Co-trimoxazole and Warfarin: Case Report of an Interaction

Errick, Jeffrey Keith; Keys, Philip W.

doi:10.1093/ajhp/35.11.1399

Cited by 6 publications

(3 citation statements)

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“…More importantly, many examples exist of drugs which were shown to lack an interaction with warfarin in a formal drug interaction study in healthy volunteers, yet have been reported to produce an interaction in clinical scenarios [3]. In addition, with the expansion of dietary and herbal supplement use, there is an emergence in the interactions of many of these agents and warfarin (See Tables 3,4,5). When changes in concurrent medications or supplements are noted, the frequency of INR monitoring should be increased in order to detect any changes in the INR early enough to enable dose adjustment before the development of an adverse event.…”

Section: Warfarinmentioning

confidence: 99%

“…Several interactions have been documented via case reports and case series including co-trimoxazole [5][6][7][8][9][10][11], fluconazole [12][13][14][15][16][17][18][19], metronidazole [20][21][22][23], miconazole [24][25][26][27][28][29][30][31][32][33][34][35][36][37] and voriconazole [38] as they are known to inhibit CYP 1A2 or CYP 2C9. Fluoroquinolones have also been documented to interact with warfarin by inhibiting CYP1A2 [39][40][41][42][43][44][45][46].…”

Section: Anti-infective Agentsmentioning

confidence: 99%

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Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Nutescu

Chuatrisorn

Hellenbart

2011

J Thromb Thrombolysis

224

153

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Clinicians and patients around the world have been intrigued by the concept of developing an oral anticoagulant with a broad therapeutic window and few drug and dietary interactions that can be administered at fixed doses with no or minimal monitoring. The recently approved oral direct thrombin inhibitor dabigatran, along with the emerging oral anti-factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban, have been developed to address many of the shortcomings of warfarin therapy. As warfarin is associated with extensive food and drug interactions, there is also a need to consider such interactions with the new oral anticoagulants. While to date few drug and dietary interactions have been reported with the new oral anticoagulants, it is still early in their development and clinical use cycle. Pharmacokinetic and pharmacodynamic profiles will have to be closely accounted for when determining the likelihood of a potential drug interaction prior to therapy initiation. As the list of drugs and supplements that interact with warfarin is continuously expanding, and the knowledge on drug interactions with the novel oral anticoagulants is still in its infancy, clinicians need to be vigilant when initiating any of these agents or when any changes in the patient's medication profile occur and perform a close screening for potential drug and dietary interactions. The objective of this paper is to give an update on drug and dietary interactions with warfarin and the novel oral anticoagulants, dabigatran, rivaroxaban, apixaban, and edoxaban.

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Section: Warfarinmentioning

confidence: 99%

Section: Anti-infective Agentsmentioning

confidence: 99%

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Nutescu

Chuatrisorn

Hellenbart

2011

J Thromb Thrombolysis

224

153

View full text Add to dashboard Cite

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“…Concomitant administration of warfarin and certain antimicrobial agents such as fluconazole, sulfamethoxazole, and erythromycin carries the risk of a drug-drug interaction that results in alteration of the international normalized ratio (INR; Table 1). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Attentive monitoring of the INR in patients receiving warfarin who are also administered antimicrobial agents is recommended because adjustments to the warfarin dosage may be needed to maintain the desired degree of anticoagulation and to minimize bleeding risk. 19,20 Elderly individuals have increased sensitivity to the anticoagulant effects of warfarin, [21][22][23][24][25][26][27] and patients aged 65 years or older experience warfarin-related bleeding events at lower INRs than do younger patients.…”

mentioning

confidence: 99%

Warfarin Monitoring in Ambulatory Older Individuals Receiving Antimicrobial Therapy

et al. 2005

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Most older patients coprescribed warfarin and an antimicrobial in our organization had INR monitoring within 7 days. This is consistent with appropriate practice to manage a risk of clinically important drug-drug interaction between an antimicrobial agent and warfarin. Prospective identification of patients requiring INR monitoring after coprescription of interacting drugs by using merged administrative pharmacy and laboratory data should be further evaluated as a tool to improve clinical outcomes.

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Coumarin anticoagulants and co-trimoxazole: avoid the combination rather than manage the interaction

Schalekamp

Geest-Daalderop

Kramer

et al. 2007

Eur J Clin Pharmacol

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Objective The objective of our study was to examine the management of the interaction between acenocoumarol or phenprocoumon and several antibiotics by anticoagulation clinics and to compare the consequences of this interaction on users of co-trimoxazole with those for users of other antibiotics. Methods A follow-up study was conducted at four anticoagulation clinics in The Netherlands. Data on measurements of the International Normalised Ratio (INR), application of a preventive dose reduction (PDR) of the coumarin anticoagulant, fever and time within or outside the therapeutic INR range were collected. Results The study cohort consisted of 326 subjects. A PDR was given more often to users of co-trimoxazole PDR than to users of other antibiotics. The PDR in co-trimoxazole users resulted in a significantly reduced risk of both moderate overanticoagulation (INR >4.5) and severe overanticoagulation (INR >6.0) compared with no PDR, with odds ratios (ORs) of 0.06 [95% confidence interval (CI): 0.01-0.51] and 0.09 (95% CI: 0.01-0.92), respectively. In co-trimoxazole users without PDR, the risk of overanticoagulation was significantly increased compared with users of other antibiotics. All co-trimoxazole users spent significantly more time under the therapeutic INR range during the first 6 weeks after the course than users of other antibiotics. Conclusion PDR is effective in preventing overanticoagulation in co-trimoxazole users, but results in a significantly prolonged period of underanticoagulation after the course. Avoidance of concomitant use of co-trimoxazole with acenocoumarol or phenprocoumon seems to be a safer approach than management of the interaction between these drugs.

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Co-trimoxazole and Warfarin: Case Report of an Interaction

Cited by 6 publications

References 0 publications

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Warfarin Monitoring in Ambulatory Older Individuals Receiving Antimicrobial Therapy

Coumarin anticoagulants and co-trimoxazole: avoid the combination rather than manage the interaction

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