PubMed Health⌕ Search

Biomedical subjects

I C Wong

Publications and source records attributed to I C Wong.

18 recordsLinked to original sources
PubMed2001

A pharmacoepidemiologic study of factors influencing the outcome of treatment with lamotrigine in chronic epilepsy.

PURPOSE: To identify prognostic factors for freedom from seizures and long-term retention of treatment in patients receiving lamotrigine (LTG). METHODS: A multicenter, retrospective, case record study of 1,050 patients with chronic epilepsy was carried out. Logistic regression and Cox regression analyses were used to identify clinical features associated with freedom from seizures and retention of treatment, respectively. Long-term retention rates of LTG therapy were estimated using Kaplan-Meier survival analysis. RESULTS: The 1,050 patients with chronic epilepsy were included in the study. Patients with generalized epilepsy (p = 0.01), who were not receiving carbamazepine (CBZ; p = 0.02) were more likely to become seizure-free. Sixty percent of patients continued on LTG therapy >1 year and estimated retention at 8 years was 38%. Patients with generalized epilepsy (p = 0.002), patients receiving concurrent sodium valproate (VPA; p < 0.0001), those not previously exposed to gabapentin and vigabatrin (p < 0.0001), and those in whom the starting dose was lower (p < 0.0012), were more likely to remain on long-term treatment with LTG. The relationships with exposure to other antiepileptic drugs remained significant in patients with focal and with generalized epilepsy when considered separately. CONCLUSIONS: The best results from LTG treatment in terms of freedom from seizures and long-term retention of treatment were obtained in patients with generalized epilepsy. Retention of treatment was enhanced by VPA not only in generalized but also in focal epilepsy. The importance of a low starting dose of LTG was again confirmed. The apparent negative effect of CBZ in patients taking LTG merits further investigation.

Anticonvulsants↗
PubMed2001

Adverse event monitoring in lamotrigine patients: a pharmacoepidemiologic study in the United Kingdom.

PURPOSE: This postmarketing surveillance study of lamotrigine (LTG) was performed to provide complementary data to large-scale Prescription-Event Monitoring study with a retrospective case records survey in five tertiary referral epilepsy centres in the United Kingdom. METHODS: Adverse events were recorded and compared with those of two other new antiepileptic drugs (AEDs), gabapentin (GBP) and vigabatrin (VGB). All deaths were followed up and standardised mortality ratios (SMRs) were calculated. Serious adverse events were assessed individually. RESULTS: A total of 2,701 patients was identified as being exposed to LTG and/or the comparators. It was necessary to exclude 1,326 patients because LTG and/or comparators had been commenced outside the study centres. The adverse events with LTG reported by this study were similar to those reported in the literature. Skin rash was the major adverse event. Life-threatening hepatic failure, acute exacerbation of ulcerative colitis, disseminated intravascular coagulation, and renal failure were reported. No death could be directly attributed to the use of LTG. The SMR was slightly higher than that reported in the literature; this probably reflects severity of epilepsy in the study population. CONCLUSIONS: The safety profile of LTG was similar to that in the large-scale Prescription-Event Monitoring study and generally acceptable. Life-threatening adverse reactions were rare.

Acetates↗
PubMed2000

Long-term retention rates of lamotrigine, gabapentin, and topiramate in chronic epilepsy.

PURPOSE: We sought to determine the long-term retention rates of lamotrigine (LTG), gabapentin (GBP), and topiramate (TPM) therapy for patients at a tertiary referral clinic for chronic, refractory epilepsy. METHODS: We analyzed 424 consecutive patients with chronic, refractory partial and/or generalized epilepsy who were started on LTG, 158 patients who were started on GBP, and 393 patients who were started on TPM. The percentages of patients who continued therapy with LTG, GBP, and TPM were estimated with the use of Kaplan-Meier survival analysis. Factors that influence retention were analyzed with the use of Cox regression analysis. RESULTS: Kaplan-Meier survival analysis showed that at 3 years, 30% continued therapy on TPM compared with 29% on LTG and fewer than 10% on GBP. Adverse events resulted in therapy withdrawal in 40% of patients on TPM compared with GBP (37%) and LTG (22%). Perceived lack of efficacy led to treatment withdrawal in 39% of patients on GBP compared with 34% on LTG and 19% on TPM. Cox regression estimated that a fourth or fewer of patients with chronic partial epilepsy are likely to continue therapy with a new antiepileptic drug beyond 5 years. CONCLUSIONS: The impact of these new antiepileptic drugs on the long-term course of chronic partial epilepsy is likely to be small, as approximately three of four patients will discontinue therapy. More patients appear to continue on TPM compared with LTG or GBP, with a possible reason being better perceived efficacy of TPM, despite having the highest incidence of adverse events.

Acetates↗
PubMed2000

Prognostic factors affecting long-term retention of topiramate in patients with chronic epilepsy.

PURPOSE: To determine the long-term retention rate of topiramate (TPM) therapy in patients with chronic epilepsy and to identify the relevant prognostic factors that influence retention. METHODS: All patients with chronic epilepsy (n = 393) prescribed TPM between October 1, 1995, and December 31, 1998, at a tertiary referral centre for epilepsy were analysed. The retention rate for TPM was calculated by using Kaplan-Meier survival analysis, and the prognostic factors influencing retention were analysed by using Cox regression. RESULTS: Of patients prescribed TPM, 30% continued taking the drug beyond 3 years. Discontinuation was mainly due to adverse events and lack of efficacy. Use of more than one new concurrent antiepileptic drug (AED) and lower maximal daily doses were more likely to result in treatment discontinuation due to adverse events. Older age at onset of epilepsy, a history of having previously taken more than one new AED [lamotrigine (LTG), gabapentin (GBP), or vigabatrin (VGB)], and lower maximal daily doses were more likely to lead to discontinuation due to lack of efficacy. CONCLUSIONS: A third of patients with chronic epilepsy started on TPM therapy will continue on treatment for >3 years. Absence of learning disabilities, late age at onset of seizures, previous use of more than one new AED, two or more concurrent AED use, and low maximal daily doses of TPM are more likely to result in discontinuation of medication. These factors should be taken into account when considering the use of TPM for the treatment of chronic epilepsy.

Adolescent↗
PubMed2000

Adverse reactions to new anticonvulsant drugs.

A lack of systematic pharmacoepidemiological studies investigating adverse drug reactions (ADRs) to anticonvulsants makes it difficult to assess accurately the incidence of anticonvulsant-related ADRs. Most of the available information in this regard stems from clinical trial experience, case reports and postmarketing surveillance, sources that are not, by any means, structured to provide precise data on adverse event epidemiology. For various ethical, statistical and logistical reasons, the organisation of structured clinical trials that are likely to provide substantial data on ADRs is extremely difficult. This review concentrates on current literature concerning serious and life-threatening ADRs. As with the older anticonvulsants, the majority of ADRs to newer anticonvulsants are CNS-related, although there are several that are apparently unique to some of these new drugs. Gabapentin has been reported to cause aggravation of seizures, movement disorders and psychiatric disturbances. Felbamate should only be prescribed under close medical supervision because of aplastic anaemia and hepatotoxicity. Lamotrigine causes hypersensitivity reactions that range from simple morbilliform rashes to multi-organ failure. Psychiatric ADRs and deterioration of seizure control have also been reported with lamotrigine treatment. Oxcarbazepine has a safety profile similar to that of carbamazepine. Hyponatraemia associated with oxcarbazepine is also a problem; however, it is less likely to cause rash than carbamazepine. Nonconvulsive status epilepticus has been reported frequently with tiagabine, although there are insufficient data at present to identify risk factors for this ADR. Topiramate frequently causes cognitive ADRs and, in addition, also appears to cause word-finding difficulties, renal calculi and bodyweight loss. Vigabatrin has been reported to cause seizure aggravation, especially in myoclonic seizures. There have been rare reports of other neurological ADRs to vigabatrin, such as encephalopathy, aphasia and motor disturbances. Vigabatrin-induced visual field constriction is the latest and most worrying ADR. Many questions regarding the nature of this potentially serious ADR remain unanswered, as no prospective controlled study examining the phenomenon has been published. Rare cases of behavioural ADRs and IgA and IgG2 deficiency associated with the use of zonisamide have been reported. However, relatively few patients so far have been exposed to this drug, and therefore more postmarketing information is required. The relatively late establishment of aplastic anaemia and hepatic failure as potentially fatal ADRs of felbamate, and of visual field constriction with vigabatrin, should serve as ample reminders that ADRs can appear at any time.

Animals↗
PubMed2000

A survey on factors that could affect adverse drug reaction reporting according to hospital pharmacists in Great Britain.

INTRODUCTION: Since April 1997, UK hospital pharmacists have been invited to submit reports of suspected adverse drug reactions (ADRs) to the Committee on Safety of Medicines (CSM) and Medicines Control Agency. Three studies have investigated the involvement of hospital pharmacists in ADR reporting; however, they did not investigate the possible factors that could affect ADR reporting. OBJECTIVES: (i) To analyse the extent to which hospital pharmacists think that specified factors could affect reporting ADRs; (ii) to identify any additional factors that could hinder reporting; and (iii) to recommend possible methods to improve reporting. METHODS: Piloted questionnaires were sent to 548 hospital pharmacists in Great Britain randomly selected by the Royal Pharmaceutical Society of Great Britain (RPSGB) from their computer database. 346 questionnaires were returned and 280 were included in this study. RESULTS: 46% of the pharmacists had identified ADRs that were considered to be reportable according to the CSM criteria in the 6 months prior to the survey. 39% did not report these ADRs either to the CSM or the manufacturers. Only 8.2% reported that their hospitals had a written policy; conversely, 73.7% agreed that such a policy could enhance ADR reporting. Although not statistically significant, the result showed an increasing tendency to report ADRs by pharmacists who had received training. Furthermore, there was an increasing tendency to report ADRs with increasing seniority. DISCUSSION: The results show that hospital pharmacists say they are more likely to report serious and rare ADRs and ADRs associated with newly marketed drugs. Factors that could reduce ADR reporting included being busy at work, lack of confidence in recognising ADRs and the fear of breaching patient confidentiality. Most common suggestions on methods to improve ADR reporting were to provide ADR training and meetings (34%) and a hospital written policy (24%). RECOMMENDATIONS: ADR training and meetings would be a useful step in improving hospital pharmacist ADR reporting. Therefore, we recommend that the CSM and the RPSGB liaise with regional drug information centres and schools of pharmacy to provide more study days and training programmes for hospital pharmacists. Furthermore, the CSM should write to the 'Drugs and Therapeutics Committee' of each hospital and encourage them to develop a written local policy for pharmacist ADR reporting. Further studies should be conducted to test the recommendations noted here, assessing the response of the pharmacists in terms of absolute numbers of reports made. It would be particularly interesting to study the need for a written hospital policy and education.

Adverse Drug Reaction Reporting Systems↗
PubMed1999

Readability of patient information leaflets on antiepileptic drugs in the UK.

The Audit Commission in the UK recommends that patient information leaflets (PILs) should be audited by health professionals using a formal readability test. However, no such study on antiepileptic drugs (AEDs) has been identified in a Medline search. The aim of this study was to audit the readability of PILs prepared for marketed proprietary AEDs in the UK. Twelve PILs were compared with six antiepileptic drug articles from medical journals and six headline articles from UK newspapers. The Gunning Fog index and the Flesch Reading Ease index were calculated for each PIL and article. The results of the Gunning Fog index and the Flesch Reading Ease score were compared using the Kruskal-Wallis non-parametric test. PILs were shown to have a statistically significant lower mean reading age than the medical articles and newspapers (P < 0.001). The Gunning Fog index and Flesch Reading Ease score showed that PILs had a mean reading age of 8.8 and mean readability score of 69, respectively. In conclusion, the PILs prepared for proprietary antiepileptic drugs in the UK are suitable for the reading age of the general adult population.

Adult↗
PubMed1999

The long-term use of gabapentin, lamotrigine, and vigabatrin in patients with chronic epilepsy.

PURPOSE: To compare the long-term retention of gabapentin (GBP), lamotrigine (LTG), and vigabatrin (VGB) by patients with chronic epilepsy and the reasons for treatment discontinuation. To assess the likelihood of seizure freedom, seizure-related injury/hospital admission and mortality after these drugs were commenced. METHODS: This was a retrospective case-records survey in five tertiary referral epilepsy centres in the U.K. The retention times on treatment (from initiation to discontinuation) for the different antiepileptic drugs (AEDs) were compared by using Kaplan-Meier survival analysis and Cox regression. Incidences of seizure freedom and seizure-related injury/hospital admissions and standardised mortality ratios were calculated. RESULTS: There were 1,375 patients with chronic epilepsy included; 361 were taking GBP, 1,050 LTG, and 713 VGB. The retention of GBP, LTG, or VGB was <40% at 6 years. Fewer than 4% of patients become seizure free while taking one of the drugs. There was no reduction in mortality or seizure-related injury/admission. CONCLUSIONS: The impact of these new AEDs on chronic epilepsy can be described only as modest. This view may be revised, however, as more experience is gained with new drugs in previously untreated patients.

Acetates↗
PubMed1999

Factors influencing the incidence of lamotrigine-related skin rash.

OBJECTIVE: To determine the incidences of serious and nonserious lamotrigine-related rash, determine the risk factors for lamotrigine-related rash, and evaluate the impact on the incidence of rash of the manufacturer's recommendation to reduce the starting dose of lamotrigine. METHODS: This was a retrospective case record survey at five tertiary referral epilepsy centers in the UK. The risk factors for lamotrigine-related rash were identified by logistic regression. The independent factors tested were gender, age, epilepsy type, concurrent medication, and starting dose of lamotrigine. The incidences of rash before and after the recommendation of reduction in starting dose were compared by chi2 analysis. RESULTS: A total of 1050 patients were included. The incidences of serious and nonserious rash were 1.1% (95% CI 0.5% to 1.8%) and 7% (95% CI 5.5% to 8.6%), respectively. Females were at higher risk of developing rash than were males, with a relative risk of 1.8 (95% CI 1.2 to 2.8). The starting dose of lamotrigine was reduced in response to the manufacturer's recommendation, and there was a significant reduction (p = 0.045) in the incidence of serious rash, from 1.5% (12/805) to 0% (0/245). However, there was no reduction in the overall incidence of lamotrigine-related rash, with 63/805 (8%) before and 23/245 (9%) after the recommendation. CONCLUSIONS: Failure to detect a reduction in the incidence of lamotrigine-related rash since the new (reduced) recommended starting dose of lamotrigine may arise from failure to reduce the starting dose below a critical threshold level, incomplete compliance with current recommendations, or insufficient sample size. The results of this and other studies show that the starting dose of lamotrigine is a significant factor affecting the incidence of rash; furthermore, this study also shows that significant reduction in the incidence of serious rash can be achieved by reducing the starting dose. Therefore, clinicians should not deviate from the recommendations.

Adolescent↗
PubMed1998

Protective heterologous antiviral immunity and enhanced immunopathogenesis mediated by memory T cell populations.

A basic principle of immunology is that prior immunity results in complete protection against a homologous agent. In this study, we show that memory T cells specific to unrelated viruses may alter the host's primary immune response to a second virus. Studies with a panel of heterologous viruses, including lymphocytic choriomeningitis (LCMV), Pichinde (PV), vaccinia (VV), and murine cytomegalo (MCMV) viruses showed that prior immunity with one of these viruses in many cases enhanced clearance of a second unrelated virus early in infection. Such protective immunity was common, but it depended on the virus sequence and was not necessarily reciprocal. Cell transfer studies showed that both CD4 and CD8 T cell populations from LCMV-immune mice were required to transfer protective immunity to naive hosts challenged with PV or VV. In the case of LCMV-immune versus naive mice challenged with VV, there was an enhanced early recruitment of memory phenotype interferon (IFN) gamma-secreting CD4(+) and CD8(+) cells into the peritoneal cavity and increased IFN-gamma levels in this initial site of virus replication. Studies with IFN-gamma receptor knockout mice confirmed a role for IFN-gamma in mediating the protective effect by LCMV-immune T cell populations when mice were challenged with VV but not PV. In some virus sequences memory cell populations, although clearing the challenge virus more rapidly, elicited enhanced IFN-gamma-dependent immunopathogenesis in the form of acute fatty necrosis. These results indicate that how a host responds to an infectious agent is a function of its history of previous infections and their influence on the memory T cell pool.

Adipose Tissue↗
PubMed1996

Interleukin-5 receptor alpha subunit gene regulation in human eosinophil development: identification of a unique cis-element that acts lie an enhancer in regulating activity of the IL-5R alpha promoter.

Further functional and biochemical characterization of the nuclear factor(s) which interacts with the EOS1 enhancer-like element in the IL-5R alpha promoter is currently in progress. Since different transcription factors recognize and interact with DNA in distinct fashions and with distinct structural motifs, we have modeled potential binding of the EOS1 factor to its cis-element based upon its methylation interference pattern (Fig. 2), using a cylindrical DNA helical projection (Fig. 6). Over a length of two helical turns, all nuclear protein contacts indicated by methylation interference map to one side of the DNA helix, suggesting that EOS1 binds in the major groove, across the minor groove, and on only one side of the helix. Further review of the model also reveals a potential diad symmetry for the binding site, suggestive of binding by a homodimer and consistent with the formation of the two DNA-protein complexes in our electrophoretic mobility shift experiments that could represent interactions with monomer versus dimer. Comparison of the EOS1 binding motif to similar models for the binding of other transcription factor families for which structural crystallographic and/or binding data is available suggests a similarity of the EOS1 complex to that of the bacterial helix-turn-helix phage lambda and 434 repressor-operator complexes, and the Cys4 zinc finger glucocorticoid response element (GRE) DNA-binding motifs, all of which show similar diad symmetry and binding in the major groove on one side of the DNA. The possibility that EOS1 functions as a GRE is being investigated, especially since there is a consensus AP-1 site at bp -440 to -432 of the IL-5R alpha promoter, immediately adjacent to the EOS1 binding site (see Fig. 5 in reference [36]) and AP-1/GRE interactions have been identified for composite response elements in the regulation of a number of different genes. The identification or cloning of EOS1, a potentially novel and eosinophil lineage-active transcription factor, should enhance our understanding of the processes involved in eosinophil development in particular and myeloid lineage commitment and differentiation in general.

Animals↗
PubMed1995

Retrospective study of vigabatrin and psychiatric behavioural disturbances.

Vigabatrin (VGB) is an effective add-on anti-epileptic drug. The major serious adverse drug reactions (ADRs) are behavioural and psychiatric disturbances. This study does not support the view that a previous history of behavioural and psychiatric features increases the risk of behavioural/psychiatric ADRs (relative risk 1.23, 95% CI 0.57-2.66, P = 0.61). The results suggest that a low starting does of vigabatrin does not reduce the risk of psychiatric and behavioural ADRs (P = 0.31) or prevent a more overt psychotic reaction from occurring.

Adolescent↗
PubMed1995

Rechallenge with lamotrigine after initial rash.

Eight patients rechallenged with lamotrigine after initial exposure which resulted in a skin rash are reported. On reintroduction of the lamotrigine, six of the patients had no recurrence of the rash. Of the other two patients, one had the occurrence of a mild fluctuating and qualitatively different skin rash on rechallenge. The other patient had developed a dose-related rash on initial challenge resulting in a dose reduction. The first attempt to re-increase the dose resulted in reappearance of the rash which again disappeared on dose reduction. However a further attempt to re-increase the dose did not result in reappearance of a rash. It is suggested that patients who experience a rash but good therapeutic response to lamotrigine might be considered for re-dosing.

Adolescent↗