Administration of tramadol or ibuprofen increases the INR level in patients on warfarin

Tramadol-warfarin interaction

Overview of: Danbury G Susan Gladstone: Prevention of future deaths report [online], 2023. Available: https://www.judiciary. uk/​prevention-​of-​future-​death-​reports/​susan-​gladstone-​prevention-​offuture-​deaths-​report/ [Accessed 8 January 2024].

Use of tramadol and the risk of bleeding complications in patients on oral anticoagulants: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to determine whether tramadol intake increases the risk of bleeding in patients receiving oral anticoagulants.

METHODS

This systematic review was registered on PROSPERO, CRD42022327230. We searched PubMed and Embase up to 14 April 2022, and references and citations of included studies were screened. Comparative and non-comparative studies exploring bleeding complications among adult patients on oral anticoagulants and tramadol were included. Risk of bias was assessed using an adaptation of the Drug Interaction Probability Scale for case reports and case series and the Newcastle-Ottawa Scale for comparative studies. A meta-analysis was performed for the risk of serious bleeding (leading to hospitalisation or death) associated with tramadol in patients on vitamin K antagonists.

RESULTS

A total of 17 studies were included: 1 case series, 12 case reports, 2 case-control studies and 2 cohort studies. Most of the studies described tramadol-vitamin K antagonists' concomitant use; one case-control study also assessed dabigatran and rivaroxaban; one case report involved dabigatran. Among case reports/series, a total of 33 patients had a bleeding complication while using tramadol and an oral anticoagulant. The 4 comparative studies reported an increased bleeding risk during tramadol and vitamin K antagonist intake which was statistically significant in one study; the pooled risk ratio of serious bleeding was 2.68 [95% CI: 1.45 to 4.96; p < 0.001].

CONCLUSION

This systematic review confirms an association between tramadol use and risk of bleeding in patients on vitamin K antagonists. Evidence is too limited to assess whether this risk extends to patients on direct oral anticoagulants, and further studies are needed.

Frailty and Co-Prescribing of Potentially Interacting Drugs in New Users of Warfarin

Background

Warfarin is underutilised in frail older people because of the fear of bleeding complications. Drug interactions are an independent bleeding risk factor. However, the extent to which potential drug interactions are taken into account at warfarin therapy initiation in frail patients is not known.

Objective

The objective of this study was to investigate the use of potentially interacting drugs increasing the bleeding risk before and after warfarin initiation in frail and non-frail patients.

Methods

We conducted an observational study including inpatients aged ≥ 60 years initiated on warfarin in a tertiary hospital in Adelaide, South Australia. Frailty status was assessed with the Reported Edmonton Frail Scale. Medication charts were reviewed before and after warfarin initiation.

Results

In total, 151 patients (102 non-frail and 49 frail) were included. Before warfarin initiation, the use of clopidogrel and acetaminophen was more common in frail patients compared with non-frail patients (25.5% vs 10.2%, p = 0.0135, 63.8% vs 35.7% p = 0.0014, respectively). The use of non-steroidal anti-inflammatory drugs, 9.2% in non-frail patients and 6.4% in frail patients before warfarin initiation, was completely stopped after warfarin initiation in both groups. The use of antiplatelet drugs decreased from 56.1% in non-frail patients and 66.0 % in frail patients to 12.2% and 14.9%, respectively. Instead, the use of drugs affecting the metabolism of warfarin or vitamin K increased in both groups. No statistically significant difference was seen in the exposure to interacting drugs between study groups after warfarin initiation. Acetaminophen, senna glycosides and cytochrome P450 2C9 inhibiting drugs were the most common interacting drugs at discharge used in 49.0%, 18.4% and 20.4% of non-frail patients and 53.2%, 29.8% and 19.1% of frail patients, respectively.

Conclusions

The overall frequency of potential drug interactions was moderate and frail patients were not exposed to warfarin drug interactions more often than non-frail patients. Further studies in larger study populations are required to verify these results.

Electronic supplementary material

The online version of this article (10.1007/s40266-020-00755-0) contains supplementary material, which is available to authorized users.

Bleeding and Elevated INR Secondary to Concomitant Tramadol and Warfarin Administration

The exact mechanism of a tramadol-warfarin interaction has not been fully determined. The authors present a case study that illustrates the risks.

[Intracranial hemorrhage and oral anticoagulants of patients treated between 2011 and 2013 at the Nancy Regional University Hospital]

OBJECTIVE

To perform a descriptive analysis of intracranial hemorrhages of patients treated with an antivitamin K (fluindione, acenocoumarol or warfarin) or a direct oral anticoagulant (dabigatran, rivaroxaban or apixaban) at the Nancy Regional University Hospital.

MATERIAL AND METHOD

The study period was from January 2011 to December 2013 and the computerized data (Programme de Médicalisation des Systèmes d'Information) of our hospital was accessed to identify the patients. Clinical data were obtained from the patients' files. Regional healthcare system was queried for reimbursement data.

RESULTS

Among the 157 identified cases of intracranial hemorrhage, 153 were related to antivitamin K, primarily fluindione (n=127), and only 4 to a direct oral anticoagulant (3 dabigatran and 1 rivaroxaban). During the same period, regional data indicated that 65,345 patients had had at least one reimbursement of antivitamin K and 20,983 patients one reimbursement of an oral direct anticoagulant. In our series, the most frequent intracranial hemorrhages were subdural hematoma (chronic in 65 cases, acute in 50 cases) and intraparenchymal hemorrhage (20 cases). The global mortality rate was 20.2% but varied with the site of hemorrhage. In multivariate analysis, the two risk factors of fatal outcome were coma on admission (OR 6.2; 95%CI: 2.6-15.0) and a history of previous intracranial hemorrhage (OR 13,4; 95% CI: 1,6-114,9).

CONCLUSION

During the 2011-2013 period, antivitamin K, especially fluindione, was the most frequently involved anticoagulants in intracranial hemorrhages with hospitalization at our Regional University Hospital. Coma on admission and a history of previous intracranial hemorrhage were the two main risk factors for fatal outcome.

Identifying Drug-Drug Interactions by Data Mining: A Pilot Study of Warfarin-Associated Drug Interactions

BACKGROUND

Knowledge about drug-drug interactions commonly arises from preclinical trials, from adverse drug reports, or based on knowledge of mechanisms of action. Our aim was to investigate whether drug-drug interactions were discoverable without prior hypotheses using data mining. We focused on warfarin-drug interactions as the prototype.

METHODS AND RESULTS

We analyzed altered prothrombin time (measured as international normalized ratio [INR]) after initiation of a novel prescription in previously INR-stable warfarin-treated patients with nonvalvular atrial fibrillation. Data sets were retrieved from clinical work. Random forest (a machine-learning method) was set up to predict altered INR levels after novel prescriptions. The most important drug groups from the analysis were further investigated using logistic regression in a new data set. Two hundred and twenty drug groups were analyzed in 61 190 novel prescriptions. We rediscovered 2 drug groups having known interactions (β-lactamase-resistant penicillins [dicloxacillin] and carboxamide derivatives) and 3 antithrombotic/anticoagulant agents (platelet aggregation inhibitors excluding heparin, direct thrombin inhibitors [dabigatran etexilate], and heparins) causing decreasing INR. Six drug groups with known interactions were rediscovered causing increasing INR (antiarrhythmics class III [amiodarone], other opioids [tramadol], glucocorticoids, triazole derivatives, and combinations of penicillins, including β-lactamase inhibitors) and two had a known interaction in a closely related drug group (oripavine derivatives [buprenorphine] and natural opium alkaloids). Antipropulsives had an unknown signal of increasing INR.

CONCLUSIONS

We were able to identify known warfarin-drug interactions without a prior hypothesis using clinical registries. Additionally, we discovered a few potentially novel interactions. This opens up for the use of data mining to discover unknown drug-drug interactions in cardiovascular medicine.

Theoretical study of optical activity of 1:1 hydrogen bond complexes of water with S-warfarin

The molecular interaction between S-warfarin (SW) and a single water molecule was investigated using the B3LYP method at 6-311++G(d,p) basis set. The vibrational spectra of the optimized complexes have been investigated for stabilization checking. Quantum theories of atoms in molecules, natural bond orbitals, molecular electrostatic potentials and energy decomposition analysis methods have been applied to analyze the intermolecular interactions. The intermolecular charge transfer in the most stable complex is in the opposite direction from those in the other complexes. The optical spectra and the hyperpolarizabilities of SW-water hydrogen bond complexes have been computed.

Adherence to guidelines for avoiding drug interactions associated with warfarin--a Nationwide Swedish Register Study

PURPOSE

To investigate the extent to which clinicians avoid well-established drug-drug interactions associated with warfarin. We hypothesised that clinicians would avoid combining non-steroidal anti-inflammatory drugs (NSAIDs), tramadol and sulfamethoxazole with warfarin.

METHODS

A cross-sectional analysis of nationwide dispensing data was performed in Swedish individuals 18 years or older (n =  7,563,649). Odds ratios of interacting NSAIDs, tramadol and sulfamethoxazole versus respective prevalence of comparator drugs codeine, and ciprofloxacin in patients co-dispensed interacting warfarin versus patients unexposed was calculated.

RESULTS

The odds of receiving an interacting NSAID versus the comparator codeine was markedly lower in patients with warfarin than in the remaining population (adjusted OR 0.21; 95% CI 0.20 - 0.22). Also, the interacting drugs tramadol and sulfamethoxazole were less common among patients dispensed warfarin as compared to the remaining population, although the decrease was much more modest (adjusted OR 0.83; CI 0.80-0.87 and 0.81; CI 0.73 - 0.90).

CONCLUSIONS

In conclusion, Swedish doctors in the vast majority of cases refrain from prescribing NSAIDs to patients already on warfarin. Tramadol and sulfamethoxazole are however rarely avoided.

["Serious" adverse drug reactions with tramadol: a 2010-2011 pharmacovigilance survey in France]

OBJECTIVE

Tramadol is a weak opioid used as a step 2 analgesic, approved in France for moderate to severe pain. After dextropropoxyphene withdrawal, a national pharmacovigilance follow-up of tramadol was decided by the French Drug Agency.

METHODS

All Serious Adverse Drug Reactions (SADR) notified with tramadol to the French PharmacoVigilance Centres (CRPV) and pharmaceutical companies between August 1(st), 2010 and July 31(th), 2011 were analyzed.

RESULTS

During the study period, 296 cases of SADR were notified to CRPV and 59 to pharmaceutical companies. Apart from opiate-related SADR, tramadol induced serotoninergic SADR, including seizures or serotoninergic syndromes. Several « unlabelled » SADR were also identified: some of them, like hyponatremia or hypoglycemia, are poorly known by health professionals. Other were never published: peripheral edema or pancreatitis.

CONCLUSION

This study shows that besides well-known opioid or serotoninergic ADR, tramadol can also induce 2 other relatively unknown ADR: hypoglycemia and hyponatremia.