Miconazole Oral Gel Potentiates Warfarin Anticoagulant Activity

Old and new oral anticoagulants: Food, herbal medicines and drug interactions

The most commonly prescribed oral anticoagulants worldwide are the vitamin K antagonists (VKAs) such as warfarin. Factors affecting the pharmacokinetics of VKAs are important because deviations from their narrow therapeutic window can result in bleedings due to over-anticoagulation or thrombosis because of under-anticoagulation. In addition to pharmacodynamic interactions (e.g., augmented bleeding risk for concomitant use of NSAIDs), interactions with drugs, foods, herbs, and over-the-counter medications may affect the risk/benefit ratio of VKAs. Direct oral anticoagulants (DOACs) including Factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and thrombin inhibitor (dabigatran) are poised to replace warfarin. Phase-3 studies and real-world evaluations have established that the safety profile of DOACs is superior to those of VKAs. However, some pharmacokinetic and pharmacodynamic interactions are expected. Herein we present a critical review of VKAs and DOACs with focus on their potential for interactions with drugs, foods, herbs and over-the-counter medications.

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

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.

Warfarin and miconazole oral gel interactions: analysis and therapy recommendations based on clinical data and a pharmacokinetic model

WHAT IS KNOWN AND OBJECTIVE

Miconazole is a strong inhibitor of CYP2C9, one of the main enzymes involved in the metabolism of warfarin. Concurrent use of the two drugs leads to potentially serious adverse effects. Although it is often assumed that use of the oral miconazole gel is acceptable with concomitant warfarin, because of the low bioavailability following buccal administration, drug-drug interactions have been reported following such use. We aimed to investigate case reports of such interactions and develop a pharmacokinetic model to model such interactions.

METHODS

The Medline database from 1966 to October 2010 was used for literature search. Case reports of the potentiation of the anticoagulant effects of warfarin, such as the elevation of prothrombin time (INR), by concomitant administration of warfarin and miconazole oral gel were collected. We quantitatively estimated the extent of inhibition of warfarin metabolism by orally administered miconazole gel and compared our findings with case reports.

RESULTS AND DISCUSSION

Metabolism of (S)-warfarin is inhibited potently following administration of a standard dose (200-400 mg/day in Japan) of miconazole gel. This may lead to in an increase in the blood concentration of warfarin and lead to serious adverse effects. The literature reports of clinical interactions with concomitant use of those drugs show that other factors may amplify the effects of any increase in blood concentration.

WHAT IS NEW AND CONCLUSION

We summarize all reported, clinically significant, cases of drug interaction between miconazole oral gel and warfarin. Pharmacokinetic modelling shows that concomitant administration of warfarin and miconazole oral gel can lead to substantial increase in warfarin concentration. However, our PK/PD model fails to capture the dramatic increases seen in INR values, and hence bleeding complications, reported in the literature. Taken together, the evidence suggests that concomitant use of miconazole gel and warfarin should be avoided. Even over-the-counter products containing miconazole should be used with caution by patients receiving warfarin.

Drug interaction presenting as acute abdomen

Warfarin is the most common oral anticoagulant prescribed around the world. Adverse drug interactions with warfarin are a huge problem especially in the elderly and in patients who take multiple medications. Most adverse drug interactions involve concomitantly prescribed oral or intravenous medications. Occasionally, topical or mucosally absorbed drugs can interact, leading to fluctuations in warfarin levels with adverse consequences. In this case report, we describe a case of intestinal intramural hematoma, a rare but known consequence of a supra therapeutic international normalized ratio (INR). The supra therapeutic INR was a consequence of mucosally absorbed miconazole, prescribed for vaginal candidiasis. We wish to highlight this rare and potentially fatal drug interaction, along with the need for frequent INR monitoring when new drugs are added or removed in patients taking warfarin.

Laryngeal dyspnea in relation to an interaction between acenocoumarol and topical econazole lotion

BACKGROUND

Bleeding is the most serious complication of oral anticoagulant therapy used for the prevention of thromboembolic complications. Drug-drug interactions are an important concern, as they may increase drug toxicity and, in the case of anticoagulant therapies, increase the risk of hemorrhage.

CASE SUMMARY

An 84-year-old woman presented to the emergency department with a bilateral cervical hematoma and symptoms of upper-airway obstruction that had been increasing for 72 hours, with dyspnea and difficulty speaking developing in the previous 24 hours. Transnasal fiberoptic laryngoscopy revealed a significant laryngeal hematoma, as well as a hematoma on the floor of the mouth and in the tonsil area. Laboratory abnormalities included a prothrombin time < 10%, an international normalized ratio exceeding the laboratory limits, and an activated partial thromboplastin time >120 seconds. The patient had been receiving acenocoumarol 4 mg/d for 10 years for episodes of atrial fibrillation and recurrent deep venous thrombosis. Seventeen days earlier, she had received a prescription for topical econazole lotion 1% to be applied 3 times daily for 1 month to treat a dermatitis affecting 12% of the body surface. The patient was admitted to the intensive care unit for treatment of respiratory failure, where oxygen was delivered by face mask. The coagulation disorders were treated with prothrombin complex concentrate 30 IU/kg IV and vitamin K1 10 mg IV, and values normalized within 36 hours. Surgical evacuation of the laryngeal hematoma was not necessary. After 48 hours, improvement in the patient's respiratory symptoms allowed transfer to the ear, nose, and throat unit, where daily endoscopic examination was performed. Aspirin was substituted for acenocoumarol, and the patient returned home after 10 days without sequelae. Based on a Naranjo score of 7, this episode was probably related to an interaction between acenocoumarol and econazole.

CONCLUSION

This report describes a case of a probable interaction between topical econazole lotion 1% and acenocoumarol that resulted in overanticoagulation and a life-threatening laryngeal hematoma in this elderly patient.

Miconazole oral gel and drug interactions

Miconazole oral gel is frequently prescribed for the treatment of oral Candidal infections. Its ability to be systemically absorbed and interact with other drugs has previously been recorded but is not universally known. As a reminder, a further case of derangement of anticoagulation following concomitant use of warfarin and miconazole is reported. Other potential drug interactions of miconazole and fluconazole are highlighted.

Structure and Generation Mechanism of a Novel Degradation Product Formed by Oxidatively Induced Coupling of Miconazole Nitrate with Butylated Hydroxytoluene in a Topical Ointment Studied by HPLC-ESI-MS and Organic Synthesis

In a petrolatum based topical ointment formulation containing miconazole nitrate (1) as the active ingredient and 2,6-di-t-butyl-4-methylphenol (BHT) as a vehicle antioxidant, an oxidatively induced coupling reaction between miconazole nitrate and BHT occurred to form a novel adduct 1-(3,5-di-tert-butyl-4-hydroxy-benzyl)-3-[2-(2,4-dichloro-benzyloxy)-2-(2,4-dichloro-phenyl)-ethyl]-3H-imidazol-1-ium nitrate (2). The structure of 2 was established using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry and was confirmed by comparing with a synthesized reference compound. The reaction proceeded through a quinone methide intermediate from BHT. Two synthetic methods were established for preparing 2.

Oral surgery in patients on anticoagulant therapy

OBJECTIVE

Surgery is the main oral healthcare hazard to the patient with a bleeding tendency, which is mostly caused by the use of anticoagulants. The traditional management entails the interruption of anticoagulant therapy for dental surgery to prevent hemorrhage. However, this practice may increase the risk of a potentially life-threatening thromboembolism. Because this issue is still controversial, it is the aim of this paper to review the evidence, to highlight the areas of major concern, and to suggest management regimens for patients on the 3 main types of anticoagulants: coumarins, heparins, and aspirin. MATERIALS REVIEWED: The pertinent literature and clinical protocols of hospital dentistry departments have been extensively reviewed and discussed.

RESULTS

Several evolving clinical practices in the last years have been detected: anticoagulant use is generally not discontinued; oral surgery is performed despite laboratory values showing significant bleeding tendency; new effective local methods are used to prevent bleeding; and patients at risk are referred to hospital-based clinics.

CONCLUSION

The management of oral surgery procedures on patients treated with anticoagulants should be influenced by several factors: extent and urgency of surgery, laboratory values, treating physician's recommendation, available facilities, dentist expertise, and patient's oral, medical, and general condition.

Antitumor effects of miconazole on human colon carcinoma xenografts in nude mice through induction of apoptosis and G0/G1 cell cycle arrest

Miconazole (MIC), a promising oral antifungal agent, has been used worldwide in the treatment of superficial mycosis. In this study, we demonstrated that MIC dose dependently arrested various human cancer cells at the G0/G1 phase of the cell cycle. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated by MIC treatment in COLO 205 cells. Electrophoretic mobility gel shift assays showed that the nuclear extracts of the MIC-treated COLO 205 cells exerted a significant binding between wild-type p53 and its consensus-binding site present in the p21/Cip1 promoter. These results suggested that the p53-associated signaling pathway is involved in the regulation of MIC-induced cancer cell growth arrest. By immunoblot analysis, we demonstrated that cyclin D3 and cyclin-dependent kinase-4 (CDK4) protein levels were inhibited by MIC treatment in the cancer cells. Significant therapeutic effect was further demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with MIC (50 mg/kg ip). The protein expression of p53 was significantly increased in MIC-treated tumor tissues by immunohistochemical staining and Western blotting analysis. DNA fragmentation and TUNEL assay were performed and demonstrated that apoptosis occurred in tumor tissues treated with MIC. Our study provides the novel mechanisms of antitumor effects of MIC and such results may have significant applications for cancer chemotherapy.