Novel oral anticoagulants: clinical pharmacology, indications and practical considerations

Background

Novel oral anticoagulants are approved in several indications: rivaroxaban, apixaban, and dabigatran for the prevention of venous thromboembolism after elective hip or knee replacement surgery, and edoxaban for hip or knee replacement surgery and hip fracture surgery (in Japan only); rivaroxaban for the treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT and PE; and rivaroxaban, apixaban, and dabigatran for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. These agents overcome some limitations of traditional anticoagulants, are suggested to have no requirement for routine coagulation monitoring, and are administered orally. Rivaroxaban, apixaban, and dabigatran have different pharmacological characteristics, and guidance is needed on optimum doses and dosing intervals and the effects of renal or hepatic impairment, age, food, and other drugs. Dabigatran has stricter prescribing advice than rivaroxaban or apixaban for patients with moderate-to-severe renal impairment. All three drugs have restrictions on use in patients with hepatic impairment. Apixaban requires twice-daily dosing in all indications, whereas rivaroxaban and dabigatran are dosed once- or twice-daily depending on indication. Although head-to-head comparisons are lacking, the novel oral anticoagulants may show favorable cost–benefit relations compared with traditional vitamin K antagonists or no therapy.

Aim

This review summarizes the pharmacology of rivaroxaban, apixaban, edoxaban, and dabigatran, and the indications for which they are approved. Issues regarding the optimization of the use of these anticoagulants for the management of thromboembolic disorders will also be discussed.     

Use of the recommended drug combination for secondary prevention after a first occurrence of acute coronary syndrome in France

Purpose

The recommended pharmacotherapy for secondary prevention of acute coronary syndrome (ACS) is long-term treatment with a combination of four therapeutic classes: beta-blockers, antiplatelet agents (including aspirin), statins or other lipid-lowering agents, and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. The aim of this study was to describe use and persistence of the recommended drug combination after the first occurrence of ACS in France.

Methods

This was a database cohort study of patients with first registration for ACS between 2004 and 2007 in a representative sample of the French healthcare insurance database (Echantillon Généraliste de Bénéficiaires, EGB). The drugs of interest were those recommended. Persistence was assessed for patients dispensed three or all four drug classes within 2 months following ACS. Discontinuation was defined by a gap of more than 6 weeks between two dispensations. The follow-up period was 24 months after ACS occurrence.

Results

Of 2,057 patients with incident ACS, 872 (42.4 %) had at least one dispensation of each of the four recommended drug classes, and 684 (33.3 %) had three of the four classes. Persistence to treatment at 24 months was 57.4 % (95 % CI [54.0-60.6]) for patients with four classes, and 55.5 % (95 % CI [51.6-59.1]) with three classes. Discontinuation of initial combination was higher in patients aged ?≥?65 years at ACS occurrence, those with associated ongoing chronic disease, and in those who did not suffer myocardial infarction.

Conclusions

Post-ACS secondary prevention in France is not optimal, especially in patients who did not have myocardial infarction.     

Off-label use of anticancer drugs in eastern Switzerland: a population-based prospective cohort study

Purpose

Prevalence data on the off-label use (OLU) of anticancer drugs are limited despite OLU being controversial for medical, pharmaco-economic, and ethical reasons. We therefore quantified and characterized the OLU of anticancer drugs and compared OLU based on the national drug label with international treatment recommendations.

Methods

We prospectively collected data on patients receiving systemic anticancer therapy between October and December 2012 at hospitals affiliated with the Eastern Switzerland Oncology Network. Individual data on patient characteristics, tumor disease, and systemic treatment were collected, and each individual treatment was compared with the national drug label and international treatment guidelines.

Results

A total of 985 consecutive patients receiving 1,737 anticancer drug treatments were included in the study. Overall, 32.4 % of all patients received at least one off-label drug, corresponding to 27.2 % of all anticancer drugs administered. Major reasons for OLU were the lack of approval for the specific disease entity (15.7 %) and modified application of the anticancer drug (10 %). OLU that was unsupported by the current European Society for Medical Oncology (ESMO) treatment recommendations was rare (6.6 %) but higher for bevacizumab (29.6 %) due to its use in treating advanced ovarian cancer beyond the second-line setting and advanced breast cancer beyond the first-line setting and for lenalidomide (22.6 %) due to its use in treating Non-Hodgkin lymphoma.

Conclusions

Based on data collected on our patient cohort, OLU of anticancer drugs in a European clinical setting applies to one-third of all cancer patients. ESMO-unsupported use of chemotherapies or molecularly-targeted drugs is rare, opposing concerns that the off-label use of newer anticancer drugs is a substantial clinical problem.     

Efficacy of d-penicillamine, a sequestering acetaldehyde agent, in the prevention of alcohol relapse-like drinking in rats

Rationale

Nowadays, very few approved anti-relapse treatments for alcoholism exist, and their overall efficacy can be considered moderate. An exciting rationale drug development opportunity for the treatment of chronic alcoholism is the use of acetaldehyde sequestering agents. Although these compounds are able to attenuate or prevent most of the behavioral and neurochemical effects of ethanol, the efficacy of acetaldehyde sequestration, by using agents such as d-penicillamine (DP), in relapse prevention has not been studied yet.

Objectives

The aim of this study was to analyze the effects of DP treatment on the alcohol deprivation effect (ADE) in long-term ethanol-experienced rats as a model of relapse behavior and measure drug plasma and brain levels during treatment.

Methods

Rats were subcutaneously implanted with mini-osmotic pumps delivering 0, 0.25, or 1 mg/h of DP during 1 week. The efficacy to prevent ADE was determined. DP plasma and brain levels achieved during its subcutaneous administration were measured. In a second experiment, animals received bilateral infusions of 0 or 1.5 μg/h of DP directly into pVTA, and the appearance of ADE was evaluated.

Results

One milligram per hour, but not 0.25 mg/h, DP infusion prevented ADE and reduced the total ethanol preference in animals. DP plasma concentrations associated with ADE suppression were around 3–4 μg/ml, and brain DP levels in these conditions were about 2–3 % of those found in plasma. Intra-pVTA DP administration also suppressed ADE.

Conclusion

DP is able to prevent alcohol-relapse-like drinking in rats suggesting that this drug may be a useful new tool in the management of relapse in alcohol-dependent patients.     

Repeated doses of methylone,a new drug of abuse,induce changes in serotonin and dopamine systems in the mouse

Rationale

Methylone, a new drug of abuse sold as “bath salts,” has similar effects to ecstasy or cocaine.

Objective

We have investigated changes in dopaminergic and serotoninergic markers, indicative of neuronal damage induced by methylone in the frontal cortex, hippocampus, and striatum of mice, according to two different treatment schedules.

Methods

Methylone was given subcutaneously to male Swiss CD1 mice at an ambient temperature of 26 °C. Treatment A consisted of three doses of 25 mg/kg at 3.5-h intervals between doses for two consecutive days, and treatment B consisted of four doses of 25 mg/kg at 3-h intervals in 1 day.

Results

Repeated methylone administration induced hyperthermia and a significant loss in body weight. Following treatment A, methylone induced transient dopaminergic (frontal cortex) and serotoninergic (hippocampus) impairment. Following treatment B, transient dopaminergic (frontal cortex) and serotonergic (frontal cortex and hippocampus) changes 7 days after treatment were found. We found evidence of astrogliosis in the CA1 and the dentate gyrus of the hippocampus following treatment B. The animals also showed an increase in immobility time in the forced swim test, pointing to a depressive-like behavior. In cultured cortical neurons, methylone (for 24 and 48 h) did not induce a remarkable cytotoxic effect.

Conclusions

The neural effects of methylone differ depending upon the treatment schedule. Neurochemical changes elicited by methylone are apparent when administered at an elevated ambient temperature, four times per day at 3-h intervals, which is in accordance with its short half-life.     

Dose adjustment in patients with liver cirrhosis: impact on adverse drug reactions and hospitalizations

Aim and background

To assess drug-related problems in patients with liver cirrhosis by investigating the prevalence of inadequately dosed drugs and their association with adverse drug reactions (ADRs) and hospitalizations.

Methods

This was a cross-sectional retrospective study assessing the dose adequacy of drug treatment of 400 cirrhotic patients at hospital admission based on the authors’ own previous studies and standard literature. The prevalence of total and preventable ADRs and of hospitalizations due to preventable ADRs was determined.

Results

Of all 1653 drugs prescribed (median 4 per patient), 336 (20 %) drugs were inadequately dosed in 184 patients. Overall, 210 ADRs (78 % preventable) occurred in 120 patients. Sixty-nine ADRs (33 % of all ADRs) were associated with inadequate drug dosing in 46 patients, of which 68 % were preventable. Nonsteroidal anti-inflammatory drugs and psycholeptics in particular frequently caused preventable ADRs associated with inadequate drug dosing. Inadequate drug dosing was more frequently associated with ADRs than adequate drug dosing, and patients receiving inadequately dosed drugs were more frequently admitted to the hospital due to ADRs. Hospitalization of patients receiving inadequately dosed drugs that caused preventable ADRs resulted in 94 additional hospital days.

Conclusion

In this retrospective study, inadequate drug dosing was associated with an increased frequency of ADRs, hospital admissions and hospital days in cirrhotic patients. We therefore conclude that the careful dosing of critical drugs is important in patients with liver cirrhosis.     

Outcomes of off-label drug uses in hospitals: a multicentric prospective study

Purpose

The study aims to assess the clinical evidence, outcome and cost of off-label use of medicines in the hospital setting.

Methods

A multicentric prospective cohort study of patients treated with off-label medicines was carried out in five tertiary hospitals from May 2011 to May 2012. Information on clinical characteristics of patients, drugs, outcomes and costs was collected. Patients were followed up to 6 months, and information was assessed by reviewing clinical records and interviewing physicians.

Results

A total of 226 patients were included. The median (interquartile range (IQR)) age of patients was 46 (33–62)?years; 59 % were women. Patients had received a median of three previous treatments, and a lack of response (or suboptimal) was the main reason for off-label use (72.1 %). A total of 232 off-label medicines were administered for 102 different indications. The most frequent medicines were rituximab (49; 21.1 %), botulinum toxin (25; 10.7 %) and omalizumab (14; 6.0 %). In 117 (51.8 %) cases, the level of clinical evidence for their use was low. A partial clinical response was observed in 82 patients (36.3 %), complete response in 71 (31.4 %) and stabilization in 11 (4.9 %). A total of 58 (26.5 %) patients had adverse effects, which in 11 (4.9 %) were severe. The median (IQR) cost per patient was €2,943.07 (541.9–5,872.54).

Conclusions

There was a high variability of off-label medicines and indications. Although the clinical evidence of off-label medicines was often low, clinical response was observed in many patients with previous multiple treatment failure, but at the expense of some adverse effects and a high cost. Registers of patients would be helpful for clinical decisions, although clinical trials are needed.     

Lithium carbonate in the management of cannabis withdrawal: a randomized placebo-controlled trial in an inpatient setting

Rationale

Preclinical studies suggest that lithium carbonate (lithium) can reduce precipitated cannabinoid withdrawal in rats by stimulating release of the neuropeptide oxytocin, while two open-label studies indicate lithium may ameliorate cannabis withdrawal symptoms in humans.

Objectives

This study was conducted to examine the efficacy and safety of lithium in the inpatient management of cannabis withdrawal and to determine whether lithium affects plasma oxytocin and the rate of elimination of plasma cannabinoids during abstinence.

Methods

Treatment-seeking cannabis-dependent adults (n?=?38) were admitted for 8 days to an inpatient withdrawal unit and randomized to either oral lithium (500 mg) or placebo given twice a day under double-blind randomized controlled trial (RCT) conditions. Primary outcomes included withdrawal severity [cannabis withdrawal scale (CWS)], rates of detoxification completion, and adverse events. Plasma cannabinoids, plasma oxytocin and serum lithium levels were measured repeatedly over admission. Follow-up research interviews were conducted at 14, 30, and 90 days postdischarge.

Results

Lithium did not significantly affect total CWS scores relative to placebo, although it significantly reduced individual symptoms of “loss of appetite,” “stomach aches,” and “nightmares/strange dreams.” No significant group differences were found in treatment retention or adverse events. Lithium did not increase plasma oxytocin levels nor influence the rate of elimination of cannabinoids. Both placebo- and lithium-treated participants showed reduced levels of cannabis use (verified by urinalysis) and improved health and psychosocial outcomes at 30- and 90-day follow-up relative to pretreatment baselines.

Conclusions

Despite the strong rationale for the present study, the efficacy of lithium over placebo in the management of cannabis withdrawal was not demonstrated.     

Integrating pharmacogenetics and therapeutic drug monitoring: optimal dosing of imatinib as a case-example

Purpose

To illustrate the interface of pharmacogenetics and therapeutic drug monitoring and to estimate target blood level for imatinib in the treatment of chronic myelogenous leukemia

Methods

A literature review to provide the evidence and necessary data to support the case for the interface, and quantitative analysis of the data to estimate the target blood level for imatinib using receiver operating curve (ROC; signal detection theory) analysis.

Results and discussion

One study estimated the optimum target level of imatinib in chronic myelogenous leukaemia as 1002 ng/mL (1.70 µM) through ROC analysis. Using individual-patient level data reported in another study and the same methodology, we estimated the target level as 0.95 µM. This is consistent with the results of other observational studies where dose–response was not the primary research objective. The available evidence suggests considerable inter-individual variability in dose–blood level response. In addition to the pharmacogenetics of metabolic enzymes and transporters, genetic mutations in genes participating in the signalling pathways may also account for the wide inter-individual variability in dose–blood level and dose–clinical response relationships.

Conclusion

A single-dose regimen for all pharmacogenetically eligible patients is not the optimum strategy for prescribing imatinib to patients with chronic myelogenous leukaemia. We suggest that therapeutic drug monitoring aimed at ensuring a trough target level of 1 µM would reduce the incidence of pseudo-resistance and hence personalize treatment and optimise response to imatinib. Persistent resistance can then be probed further for other causes.