Therapeutic drug monitoring of voriconazole: a case report of multiple drug interactions in a patient with an increased CYP2C19 activity.

BACKGROUND: Voriconazole is metabolized by cytochrome P450 (CYP) 2C19 and CYP 3A4. Drug-drug interactions and genetic polymorphisms modulate their activities. CASE PRESENTATION: A 35-year old African female patient with resistant HIV and a cerebral mass of unknown origin was treated with voriconazole for a suspicion of disseminated Aspergillosis infection. Voriconazole trough concentrations (C0) were within target range while the patient was under esomeprazole, a CYP2C19 inhibitor. Phenotyping showed decreased CYP2C19 activity, whereas genotyping showed a variant allele associated with increased enzyme activity. The patient was switched to ranitidine because of the introduction of atazanavir. CYP3A4 inhibition by atazanavir combined with uninhibited CYP2C19 activity resulted in subtherapeutic voriconazole C0. The reintroduction of esomeprazole allowed restoring voriconazole C0 back to target range. CONCLUSION: The integration of drug-drug interactions and pharmacogenetics data is crucial to interpret drug concentrations correctly, thus preventing suboptimal exposure to voriconazole.

Impact of recommendation updates in well-controlled patients on nonrecommended antiretroviral therapies: the Swiss HIV cohort study.

BACKGROUND: HIV treatment recommendations are updated as clinical trials are published. Whether recommendations drive clinicians to change antiretroviral therapy in well-controlled patients is unexplored. METHODS: We selected patients with undetectable viral loads (VLs) on nonrecommended regimens containing double-boosted protease inhibitors (DBPIs), triple-nucleoside reverse transcriptase inhibitors (NRTIs), or didanosine (ddI) plus stavudine (d4T) at publication of the 2006 International AIDS Society recommendations. We compared demographic and clinical characteristics with those of control patients with undetectable VL not on these regimens and examined clinical outcome and reasons for treatment modification. RESULTS: At inclusion, 104 patients were in the DBPI group, 436 in the triple-NRTI group, and 19 in the ddI/d4T group. By 2010, 28 (29%), 204 (52%), and 1 (5%) patient were still on DBPIs, triple-NRTIs, and ddI plus d4T, respectively. 'Physician decision,' excluding toxicity/virological failure, drove 30% of treatment changes. Predictors of recommendation nonobservance included female sex [adjusted odds ratio (aOR) 2.69, 95% confidence interval (CI) 1 to 7.26; P = 0.01] for DPBIs, and undetectable VL (aOR 3.53, 95% CI 1.6 to 7.8; P = 0.002) and lack of cardiovascular events (aOR 2.93, 95% CI 1.23 to 6.97; P = 0.02) for triple-NRTIs. All patients on DBPIs with documented diabetes or a cardiovascular event changed treatment. Recommendation observance resulted in lower cholesterol values in the DBPI group (P = 0.06), and more patients having undetectable VL (P = 0.02) in the triple-NRTI group. CONCLUSION: The physician's decision is the main factor driving change from nonrecommended to recommended regimens, whereas virological suppression is associated with not switching. Positive clinical outcomes observed postswitch underline the importance of observing recommendations, even in well-controlled patients.

The potential role of cobalt ions released from metal prosthesis on the inhibition of Hv1 proton channels and the decrease in Staphyloccocus epidermidis killing by human neutrophils.

Infection by Staphylococcus epidermidis is a devastating complication of metal-on-metal (MM) total hip arthroplasty (THA). Neutrophils are the first line of defense against infection, and these innate immune cells are potentially exposed to Co(2+) ions released in the peri-prosthetic tissue by the wear of MM THA. The toxicity of Co(2+) is still debated, but Co(2+) is a potential inhibitor of the Hv1 proton channel that sustains the production of superoxide by neutrophils. In this study, we show that the Co(2+) concentration in peri-prosthetic tissue from patients with MM THA averages 53 µM and that such high concentrations of Co(2+) alter the antibacterial activity of human neutrophils in vitro by inhibiting Hv1 proton channels. We show that submillimolar concentrations of Co(2+) inhibit proton currents, impair the extrusion of cytosolic acid, and decrease the production of superoxide in human neutrophils. As a result, Co(2+) reduces the ability of human neutrophils to kill two strains of Staphyloccocus epidermidis by up to 7-fold at the maximal concentration tested of 100 µM Co(2+). By inhibiting proton channels, the Co(2+) ions released by metal prostheses might therefore promote bacterial infections in patients with metal-on-metal total hip arthroplasty.

Evidence of a role for monocytes in dissemination and brain invasion by Cryptococcus neoformans.

The pathogenesis of cryptococcosis, including the events leading to the production of meningoencephalitis, is still largely unknown. Evidence of a transcellular passage of Cryptococcus neoformans across the blood-brain barrier (BBB) and subsequent BBB disruption exists, but the paracellular passage of free yeasts and the role of monocytes in yeast dissemination and brain invasion (Trojan horse method) remain uncertain. We used our model of disseminated cryptococcosis, in which crossing of the BBB starts 6 h after intravenous inoculation, to study paracellular passage of the BBB. We prepared bone marrow-derived monocytes (BMDM) infected in vitro with C. neoformans (BMDM yeasts) and free yeasts and measured fungal loads in tissues. (i) Spleen and lung CFU were >2-fold higher in mice treated with BMDM yeasts than in those treated with free yeasts for 1 and 24 h (P < 0.05), while brain CFU were increased (3.9 times) only at 24 h (P < 0.05). (ii) By comparing the kinetics of brain invasion in naïve mice and in mice with preestablished cryptococcosis, we found that CFU were lower in the latter case, except at 6 h, when CFU from mice inoculated with BMDM yeasts were comparable to those measured in naïve mice and 2.5-fold higher than those in mice with preestablished cryptococcosis who were inoculated with free yeasts. (iii) Late phagocyte depletion obtained by clodronate injection reduced disease severity and lowered the fungal burden by 40% in all organs studied. These results provide evidence for Trojan horse crossing of the BBB by C. neoformans, together with mechanisms involving free yeasts, and overall for a role of phagocytes in fungal dissemination.

Idiopathic thrombocytopenic purpura in elderly patients: a study of 47 cases from a single reference center.

BACKGROUND: Idiopathic thrombocytopenic purpura (ITP) is often diagnosed in the elderly, but no specific guidelines exist for such patients. We describe our experience with ITP management in elderly patients and analyze the therapeutic response. METHODS: We retrospectively reviewed a cohort of 47 consecutive elderly ITP patients (> or =60 years old) followed in a single reference center. We specifically analyzed the clinical characteristics, therapies used, patient response rates, and side effects. RESULTS: The mean age of the 47 patients was 66 (range 60-82) years; 31 patients were female. Their initial presentation included bleeding limited to the skin (n=10, 21%) and bleeding at one or more other sites (n=26, 56%); 11 patients (23%) were asymptomatic. The mean platelet count was 52 x 10(9)/L (range 1-120 x 10(9)/L). After 1 and 6 months, the overall response rate was: 61% and 33% with corticosteroids (n=43), 80% and 50% with splenectomy (n=10), and 14% and 60% with danazol (n=15), respectively. Side effects of these therapies were reported in 100% of these elderly ITP patients, 60% and 50% with these drugs, respectively. No response was reported using IVIg. One case of fatal sepsis was noted after splenectomy. CONCLUSIONS: The results confirm (1) that age influences the hemorrhagic pattern of ITP expression, response, and adverse effects of conventional ITP therapies, and (2) that danazol has the potential to be an effective therapeutic alternative to splenectomy in elderly ITP patients.