Potential perioperative cardiovascular outcomes in cannabis/cannabinoid users. A call for caution

Background

Cannabis is one of the most widely used psychoactive substances. Its components act through several pathways, producing a myriad of side effects, of which cardiovascular events are the most life-threatening. However, only a limited number of studies address cannabis's perioperative impact on patients during noncardiac surgery.

Methods

Studies were identified by searching the PubMed, Medline, EMBASE, and Google Scholar databases using relevant keyword combinations pertinent to the topic.

Results

Current evidence shows that cannabis use may cause several cardiovascular events, including abnormalities in cardiac rhythm, myocardial infarction, heart failure, and cerebrovascular events. Additionally, cannabis interacts with anticoagulants and antiplatelet agents, decreasing their efficacy. Finally, the interplay of cannabis with inhalational and intravenous anesthetic agents may lead to adverse perioperative cardiovascular outcomes.

Conclusions

The use of cannabis can trigger cardiovascular events that may depend on factors such as the duration of consumption, the route of administration of the drug, and the dose consumed, which places these patients at risk of drug-drug interactions with anesthetic agents. However, large prospective randomized clinical trials are needed to further elucidate gaps in the body of knowledge regarding which patient population has a greater risk of perioperative complications after cannabis consumption.

Drug Interactions Affecting Oral Anticoagulant Use

Oral anticoagulants (OACs) are medications commonly used in patients with atrial fibrillation and other cardiovascular conditions. Both warfarin and direct oral anticoagulants are susceptible to drug-drug interactions (DDIs). DDIs are an important cause of adverse drug reactions and exact a large toll on the health care system. DDI for warfarin mainly involve moderate to strong inhibitors/inducers of cytochrome P450 (CYP) 2C9, which is responsible for the elimination of the more potent S-isomer of warfarin. However, inhibitor/inducers of CYP3A4 and CYP1A2 may also cause DDI with warfarin. Recognition of these precipitating agents along with increased frequency of monitoring when these agents are initiated or discontinued will minimize the impact of warfarin DDI. Direct oral anticoagulants are mainly affected by medications strongly affecting the permeability glycoprotein (P-gp), and to a lesser extent, strong CYP3A4 inhibitors/inducers. Dabigatran and edoxaban are affected by P-gp modulation. Strong inducers of CYP3A4 or P-gp should be avoided in all patients taking direct oral anticoagulant unless previously proven to be otherwise safe. Simultaneous strong CYP3A4 and P-gp inhibitors should be avoided in patients taking apixaban and rivaroxaban. Concomitant antiplatelet/anticoagulant use confers additive risk for bleeding, but their combination is unavoidable in many cases. Minimizing duration of concomitant anticoagulant/antiplatelet therapy as indicated by evidence-based clinical guidelines is the best way to reduce the risk of bleeding.

Dry Needling and Antithrombotic Drugs

Many clinicians increasingly use dry needling in clinical practice. However, whether patients' intake of antithrombotic drugs should be considered as a contraindication for dry needling has not been investigated to date. As far as we know, there are no publications in analyzing the intake of antiplatelet or anticoagulant agents in the context of dry needling techniques. A thorough analysis of existing medications and how they may impact various needling approaches may contribute to improved evidence-informed clinical practice. The primary purpose of this paper is to review the current knowledge of antithrombotic therapy in the context of dry needling. In addition, reviewing guidelines of other needling approaches, such as electromyography, acupuncture, botulinum toxin infiltration, and neck ultrasound-guided fine-needle aspiration biopsy, may provide specific insights relevant for dry needling. Based on published data, taking antithrombotic medication should not be considered an absolute contraindication for dry needling techniques. As long as specific dry needling and individual risks are properly considered, it does not change the risk and safety profile of dry needling. Under specific circumstances, the use of ultrasound guidance is recommended when available.

Farmacogenômica e Doença Cardiovascular: Onde Estamos e Para Onde Vamos

A farmacogenômica (FGx) investiga a interação entre genes e medicamentos. Através da análise de regiões específicas do DNA, informações sobre o perfil de metabolização do paciente para um determinado fármaco podem ser descritas, assim como o perfil esperado de resposta ao tratamento. Objetivamente, esse tipo de teste pode ter impacto no tratamento de pacientes que não estão respondendo adequadamente a um determinado medicamento, seja pela ausência dos efeitos esperados ou em virtude do aparecimento de efeitos adversos. Neste cenário, o objetivo desta revisão é o de informar o cardiologista clínico sobre esta importante área do conhecimento e atualizá-lo sobre o tema, procurando preencher as lacunas no que diz respeito à relação custo-benefício da aplicação da FGx nas doenças cardiovasculares, além de fornecer informações para a implementação da terapia guiada pela FGx na prática clínica.

Clinically relevant drug interactions between newer antidepressants and oral anticoagulants

Introduction: This is a review of the drug interactions (DIs) between newer antidepressants and oral anticoagulants (OACs): vitamin K antagonists (VKAs) and direct-acting OACs (DOACs).Areas covered: Articles were obtained from PubMed searches performed for each of the newer antidepressants and oral anticoagulants. The basic pharmacokinetic and pharmacodynamic mechanisms for DIs with these drugs were summarized. Some newer antidepressants are inhibitors of a number of cytochrome P450 (CYP) isoforms and many antidepressants appear to have potential to impair serotonin platelet function and increase bleeding risk.Expert opinion: Clinicians should not forget that the DIs between newer antidepressants and VKAs can be potentially lethal. Among SSRIs, fluoxetine and fluvoxamine appear to be associated with the highest DI risk with warfarin, the most commonly prescribed VKA worldwide. Case reports featuring duloxetine, mirtazapine and trazadone suggested potential for interaction with warfarin. As CYP3A4 is an important metabolic pathway for all DOACs except dabigatran, it appears reasonable to recommend avoiding the co-prescription of fluoxetine and fluvoxamine (weak to moderate CYP3A4 inhibitors) and St John's wort (CYP3A4 inducer). Many package inserts for the newer antidepressants include a warning regarding an increased risk of bleeding events with concomitant use of these agents with OACs.

Pharmacokinetic interference of doxorubicin with tolbutamide due to reduced metabolic clearance with increased serum unbound fraction in rats

The study examined the effect of doxorubicin (DOX) on the hepatic expression of CYP2C and its activity for metabolizing tolbutamide (TB), a specific CYP2C substrate, in rats and whether the pharmacokinetics of tolbutamide were altered by doxorubicin exposure. The expression level of hepatic CYP2C11 was depressed 1 day after doxorubicin administration (day 1), and this effect on CYP2C11 was augmented on day 4. However, the expression level of hepatic CYP2C6 remained unchanged. The activity of tolbutamide 4-hydroxylation in hepatic microsomes was decreased with time following doxorubicin administration. Regarding the enzyme kinetic parameters for tolbutamide 4-hydroxylation on day 4, the maximum velocity (V_max ) was significantly lower in the DOX group than that in the control group, while the Michaelis constant (K_m ) was unaffected. On pharmacokinetic examination, the total clearance (CL_tot ) of tolbutamide on day 4 was increased, despite the decreased metabolic capacity. On the other hand, the serum unbound fraction (f_u ) of tolbutamide was elevated with a reduced serum albumin concentration in the DOX group. Contrary to CL_tot , CL_tot /f_u , a parameter approximated to the hepatic intrinsic clearance of unbound tolbutamide, was estimated to be significantly reduced in the DOX group. These findings indicate that the metabolic capacity of CYP2C11 in the liver is depressed time-dependently by down-regulation after doxorubicin exposure in rats, and that the decreased enzyme activity of TB 4-hydroxylation in hepatic microsomes reflects the pharmacokinetic change of unbound tolbutamide, not total tolbutamide, in serum.

The critical interaction between valproate sodium and warfarin: case report and review

BACKGROUND

Valproic acid (VPA) and warfarin are commonly prescribed for patients with epilepsy and concomitant atrial fibrillation (AF). When VPA and warfarin are prescribed together, clinically important interactions may occur. VPA may replace warfarin from the protein binding sites and result in an abnormally increased anticoagulation effect. This is commonly underrecognized.

CASE PRESENTATION

In our case, we report a 78-year-old woman with a glioma who presented with status epilepticus. The patient was on warfarin to prevent cardiogenic embolism secondary to AF. Intravenous loading dose of VPA was administered, but international normalized ratio (INR) increased significantly to 8.26. Intravenous vitamin K1 was then given and the patient developed no overt bleeding during the hospitalization.

CONCLUSION

By reviewing the literature and discussing the critical interaction between valproate sodium and warfarin, we conclude that intravenous VPA and the co-administrated warfarin may develop critical but underrecognized complications due to effects on the function of hepatic enzymes and displacement of protein binding sites.

Deliberate self-poisoning with long-acting anticoagulant rodenticides

Long-acting anticoagulant rodenticides, also called superwarfarins, are known for their greater potency, longer half-life and delayed onset of symptoms. Cases of superwarfarin poisoning can pose a diagnostic and clinical challenge due to a wide array of presentations and prolonged severe coagulopathy requiring months of high-dose oral vitamin K therapy. The most common presentation of long-acting anticoagulant rodenticide poisoning is mucocutaneous bleeding, with other common presentations including haematuria, gingival bleeding, epistaxis and gastrointestinal bleeding. We discuss a case of deliberate self-poisoning with long-acting anticoagulant rodenticides presenting with haematuria and coagulation values above measurable limits. This case is important as it required immediate and maintenance therapy in order to prevent profound bleeding, as well as the evaluation of the patient's psychosocial factors to ensure medical compliance and to prevent refractory complications or repeated self-harm.

A systematic review of St. John's wort for major depressive disorder

BACKGROUND

This systematic review evaluated St. John's wort (SJW) for the treatment of Major Depressive Disorder (MDD). The objectives of this review are to (1) evaluate the efficacy and safety of SJW in adults with MDD compared to placebo and active comparator and (2) evaluate whether the effects vary by severity of MDD.

METHODS

We searched PubMed, CINAHL, PsycINFO, CENTRAL, Embase, AMED, MANTIS, Web of Science, and ICTRP and existing reviews to November 2014. Two independent reviewers screened the citations, abstracted the data, and assessed the risk of bias. We included randomized controlled trials (RCTs) examining the effect of at least a 4-week administration of SJW on depression outcomes against placebo or active comparator in adults with MDD. Risk of bias was assessed using the Cochrane Risk of Bias tool and USPSTF criteria. Quality of evidence (QoE) was assessed using the GRADE approach.

RESULTS

Thirty-five studies examining 6993 patients met inclusion criteria; eight studies evaluated a hypericum extract that combined 0.3 % hypericin and 1-4 % hyperforin. The herb SJW was associated with more treatment responders than placebo (relative risk [RR] 1.53; 95 % confidence interval [CI] 1.19, 1.97; I(2) 79 %; 18 RCTs; N = 2922, moderate QoE; standardized mean differences [SMD] 0.49; CI 0.23, 0.74; 16 RCTs; I(2) 89 %, N = 2888, moderate QoE). Compared to antidepressants, SJW participants were less likely to experience adverse events (OR 0.67; CI 0.56, 0.81; 11 RCTs; moderate QoE) with no difference in treatment effectiveness (RR 1.01; CI 0.90, 1.14; 17 RCTs, I(2) 52 %, moderate QoE; SMD -0.03; CI -0.21, 0.15; 14 RCTs; I(2) 74 %; N = 2248, moderate QoE) in mild and moderate depression.

CONCLUSIONS

SJW monotherapy for mild and moderate depression is superior to placebo in improving depression symptoms and not significantly different from antidepressant medication. However, evidence of heterogeneity and a lack of research on severe depression reduce the quality of the evidence. Adverse events reported in RCTs were comparable to placebo and fewer compared with antidepressants. However, assessments were limited due to poor reporting of adverse events and studies were not designed to assess rare events. Consequently, the findings should be interpreted with caution.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015016406 .

Review on mechanisms and interactions in concomitant use of herbs and warfarin therapy

The effectiveness of warfarin, an oral anticoagulant originally derived from a plant, is strongly affected by patient's characteristics such as the age, presence of comorbidities, and concomitant use of another drug. Warfarin has the potential to interact with many drugs, medicinal plants, and food, which increases the risk of adverse events. A critical analysis of scientific literature was conducted to assess the interferences of medicinal plants with blood haemostasis and then with warfarin anticoagulation. We found 58 different plants that may alter the blood haemostasis and anticoagulation with warfarin. The herbs that showed the greatest potential to interact with warfarin include garlic, ginger, ginkgo, St. John's wort, and ginseng, i.e. plants normally consumed as food and also used for therapeutic purposes. The interactions between drugs and herbs are varied because of the complex chemical matrix of plants. Mainly coumarins, quinones, xanthones, terpenes, lignans, and vitamin K showed significant influence on warfarin treatment. In general, these plants can potentiate the effect of warfarin by stimulating anticoagulation in multiple ways, and the clinical outcome associated with this interaction is the increase of bleeding risk. Moreover, potential interactions between herbal products and drugs are a safety concern, especially for drugs with a narrow therapeutic index or for patients receiving drug treatment for chronic diseases, and both of these apply to warfarin pharmacotherapy. Therefore, this review article summarises the data on the influence of medicinal plants on warfarin treatment and analyses this information in view of the interaction targets. The relevant plants were categorised according to their target, and their effects are discussed in order to organise the isolated information and to highlight the need of further discussion and new studies on the safety of herbal medicines and warfarin.

Valproic Acid for Treatment of Hyperactive or Mixed Delirium: Rationale and Literature Review

BACKGROUND

Delirium is the most often encountered psychiatric diagnosis in the general hospital, with an incidence of up to 82% in the intensive care unit setting and with significant detrimental effects on patients' morbidity and mortality. Antipsychotics are often considered the first-line pharmacological treatment of delirium, but their use may be limited by lack of efficacy, existing contraindications (e.g., prolonged QTc intervals), or resulting side effects (e.g., akathisia). Valproic acid (VPA) is a potential alternative or adjunct treatment. It has multiple mechanisms of action, including effects on neurotransmitter modulation, neuroinflammation, oxidative stress, and transcription, all of which are implicated in the pathophysiology of delirium. Yet, data on the use of this agent in delirium are limited.

OBJECTIVE/METHODS

In this article, we discuss postulated mechanisms of VPA action that provide a theoretical basis for its use in the treatment of hyperactive and mixed type delirium, based on the known and theorized pathophysiology of delirium. We also discuss potential side effects and considerations with use of VPA.

CONCLUSIONS

VPA has multiple modulatory effects on neurotransmitter systems, inflammation, oxidative stress, and transcriptional changes implicated in pathophysiology of delirium. When carefully chosen, VPA can be an effective and well-tolerated treatment option for the management of hyperactive and mixed type delirium. Randomized controlled trials are needed to establish tolerability and efficacy of VPA for treatment of delirium.

Independent predictors of delay in emergence from general anesthesia

Some patients with intellectual disabilities spend longer than others in emergence from ambulatory general anesthesia for dental treatment. Although antiepileptic drugs and anesthetics might be involved, an independent predictor for delay of the emergence remains unclear. Thus, a purpose of this study is to identify independent factors affecting the delay of emergence from general anesthesia. This was a retrospective cohort study in dental patients with intellectual disabilities. Patients in need of sedative premedication were removed from participants. The outcome was time until emergence from general anesthesia. Stepwise multivariate regression analysis was used to extract independent factors affecting the outcome. Antiepileptic drugs and anesthetic parameters were included as predictor variables. The study included 102 cases. Clobazam, clonazepam, and phenobarbital were shown to be independent determinants of emergence time. Parameters relating to anesthetics, patients' backgrounds, and dental treatment were not independent factors. Delay in emergence time in ambulatory general anesthesia is likely to be related to the antiepileptic drugs of benzodiazepine or barbiturates in patients with intellectual disability.

The usefulness of genotyping cytochrome P450 enzymes in the treatment of depression

INTRODUCTION

Pharmacogenomics, which is derived from genome-wide association studies (GWAS), and pharmacogenetics, which involves candidate gene association studies (CGASs), are proving increasingly useful in personalized cancer care. Research in psychiatric applications has primarily involved genetic polymorphisms of P450 CYP enzymes, which mediate oxidative metabolism, particularly CYP2D6, which is involved in the metabolism of at least 30 psychotropic medications. This work has been supplemented by genotyping of proteins for the drug efflux pump P-glycoprotein (P-gp), serotonin receptors, and the serotonin reuptake pump.

AREAS COVERED

This review covers principles of pharmacogenetics and pharmacogenomics, previous analyses of pharmacokinetic and pharmacodynamics studies, newer studies of the predictive value of genetic testing in the treatment of depression, obstacles to implementation of genetic testing in predicting treatment response and side effects, and suggestions for future research.

EXPERT OPINION

Studies of multiple genes have produced some positive results in groups of patients, but genetic testing does not yet seem to be applicable to choosing medications for a specific patient.

An overview of clinically significant drug interactions between medications used to treat psychiatric and medical conditions

Prescription rates and polypharmacy are increasing, resulting in a greater potential for drug interactions. Psychiatric patients frequently have co-morbid medical conditions, which further increases the risk of polypharmacy and drug interactions. Drug interactions that affect drugs with narrow therapeutic windowsare of particular concern. This review presents some of these drug interactions and provides strategies for identifying and resolving them.

Probable Interaction Between Warfarin and Divalproex Sodium

Objective: A potential interaction between warfarin and divalproex sodium is described. Case Summary: A 65-year-old Arabic-speaking Egyptian woman chronically anticoagulated with warfarin for atrial fibrillation and a history of stroke presented to the anticoagulation clinic with an elevated international normalized ratio (INR) of 3.2. This was an increase of 1.4 over her previous INR of 1.8 only 9 days prior. Discussion with the patient’s daughter revealed the addition of divalproex sodium (a derivative of valproic acid) 250 mg twice daily to the patient’s medication regimen 6 days prior. Other contributing factors that could cause an elevated INR were ruled out. The patient’s total weekly dose (TWD) of warfarin was decreased from 22.5 mg to 20 mg, and the patient was instructed to return for a repeat INR in 1 week. On the day the patient was due to return for a repeat INR, she was admitted to the hospital and her INR was 2.2 on admission. Based on medication reconciliation information, the patient had decreased her warfarin TWD as instructed and had self-discontinued the divalproex sodium due to intolerable fatigue. During this time, the patient received no additional divalproex sodium. She was instructed to resume her previous TWD of warfarin of 22.5 mg on discharge and subsequently had a therapeutic INR (2.6) 11 days later. Discussion: Warfarin and divalproex sodium are commonly prescribed agents with few case reports to describe their interaction. Primary literature supports a multifactorial mechanism, including CYP450 metabolism inhibition and protein-binding displacement, both of which can result in an elevated INR. Use of the Drug Interaction Probability Scale indicated a probable interaction between warfarin and divalproex sodium. Conclusions: Patients receiving concurrent warfarin and divalproex sodium therapy should be monitored closely for changes in INR values as the combination may increase the INR and put the patient at increased risk for bleeding.