Incorrect overdose management advice in the Physicians' Desk Reference

Assessment of Consistency of Drug Interaction Information in Drug Labels Among the United States, the United Kingdom, China, Japan, and Korea

Information gap in drug labeling among countries create challenges in therapeutic use of drugs. We aimed to evaluate the consistency of drug interaction information in drug labels among five countries. The study drugs were chosen from the commonly approved drug list in the US, UK, China, Japan, and Korea. The degree of agreement of drug interaction data was evaluated by kappa coefficient. Thirty-eight drugs were evaluated, and moderate degree of agreement was observed among all countries' labeling (κ = 0.43, 95% confidence interval (CI) = 0.41-0.46). The degree of agreement was the highest for the UK and Korea (κ = 0.71, 95% CI = 0.67-0.75) and the lowest for the UK and Japan (κ = 0.02, 95% CI = 0.00-0.04). Information regarding drug interactions listed in the studied drug labels was not in high agreement. International standardization of drug labeling is required to ensure safe drug therapy.

A review of pharmaceutical labeling for overdose treatment and toxicity data

PURPOSE

Adverse drug reactions, including overdose are a major cause of morbidity and mortality, yet clinical toxicology data is limited at the time of drug approval. This study was conducted to determine the quality of clinical toxicology data available for newly approved pharmaceuticals and time to labeling revisions.

METHODS

The labeling data of 100 new molecular entities (NMEs) approved between 2005 and 2011 was systematically reviewed. Initial approval data and subsequent labeling revisions were evaluated. The type and quality of clinical toxicology data present at the time of approval as well as the time to any labeling revisions was recorded. The presence of black box warnings and Risk Evaluation and Mitigation Strategies (REMS) was noted.

RESULTS

Of the NMEs reviewed, 27 had agent-specific toxicology data at approval. General recommendations for overdose management were made in 45 cases. Eight pharmaceuticals had toxicology updates during the study period. The average time to labeling revision was 27.4 months. Expanded adverse effects from case reports comprised 7/8 of the updates, and animal data was added in one case. Over a third of the NMEs had a black box warning or REMS status, suggesting potential for significant human toxicity.

CONCLUSIONS

Our study suggests there is a paucity of clinical toxicology data at the time of drug approval, with a notable lag time between initial approval and labeling revisions. This lack of toxicology data limits the ability of providers to optimally care for poisoned patients.

An Evaluation of Selected Herbal Reference Texts and Comparison to Published Reports of Adverse Herbal Events

OBJECTIVE

There has been a recent proliferation of medical reference texts intended to guide practitioners whose patients use herbal therapies. We systematically assessed six herbal reference texts to evaluate the information they contain on herbal toxicity.

METHODS

We selected six major herbal references published from 1996 to 2000 to evaluate the adequacy of their toxicological information in light of published adverse events. To identify herbs most relevant to toxicology, we reviewed herbal-related calls to our regional California Poison Control System, San Francisco division (CPCS-SF) in 1998 and identified the 12 herbs (defined as botanical dietary supplements) most frequently involved in these CPCS-SF referrals. We searched Medline (1966 to 2000) to identify published reports of adverse effects potentially related to these same 12 herbs. We scored each herbal reference text on the basis of information inclusiveness for the target 12 herbs, with a maximal overall score of 3.

RESULTS

The herbs, identified on the basis of CPCS-SF call frequency were: St John's wort, ma huang, echinacea, guarana, ginkgo, ginseng, valerian, tea tree oil, goldenseal, arnica, yohimbe and kava kava. The overall herbal reference scores ranged from 2.2 to 0.4 (median 1.1). The Natural Medicines Comprehensive Database received the highest overall score and was the most complete and useful reference source. All of the references, however, lacked sufficient information on management of herbal medicine overdose, and several had incorrect overdose management guidelines that could negatively impact patient care.

CONCLUSION

Current herbal reference texts do not contain sufficient information for the assessment and management of adverse health effects of botanical therapies.

Variability in the quality of overdose advice in Summary of Product Characteristics (SPC) documents: gut decontamination recommendations for CNS drugs

AIMS

Deliberate self-poisoning is a major cause of morbidity and mortality. The Summary of Product Characteristics (SPC) document is a legal requirement for all drugs, and Section 4.9 addresses the features of toxicity and clinical advice on management of overdose. The quality and appropriateness of this advice have received comparatively little attention.

METHODS

Section 4.9 of the SPC was examined for all drugs in the central nervous system (CNS) category of the British National Formulary. Advice concerning gut decontamination was examined with respect to specific interventions: induced vomiting, oral activated charcoal, gastric lavage, and other interventions. Data were compared with standard reference sources for clinical management advice in poisoning. These were graded 'A' if no important differences existed, 'B' if differences were noted but not thought clinically important, and 'C' if differences were thought to be clinically significant.

RESULTS

SPC documents were examined for 258 medications from 67 manufacturers. The overall agreement was 'A' in 23 (8.9%), 'B' in 28 (10.9%) and 'C' in 207 (80.2%). Discrepancies were due to inappropriate recommendation of induced emesis in 21.7% (95% confidence interval 17.1, 27.1), gastric lavage in 38.4% (32.7, 44.4), other gut decontamination in 5.8% (3.6, 9.4) and failure to recommend oral activated charcoal in 57.4% (51.1, 63.4).

CONCLUSIONS

Gut decontamination advice in SPC documents with respect to CNS drugs was inadequate. Possible reasons for the observed discrepancies and ways of improving the consistency of advice are proposed.

An exploratory study of drug abuse and dependence information in package inserts

Information about drug abuse and dependence from package inserts of centrally acting drugs was evaluated for content. Of the 77 labels reviewed, 40 were opiate agonists, 18 were stimulants, and the remainder fell into other selected categories. The amount of information ranged from 0-66 sentences, with greatest variability found in the opiate agonists (range 9-66). Information amount was significantly correlated with the year of drug approval (p < 0.001) but not with the latest label revision (p = 0.749). Information amount did not differ significantly with warning strength or schedule. While most package inserts explain physical dependence, tolerance, and withdrawal, there is a lack of information about psychological dependence. Variability in information about abuse and dependence potential is high and can affect prescribing by physicians and counseling by pharmacists, underscoring the need for further studies.

Barriers to contraceptive use in product labeling and practice guidelines

Many contraceptives are encumbered with potentially unnecessary restrictions on their use. Indeed, fear of side effects, fostered by alarmist labeling, is a leading reason that women do not use contraceptives. In the United States, hormonal methods currently require a prescription, although research suggests that women can adequately screen themselves for contraindications, manage side effects, and determine an appropriate initiation date, leaving little need for routine direct physician involvement. Sizing, spermicidal use, and length-of-wear limits burden users of cervical barriers and may be unnecessary. Despite recent changes in the labeling of intrauterine devices, clinicians commonly restrict use of this method and in some countries may limit the types of providers authorized to insert them. Although in some cases additional research is necessary, existing data indicate that evidence-based demedicalization of contraceptive provision could reduce costs and improve access.

Quality of poisoning management advice in the Monthly Index of Medical Specialties Annual

BACKGROUND

The Monthly Index of Medical Specialties (MIMS) contains Therapeutic Goods Administration-approved product information supplied by manufacturers. It is widely used by health-care professionals but is not specifically designed as a toxicology reference.

OBJECTIVES

To determine how widespread the use of MIMS is as a toxicology reference. To evaluate the quality of poisoning management advice it contains.

METHODS

First, a survey of 500 consecutive calls to the NSW Poison Information Centre (PIC) was undertaken asking health-care workers which toxicology references were consulted prior to calling and which references they would use if the PIC were not available. Second, a consensus opinion for poisoning management was obtained, for 25 medications which are either commonly involved in poisoning or potentially life-threatening in overdose, by review of 5 current toxicology references for contraindicated treatments, ineffective treatments and specific recommended treatments and antidotes. MIMS poisoning management advice was then compared with this toxicology consensus opinion.

RESULTS

In total, 276 doctors and 222 nurses were surveyed. Prior to calling the PIC 22.8% of doctors and 6.8% of nurses consulted MIMS. In total, 25.7% of doctors and 39.6% nurses stated they would use the MIMS for poisoning management advice if the PIC were not available. For the 25 drugs assessed, 14 contained inaccurate poisoning management: 1 recommended ineffective treatments and 14 omitted specific treatments or antidotes.

CONCLUSION

The MIMS is often used as a toxicology reference by physicians prior to calling the PIC. It contains a number of significant inaccuracies pertaining to management of poisonings and should not be used as a primary reference for poisoning advice.

Information deficits in the summary of product characteristics preclude an optimal management of drug interactions: a comparison with evidence from the literature

OBJECTIVE

To compare comprehensiveness and accuracy of drug interaction information in the German summary of product characteristics (SPC) with current evidence from the literature and to evaluate the SPC's usefulness with respect to management of drug interactions.

METHODS

Information on clinically relevant drug interactions was compared between the SPC and three standard information sources on drug interactions (DRUGDEX, Hansten/Horn's Drug Interactions Analysis and Management, Stockley's Drug Interactions) according to five consecutive criteria (inclusion, appropriateness of class labelling, effect description, management recommendation, explicit dose adjustment). Using medication data of an outpatient population (n=4,949), we determined what percentage of insufficiently characterized combinations indeed occurred in outpatients treated with combination drug therapy.

RESULTS

Only for 33% (192/579) of the evaluated combinations did SPCs provide drug interaction information equivalent to the evidence from the published literature. Of the clinically relevant drug interactions, 16% were completely missing and 51% were insufficiently characterized compared with standard sources. Explicit management recommendations were either missing or differed from standard sources in 18% of the evaluated pairs of compounds. Of these missing or insufficiently characterized combinations, 12% (47/387) were indeed prescribed to outpatients. Those drug combinations for which the interaction potential was not mentioned in the SPC were received by 0.6% (32/4,949) of patients, and 4% (192/4,949) of patients received combinations that had insufficiently characterized drug interactions.

CONCLUSIONS

If physicians only rely on SPC information for drug interactions, adverse events due to lacking management recommendations may occur. To meet the SPCs claim of being the basis of information for health professionals on how to use medicinal products safely and effectively, information on drug interactions should be thoroughly up-dated and expanded.

Dose individualisation in patients with renal insufficiency: does drug labelling support optimal management?

OBJECTIVE

An important information source for pharmacotherapy in populations at risk is drug labelling. We compared the recommendations for patients with renal insufficiency included in German drug labellings with evidence from the literature.

METHODS

From the 120 drugs with the highest turnover in a large university hospital, all drugs with pharmacokinetics independent of renal function (n=48) and those with substantial accumulation in renal failure (n=28) were identified. For both groups of compounds, pharmacokinetic and pharmacodynamic aspects relevant for dose individualisation in those with renal insufficiency were extracted from the literature and compared with the information given in the German drug labelling.

RESULTS

Over half of the labellings (15 of 26) of non-accumulating drugs without renal adverse drug reactions contained no dose recommendation for patients with renal insufficiency. The labelling of nephrotoxic compounds that do not accumulate included more frequently a recommendation to adapt the dose or to monitor than the labelling of drugs without nephrotoxic potential (15 of 22 versus 5 of 26, P=0.002). For over half of accumulating drugs (16 of 28), the dose given in the labelling depends primarily on creatinine clearance. The ratio between the labelling dose and the dose based on the pharmacokinetic concept to achieve identical plasma concentrations (Q0 concept) differed widely (0.4-2).

CONCLUSIONS

When renal failure had no impact on dosing, information was often missing. Such information is however important to differentiate, whether no dose adaptation is necessary or no information is available. If dose adjustment is required, application of a uniform concept is desirable.

Requirements for a successful implementation of drug interaction information systems in general practice: results of a questionnaire survey in Germany

OBJECTIVE

To determine drug interaction information requirements in general practice with respect to both content and mode of presentation.

METHODS

In a mail survey among 2,000 general practitioners in south-west Germany, we collected information on risk evaluation of drug interactions and combinations of concern, usage of and satisfaction with the current information sources, desirable content and mode of future presentation and demographic variables. Categorical variables were compared using chi2 test. Trends were analysed with Cochran-Armitage test and determinants of literature usage with logistic regression.

RESULTS

Response rate was 60.8%. The majority of general practitioners considered drug interactions a risk factor in prescribing (88.6%). For 18.2% of the drug combinations most frequently indicated as interacting, there was no published evidence of a clinically relevant interaction. More than half of the participants were dissatisfied with the information on severity, mechanism, and dose adjustment currently available in their sources. In particular, non-interacting alternatives were thought to be lacking (86.9%). Users of drug interaction software more frequently retrieved drug interaction information than non-users [odds ratio (OR) 1.95; 95% confidence intervals (CI) 1.50, 2.52], but only 28.6% of general practitioners had access to such systems. There was a significant trend towards electronic sources among younger physicians, but at present, 41.7% of general practitioners favour printed sources, and 8.8% would refuse to use electronic sources.

CONCLUSION

General practitioners wish for more informative support on drug interactions, especially concerning management. Despite a trend towards electronic information sources, printed documents are presently still required to reach all prescribers.

Is the sildenafil product information adequate to facilitate informed therapeutic decisions?

BACKGROUND

Optimal therapeutics and the prevention of adverse drug effects begin with complete information. When new drugs are released, the manufacturer's product information is the main and often only readily available source of drug information and, therefore, greatly influences treatment strategies. Thus, it is vital that the information in the package insert is not only complete, but also as relevant as possible for the great diversity of patients that physicians encounter.

OBJECTIVE

To review the product information for sildenafil for comprehensiveness and accuracy, with respect to whether the information is sufficient to facilitate optimal therapeutics and to prevent avoidable adverse events in the wide diversity of patients with erectile dysfunction seen in clinical practice.

DATA SOURCES

Sildenafil package inserts, unpublished information provided by the manufacturer, Food and Drug Administration reports, and articles retrieved through MEDLINE through March 2000.

DATA SYNTHESIS

Deficiencies or inaccuracies persist in the sildenafil product information regarding sildenafil's effects on blood pressure; potential drug interactions with cimetidine, protease inhibitors, some antihypertensive drugs, alcohol, and drugs that may competitively inhibit cytochrome P450 pathways; and recommended sildenafil doses for older patients.

CONCLUSIONS

For physicians to practice optimal therapeutics, adequate, clinically relevant drug information is required. Several brief changes and additions in the sildenafil product information would assist physicians in making therapeutic decisions regarding the use of sildenafil in a very diverse patient population and in avoiding preventable adverse events.