Miconazole oral gel and drug interactions

The Pharmacokinetics and Target Attainment of Antimicrobial Drugs Throughout Pregnancy: Part III Non-penicillin and Non-cephalosporin Drugs

INTRODUCTION

Understanding the pharmacokinetics (PK) of antimicrobial drugs in pregnant women is crucial to provide effective and safe treatment. This study is part of a series that systematically reviews literature on the PK and analyzes if, based on the changed PK, evidence-based dosing regimens have been developed for adequate target attainment in pregnant women. This part focusses on antimicrobials other than penicillins and cephalosporins.

METHODS

A literature search was conducted in PubMed according to the PRISMA guidelines. Search strategy, study selection, and data extraction were independently performed by two investigators. Studies were labeled as relevant when information on the PK of antimicrobial drugs in pregnant women was available. Extracted parameters included bioavailability for oral drugs, volume of distribution (Vd) and clearance (CL), trough and peak drug concentrations, time of maximum concentration, area under the curve and half-life, probability of target attainment, and minimal inhibitory concentration (MIC). In addition, if developed, evidence-based dosing regimens were also extracted.

RESULTS

Of the 62 antimicrobials included in the search strategy, concentrations or PK data during pregnancy of 18 drugs were reported. Twenty-nine studies were included, of which three discussed aminoglycosides, one carbapenem, six quinolones, four glycopeptides, two rifamycines, one sulfonamide, five tuberculostatic drugs, and six others. Eleven out of 29 studies included information on both Vd and CL. For linezolid, gentamicin, tobramycin, and moxifloxacin, altered PK throughout pregnancy, especially in second and third trimester, has been reported. However, no target attainment was studied and no evidence-based dosing developed. On the other hand, the ability to reach adequate targets was assessed for vancomycin, clindamycin, rifampicin, rifapentine, ethambutol, pyrazinamide, and isoniazid. For the first six mentioned drugs, no dosage adaptations during pregnancy seem to be needed. Studies on isoniazid provide contradictory results.

CONCLUSION

This systematic literature review shows that a very limited number of studies have been performed on the PK of antimicrobials drugs-other than cephalosporins and penicillins-in pregnant women.

Pharmacokinetics and Target Attainment of Antimicrobial Drugs Throughout Pregnancy: Part I-Penicillins

BACKGROUND AND OBJECTIVE

Pharmacokinetics (PK) are severely altered in pregnant women due to changes in volume of distribution (Vd) and/or drug clearance (CL), affecting target attainment of antibiotics in pregnant women. This review is part of a series that reviews literature on the description of PK and target attainment of antibiotics in pregnant women with specific focus on penicillins.

METHODS

A systematic literature search was carried out in PubMed. Articles were labelled as relevant when information on PK of penicillins in pregnant women was available.

RESULTS

Thirty-two relevant articles were included, 8 of which discussed amoxicillin (with and without clavulanic acid), 15 ampicillin, 4 benzylpenicillin, 1 phenoxymethylpenicillin, and 4 piperacillin (with and without tazobactam). No studies were found on pheneticillin and flucloxacillin in pregnant women. Ten out of 32 articles included information on both Vd and CL. During the second and third trimester of pregnancy, a higher CL and larger Vd was reported than in non-pregnant women and in pregnant women during first trimester. Reduced target attainment was described in second and third trimester pregnant women. Only 7 studies reported dosing advice, 4 of which were for amoxicillin.

CONCLUSION

The larger Vd and higher CL in second and third trimester pregnant women might warrant a higher dosage or shortening of the dosing interval of penicillins to increase target attainment. Studies frequently fail to provide dosing advice for pregnant women, even if the necessary PK information was available.

A detailed insight on the molecular and cellular mechanism of action of the antifungal drugs used in the treatment of superficial fungal infections

Background:

Dermatomycosis, a type of fungal infection that can infect human skin, hair, and nails; day by day the growth of fungal infections ranging from superficial to systemic infection is alarming. Common causative agents included are Candida, Cryptococcus, Aspergillus, and Pneumocystis species.

Objective:

The effective treatment of the fungal infection includes the use of proper antifungal drug therapy. Antifungal drugs are classified into various classes. This paper focuses on understanding and interpreting the detailed molecular and cellular mechanism of action of various classes of an anti-fungal drug along with their important characteristics along with the safety and efficacy data of individual drugs of the particular class.

Methods:

The data selection for carrying out the respective study has been done by studying the combination of review articles and research papers from different databases like Research Gate, PubMed, MDPI, Elsevier, Science Direct, and Med Crave ranging from the year 1972 to 2019 by using the keywords like “anti-fungal agents”, “dermatophytes”, “cutaneous candidiasis”, “superficial fungal infections”, “oral candidiasis”, “amphotericin”, “echinocandins”, “azoles”, “polyenes” “ketoconazole”, “terbinafine”, “griseofulvin”, “azoles”.

Result:

Based on interpretation, we have concluded that the different classes of antifungal drugs follow the different mechanisms of action and target the fungal cell membrane, and are efficient in reducing fungal disease by their respective mechanism.

Conclusion:

The prevention and cure of fungal infections can be done by oral or topical antifungal drugs that aim to destroy the fungal cell membrane. These drugs show action by their respective pathways that are either preventing the formation of ergosterol or squalene or act by inhibiting β-1,3-glucan synthase enzyme. All the drugs are effective in treating fungal infections.

Inhibition of Cytochrome P450s by Strobilanthes crispus Sub-Fraction (F3): Implication for Herb-Drug Interaction

BACKGROUND AND OBJECTIVE

Strobilanthes crispus Blume sub-fraction (F3) has been reported to be cytotoxic against cancer cells and to cause murine mammary tumor regression. Potential utilization of F3 as an adjuvant in breast cancer treatment to alleviate chemotherapeutic drug resistance is currently hampered by potential cytochrome P450 (CYP)-mediated herb-drug interactions (HDIs). The current study assessed the inhibitory potency of F3 towards five CYP enzymes involved in tamoxifen metabolism.

METHODS

Potential CYP inhibition by F3 was first determined using fluorescence assays, using known CYP inhibitors as reference. To further ascertain the inhibitory potency and mode of inhibition, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis of specific metabolites of a CYP probe substrate was conducted.

RESULTS

The half-maximal inhibitory concentration (IC₅₀) values indicate that F3 exhibited relatively weak inhibition on CYP2B6, CYP2C19, CYP2D6, and CYP3A4. Highest susceptibility to inhibition by F3 was observed for CYP2C9, where the IC₅₀ value from fluorescence-based assay was 35-fold higher than control. Further analysis by HPLC-MS/MS revealed relatively weak mixed-type inhibition of F3 on CYP2C9, as indicated by IC₅₀ and inhibition constant (K_I) values. The risk of clinically significant CYP2C9 inhibition by F3 was then predicted based on the attained K_I value and the presumed amount of F3 absorbed from S. crispus leaves following consumption. The calculated maximum plasma concentration to inhibition constant C_max/K_I) ratio suggests that F3 consumption could potentially result in clinically significant drug interactions with medications metabolized by CYP2C9.

CONCLUSION

Taken together, the results revealed a low probability of inhibition by F3 on CYP enzymes involved in tamoxifen metabolism. However, further in vivo investigation is necessary for potential F3 interaction with CYP2C9. The utility of a preliminary in vitro approach in the assessment of potential HDI was demonstrated in this study.

Risk prediction of drug-drug interaction potential of phenytoin and miconazole topical formulations

The drug-drug interaction (DDI) risk of phenytoin with several topical formulations of miconazole is still unclear. The present investigation conducted in vitro-in vivo extrapolation to predict the potential risks. Our data indicated that miconazole potently inhibited phenytoin hydroxylation in both pooled human liver microsomes (HLMs) and recombinant cytochrome P450 2C9 (CYP2C9) with the K_i values of 125 ± 7 nM and 30 ± 2 nM, respectively. Quantitative prediction of DDI risk suggests that, beside intravenous administration or swallowed tablet, combination of phenytoin and miconazole high dose oral gel or buccal tablet may also result in a clinically significant increase of phenytoin AUC (>53%) by the inhibition of miconazole against phenytoin hydroxylation, consequently a higher frequency of adverse events, while the coadministration of miconazole vaginal formulation and phenytoin will be safe.

Comprehensive Exploration of Medications That Affect the Bleeding Risk of Oral Anticoagulant Users

Oral anticoagulants (OACs) pose a major bleeding risk, which may be increased or decreased by concomitant medications. To explore medications that affect the bleeding risk of OACs, we conducted a nested case-control study including 554 bleeding cases (warfarin, n = 327; direct OACs [DOACs], n = 227) and 1337 non-bleeding controls (warfarin, n = 814; DOACs, n = 523), using a Japanese health insurance database from January 2005 to June 2017. Major bleeding risk associated with exposure to concomitant medications within 30 d of the event/index date was evaluated, and adjusted odds ratios (aORs) were calculated using logistic regression analysis. Several antihypertensive drugs, such as amlodipine and bisoprolol, were associated with a decreased risk of bleeding (warfarin + amlodipine [aOR, 0.64; 95% confidence interval (CI): 0.41-0.98], DOACs + bisoprolol [aOR, 0.51; 95% CI, 0.33-0.80]). As hypertension is considered a significant risk factor for intracranial bleeding in antithrombotic therapy, antihypertensive drugs may suppress intracranial bleeding. In contrast, telmisartan, a widely used antihypertensive drug, was associated with an increased risk of bleeding [DOACs + telmisartan (aOR, 4.87; 95% CI, 1.84-12.91)]. Since telmisartan is an inhibitor of P-glycoprotein (P-gp), the elimination of rivaroxaban and apixaban, which are substrates of P-gp, is hindered, resulting in increased blood levels of both drugs, thereby increasing the risk of hemorrhage. In conclusion, antihypertensive drugs may improve the safety of OACs, and the pharmacokinetic-based drug interactions of DOACs must be considered.

Antifungal activity of polymethyl methacrylate/Si3N4 composites against Candida albicans

Previous studies using gram-positive and -negative bacteria demonstrated that hydrolysis of silicon nitride (Si₃N₄) in aqueous suspensions elutes nitrogen and produces gaseous ammonia while buffering pH. According to immunochemistry assays, fluorescence imaging, and in situ Raman spectroscopy, we demonstrate here that the antipathogenic surface chemistry of Si₃N₄ can be extended to polymethylmethacrylate (PMMA) by compounding it with a minor fraction (~8 vol.%) of Si₃N₄ particles without any tangible loss in bulk properties. The hydrolytic products, which were eluted from partly exposed Si₃N₄ particles at the composite surface, exhibited fungicidal action against Candida albicans. Using a specific nitrative stress sensing dye and highly resolved fluorescence micrographs, we observed in situ congestion of peroxynitrite (ONOO^-) radicals in the mitochondria of the Candida cells exposed to the PMMA/Si₃N₄ composite, while these radicals were absent in the mitochondria of identical cells exposed to monolithic PMMA. These in situ observations suggest that the surface chemistry of Si₃N₄ mimics the antifungal activity of macrophages, which concurrently produce NO radicals and superoxide anions (O₂•^-) resulting in the formation of candidacidal ONOO^-. The fungicidal properties of PMMA/Si₃N₄ composites could be used in dental appliances to inhibit the uncontrolled growth of Candida albicans and ensuing candidiasis while being synergic with chemoprophylaxis. STATEMENT OF SIGNIFICANCE: In a follow-up of previous studies of gram-positive and gram-negative bacteria, we demonstrate here that the antipathogenic surface chemistry of Si₃N₄ could be extended to polymethylmethacrylate (PMMA) containing a minor fraction (~8 vol.%) of Si₃N₄ particles without tangible loss in bulk properties. Hydrolytic products eluted from Si₃N₄ particles at the composite surface exhibited fungicidal action against Candida albicans. Highly resolved fluorescence microscopy revealed congestion of peroxynitrite (ONOO^-) radicals in the mitochondria of the Candida cells exposed to the PMMA/Si₃N₄ composite, while radicals were absent in the mitochondria of identical cells exposed to monolithic PMMA. The fungicidal properties of PMMA/Si₃N₄ composites could be used in dental appliances to inhibit uncontrolled growth of Candida albicans and ensuing candidiasis in synergy with chemoprophylaxis.

Oral Medicine Considerations for Older Patients

With the projected increase to 1.3 billion people aged 65 years or older by 2040, healthcare professionals are faced with significant challenges in managing this population of patients. In the oral cavity, oral mucosal disease is a significant problem found in older populations. Several facial pain conditions are more likely to be seen in this cohort of patients. Although management of this group of patients may not always be appropriate in general practice, an awareness of the range of oral medicine conditions that may be encountered in older patients is essential to allow prompt referral and treatment.

Prevalence of drug-drug interaction in atrial fibrillation patients based on a large claims data

This study aimed to compare and determine the prevalence of drug–drug interaction (DDI) and bleeding rate in atrial fibrillation (AF) patients receiving anticoagulants in a clinical setting. We used large claims data of AF patients obtained from the Japan Medical Data Center. The prevalence of DDIs and cases leading to bleeding events were surveyed clinically relevant DDIs extracted from 1) reported from a spontaneous adverse event reporting system (Japanese Adverse Drug Events Report system; JADER) ≥4 patients; 2) DDIs cited in the package inserts of each anticoagulant (each combination assessed according to “Drug interaction 2015” list; 3) warfarin and quinolone antibiotics DDIs. DDIs were categorized the mechanisms for pharmacokinetic DDI (Cytochrome P450 (CYP) or transporter etc. that modulate blood concentration of anticoagulants)/pharmacodynamic DDI (combination with similar pharmacological actions) or both in the analysis for each patients’ prescriptions obtained from a claims data. AF patients were compared between cases with and without bleeding after administered of anticoagulants. Bleeding was observed in 220/3290 (6.7%) AF patients. The bleeding rate in patients with both pharmacokinetic and pharmacodynamic DDI mechanisms (26.3%) was higher than that in patients with either mechanism (8.6% and 9.2%, respectively) or without DDIs (4.9%). The odds ratio for bleeding in AF patients with both of pharmacokinetic and pharmacodynamic was (7.18 [4.69–11.00], p<0.001). Our study concluded multi mechanism based DDIs leads serious outcome as compared to that of single mechanism based DDIs in AF patients. We determined the prevalence and frequency of bleeding for anticoagulant-related DDIs. To manage DDIs, both pharmacokinetic and pharmacodynamic DDI mechanisms should be closely monitored for initial symptoms of bleeding within the first 3 months.

Diagnosis and management of oral candidosis

Candida is a fungus (yeast) that is generally regarded as a normal and harmless member of the oral microbiome in humans. Should host defences against these commensals be compromised in any way then Candida can cause clinical signs and symptoms, which manifest as distinct forms of oral candidosis (candidiasis). Candida albicans is the most frequently isolated candidal species from the oral cavity, although a range of non-C. albicans Candida species are being increasingly encountered. The basic principle of the management of candidosis is to identify and eliminate any underlying host predisposing factor. However, in many cases, antifungal therapy will also be required as part of initial management. This article will provide an overview of the isolation, identification and pathogenicity of Candida species encountered within the mouth and relate these to clinical management of oral candidosis.

Efficacy of Propolis on the Denture Stomatitis Treatment in Older Adults: A Multicentric Randomized Trial

Our hypothesis tested the efficacy and safety of a mucoadhesive oral gel formulation of Brazilian propolis extract compared to miconazole oral gel for the treatment of denture stomatitis due to Candida spp. infection in older adults. Forty patients were randomly allocated in a noninferiority clinical trial into two groups. The control group (MIC) received 20 mg/g miconazole oral gel and the study group (PROP) received mucoadhesive formulation containing standardized extract of 2% (20 mg/g) propolis (EPP-AF®) during 14 days. Patients were examined on days 1, 7, and 14. The Newton's score was used to classify the severity of denture stomatitis. The colony forming unity count (CFU/mL) was quantified and identified (CHROMagar Candida®) before and after the treatment. Baseline characteristics did not differ between groups. Both treatments reduced Newton's score (P < 0.0001), indicating a clinical improvement of the symptoms of candidiasis with a clinical cure rate of 70%. The microbiological cure with significant reduction in fungal burden on T14 was 70% in the miconazole group and 25% in the EPP-AF group. The EPP-AF appears to be noninferior to miconazole considering the clinical cure rate and could be recommended as an alternative treatment in older patients.

[Pharmacokinetic drug interaction between miconazole mucoadhesive tablet and tacrolimus: About 3 case-reports in transplant patients]

Loramyc^® is a mucoadhesive tablet of miconazole, indicated for the treatment of oropharyngeal candidiasis in immunocompromised patients. Miconazole, as others azole antifungals, is known for its potent inhibitory properties of cytochromes P450 enzymes and P-glycoprotein (P-gp). Inhibition of cytochromes P450 enzymes and P-gp can produce pharmacokinetic drug interaction. Immunosuppressive agents, such as calcineurin inhibitors (tacrolimus, cyclosporine) are substrates of cytochromes P450 3A4 and P-gp. Nevertheless, the impact of systemic absorption of miconazole mucoadhesive tablet has not been investigated by the laboratory before regulatory approval. No recommendation currently exists in case of co-prescription of Loramyc^® and immunosuppressive agents which are counter-indicated as a matter of principle. Herein, we present 3 cases of transplanted patients, requiring miconazole mucoadhesive tablet, who presented a tacrolimus overdose. These cases illustrate that of therapeutic drug monitoring is feasible in order to prevent the occurrence of overdoses and adverse reactions related.

Effects of Miconazole Oral Gel on Blood Concentrations of Tacrolimus and Cyclosporine: A Retrospective Observational Study

BACKGROUND

Although azole antifungal agents have been shown to affect the pharmacokinetics of calcineurin inhibitors such as tacrolimus (TAC) and cyclosporine (CyA) by inhibiting drug metabolism, there are few clinical reports on drug interactions between miconazole (MCZ) oral gel and calcineurin inhibitors. In this study, the effects of MCZ oral gel on the blood concentrations of TAC and CyA were investigated.

METHODS

In this retrospective study, 18 patients concomitantly administered MCZ oral gel and TAC (9 for dermatomyositis, 3 for myasthenia gravis, 2 for systemic lupus erythematosus, 2 for rheumatoid arthritis, 1 for polymyositis, 1 for prevention of graft-versus-host disease after bone marrow transplantation), and 15 patients concomitantly administered MCZ oral gel and CyA (11 for interstitial pneumonia, 2 for pemphigus, 1 for eosinophilic granulomatosis with polyangiitis, 1 for systemic lupus erythematosus) were evaluated. The dose-adjusted blood concentrations of TAC or CyA were compared before and after the initiation of MCZ oral gel.

RESULTS

The trough blood concentration/dose (C/D) ratios of TAC and CyA increased significantly with the administration of MCZ oral gel. The median C/D ratios of TAC and CyA increased by 108% (range: -44% to 216%) and 44% (range: -34% to 195%), respectively.

CONCLUSIONS

These results suggest that MCZ oral gel affects the pharmacokinetics of TAC and CyA. Detailed monitoring of the blood concentrations of these drugs, followed by dose adjustments, is needed for each patient because of the difficulties associated with accurately predicting the degree of the effects of MCZ oral gel.

Warfarin and Drug Interactions: Prescribing Vigilance

A patient taking warfarin presented to the Oral Medicine Clinic at Liverpool University Dental Hospital, having been prescribed metronidazole and miconazole by his general dental practitioner (GDP) for his oral mucosal problem. He subsequently developed bruising on his torso following mild trauma. Having read the drug information leaflet provided with his metronidazole and miconazole, he noted the potential drug interactions between these and warfarin. He therefore stopped his warfarin. The details of this case are outlined, and the potential for significant drug interactions with warfarin are highlighted. The need for dental practitioners to be vigilant concerning drug interactions is emphasized, together with the importance of CPD in relation to drug prescribing. CPD/CLINICAL RELEVANCE: This case report, which is of relevance to all dental practitioners, highlights the importance of up-to-date medical and drug histories and the continuing awareness of potential drug interactions. In this case, patient intervention after checking drug information leaflets prevented serious consequences. The importance and potentially serious consequences of significant drug interactions needs to be understood.

Prescribing in primary dental care: general principles

Prescribing medicines is an essential part of comprehensive dental care. Behind this seemingly simple act lies a range of skills. These include understanding the physiological interaction of the medicines in the body as well as their potential for harm either to body systems or when conflicting with other medicines taken by the patient. The decision to prescribe is thus complex even before the efficacy of the drug for the dental condition is considered. This paper reviews some of the issues that the primary care practitioner must consider when prescribing, as well as practical concerns to make prescribing safe and effective.

Current treatment of oral candidiasis: A literature review

Candidiasis or oral candidosis is one of the most common human opportunistic fungal infections of the oral cavity. This pathology has a wide variety of treatment which has been studied until these days. The present study offers a literature review on the treatment of oral candidiasis, with the purpose of establish which treatment is the most suitable in each case. Searching the 24 latest articles about treatment of candidiasis it concluded that the incidence depends on the type of the candidiasis and the virulence of the infection. Although nystatin and amphotericin b were the most drugs used locally, fluconazole oral suspension is proving to be a very effective drug in the treatment of oral candidiasis. Fluconazole was found to be the drug of choice as a systemic treatment of oral candidiasis. Due to its good antifungal properties, its high acceptance of the patient and its efficacy compared with other antifungal drugs. But this drug is not always effective, so we need to evaluate and distinguish others like itraconazole or ketoconazole, in that cases when Candida strains resist to fluconazole.

Key words:Candidiasis, treatment, miconazole, fluconazole, nystatin.

Comparison of the efficacy of a novel sustained release clotrimazole varnish and clotrimazole troches for the treatment of oral candidiasis

OBJECTIVES

Candida albicans is a common fungal infection and is commensal in 40-65 % of healthy adults. The development and pharmacokinetics of a novel sustained release clotrimazole varnish (Clot-SRV) for topical oral use have been reported. The aim of this study was to compare the efficacy of this varnish with clotrimazole troche treatment of oral candidiasis.

MATERIALS AND METHODS

Of the 12 patients with denture stomatitis treated for 14 days, six used Clot-SRV (study group) and six clotrimazole troches (control). The patients were instructed to use Clot-SRV (50 mg of clotrimazole) once a day, and the control group was instructed to use five troches of 10 mg clotrimazole/day. Microbiological samples were obtained from saliva, buccal mucosa, palate, and denture. The degree of erythema was recorded at three time points, and subjective opinions noted using a questionnaire.

RESULTS

At the end of the study, the control group had relatively more cases of erythema on all examined surfaces; patients who applied the Clot-SRV had significantly lower levels of candida on the denture surfaces and in saliva, and had better compliance to the medication.

CONCLUSIONS

The novel clotrimazole sustained release varnish may be an important part of a new protocol for oral candidiasis, with improved clinical outcomes.

Drug interactions in general dental practice--considerations for the dental practitioner

The aim of this article is to explore the diverse and complex nature of pharmacological drug-drug interactions in the general dental practice setting. Using published NHS statistics, this article will highlight medications for common medical conditions that could interact with frequently prescribed drugs by the general dental practitioner.

Urban legends series: oral candidosis

Candida species (spp) are commensal yeast that can only instigate oral infection (oral candidosis - OC) when there is an underlying predisposing condition in the host. We investigated four controversial topics on OC: (i) How can a microbiological determination of OC be made as Candida spp. are commensal yeasts and not all of them form hyphae or pseudohyphae during infection? (ii) Is median rhomboid glossitis (MRG) a manifestation of candidal infection? (iii) Can candidal infection cause palate papillary hyperplasia (PPH)? (iv) What is the best therapeutic treatment for denture-associated erythematous stomatitis (DAES)? Results from extensive literature searches, including a systematic review, suggested the following: (i) the diagnosis of OC merely on the basis of the presence of yeasts is an oversimplification of a complex process. No convincing evidence of a single test or method better able to discriminate the transition from candidal saprophytism to pathogenicity has been reported in the literature; (ii-iii) conclusive evidence of a direct aetiopathogenic relationship between MRG and PPH and candidal infection has not been found; and (iv) only limited evidence is available for any DAES treatment, thus making it impossible to make strong therapeutic recommendations.

Serotonin syndrome during treatment with low dose of escitalopram associated with miconazole mucoadhesive tablet: a suspected drug interaction

Antidepressant treatments, including selective serotonin reuptake inhibitors, are associated in older adults with an increased risk of adverse effects compared to younger adults. This is partly explained by multiple drug use causing drug-drug interactions. In the present report, we describe a case of serotonin syndrome in an 88-year-old woman receiving a low dose of escitalopram. The onset of this episode could have been induced by a drug-drug interaction with an acute treatment by miconazole gingival adhesive tablets. The lack of pharmacokinetic data in the elderly population should prompt us to be especially cautious about prescription of this new formulation of miconazole in association with drugs metabolized by cytochromes P450 isoenzymes.

Interaction of miconazole oral gel with warfarin and cyclosporine in a patient with nephrotic syndrome

It is well known that miconazole inhibits cytochrome P450 (CYP). However, this drug in oral gel form is believed not to absorb into systemic circulation, and therefore not to inhibit CYP. We experienced a case of increased oral bioavailability of warfarin and cyclosporine with this gel for treatment of oral candidiasis in a patient with nephrotic syndrome. Her prothrombin time-international normalized ratio (PT-INR) increased from 2 to 7.25, and the cyclosporine concentration at 2 h after final dosing (C2) increased from 633.8 to 1396.5 ng/ml 6 days after the coadministration. These problems were resolved by termination of the gel and switching to amphotericin B gargle. We further detected a significant amount of miconazole in her plasma, directly showing for the first time in a patient with this interaction that oral miconazole gel was actually absorbed into systemic circulation. Because warfarin and cyclosporine are often used simultaneously by nephrologists, caution should be applied with combined use of these drugs and oral miconazole gel to avoid adverse reaction.

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.

Miconazole oral gel increases exposure to oral oxycodone by inhibition of CYP2D6 and CYP3A4

Our aim was to assess the effect of miconazole oral gel on the pharmacokinetics of oral oxycodone. In an open crossover study with two phases, 12 healthy volunteers took a single oral dose of 10 mg of immediate-release oxycodone with or without thrice-daily 85-mg miconazole oral gel treatment. The plasma concentrations of oxycodone and its oxidative metabolites were measured for 48 h. Pharmacological effects of oxycodone were recorded for 12 h. Pharmacokinetic parameters were compared by use of the geometric mean ratios (GMRs) and their 90% confidence interval (CIs). Pretreatment with miconazole oral gel caused a strong inhibition of the CYP2D6-dependent metabolism and moderate inhibition of the CYP3A4-dependent metabolism of oxycodone. The mean area under the concentration-time curve (AUC) from time zero to infinity (AUC(0-∞); GMR, 1.63; 90% CI, 1.48 to 1.79) and the peak concentration of oxycodone (GMR, 1.31; 90% CI, 1.19 to 1.44) were increased. The AUC of the CYP2D6-dependent metabolite oxymorphone was greatly decreased (GMR, 0.17; 90% CI, 0.09 to 0.31) by miconazole gel, whereas that of the CYP3A4-dependent metabolite noroxycodone was increased (GMR, 1.30; 90% CI, 1.15 to 1.47) by miconazole gel. Differences in the pharmacological response to oxycodone between phases were insignificant. Miconazole oral gel increases the exposure to oral oxycodone, but the clinical relevance of the interaction is moderate. Miconazole oral gel produces a rather strong inhibitory effect on CYP2D6, which deserves further study.

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.

Management of dental patients taking common hemostasis-altering medications

OBJECTIVE

Millions of patients worldwide are taking medications that alter hemostasis and decrease the risk for thromboembolic events. This systematic review is intended to provide recommendations regarding optimal management of such patients undergoing invasive dental procedures. The primary focus of this report is on warfarin therapy, although issues related to heparin and aspirin are briefly discussed because of the frequency with which they are encountered in dental practice.

STUDY DESIGN

The review of literature and development of recommendations was based on the Reference Manual for Management Recommendations for the World Workshop in Oral Medicine IV (WWOM IV). A total of 64 publications were identified for initial review. From these publications, the following types of articles were critically analyzed using WWOM standard forms: randomized controlled trials (RCT), non-RCT studies that assess effects of interventions, and studies that assess modifiable risk factors. Development of recommendations was based on the findings of these reviews as well as expert opinion.

RESULTS

The following evidence-based recommendations were developed: (1) For patients within the therapeutic range of International Normalized Ratio (INR) below or equal to 3.5, warfarin therapy need not be modified or discontinued for simple dental extractions. Nevertheless, the clinician's judgment, experience, training, and accessibility to appropriate bleeding management strategies are all important components in any treatment decision. Patients with INR greater than 3.5 should be referred to their physician for consideration for possible dose adjustment for significantly invasive procedures. (2) A 2-day regimen of postoperative 4.8% tranexamic acid mouthwash is beneficial after oral surgical procedures in patients on warfarin. (3) It is not necessary to interrupt low-dose aspirin therapy (100 mg/day or less) for simple dental extractions.

CONCLUSION

For most patients undergoing simple single dental extractions, the morbidity of potential thromboembolic events if anticoagulant therapy is discontinued clearly outweighs the risk of prolonged bleeding if anticoagulant therapy is continued.