Risk of major bleeding during concomitant use of antibiotic drugs and coumarin anticoagulants

Important considerations regarding the widespread use of doxycycline chemoprophylaxis against sexually transmitted infections

Rates of sexually transmitted infections (STIs) continue to rise across the world and interventions are essential to reduce their incidence. Past and recent studies have indicated this may be achieved using doxycycline post-exposure prophylaxis (PEP) and this has sparked considerable interest in its use. However, many unanswered questions remain as to its long-term effects and particularly potentially negative impact on human microbiomes and antimicrobial resistance among STIs, other pathogens, and commensals. In this review, we discuss seven areas of concern pertaining to the widespread use of doxycycline PEP.

Potential Association of Holidays on Internationalized Normalized Ratio in Warfarin-Users at a Multidisciplinary Clinic

Background

Warfarin is approved by the United States Food and Drug Administration for numerous clinical indications. The effectiveness of warfarin is highly dependent on the time-in-therapeutic range based on the international normalized ratio (INR) goal, which may be altered by changes in diet, alcohol intake, concomitant drugs, and travel, all of which are prevalent during the holidays. At this time, there are no published studies assessing the impact of holidays on INR in warfarin-users.

Methods

A retrospective chart review was conducted on all adult patients taking warfarin and managed at a multidisciplinary clinic. Patients were included if they were taking warfarin at home regardless of indication for anticoagulation. The INR pre- and post-holiday was assessed.

Results

Of a total of 92 patients, the mean age was 71.5 ± 14.3 years, and most patients were on warfarin with an INR goal of 2 - 3 (89%). There were significant differences in INR before and after Independence Day (2.55 vs. 2.81, P = 0.043) and Columbus Day (2.39 vs. 2.82, P < 0.001). The remaining holidays showed no significant differences in INR before and after each respective holiday.

Conclusions

There may be factors related to Independence and Columbus Day that are increasing the level of anticoagulation in warfarin-users. Although the mean post-holiday INR values, in essence, maintained within the typical target of 2 - 3, our study underscores the specialized care that is warranted in higher risk patients to prevent a continued increase in INR and subsequent toxicities. We hope our results would be hypothesis-generating and aid in the development of larger, prospective evaluations to validate the findings of our present study.

Tooth extraction without discontinuation of oral antithrombotic treatment: A prospective study

OBJECTIVE

To identify which variable, among those related to surgeries, to patients, or to antithrombotic treatments, could be considered as a bleeding indicator, and to analyze effectiveness of the local hemostatic protocols used, incidence of bleeding and healing index, depending on the number of extracted teeth, and patient antithrombotic treatment.

METHODS

Patients who underwent tooth extractions without interruption or reduction of antithrombotic treatment were prospectively followed. The exact two-tailed Fisher test was used to investigate the relationship between presence/absence of bleeding and type of hemostatic material. The effect of variables on the probability of bleeding and healing index was assessed by means of a multivariate logistic regression.

RESULTS

Two hundred and fifty-four procedures were analyzed. The incidence of bleeding was 15.75%. Severe bleeding occurred in only 6 patients (2.34%). The number of involved dental quadrants and pre-surgical antibiotic treatments were found to be positively related with bleeding. The use of vasoconstrictors during surgery resulted in a reduction of healing index scores.

CONCLUSIONS

Tooth extractions in patients on antithrombotic treatment were found to be free from significant bleeding although the involvement of more than 1 quadrant in the same procedure should be avoided.

Rationale and design of a European epidemiological post-authorization safety study (PASS) program: rivaroxaban use in routine clinical practice

BACKGROUND

Rivaroxaban is a highly selective factor Xa inhibitor approved for use in Europe for multiple indications.

STUDY DESIGN AND METHODS

The European rivaroxaban epidemiological post-authorization safety study (PASS) program consists of seven complementary observational studies. For four of the studies, data are obtained from health-care databases in the UK, the Netherlands, Germany, and Sweden. These database studies describe patterns of rivaroxaban use and patient characteristics over time, and investigate safety and effectiveness outcomes in new users of rivaroxaban using a cohort analysis and nested case-control analysis. To put these results in context, safety outcomes are also analyzed in new users of standard of care. In addition, a modified prescription event monitoring study conducted in the early post-launch phase in primary care, and two specialist cohort event monitoring studies that investigated rivaroxaban use in the secondary care hospital setting, systematically collected drug utilization and safety data via questionnaires completed by health-care professionals in the UK.

DISCUSSION

The European rivaroxaban epidemiological PASS is a comprehensive program of complementary studies generating evidence from patients treated in routine clinical practice that will expand our understanding of the risk-benefit profile of rivaroxaban.

Improving antibacterial prescribing safety in the management of COPD exacerbations: systematic review of observational and clinical studies on potential drug interactions associated with frequently prescribed antibacterials among COPD patients

Background

Guidelines advise the use of antibacterials (ABs) in the management of COPD exacerbations. COPD patients often have multiple comorbidities, such as diabetes mellitus and cardiac diseases, leading to polypharmacy. Consequently, drug–drug interactions (DDIs) may frequently occur, and may cause serious adverse events and treatment failure.

Objectives

(i) To review DDIs related to frequently prescribed ABs among COPD patients from observational and clinical studies. (ii) To improve AB prescribing safety in clinical practice by structuring DDIs according to comorbidities of COPD.

Methods

We conducted a systematic review by searching PubMed and Embase up to 8 February 2018 for clinical trials, cohort and case–control studies reporting DDIs of ABs used for COPD. Study design, subjects, sample size, pharmacological mechanism of DDI and effect of interaction were extracted. We evaluated levels of DDIs and quality of evidence according to established criteria and structured the data by possible comorbidities.

Results

In all, 318 articles were eligible for review, describing a wide range of drugs used for comorbidities and their potential DDIs with ABs. DDIs between ABs and co-administered drugs could be subdivided into: (i) co-administered drugs altering the pharmacokinetics of ABs; and (ii) ABs interfering with the pharmacokinetics of co-administered drugs. The DDIs could lead to therapeutic failures or toxicities.

Conclusions

DDIs related to ABs with clinical significance may involve a wide range of indicated drugs to treat comorbidities in COPD. The evidence presented can support (computer-supported) decision-making by health practitioners when prescribing ABs during COPD exacerbations in the case of co-medication.

Design, synthesis and in vivo evaluation of 3-arylcoumarin derivatives of rhenium(I) tricarbonyl complexes as potent antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA)

We have prepared a series of ten 3-arylcoumarin molecules, their respective fac-[Re(CO)₃(bpy)L]⁺ and fac-[Re(CO)₃(L⁀L)Br] complexes and tested all compounds for their antimicrobial efficacy. Whereas the 3-arylcoumarin ligands are virtually inactive against the human-associated pathogens with minimum inhibitory concentrations (MICs) > 150 μM, when coordinated to the fac-[Re(CO)₃]⁺ core, most of the resulting complexes showed remarkable antibacterial potency. Several rhenium complexes exhibit activity in nanomolar concentrations against Gram-positive pathogens such as Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA) and Enterococcus faecium. The molecules do not affect bacterial cell membrane potential, but some of the most potent complexes strongly interact with DNA, indicating it as a possible target for their mode of action. In vivo studies in the zebrafish model showed that the complexes with anti-staphylococcal/MRSA activity were non-toxic to the organism even at much higher doses of the corresponding MICs. In the zebrafish-MRSA infection model, the complexes increased the survival rate of infected fish up to 100% and markedly reduced bacterial burden. Moreover, all rescued fish developed normally following the treatments with the metallic compounds.

Drug-drug interactions with metronidazole and itraconazole in patients using acenocoumarol

PURPOSE

Various population-based cohort studies have shown that antimicrobial agents increase the risk of overanticoagulation in patients using coumarins. In this study, we assessed this association in hospitalized patients.

METHODS

We included all patients hospitalized in the Spaarne Gasthuis (Haarlem/Hoofddorp, the Netherlands), who started using an antimicrobial agent during acenocoumarol treatment or vice versa between 1 January 2015 and 1 July 2019. Patients were followed from start of concomitant therapy until 48 h after termination of the concomitant therapy or discharge, whichever came first. We analyzed the association between the antimicrobial agents and the risk of overanticoagulation, defined as an interpolated INR above 6, using Cox regression analysis. We corrected for multiple testing with the Bonferroni correction. Patients who started using acenocoumarol and amoxicillin/clavulanic acid were used as reference group.

RESULTS

In the study population, sixteen antimicrobial agents were started frequently concomitantly with acenocoumarol treatment. We included 2157 interaction episodes in 1172 patients. Patients who started using the combination of co-trimoxazole (HR 3.76; 95% CI 1.47-9.62; p = 0.006), metronidazole (HR 2.55; 95% CI 1.37-4.76; p = 0.003), or itraconazole (HR 4.11; 95% CI 1.79-9.45; p = 0.001) concomitantly with acenocoumarol treatment had an increased risk of overanticoagulation compared with patients using acenocoumarol and amoxicillin/clavulanic acid concomitantly. The associations for metronidazole (p = 0.045) and itraconazole (p = 0.015) remained statistically significant after correction for multiple testing.

CONCLUSION

Co-trimoxazole, metronidazole, and itraconazole increase the risk of overanticoagulation in patients using acenocoumarol. These combinations should be avoided if possible or otherwise acenocoumarol doses should be reduced and INR measured more frequently.

Drug interactions with antimalarial medications in older travelers: a clinical guide

Increasingly older adults are traveling to international destinations with malaria as a present risk. Surveillance systems indicate that older adults are more likely to suffer severe complications from malaria. The role of health care providers in selecting an appropriate medication for chemoprophylaxis or treatment of malaria in adults becomes more difficult as older adults undergo physiologic changes that alter the pharmacokinetic and pharmacodynamic nature of medications potentially causing increased drug interactions, adverse events and altered drug action. A comprehensive literature search from 1970 to present, with a focus on the past 10 years, was conducted on drug interactions, pharmacokinetic and pharmacodynamic effects on antimalarials in adults. It was determined that due to pharmacodynamic and pharmacokinetic changes in older adults, especially renal and cardiovascular, special attention should be given to this population of travelers in order to minimize the likelihood of adverse events or altered drug efficacy. Antimalarial drug-disease interactions in older adults can occur more often due to QT prolongation, exacerbation of hypoglycemia, decreased renal elimination and decreased hepatic metabolism. Older antimalarials have well-documented drug-drug interactions. Tafenoquine, a new antimalarial, requires glucose-6-phosphate dehydrogenase screening like primaquine and monitoring of new potential drug interaction with MATE1 and OCT2 substrates. While drug-drug interactions in older travelers may occur more often as a result of polypharmacy, data did not indicate adverse reactions or decreased drug efficacy is greater compared with younger adults. Overall, with the exception of recently approved tafenoquine, much is known about antimalarial drug and disease interactions, but new drugs are always being approved, requiring travel health providers to understand the pharmacokinetics and pharmacodynamics of antimalarial drugs to predict the impact on safety and efficacy in travelers. This guide provides travel health providers with valuable insights on potential outcomes associated with drug interactions in adults and recommended monitoring or drug regimen modification.

[Ocular surface aging: Pathophysiology and consequences for management]

All the components of the ocular surface and the lacrimal system are affected by aging. Aging induces lacrimal gland fibrosis, Meibomian gland dysfunction, loss of corneal sensitivity, decreased corneal cell density, impairment of immune defences, increased local inflammation associated with hormonal changes, conjunctivochalasis, lid abnormalities, etc. Furthermore, homeostasis of the ocular surface may be altered by various age-related systemic comorbidities and iatrogenic interventions. Altogether, aging is considered the most predominant risk factor for dry eye disease. The increasing knowledge of the pathophysiology of aging of the ocular surface allows for refinement of the management of ocular surface disease in the elderly.

Evidence for Clinical Implementation of Pharmacogenomics in Cardiac Drugs

OBJECTIVE

To comprehensively assess the pharmacogenomic evidence of routinely used drugs for clinical utility.

METHODS

Between January 2, 2011, and May 31, 2013, we assessed 71 drugs by identifying all drug/genetic variant combinations with published clinical pharmacogenomic evidence. Literature supporting each drug/variant pair was assessed for study design and methods, outcomes, statistical significance, and clinical relevance. Proposed clinical summaries were formally scored using a modified AGREE (Appraisal of Guidelines for Research and Evaluation) II instrument, including recommendation for or against guideline implementation.

RESULTS

Positive pharmacogenomic findings were identified for 51 of 71 cardiovascular drugs (71.8%), representing 884 unique drug/variant pairs from 597 publications. After analysis for quality and clinical relevance, 92 drug/variant pairs were proposed for translation into clinical summaries, encompassing 23 drugs (32.4% of drugs reviewed). All were recommended for clinical implementation using AGREE II, with mean ± SD overall quality scores of 5.18±0.91 (of 7.0; range, 3.67-7.0). Drug guidelines had highest mean ± SD scores in AGREE II domain 1 (Scope) (91.9±6.1 of 100) and moderate but still robust mean ± SD scores in domain 3 (Rigor) (73.1±11.1), domain 4 (Clarity) (67.8±12.5), and domain 5 (Applicability) (65.8±10.0). Clopidogrel (CYP2C19), metoprolol (CYP2D6), simvastatin (rs4149056), dabigatran (rs2244613), hydralazine (rs1799983, rs1799998), and warfarin (CYP2C9/VKORC1) were distinguished by the highest scores. Seven of the 9 most commonly prescribed drugs warranted translation guidelines summarizing clinical pharmacogenomic information.

CONCLUSION

Considerable clinically actionable pharmacogenomic information for cardiovascular drugs exists, supporting the idea that consideration of such information when prescribing is warranted.

The clinical significance of drug interactions between dermatological and psychoactive medications

Dermatological disease is commonly associated with psychological morbidity because of its visible nature. The burden of living with a chronic dermatological illness can contribute to the development of psychiatric illness and conversely, such conditions can result in the exacerbation of preexisting dermatological disease. It may also reduce a patient's compliance to treatment, result in loss to follow-up and a decreased level of functioning and quality of life. In dermatological patients who suffer from psychiatric symptoms, medical management used in their treatment may have significant interactions with systemic medications used to treat their dermatological condition. A well-known example of this is lithium's ability to exacerbate psoriasis. Such interactions can result in suboptimal treatment of their psychiatric and/or dermatological condition. The present paper aimed to review the literature for documented interactions and the level of clinical significance between dermatological and psychoactive medications. Such information is clinically relevant to the practicing dermatologist in order to minimize adverse effects and drug-drug interactions in dermatological patients.

Interaction of vitamin K antagonists and trimethoprim-sulfamethoxazole: ignore at your patient's risk

The aim of the study was to summarize available literature regarding the interaction between vitamin K antagonists (VKAs) and trimethoprim-sulfamethoxazole (co-trimoxazole, TMP-SMX), and to provide recommendations for managing patient risk from this interaction. Data sources were English-language publications in the medical literature and Internet databases. Relevant publications that directly or indirectly addressed the VKA-TMP-SMX interaction were selected and reviewed. The mechanism of the VKA-TMP-SMX interaction, frequency of concurrent use, effect on international normalized ratio (INR), increased risk of bleeding, and strategies for risk reduction are summarized. The concurrent use of VKA and TMP/SMX rapidly and consistently raises INR and is associated with a two- to five-fold increase in bleeding. Concurrent use of VKA and TMP-SMX should be avoided when possible. When VKA and TMP-SMX are co-prescribed, VKA dose reduction is usually required. Patient education as well as early and frequent INR monitoring is recommended to reduce risk from this interaction.

CYP2C9, VKORC1, CYP4F2, ABCB1 and F5 variants: influence on quality of long-term anticoagulation

AIMS

The study aims to evaluate the impact of genetic, demographic and clinical data on various measures of outcome of anticoagulation quality in patients.

PATIENTS AND METHODS

The study consisted of 310 patients receiving long-term oral anticoagulation therapy in our hospital. Apart from demographic and clinical variables, 21 SNPs (in 7 genes) were analyzed and compared with the outcomes of anticoagulation therapy. Various outcomes that were measured are; supra therapeutic INRs (INR >3, >6), anticoagulation stabilization, time taken to stabilize and proportion of INRs within (2-3), above (>3) and below (<2) therapeutic range.

RESULTS

Supra therapeutic INRs were influenced by CYP2C9*2, *3, CYP4F2 rs2108622, VKORC1-1639G>A, 1173C>T, rs55894764 along with concomitant drugs, smoking, body weight and height. Persistently fluctuating INRs/absolute instability correlated with VKORC1-1639G>A, gender, height and body mass index. The time taken to stabilize was associated with CYP4F2 rs2108622, CYP2C9*14, smoking, clinical indication and concomitant drugs. The overall distribution of INR was influenced by variants in CYP4F2 rs2108622, CYP2C9*3, rs9332230, VKORC1 1173C>T, -1639G>A, rs55894764, ABCB1 rs2032582, rs1128503, rs1045642 and F5 rs6025, age, smoking and concomitant drugs.

CONCLUSIONS

Knowledge of factors influencing the quality of long term anticoagulation can help clinicians to customize therapy either by dose variation, therapy with alternate choice of drug, concurrent heparin therapy and/or frequent INR monitoring.

Risk of bleeding and antibiotic use in patients receiving continuous phenprocoumon therapy. A case-control study nested in a large insurance- and population-based German cohort

There is major concern about coumarins interacting with various drug classes and increasing the risk of overanticoagulation. The aim of the study was to assess bleeding risk in patients with concurrent use of antibiotics and phenprocoumon, the most widely prescribed coumarin in many European countries. We conducted a nested-case-control study within a cohort of 513,338 incident and continuous phenprocoumon users ≥ 18 years of age using claims data of the statutory health insurance company AOK, covering 30% of the German population. Bleeding risk associated with current use of antibiotics for systemic use (antibacterials/antimycotics) was calculated using conditional logistic regression in 13,785 cases with a bleeding event and 55,140 risk-set sampling-matched controls. Bleeding risk associated with any antibacterial use in phenprocoumon users was significantly increased [odds ratio (OR) 2.37, 95% confidence interval (CI) 2.20-2.56]. The association was stronger for gastrointestinal than for cerebral bleeding (OR 2.09, 95% CI 1.84-2.38 and OR 1.34, 95% CI 1.03-1.74, respectively) and highest for other/unspecified bleeding (OR 2.92, 95% CI 2.62-3.26). Specific antibiotic classes were strongly associated with bleeding risk, e.g. cotrimoxazole (OR 3.86, 95% CI 3.08-4.84) and fluorquinolones (OR 3.13, 95% CI 2.74-3.59), among those highest for ofloxacin (OR 5.00, 95% CI 3.01-8.32). Combined use of phenprocoumon and antimycotics was not significantly associated with bleeding risk. Risk was not significantly modified by age (pint=0.25) or sex (pint=0.96). The association was stronger the closer the antibiotic exposure was to the bleeding event. Among continuous phenprocoumon users, antibiotics - particularly quinolones and cotrimoxazole - should be prescribed after careful consideration due to an increased bleeding risk. Close monitoring of international normalised ratio levels after prescription is recommended.

A new and efficient method for the synthesis of novel 3-acetyl coumarins oxadiazoles derivatives with expected biological activity

This paper presents the design of some novel 3-acetylcoumarin derivatives, based on minimal inhibitory concentration values (MICs) previously obtained against some microorganism cultures, Gram positive and negative bacteria and fungi. Some of these molecules exhibited antibacterial activity against S.aureus, comparable to that of the standard used (impinem). The invitro antioxidant activities of the novel 3-acetylcoumarin oxadiazoles were assayed by the quantitative 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity method. The compounds 5c,d proved to be the most active, showing the highest capacity to deplete the DPPH radicals. Structure elucidation of the products has been accomplished on the basis of IR, ¹H-NMR, ¹³C-NMR, NOESY and HMBC NMR data.

Major bleeding of the upper aerodigestive tract due to oral anticoagulant/antibiotic interactions

INTRODUCTION

Although a well-known complication in certain medical specialties, major bleeding due to the interaction between oral anticoagulants and antibiotics has been rarely reported concerning the upper aerodigestive tract. We report three cases of life-threatening bleeding of the upper aerodigestive tract in a context of antibiotic therapy in patients treated with oral anticoagulants.

CASE SERIES

Three male patients under coumadin anticoagulation therapy presented major bleeding in three different contexts (epistaxis, peritonsillar abscess and postoperative course after total laryngectomy). Surgical intervention for hemostasis was required in all cases, with coagulation correction in two. Complications were severe anemia (2/3) and chronic heart failure (1/3).

DISCUSSION/CONCLUSIONS

Interactions between two drugs commonly used in otolaryngology can result in major bleeding. The goal of this article is to raise practitioners' awareness of a potentially fatal, although rare, complication. We also review the main preventive strategies.

Bleeding risks and response to therapy in patients with INR higher than 9

An international normalized ratio (INR) higher than 9 is associated with a high risk of bleeding, yet most studies have focused on outpatients with lower INR. We retrospectively analyzed diagnosis, bleeding, treatment, and mortality in 162 patients with INR higher than 9, including inpatients and outpatients with and without warfarin treatment. Patients without anticoagulant treatment with INR higher than 9 had a poor prognosis, 67% experienced bleeding and 74% died. Among outpatients receiving warfarin with INR higher than 9, 11% had bleeding, but none died. Among inpatients receiving warfarin, 35% had bleeding and 17% died. Factors associated with bleeding were older age, renal failure, and alcohol use. Withholding warfarin or giving vitamin K treatment was ineffective at reducing the INR within 24 hours, whereas plasma infusion immediately dropped the INR to 2.4 ± 0.9. Because of underlying disease, comorbidities, and medications, hospitalized patients with INR higher than 9 may not respond quickly to withholding warfarin or vitamin K treatment, and plasma infusion may be needed to reduce INR and the risk of bleeding within 24 hours.

Synthesis and antibacterial activities of novel 4-hydroxy-7-hydroxy- and 3-carboxycoumarin derivatives

Coumarin derivatives are used as fluorescent dyes and medicines. They also have some notable physiological effects, including the acute hepatoxicity and carcinogenicity of certain aflatoxins, the anticoagulant action of dicoumarol, and the antibiotic activity of novobicin and coumerymycin A1. Because the number of drug resistant strains is increasing at present, the synthesis of new antibacterial compounds is one of the critical methods for treating infectious diseases. Therefore, a series of coumarin-substituted derivatives, namely 4-hydroxy- and 7-hydroxycoumarins, and 3-carboxycoumarins were synthesized. 4-Hydroxycoumarin derivatives 4a–c underwent rearrangement reactions. Both 4- and 7-hydroxycoumarins were treated with activated aziridines which produced series of ring-opened products 7, 8, 10, and 11. 3-Carboxy-coumarin amide dimer derivatives 14–21 were prepared by reacting aliphatic alkylamines and alkyldiamines with PyBOP and DIEA. In this study, we use a new technique called modified micro-plate antibiotic susceptibility test method (MMAST), which is more convenient, more efficient, and more accurate than previous methods and only a small amount of the sample is required for the test. Some of the compounds were produced by reactions with acid anhydrides and demonstrated the ability to inhibit Gram-positive microorganisms. The dimer derivatives displayed lower antibacterial activities.

Drug interactions--principles, examples and clinical consequences

BACKGROUND

Drug interactions can have desired, reduced or unwanted effects. The probability of interactions increases with the number of drugs taken. The high rate of prescribed drugs in elderly patients (65-year-old patients take an average of 5 drugs) increases the likelihood of drug interactions and thus the risk that drugs themselves can be the cause of hospitalization. According to meta-analyses, up to 7% of hospitalizations are drug-related.

METHODS

Selective literature review.

RESULTS

Drug interactions occur on pharmacodynamic and pharmacokinetic levels. Examples of pharmacodynamic interactions are simultaneous administration of a NSAID and phenprocoumon (additive interaction), or of aspirin and ibuprofen (antagonistic interaction). Pharmacokinetic interactions occur at the levels of absorption (e.g., levothyroxine and neutralizing antacids), elimination (e.g., digoxin and macrolides), and metabolism, as in the competition for cytochrome P450 enzymes (e.g., SSRIs and certain beta-blockers).

CONCLUSION

The systematic knowledge of drug interaction, in particular on the level of absorption, elimination, transport and drug metabolism may help to prevent adverse effects. Predicting pharmacodynamic interactions often demands a deeper understanding of the mechanisms of effect. Electronic prescribing systems are helpful.

Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

High-quality anticoagulation management is required to keep these narrow therapeutic index medications as effective and safe as possible. This article focuses on the common important management questions for which, at a minimum, low-quality published evidence is available to guide best practices.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

Most practical clinical questions regarding the management of anticoagulation, both oral and parenteral, have not been adequately addressed by randomized trials. We found sufficient evidence for summaries of recommendations for 23 questions, of which only two are strong rather than weak recommendations. Strong recommendations include targeting an international normalized ratio of 2.0 to 3.0 for patients on vitamin K antagonist therapy (Grade 1B) and not routinely using pharmacogenetic testing for guiding doses of vitamin K antagonist (Grade 1B). Weak recommendations deal with such issues as loading doses, initiation overlap, monitoring frequency, vitamin K supplementation, patient self-management, weight and renal function adjustment of doses, dosing decision support, drug interactions to avoid, and prevention and management of bleeding complications. We also address anticoagulation management services and intensive patient education.

CONCLUSIONS

We offer guidance for many common anticoagulation-related management problems. Most anticoagulation management questions have not been adequately studied.

Needs and barriers to improve the collaboration in oral anticoagulant therapy: a qualitative study

Background

Oral anticoagulant therapy (OAT) involves many health care disciplines. Even though collaboration between care professionals is assumed to improve the quality of OAT, very little research has been done into the practice of OAT management to arrange and manage the collaboration. This study aims to identify the problems in collaboration experienced by the care professionals involved, the solutions they proposed to improve collaboration, and the barriers they encountered to the implementation of these solutions.

Methods

In the Netherlands, intensive follow-up of OAT is provided by specialized anticoagulant clinics (ACs). Sixty-eight semi-structured face-to-face interviews were conducted with 103 professionals working at an AC. These semi-structured interviews were transcribed verbatim and analysed inductively. Wagner's chronic care model (CCM) and Cabana's framework for improvement were used to categorize the results.

Results

AC professionals experienced three main bottlenecks in collaboration: lack of knowledge (mostly of other professionals), lack of consensus on OAT, and limited information exchange between professionals. They mentioned several solutions to improve collaboration, especially solutions of CCM's decision support component (i.e. education, regular meetings, and agreements and protocols). Education is considered a prerequisite for the successful implementation of other proposed solutions such as developing a multidisciplinary protocol and changing the allocation of tasks. The potential of the health care organization to improve collaboration seemed to be underestimated by professionals. They experienced several barriers to the successful implementation of the proposed solutions. Most important barriers were the lack motivation of non-AC professionals and lack of time to establish collaboration.

Conclusions

This study revealed that the collaboration in OAT is limited by a lack of knowledge, a lack of consensus, and a limited information exchange. Education was identified as the best way to improve collaboration and considered a prerequisite for a successful implementation of other proposed solutions. Hence, the implementation sequence is of importance in order to improve the collaboration successfully. First step is to establish alignment regarding collaboration with all involved professionals to encounter the lack of motivation of non-AC professionals and lack of time.

Effect of ampicillin on bleeding time in very low birth-weight neonates during the first week after birth

OBJECTIVE

On the day of birth, the bleeding time of very low birth-weight (VLBW, <1500 g) neonates is generally prolonged, compared with term neonates. However, their bleeding time generally improves (shortens) over the next 7 to 10 days. Ampicillin can prolong the bleeding times of term and late preterm neonates, but its effect on VLBW neonates, who already have a somewhat prolonged bleeding time initially, is not known.

STUDY DESIGN

This was a prospective, single-centered, paired, before vs after test of the effect of ampicillin on template bleeding time and PFA-100 time (platelet function analyzer). Ampicillin was dosed at every 12 h intravenously, but decisions about discontinuation were made by the responsible clinician, independent of this study.

RESULT

A total of 20 VLBW neonates were studied. They ranged from 23- to 30-weeks gestation at birth and weighed 500 t 1410 g. Initial bleeding times averaged 166 s (95% CI, 138 to 194) and initial PFA-100 times averaged 119 s (95% CI, 90 to 148). In all, 10 had ampicillin dosing stopped after a shorter course (4 to 7 doses) and 10 had it continued for a longer course (10 to 15 doses). Blood cultures were sterile in all 20, and no differences in laboratory or clinical features were found between those treated with a shorter vs longer course. After stopping the ampicillin following a short course the bleeding times and PFA-100 times were similar to the initial values. However, after a longer course the bleeding times were prolonged by an average of 2 min, to 284 s (95% CI, 242 to 326; P=0.001 vs initial). The PFA-100 times also trended longer by an average of 44 s (P=0.07). The number of doses of ampicillin received in the first week correlated with the degree of prolongation in bleeding time (r=0.68).

CONCLUSION

Over the first week of life, a period when the bleeding time of VLBW neonates normally shortens, the opposite occurred (the bleeding time lengthened) if ≥ 10 doses of ampicillin were administered.

Drug interactions with phenprocoumon and the risk of serious haemorrhage: a nested case-control study in a large population-based German database

PURPOSE

Phenprocoumon is the most frequently used vitamin K antagonist in Germany. The aim of this study was to estimate the risk of serious bleeding as a result of the use of drugs with potential interaction with phenprocoumon.

METHODS

We conducted a nested case-control study in a cohort of 246,220 phenprocoumon users in the German Pharmacoepidemiological Research Database. Cases were patients hospitalised for haemorrhage of different kinds. Ten controls were matched to each case by health insurance, birth year and sex using incidence density sampling. Odds ratios (OR) with 95% confidence intervals (CI) of the risk of serious bleeding associated with combined use of phenprocoumon and potentially interacting drugs versus phenprocoumon alone were estimated using conditional logistic regression analysis. Our analyses considered multiple risk factors, such as bleeding history, other comorbidities or co-medication.

RESULTS

Our study included 2,553 cases and 25,348 matched controls. An increased risk of bleeding was observed for the combined use of phenprocoumon and clopidogrel vs phenprocoumon use alone (OR: 1.83, 95% CI: 1.41-2.36). Antibiotic drugs associated with an increased risk of haemorrhage in the population of phenprocoumon users included the group of quinolones with ORs ranging from 2.74 (95% CI: 1.80-4.18) for ciprofloxacin to 4.40 (95% CI: 2.45-7.89) for levofloxacin, amoxicillin plus clavulanic acid (OR: 2.99, 95% CI: 1.39-6.42) and cotrimoxazole (OR 3.57, 95% CI: 2.36-5.40). Among non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen and naproxen were associated with the highest risks.

CONCLUSION

Significantly elevated risks of major bleeding were mainly observed for drugs with known pharmacodynamic interaction with phenprocoumon, and less for drugs with possible pharmacokinetic interaction.

Differences in patient outcomes and chronic care management of oral anticoagulant therapy: an explorative study

BACKGROUND

The oral anticoagulant therapy - provided to prevent thrombosis - is known to be associated with substantial avoidable hospitalization. Improving the quality of the oral anticoagulant therapy could avoid drug related hospitalizations. Therefore, this study compared the patient outcomes between Dutch anticoagulant clinic (AC) regions taking the variation in chronic care management into account in order to explore whether chronic care management elements could improve the quality of oral anticoagulant therapy.

METHODS

Two data sources were combined. The first source was a questionnaire that was send to all ACs in the Netherlands in 2008 (response = 100%) to identify the application of chronic care management elements in the AC regions. The Chronic Care Model of Wagner was used to make the concept of chronic care management operational. The second source was the report of the Dutch National Network of ACs which contains patient outcomes of the ACs.

RESULTS

Patient outcomes achieved by the ACs were good, yet differences existed; for instance the percentage of patients in the appropriate therapeutic ranges varied from 67 to 87% between AC regions. Moreover, differences existed in the use of chronic care management elements of the chronic care model, for example 12% of the ACs had multidisciplinary meetings and 58% of the ACs had formal agreements with at least one hospital within their region. Patient outcomes were significantly associated with patient orientation and the number of specialized nurses versus doctors (p-values < 0.05). Furthermore, the overall extent to which chronic care management elements were applied was positively associated with patient outcomes (p-values < 0.05).

CONCLUSIONS

Substantial differences in the patient outcomes as well as chronic care management of oral anticoagulant therapy existed. Since our results showed a positive association between overall application of chronic care management and patient outcomes, additional research is needed to fully understand the working mechanism of chronic care management.