Pharmacokinetics/Pharmacodynamics and tolerability of cefiderocol in the clinical setting.

Cefiderocol is a new cephalosporin with a catechol in its chemical structure faciliting its access to the interior of bacteria through iron channels. In addition, it is broadly stable to beta-lactamases. The pharmacokinetic profile is a beta-lactam one: no oral absorption, and with a wide distribution within the vascular space and the interstitial fluid of well vascularized tissues, reaching therapeutic concentrations in the alveolar lavage fluid and within the macrophage. The binding of cefiderocol to human plasma proteins, primarily albumin, is moderate (range 40-60%). The terminal elimination half-life in healthy adult subjects was 2 to 3 hours. Cefiderocol is mainly renally eliminated, so dose adjustments are recommended in subjects with moderate / severe renal impairment, in case of dialysis, and probably in patients with external clearance. Like other beta-lactams, the PK / PD parameter that has been shown to best correlate with efficacy is the efficacy time of unbound plasma concentrations (%fT>MIC), which must be close to 100% to achieve a bactericidal effect. This is possible with 2 g in a 3-hour infusion every 8 hours. In controlled trials appears to be well tolerated, similar to comparators: meropenem or imipenem-cilastatin. Cefiderocol has no apparent clinically significant effect on ECG parameters nor on plasma iron values.

Ceftobiprole: pharmacokinetics and PK/PD profile.

Ceftobiprole shows many similar pharmacokinetic properties to other cephalosporins, except for not being orally bioactive, and that it is administered by IV infusion as the prodrug ceftobiprole medocaril, which is subsequently hydrolyzed in the blood into the active molecule. Distribution focus in extracellular fluid and active antibiotic concentration has been proven in different corporal tissues using dosing regimen of 500 mg intravenous infusion over 2 h every 8 h. Ceftobiprole is eliminated exclusively into the urine, thus the reason why dose adjustment is required for patients with moderate or severe renal impairment, or increased creatinine clearance. However, there is no need for dose adjustments related with other comorbidities and patients' conditions such as age, body weight. Although considering distribution features, molecular weight and dose fraction, increase dosing regimen might be necessary in patients using renal replacement therapy. The half-life of ceftobiprole is more than 3 h, allowing to easily reach optimal PK/PD parameters with the infusion time of 2 h, using the usual dosing regimen.

Bioavailability of two oral fentanyl transmucosal formulations in healthy volunteers: an open-label, crossover, randomised study / Biodisponibilidad de dos formulaciones de fentanilo oral transmucosa en voluntarios sanos: un estudio abierto, cruzado y aleatorizado

Introduction: Oral transmucosal fentanyl citrate (OTFC) was the first product specifically designed for the treatment of breakthrough pain. It is formulated as a sweetened lozenge on a plastic handle (stick) and it is self-administered by the patient, allowing the modulability or flexibility in dosing. Objectives: To prove bioequivalence of a test (T) OTFC product compared to the reference (R) formulation. Material and methods: Open-label, crossover, randomized, single-dose bioequivalence study in healthy volunteers, with two study periods and two sequences, with a washout period of at least 10 days. On each study day, subjects received 400 μg of fentanyl. They were instructed to rub the tablet gently against the buccal mucosa and not to suck on or chew it, and the investigators controlled each administration to ensure that it was consumed during 15 minutes. Given the high pharmacokinetic variability, a two-stage design was established and bioequivalence decision was based on 94.12% confidence intervals of Cmax and AUC0-t geometric means ratio. Results: 36 subjects completed the study according to the protocol. Mean Cmax were similar with both formulations (814.78 pg/ml for T and 781.83 pg/ml for R) and were attained at the same time (40 min. for T and 50 min. for R), and their bioavailability was also very close (AUC0-t: 3920.12 pg.h/ml for T and 3679.39 pg.h/ml for R). Bioequivalence was confirmed for the two primary parameters, Cmax and AUC0-t. No period or sequence effects were observed in any parameter. As bioequivalence was proved in the first phase of the study, it was not necessary to proceed to the second stage. The estimated intraindividual variability was 24.66% and 19.01%, respectively for T and R formulations. Both formulations were well tolerated; 15 mild adverse events were reported. Discussion: The test OTFC product is bioequivalent to the reference one and therefore interchangeable when used clinically. OTFC administration provides faster fentanyl absorption than enteral route and the rate of absorption can be modulated by the administration technique, providing a unique flexibility among all breakthrough pain treatments. The results showed a fast time to maximum concentrations (tmax), in accordance with those originally reported for the reference product, probably favoured by the strict administration technique. Proper patient education is essential to optimize the use of OTFC, as well-trained patients can take advantage of its flexibility to self-controlling pain relief

Introducción: El citrato de fentanilo oral transmucosa (CFOT) fue el primer medicamento diseñado específicamente para tratar el dolor irruptivo. Está formulado como una matriz de polvo comprimido con aplicador de plástico (palito), y el paciente se lo administra, lo que proporciona modulabilidad o flexibilidad de dosis. Objetivos: Probar la bioequivalencia entre el medicamento CFOT test (T) y el de referencia (R). Material y métodos: Estudio abierto, cruzado, aleatorizado, de bioequivalencia a dosis única en voluntarios sanos, con dos periodos y dos secuencias, y con un tiempo de lavado de al menos 10 días. Los sujetos tomaron 400 μg de fentanilo cada día de estudio. Se les instruyó para que restregaran el comprimido contra la mucosa bucal sin chuparlo ni masticarlo, y los investigadores controlaron cada administración para asegurar que se consumía en 15 minutos. Se estableció un diseño en dos etapas por la alta variabilidad farmacocinética esperada, y la decisión de bioequivalencia se basó en los intervalos de confianza al 94,12 % de la razón de las medias geométricas de la Cmax y el AUC0-t. Resultados: 36 sujetos completaron el estudio de acuerdo con el protocolo. Las medias de Cmax fueron similares con ambas formulaciones (814,78 pg/ml para T y 781,83 pg/ml para R) y se alcanzaron al mismo tiempo (40 min para T y 50 min para R), y su biodisponibilidad también fue muy semejante (AUC0-t: 3920,12 pg.h/ml para T y 3679,39 pg.h/ml para R). Se confirmó la bioequivalencia para los dos parámetros principales, Cmax y AUC0-t. No se observaron efecto periodo ni secuencia para ningún parámetro. Como se probó la bioequivalencia en la primera fase del estudio no fue necesario proceder a la segunda fase. La variabilidad intraindividual estimada fue 24,66 y 19,01 %, respectivamente para T y R. Los dos medicamentos fueron bien tolerados; se registraron 5 acontecimientos adversos de intensidad leve. Conclusiones: La formulación CFOT test es bioequivalente con la de referencia, y por tanto son clínicamente intercambiables. La administración de CFOT proporciona una absorción más rápida de fentanilo que la vía enteral y la tasa de absorción puede modularse con la técnica de administración, aportando una flexibilidad única al resto de tratamientos del dolor irruptivo. Los resultados muestran un breve tiempo hasta concentraciones plasmáticas máximas (tmax), coincidente con el descrito originalmente para la formulación de referencia, favorecido probablemente por la estricta técnica de administración. Es esencial una adecuada formación de los pacientes para optimizar el uso de CFOT, ya que los pacientes bien entrenados pueden sacar buen provecho de su flexibilidad para auto-regularse el alivio del dolor

Bilastine for the relief of allergy symptoms.

Bilastine is a potent inhibitor of the histamine H1 receptor. It was recently approved in 28 countries of the European Union for the symptomatic treatment of allergic rhinoconjunctivitis and urticaria in adults and children older than 12 years. Data from preclinical studies confirmed its selectivity for the histamine H1 receptor over other receptors, and demonstrated antihistaminic and antiallergic properties in vivo. Studies in healthy volunteers and patients have shown that bilastine does not affect driving ability, cardiac conduction or alertness. Bilastine has demonstrated a good safety profile, without serious adverse effects or antimuscarinic effects in clinical trials. There were no significant changes in laboratory tests, electrocardiograms or vital signs. In clinical studies, oral treatment with bilastine 20 mg once daily improved allergic rhinitis with greater efficacy than placebo and comparable to cetirizine and desloratadine. Bilastine 20 mg was more effective than placebo and equivalent to levocetirizine in chronic urticaria, relieving symptoms, improving quality of life and controlling sleep disorders.

Farmacología de antimicrobianos utilizados en el tratamiento de las infecciones graves por bacterias grampositivas / Pharmacology of antimicrobials used in the treatment of serious Gram-positive bacteria infections

Los antimicrobianos con actividad frente a patógenos grampositivos (glucopéptidos, estreptograminas y oxazolidinonas) presentan diferencias farmacocinéticas que es importante conocer. Linezolid y teicoplanina pueden ser administrados por vía extravascular, al presentar una absorción adecuada. Este hecho permite su uso en terapia secuencial en pacientes que precisan tratamiento prolongado. La difusión de todos ellos al espacio extracelular es adecuada, incluso en el caso de teicoplanina debido al equilibrio existente entre la fracción de fármaco fijada y la no fijada a proteínas y su elevada semivida de eliminación. La eliminación de los glucopéptidos es casi exclusivamente renal, por lo que se precisa ajustar su posología en pacientes con deterioro renal. Quinupristina-dalfopristina y linezolid son eliminados en su mayor parte por metabolismo. El sistema CYP450 se encuentra implicado en la eliminación de las estreptograminas (AU)

[Pharmacology of antimicrobials used in the treatment of serious Gram-positive bacteria infections]. / Farmacología de antimicrobianos utilizados en el tratamiento de las infecciones graves por bacterias grampositivas.

Antimicrobials with specific activity against Gram-positive cocci (glycopeptides, oxazolidinones and streptogramins) have pharmacokinetic differences that are important to know. Linezolid and teicoplanin can be administered extravascularly due to their good bioavailability, allowing their use as sequential therapy in patients requiring prolonged treatment. All of these antimicrobials have an adequate distribution in extracellular tissues, even teicoplanin, due to the balance between the fraction that is bound and unbound to plasma proteins and its long terminal half-life. As the elimination of glycopeptides is almost exclusively renal, it is necessary to perform a posology adjustment in patients with renal failure. Quinupristin/dalfopristin and linezolid are metabolized by the liver, but CYP450 is only involved in streptogramin elimination.

Perfil de seguridad de las fluoroquinolonas / Safety profile of the fluoroquinolones

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