aided analysis of clinical factors and biochemical markers such as myoglobin. This study demonstrates that the two approaches could be usefully combined, the major benefit of the decision support system being in the first 3 h before biochemical markers have become abnormal.

Early diagnosis of acute myocardial infarction using clinical and electrocardiographic data at presentation: derivation and evaluation of logistic regression models

The aim of this study was to determine which, and how many, data items are required to construct a decision support algorithm for early diagnosis of acute myocardial infarction using clinical and electrocardiographic data available at presentation. Logistic regression models were derived using data items from 600 consecutive patients at one centre (Edinburgh), then tested prospectively on 510 cases from the same centre and 662 consecutive cases from another centre (Sheffield). Although performance of the models increased with progressive addition of data inputs when applied to training data, a simple six-factor model was the most effective on test data, yielding accuracies of 84.3 and 83.6% on the two test sets. A model constructed solely of electrocardiographic data performed nearly as well as those incorporating clinical data. Previously published logistic regression models did not perform so well as the models derived from data collected for this study.

Diabetes care in middle-income countries: a Caribbean case study

Many middle-income countries now have a high prevalence of diabetes and need to address the problem of providing care for people with diabetes within limited resources. This study evaluated standards of preventive care in primary settings in three Caribbean countries. We studied case records at 17 clinics in 15 government health centres and 17 private general practitioners' offices in Barbados, Trinidad and Tobago and Tortola (British Virgin Islands). A census of all attenders over a 4 to 7 week period identified 1661 attenders with diabetes mellitus, approximately two-thirds were women with a median age over 60 years. Overall 676/1342 (50%) had 'poor' blood glucose control (> or = 8 mmol l-1 fasting or > or = 10 mmol l-1 random). The proportion with BP > or = 160/95 mmHg or receiving treatment for hypertension was 943/1661 (57%), of whom 781/943 (83%) were prescribed drug treatment. Among those treated for hypertension only 181/781 (23%) had blood pressures < 140/90 mmHg. Surveillance for complications affecting the feet (11%) or eyes (2%) was not performed systematically in any setting. Only 533 (32%) had recorded dietary advice and 79 (5%) had recorded exercise advice in the last 12 months. To begin to address some of these problems at a regional level, we incorporated results from this survey into a series of workshops held in collaboration with health ministries in 10 Caribbean countries, with participants from 13 countries. At these workshops health care workers participated in the process of developing guidelines for diabetes management in primary care. The guidelines have subsequently been widely disseminated through health ministries and non-governmental organizations in the region. Further research is needed to evaluate the effectiveness of this approach, the constraints on diabetes care, and the most cost-effective means of addressing them.

Writing a scientific paper

There are many varieties of medical writing. This paper suggests a sound, practical approach for writing up a research project in the conventional format for a medical or scientific journal. The structure of a scientific paper is well established, to accommodate the "Why" of the project (the Introduction), the "Who, when, where and how" (the Methods) and the "What" (the Results). The Discussion (the "So what") should be in three parts--discussion and explanation of results, disputation, and disquisition (implications for practice and for future work). Guidelines are given for getting started and for producing a paper that will, hopefully, be published and read.

Human T-lymphotropic virus type I DNA in spinal cord of tropical spastic paraparesis with concomitant human T-lymphotropic virus type I-negative Hodgkin's disease

We studied a 58-year-old black woman from Barbados who simultaneously developed myelopathy and lymphoma with human T-lymphotropic virus type I (HTLV-I) antibodies in serum and cerebrospinal fluid and died 3 years after onset. Neuropathological examination showed typical tropical spastic paraparesis (TSP). The polymerase chain reaction (PCR) demonstrated defective proviral genome retaining the HTLV-I pX and env regions in thoracic spinal cord, the level most severely affected. Defective HTLV-I in the nervous system retaining the pX region may be relevant to pathogenesis because circulating CD8+ cytotoxic lymphocytes specific for HTLV-I pX occur in HTLV-I myelopathy. This patient's lymph node biopsy specimen was consistent with Hodgkin's disease (HD), nodular sclerosis subtype, of B-cell origin. The PCR in the paraffin-embedded lymph node involved by HD failed to amplify HTLV-I proviral sequences. Complete HTLV-I proviral amplification was obtained in paraffin-embedded lymph nodes form positive controls (adult T-cell leukemia). To our knowledge the association of TSP and HD has not been reported previously. Despite claims that HD may be associated with HTLV-I, we demonstrated absence of HTLV-I-infected T cells in the lymphoid infiltrate of HD in this case, positive HTLV-I serology notwithstanding.

Incidence of type I diabetes in people under 30 years of age in Barbados, West Indies, 1982-1991

OBJECTIVE

To determine the incidence of type I diabetes among individuals < 30 years of age on the island of Barbados in the Caribbean. The population is predominantly African in origin but exhibits a relatively westernized lifestyle.

RESEARCH DESIGN AND METHODS

Cases occurring during the years 1982-1991 were drawn from records at Queen Elizabeth Hospital and from physicians treating insulin-dependent diabetes mellitus (IDDM) patients. Patients using insulin and < 30 years of age at onset were included. Ascertainment was estimated at 94%.

RESULTS

The average annual incidence of type I diabetes among Barbadians was 4.1/100,000 when age-adjusted to the world's population. There were 59 incident cases during this 10-year interval. The risk for males was 4.4 and for females 4.0/100,000. Among those 0-14 years of age, the risk was 5.0/100,000. Mean age at onset (+/- SD) was 14.7 +/- 6.9 for males and 12.5 +/- 5.7 for females. Males showed marked seasonal variation in risk and a more than threefold increase in annual incidence during 1984-1985. In contrast, females exhibited a stable pattern of IDDM risk during the 10-year interval.

CONCLUSIONS

The incidence rate in Barbados falls near the lower limits of rates reported for Caribbean populations. There was a marked seasonal effect among males, even though the climate varies little throughout the year. This observation, and the incidence peak during 1984-1985, provide support for the role of environmental factors in the etiology of IDDM.

Use by visitors of the services of the Queen Elizabeth Hospital, Barbados, W.I

This paper analyses data for 1990 culled from the medical records of the Queen Elizabeth Hospital, Barbados and examines the use of inpatient and emergency services by visitors to Barbados. The 473 visitors admitted represented 2.1% of all admissions. The records of 425 contained information on country of origin: 145 were from non-Caribbean and 280 from Caribbean countries. The distribution by country of non-Caribbean visitors was the same as that of regular tourist arrivals--the majority came from the USA. Canada and the UK. Caribbean visitors represented 14.4% of the tourists, but accounted for 65.9% of visitor admissions. Non-Caribbean visitors were 85.6% of tourists, but 34.1% of admissions. Young patients predominated among Caribbean, and older patients among non-Caribbean. Accidents, cardiovascular disease, alcohol-related illnesses and near drowning were commoner in the non-Caribbean visitors, while cancer and obstetrical/gynaecological problems were commoner in Caribbean visitors. Seven per cent of visitor admissions went to the Intensive Care Unit as against 0.15% of other patients. The average hospital stay of visitors was 11.7 days compared with 7.0 days for Barbadians. There were 898 visitors treated in the Accident and Emergency Department and the commonest problems were lacerations, abrasions and infections. The UK provided most of these patients. These data show that there is appreciable visitor use of the public health services. Non-Caribbean visitors use them because they fall ill on holiday, but many Caribbean visitors may come specifically for health care. The cost to the Barbadian health service is not insignificant: at the 1990 estimated bed-day cost of Bds$250, it represents a cost of Bds$1.1 million per annum to the Government for inpatient services alone, or 2% of total hospital costs.

Clinically significant hemorrhage due to warfarin-carbamazepine interaction

A 61-year-old woman receiving warfarin for postoperative atrial fibrillation and carbamazepine for a peripheral neuropathy had extreme elevation of prothrombin time associated with clinically significant hemorrhage when the carbamazepine therapy was discontinued. The mechanism of this significant drug interaction involves the withdrawal of carbamazepine-induced enhancement of hepatic warfarin breakdown with resultant delay of warfarin excretion and excessive hypoprothrombinemia. The clinically significant hemorrhage associated with warfarin-carbamazepine interaction is an indication for caution when these two agents are prescribed concomitantly.

Blood pressure in blacks. Twin studies in Barbados

We have recently reported that there are significant genetic influences on the population variation in blood pressure in black twins in Los Angeles. The present cross-sectional study was undertaken to replicate these findings in a black twin population that lives in a different biosocial environment. We chose the Caribbean island nation of Barbados, where 96% of the population is black, the literacy rate is 99%, and the access to health care is guaranteed. The goals were 1) to test the feasibility of twin studies in blood pressure research in a developing country and 2) to estimate the relative contribution of genes and environment to blood pressure variability in blacks in the Caribbean. The names of 200 twin sets were obtained with the assistance of community resources including a twin club, by media advertisement, and by asking people at public blood pressure screenings if they knew any twins. By using these methods, we identified 200 sets of twins. Of these, 37.5% (75/200) met our criteria for study. Although 97% of the sets of twins (73/75) said they were willing to participate, only 69% (52/75) were able to be scheduled during the 1 week of the study when the full team of investigators was in Barbados. Of those scheduled, 83% (43/52) were examined. Examination included medical history, physical examination, recumbent blood pressure measurements by two observers, anthropometric measurements, 24-hour urine collections for sodium and potassium tests, and blood tests for zygosity.(ABSTRACT TRUNCATED AT 250 WORDS)

A scoring system for selection of essential drugs

A scoring system is presented for selection of essential drugs, using criteria of efficacy, safety, cost of a course of therapy, compliance, multiple usage and storage, ease of administration and local availability. Such a system allows for different weighting of factors whose relative importance varies from country to country and would help in choosing the most appropriate and cost-effective drugs for use in developing countries. The importance of such factors as cost and compliance has been illustrated with suitable examples. This approach could also be used for individual patient decisions with the aid of a computer program.

The Drug Formulary Committee in a developing country

Most developing countries suffer badly from misguided drug selection and purchases, erratic supplies and distribution, and wasteful or inappropriate drug use. Barbados is one of the few developing countries with an active Drug Formulary Committee. This committee develops a formulary that is revised and updated annually, providing guidance on rational prescribing. The Barbados Drug Formulary Committee has operated for 5 years on principles similar to those of a P & T Committee, but with a more restricted list and a flexible approach geared to specific local problems. The Drug Formulary and ongoing educational activities, which have been effective agents in promoting rational prescribing, are described.

The management of severe hypertension with minoxidil in a once-a-day treatment regimen

We evaluated the antihypertensive efficacy of "once-a-day" minoxidil, given in conjunction with a diuretic and sympatholytic, and the effect of this simple regimen on patient compliance. Twenty-one severely hypertensive patients had their existing antihypertensive regimens changed to a single daily dose of chlorthalidone (50-100 mg) and either nadolol (160 mg) or reserpine (.25 mg) for a 3-week period. After stabilization on these two drugs, a single daily dose of minoxidil (2.5 mg) was added to each patient's regimen. Doses were titrated as necessary to achieve diastolic blood pressures of less than 90 mmHg. After 3 and 6 months of maintenance therapy, blood pressures were measured 24 hours after the previous day's dosing to evaluate the persistence of the antihypertensive effect. Twenty-four-hour blood pressure control was achieved on 76% of these occasions, and on at least one occasion in 90% of the patients. In addition, compliance was excellent.

Environmental factors affecting paracetamol metabolism in London factory and office workers

A Paracetamol elimination was measured, using serial saliva samples, in 114 London factory and office workers, 76 Whites and 38 Asian immigrants. 2. Use of social drugs such as alcohol, tobacco and the oral contraceptive varied considerably within the sample, being appreciably greater in White subjects. 3. Paracetamol clearance was 21% slower in Asians than in Whites and half-life 18% longer. The total range of clearance was 1.86--6.78 ml min-1 kg-1. 4. Clearance was slower in women than in men, increased with increasing alcohol intake and cigarett consumption, and was more rapid in those women using the oral contraceptive. The effects of alcohol and the oral contraceptive were also found in White subjects alone. 5 The variables found to correlate independently with paracetamol clearance accounted for only 27% of the total sample variance, however, and are unlikely to be the major determinants of paracetamol elimination in man.

Antipyrene clearance in Indian villagers

1 Antipyrine clearance has been measured using saliva samples in 50 Maharashtrans from a village to the north of Bombay. 2 All subjects were very lean and were also anaemic probably as a result of hookworm infestation. 3 Antipyrine clearance was 36% faster than in White Londoners studied previously and more than twice as fast as in Asian immigrants living in London. 4 Clearance was 25% faster in men than in women but volume of distribution was also greater in men and mean half-lives did not differ significantly between the sexes. 5 There was a negative correlation between antipyrine clearance and haemoglobin concentration. 6 The study has identified geographic differences in antipyrine metabolism which could be clinically important. The role of anaemia merits further study.

Reduction of circulating 25-hydroxyvitamin D by antipyrine

1 Twenty-four Asian vegetarians had significantly lower 25-hydroxyvitamin D (25-OHD) levels and longer antipyrine half-lives than twenty white non-vegetarians (P less than 0.001). 2 Treatment with oral antipyrine over 4 or 5 weeks in seven vegetarian Asians and five racially different non-vegetarians increased drug oxidation significantly in both groups as measured by a fall in antipyrine half-lives and a rise in serum gamma-glutamyltranspeptidase levels and urinary 6 beta-hydroxycortisol/17-hydroxycorticosteroid ratios. 3 Antipyrine treatment produced a fall in circulating 25-hydroxyvitamin D of around 60% in all subjects in whom pretreatment levels could be measured, independent of race and diet. 4. In the Caucasian non-vegetarian group 1,25 dihidroxyvitamin D levels, the most active metabolite of vitamin D, were also measured and remained unaltered despite a substantial fall in 25-hydroxy substrate. 5 The acute fall in 25-hydroxyvitamin D concentration with a maintained level of 1,25 dihidroxyvitamin D may represent the early changes of drug-induced osteomalacia.

Environmental factors affecting antipyrine metabolism in London factory and office workers

1 Measurements of antipyrine clearance in saliva have been made in 128 London factory and office workers. 2 Mean antipyrine clearance in 56 Asian immigrants was 40% slower than in 72 White subjects. 3 Although dietary differences existed between the two groups, analysis of their effect independently of race was impossible since all but one of the vegetarians were Asian and the non-vegetarians were nearly all White. 4 In the White subjects, use of the oral contraceptive reduced clearance by 38% in women, while cigarette smoking increase clearance by 38% in men.

Contribution of environmental factors to variability in human drug metabolism

Drug metabolism in 96 London factory and office workers has been studied after simultaneous single doses of antipyrine (phenazone) and paracetamol (acetaminophen). Metabolic clearance of both drugs was significantly greater in subjects eating meat more than once a week than in those who ate meat less frequently. The precise contribution of diet could not be clearly defined since 90% of "meat-eaters" were European while all except one of the "vegetarians" were Asian. Clearance of both drugs increased with both alcohol and cigarette consumption. Regular intake of coffee and/or tea had a similar effect but, in the case of paracetamol, this did not attain statistical significance. Antipyrine clearance was lower among women who took the oral contraceptive pill than among those who did not, while paracetamol clearance was not significantly different. These findings may have implications for the use of drugs which are administered regularly in order to achieve steady-state plasma and tissue concentrations.