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R H Meyboom

Publications and source records attributed to R H Meyboom.

At least 19 recordsLinked to original sources
PubMed2001

Antipsychotic drugs and heart muscle disorder in international pharmacovigilance: data mining study.

OBJECTIVES: To examine the relation between antipsychotic drugs and myocarditis and cardiomyopathy. DESIGN: Data mining using bayesian statistics implemented in a neural network architecture. SETTING: International database on adverse drug reactions run by the World Health Organization programme for international drug monitoring. MAIN OUTCOME MEASURES: Reports mentioning antipsychotic drugs, cardiomyopathy, or myocarditis. RESULTS: A strong signal existed for an association between clozapine and cardiomyopathy and myocarditis. An association was also seen with other antipsychotics as a group. The association was based on sufficient cases with adequate documentation and apparent lack of confounding to constitute a signal. Associations between myocarditis or cardiomyopathy and lithium, chlorpromazine, fluphenazine, haloperidol, and risperidone need further investigation. CONCLUSIONS: Some antipsychotic drugs seem to be linked to cardiomyopathy and myocarditis. The study shows the potential of bayesian neural networks in analysing data on drug safety.

Antipsychotic Agents↗
PubMed2000

Anaphylactic reactions to proton-pump inhibitors.

OBJECTIVE: To report two cases of anaphylactic reactions to proton-pump inhibitors (PPIs). CASE SUMMARIES: A 54-year-old woman who had taken omeprazole in the past was treated with omeprazole 40 mg and developed periorbital edema, edema of the skin, pruritus, nausea, and vomiting about 45 minutes after taking one capsule. Five months later, she was treated with lansoprazole 30-mg capsules. Again, within 45 minutes she developed an even more serious reaction, with pruritus and urticaria on her whole body, increased sweating, facial edema, and loss of consciousness. A 61 -year-old man took one tablet of pantoprazole 40 mg one year after first being treated with the drug. Within hours after ingestion, he developed malaise, generalized pruritus and urticaria, a swollen tongue and eyes, and diffuse sweating; his blood pressure decreased to 75/50 mm Hg. DISCUSSION: Because of the acute onset of symptoms and close temporal association with exposure to the drug, as well as previous exposure to it, the reactions can be classified as anaphylactic shock to PPIs. These benzimidazole derivatives are chemically related; observations in a few patients, such as the first case above, suggest that cross-sensitivity may occur. The Uppsala Monitoring Centre (UMC) has received a total of 42 reports of anaphylactic reactions or anaphylactic shock in association with PPIs. These reports account for 0.2% of the total of reported suspected adverse drug reactions to PPIs, compared with 0.8% anaphylactic reactions in the UMC database as a whole. CONCLUSIONS: These findings suggest that the chemically related PPIs can, as a group, cause anaphylactic reactions; however, the rate is comparatively low. Since anaphylaxis is a potentially serious reaction, more precise information is needed regarding its frequency, and healthcare professionals need to be aware of this possibility when prescribing these agents.

Anaphylaxis↗
PubMed2000

An ABC of drug-related problems.

The problems relating to the use of medicines are manifold. They may differ in pharmacological, pathological, epidemiological and legal respects, and may have different consequences, for example, as regards scientific study, regulation or rational use. Pharmacovigilance is concerned with all such problems: adverse effects and interactions as well as problems relating to ineffectiveness, inappropriate use, counterfeiting, dependence or poisoning. Practically all medicine-related problems can be classified in one basic system, taking into account their characteristics and distinctions. This system distinguishes between appropriate and inappropriate drug use; dose-related and dose-unrelated problems [corrected]; and types A ('drug actions'), B ('patient reactions') and C ('statistical') adverse effects. This classification may serve as an educational tool and may be useful in when choosing a study method and for the design of effective strategies in pharmacovigilance.

Drug Interactions↗
PubMed2000

The value of reporting therapeutic ineffectiveness as an adverse drug reaction.

Therapeutic ineffectiveness is a frequent drug-related problem that can occur in a variety of different situations and be caused by different mechanisms. Examples are inappropriate use, interactions or metabolic abnormalities. Observations in patients of unexpected ineffectiveness can provide important information with regard to such situations. Therefore, ineffectiveness--especially when unexpected or unexplained--is a potentially important reportable event in pharmacovigilance. The terms regarding ineffectiveness in the WHO Adverse Reaction Terminology (WHOART) have been recently revised in order to enable optimal coding of such case reports.

Drug Interactions↗
PubMed2000

A retrospective evaluation of a data mining approach to aid finding new adverse drug reaction signals in the WHO international database.

BACKGROUND: The detection of new drug safety signals is of growing importance with ever more new drugs becoming available and exposure to medicines increasing. The task of evaluating information relating to safety lies with national agencies and, for international data, with the World Health Organization Programme for International Drug Monitoring. RATIONALE: An established approach for identifying new drug safety signals from the international database of more than 2 million case reports depends upon clinical experts from around the world. With a very large amount of information to evaluate, such an approach is open to human error. To aid the clinical review, we have developed a new signalling process using Bayesian logic, applied to data mining, within a confidence propagation neural network (Bayesian Confidence Propagation Neural Network; BCPNN). Ultimately, this will also allow the evaluation of complex variables. METHODS: The first part of this study tested the predictive value of the BCPNN in new signal detection as compared with reference literature sources (Martindale's Extra Pharmacopoeia in 1993 and July 2000, and the Physicians Desk Reference in July 2000). In the second part of the study, results with the BCPNN method were compared with those of the former signalling procedure. RESULTS: In the study period (the first quarter of 1993) 107 drug-adverse reaction combinations were highlighted as new positive associations by the BCPNN, and referred to new drugs. 15 drug-adverse reaction combinations on new drugs became negative BCPNN associations in the study period. The BCPNN method detected signals with a positive predictive value of 44% and the negative predictive value was 85%. 17 as yet unconfirmed positive associations could not be dismissed with certainty as false positive signals. Of the 10 drug-adverse reaction signals produced by the former signal detection system from data sent out for review during the study period, 6 were also identified by the BCPNN. These 6 associations have all had a more than 10-fold increase of reports and 4 of them have been included in the reference sources. The remaining 4 signals that were not identified by the BCPNN had a small, or no, increase in the number of reports, and are not listed in the reference sources. CONCLUSION: Our evaluation showed that the BCPNN approach had a high and promising predictive value in identifying early signals of new adverse drug reactions.

Algorithms↗
PubMed1999

Bladder dysfunction during the use of tramadol.

The Netherlands Pharmacovigilance Foundation LAREB received five case reports concerning transient impairment of micturition or urinary retention, suspected to be induced by tramadol. In all patients--three women and two men--the symptoms occurred in temporal association with the use of tramadol and promptly recovered after stopping of the drug. Tramadol was taken orally in doses within the recommended therapeutic range (150 mg or less daily). Disturbance of micturition is not mentioned as a side-effect in the summary of product characteristics of Tramal 50 and 100. Tramadol is an opioid agonist, however, and morphine is known to increase the tonus of the bladder sphincter and to cause urinary retention.

Journal Article↗
PubMed1999

Signalling possible drug-drug interactions in a spontaneous reporting system: delay of withdrawal bleeding during concomitant use of oral contraceptives and itraconazole.

AIMS: In spontaneous adverse drug reaction reporting systems, there is a growing need for methods facilitating the automated detection of signals concerning possible adverse drug reactions. In addition, special attention is needed for the detection of adverse drug reactions resulting from possible drug-drug interactions. We describe a method for detecting possible drug-drug interactions using logistic regression analysis to calculate ADR reporting odds ratios. METHODS: To illustrate this method, we analysed the adverse drug reaction 'delayed withdrawal bleeding' resulting from a possible interaction between itraconazole and oral contraceptives in reports received by the Netherlands Pharmacovigilance Foundation LAREB between 1991 and 1998. RESULTS: In total 5,503 reports were included in the study. The odds ratio, adjusted for year of reporting, age and source of the reports, for a delayed withdrawal bleeding in women who used both drugs concomitantly compared with women who used neither oral contraceptives, nor itraconazole, was 85 (95% CI: 32-230). CONCLUSIONS: Since spontaneous reporting systems can only generate signals concerning possible relationships, this association needs to be analysed by other methods in more detail in order to determine the real strength of the relationship. This approach might be a promising tool for the development of procedures for automated detection of possible drug-drug interactions in spontaneous reporting systems.

Adolescent↗
PubMed1999

Pharmacovigilance in perspective.

Pharmacovigilance is more than spontaneous reporting alone, and the evaluation of marketed medicines is more than just pharmacovigilance. The positioning of a drug usually takes place during the years following introduction, when worldwide experience has accumulated. Originally a modest appendix of drug regulation, pharmacovigilance has become a major activity. The provision of the information needed for the evaluation of the benefits and risks of drugs is in the first place a scientific challenge. In addition, there are important ethical, logistical, legal, financial and commercial constraints. Good pharmacovigilance practice needs to be developed to ensure that data are collected and used in the right way and for the right purpose. Pharmacovigilance, and more generally the study of the benefits and risks of drugs, plays a major role in pharmacotherapeutic decision-making, be it individual, regional, national or international. In addition, pharmacovigilance is becoming a scientific discipline in its own right. A variety of changes are taking place in the complex system of drug development, regulation and distribution. Pharmacovigilance should be proactive in monitoring their possible consequences.

Adverse Drug Reaction Reporting Systems↗
PubMed1998

[Convulsions during prophylactic use of mefloquine].

In 1996 and 1997 the Dutch Pharmacovigilance Foundation LAREB received 6 reports of patients with convulsions that were attributed to prophylactic use of mefloquine. Five patients had no neurological history; one patient had a history of epilepsy but had not had any convulsion during the preceding 5-year period. The convulsions took place 1 to 23 days after start of the treatment with mefloquine. Because of the convulsions, the treatment was discontinued. The 4 patients with known follow-up showed full recovery with regard to the convulsions. The practising physician should be aware of the possible occurrence of rare neuropsychiatric adverse events like convulsions during the prophylactic use of mefloquine.

Adult↗
PubMed1998

[Pill cycle disturbance in simultaneous use of itraconazole and oral contraceptives].

Since the introduction of itraconazole in the Netherlands, the Netherlands Pharmacovigilance Foundation LAREB and the Inspectorate for Health Care received 15 reports of pill cycle disturbances and one of pregnancy occurring during simultaneous use of itraconazole and oral contraceptives. Twelve women used oral contraceptives containing ethinylestradiol and desogestrel. In these women, the withdrawal bleeding was either delayed or did not occur at all; one of these women reported a transiently positive pregnancy test after previous breakthrough bleedings. Three women who used a contraceptive containing ethinylestradiol and levonorgestrel had a breakthrough bleeding. One woman who used an oral contraceptive containing ethinylestradiol and cyproterone acetate became pregnant during the concomitant use of itraconazole. The possible mechanism involved remains to be explained. Although an influence of itraconazole on the reliability of oral contraceptives is uncertain, additional contraceptive measurements might be considered.

Adult↗
PubMed1998

Semen-like urethral discharge during the use of mazindol.

Two case reports are described of male patients experiencing a semen-like urethral discharge during micturition, suspected to be induced by mazindol. Mazindol has an indirect sympathomimetic action and is known to cause urogenital side effects such as urinary retention and testicular pain. It is suggested that seminal discharge may be added to this list.

Adult↗
PubMed1997

ADR related questions received by a telephone medicines information service and ADRs received by a spontaneous ADR reporting system: a comparison regarding patients and drugs.

A telephone medicines information service (telephone service) has been available in the Netherlands since 1990. Patients can anonymously and free of charge ask a pharmacist all kinds of questions related to medication use. An analysis of the questions (n=7541) received by this service in 1994 showed that 28% of the questions predominantly related to adverse drug reactions (ADRs). A comparison was made between questions concerning ADRs received by the telephone service and suspected ADRs reported to the regionalized ADR reporting system LAREB regarding characteristics of the associated patients and medicines. In both systems approximately two out of three patients were women. LAREB received relatively more reports concerning patients of 60 years and older, whereas the telephone service received relatively more questions from patients aged 20-40 years. For most classes of medicines the observed proportion of encounters at both systems differed from the expected proportion estimated by the number of prescriptions in the same year. Antidepressants in particular were more frequently encountered at both systems than expected. There were clear differences between the telephone service and LAREB regarding the classes of medicines encountered. Reports of suspected ADRs submitted to LAREB more frequently involved antibiotics, antirheumatic products, anti-asthmatics, antihypertensives and topical antifungals, whereas questions concerning ADRs received by the telephone service significantly more frequently concerned drugs acting on the central nervous system (anxiolytics/hypnotics/sedatives, antidepressants and antipsychotic drugs) and corticosteroids. We are setting up further studies to investigate whether telephone services can serve as an additional tool in postmarketing surveillance for identifying potential drug safety issues.

Journal Article↗
PubMed1997

Good practice in the postmarketing surveillance of medicines.

In addition to Good Clinical Trial Practice for the study of experimental drugs, regulations are also needed for good practice in the assessment of medicines after approval (Good PMS Practice, GPP). GPP has to protect the interests of public health at large as well as those of individual patients, investigators and pharmaceutical companies. GPP may be the natural way to solve threatening conflicts between privacy legislation and the public interest.

Forecasting↗