Drug-Drug Interaction between Tacrolimus and Fluconazole in a Kidney Transplant Recipient.

We report a case of tacrolimus and fluconazole drug-drug interaction in a 20-year-old female kidney transplant recipient with stable kidney function. The patient's tacrolimus blood concentrations were in the therapeutic range until fluconazole was administrated for Candida albicans infection, on day 58 posttransplant. Tacrolimus blood concentration increased by 125% (18.4 ng/mL) on day 79 and by 212% (25.4 ng/mL) on day 84 posttransplant. On day 92, tacrolimus trough blood concentration returned to the therapeutic range (5.6 ng/mL), with decrease of tacrolimus daily dose by 50% (to 4 mg). After fluconazole withdrawal, the patient was returned to the initial tacrolimus daily dose (8 mg) to maintain a tacrolimus trough blood concentration in the therapeutic range. Fluconazole coadministration with tacrolimus shows a significant clinical effect on tacrolimus trough blood concentration in kidney transplant patients. Maintaining a tacrolimus trough blood concentration in the therapeutic range is crucial for these patients; therefore, physicians should be aware of fluconazole prescriptions.

Interaction Between Tacrolimus and Proton Pump Inhibitor in a Kidney Transplant Recipient.

We aimed to present a drug monitoring profile of tacrolimus and proton pump inhibitor coadministration in a 23-year-old male patient with a history of high blood pressure who underwent kidney transplant. The patient's serum trough levels of tacrolimus were in the therapeutic range until omeprazole 20 mg daily was prescribed. Tacrolimus trough serum level increased to 29.5 ng/mL under the same daily dose and to 13.9 ng/mL after tacrolimus daily dose was decreased to 6 mg/day. This increase in tacrolimus serum level was behind a renal function alteration. After withdrawal of omeprazole, tacrolimus trough serum level returned to the therapeutic range. Because interactions between tacrolimus and omeprazole could result in toxicities, careful monitoring of tacrolimus serum levels should be considered to adjust the dosage.

Azathioprine and Acenocoumarol Drug Interaction in Patients with Crohn's Disease: A Case Report.

BACKGROUND: Acenocoumarol is an anticoagulant with numerous drug reactions. We report here, an unusual interaction between acenocoumarol and azathioprine. CASE PRESENTATION: A 35-year-old woman, treated with acenocoumarol for thrombosis of the superior mesenteric vein, was prescribed azathioprine for Crohn's disease. Three days later, INR values decreased from 2.36 to 1.48. The dose of acenocoumarol had to almost be doubled to reach an INR value of 2.56. The interaction between azathioprine and acenocoumarol was then suspected. Few similar cases of interactions between azathioprine and another coumarin derivative, warfarin, have been reported. To our knowledge, this is the second case of such interaction reported with acenocoumarol in literature. CONCLUSION: Thus, despite the rarity of this interaction reporting, we draw attention to the importance of close monitoring of INR values in patients treated with acenocoumarol associated with azathioprine.

Skin Tests for the Exploration of Hypersensitivity Reactions Associated with Iodinated Contrast Media.

BACKGROUND: Iodinated contrast media (ICM) are responsible for multiple side effects, especially hypersensitivity reactions. These reactions can either be authentic allergies or non-allergic hypersensitivity reactions. Skin tests (prick and intradermal tests) are simple to perform and can be of great help, especially if the ICM needs to be re-used. The aim of the study was to assess the characteristics of the patients in whom skin tests were performed and the results of these tests. METHODS: This is a retrospective study from June 2014 to June 2019. All included patients had at least one episode of hypersensitivity reaction to ICM and underwent skin tests. RESULTS: We included 35 patients aged 18 to 85 years. The iopromide was the most implicated ICM. The reactions were mainly cutaneous (n=30) and immediate (n=27). The skin tests were negative, except for two patients. The re-use of ICM occurred in 11 patients: 9 with an ICM other than the one suspected and two patients with the same ICM. Among these patients, 5 did not have any premedication. Two of them had a second hypersensitivity reaction, the first with another ICM and the second with the same ICM. CONCLUSION: One of the main pillars of allergic exploration is ICM skin testing, not only to prevent a recurrence, but also to allow patients to benefit from ICM re-use, which are sometimes essential.