El sodio como excipiente de medicamentos y su potencial relación con la elevación de la presión arterial / Sodium as a drug excipient and its potential relationship with blood pressure elevation

Objetivos: Conocer la composición cuantitativa de sodio en las formas farmacéuticas efervescentes y en soluciones de analgésicos, suplementos de calcio y mucolíticos utilizadas crónicamente; evaluar en qué proporción se tiene en cuenta el potencial riesgo a la hora de prescribir estos medicamentos a pacientes hipertensos y analizar si la toma de estas formas farmacéuticas por la población hipertensa se acompañaba de una descompensación de los valores de presión arterial (PA). Métodos: Se calculó el porcentaje de hipertensos tratados con paracetamol, calcio y acetilcisteína efervescentes (bicarbonato y carbonato sódico) en 10 Centros de Atención Primaria. Se realizó un estudio de cohortes retrospectivo con grupo control (ajustado por edad y género) en uno de los centros; seguimiento de un año. Las variables estudiadas fueron: PA sistólica (PAS) y diastólica (PAD) pre-post inicio del tratamiento con las formas farmacéuticas efervescentes, considerando clínicamente relevantes incrementos >5 mmHg; intensificación del tratamiento antihipertensivo.Resultados: Un 7,7% (rango: 5,4%-9,9%) de pacientes hipertensos se trataron con los medicamentos efervescentes estudiados. El porcentaje de hipertensos que mostraron un aumento de PAS relevante fue significativamente superior en el grupo tratado con medicamentos efervescentes en comparación al del grupo control: 35,9% (IC 95% 27,2%-44,6%) vs. 18,8% (IC 95% 12,7%-24,8%) y también respecto a la intensificación del tratamiento antihipertensivo, 46,6% (IC 95% 37,5%-55,6%) vs. 30% (IC 95% 22,9%-37,1%).Conclusiones: La sensibilización al potencial efecto adverso es muy variable. Los medicamentos efervescentes que incluyen carbonato-bicarbonato de sodio pueden incrementar la PA. El uso de las formas farmacéuticas efervescentes, especialmente en pacientes de riesgo, debe evitarse. (AU)

Aim: To know the quantitative composition of sodium in effervescent pharmaceutical forms and in solutions of analgesics, calcium supplements and mucolytics used chronically; to evaluate in what proportion the potential risk is taken into account when prescribing these drugs to hypertensive patients and to analyze whether the taking of these pharmaceutical forms by the hypertensive population was accompanied by a decompensation of blood pressure (BP) values.Methods: The percentage of hypertensive patients treated with effervescent paracetamol, calcium and acetylcysteine (bicarbonate and sodium carbonate) in 10 Primary Care Centers was calculated. A retrospective cohort study with a control group (adjusted for age and gender) was carried out in one of the centers. The follow-up was one year. The study variables were systolic (SBP) and diastolic (DBP) pre-post initiation of treatment with effervescent preparations, considering clinically relevant increases >5 mmHg; intensification of antihypertensive treatment.Results: 7.7% (range 5.4%-9.9%) of hypertensive patients were treated with the study effervescent drugs. The percentage of hypertensive patients who showed a relevant increase in SBP was significantly higher in the group treated with effervescent drugs compared to the control group: 35.9% (95% CI 27.2%-44.6%) vs. 18.8% (95% CI 12.7%-24.8%) and also regarding the intensification of antihypertensive treatment, 46.6% (95% CI 37.5%-55.6%) vs. 30% (95% CI 22.9%-37.1%).Conclusions: Sensitivity to the potential adverse effect is highly variable. Effervescent medications that include sodium carbonate-bicarbonate can increase BP. The use of effervescent pharmaceutical forms, especially in patients at risk, should be avoided. (AU)

Assessment of the quality of patient information sheets and informed consent forms for clinical trials at a hospital neurology service.

BACKGROUND AND PURPOSE: Clinical trials (CTs) aimed at vulnerable groups, such as patients with mental disorders, create ethical complexity. The patient information sheet (PIS) should provide all of the information about the CT that is relevant to the subject's decision to participate. After being informed, the subject will decide freely whether to take part in the CT and will read and sign the informed consent form (ICF). The objective was to assess the quality of PISs/ICFs from a hospital neurology service. The assessment was made using validated and reliable checklists of the information included in the PISs/ICFs of CTs with medicinal products. METHODS: The study comprised analyses of compliance with the checklists of 21 PISs and ICFs reviewed/approved during 2016-2017 by a medicinal research ethics committee. RESULTS: All PISs/ICFs were from multicenter CTs sponsored by pharmaceutical companies in different therapeutic areas, mainly Parkinson's (52.4%) and Alzheimer's (38.1%) diseases. The PISs from the neurology service demonstrated good compliance (≥80%) with the checklist, whereas ICFs should be improved. Sponsors omitted some relevant information, such as the study title or that the participant be informed of any information arising from the research that may be relevant to the subject's health, although this information may be in the PIS. CONCLUSIONS: The PISs/ICFs of CTs of medicinal products that are currently used need improvement. PISs and ICFs should be separate documents for each CT. In particular, the PISs/ICFs should consider the criteria related to the decision of participants, protect their rights and ensure that the information received is complete.

Desarrollo y validación de métodos analíticos para la cuantificación de antirretrovirales por HPLC / Development and validation of laboratory methods for antiretroviral quantitation using HPLC

Objetivo: Desarrollo, validación y caracterización de la funcióndel error de tres métodos analíticos mediante la técnica decromatografía líquida de alta eficacia (HPLC) para el análisis cuantitativode ritonavir, saquinavir y abacavir en plasma humano.Método: Se han indicado los reactivos y aparatos empleados,la preparación de los diferentes estándares de referencia, el procedimientode extracción desde la matriz biológica y las condicionesde análisis ensayadas para la puesta a punto de los tres métodosanalíticos. Además, también se han descrito las metodologías devalidación y de obtención de la función del error analítico.Resultados: Los métodos analíticos desarrollados para ritonavir,saquinavir y abacavir en plasma humano fueron selectivos,lineales (r2 > 0,99), precisos (coeficientes de variación < 15%) yexactos (errores relativos < 15%) en el rango de concentracionesseleccionado. La recuperación fue mayor del 95% en todos losmétodos. Los antirretrovirales estudiados fueron estables en lascondiciones ensayadas de acuerdo con la rutina del laboratorio.La función del error discriminada para cada uno de los métodosanalíticos validados resultó ser lineal en saquinavir (DE = 4,84 +7,14·10-2C) y abacavir (DE = -1,072 + 3,70·10-2C) y no lineal enel caso de ritonavir (DE = 39,98 + 2,40·10-5C2).Conclusiones: Se han desarrollado y posteriormente validadotres métodos analíticos, encontrándose los parámetros de validacióndentro de las especificaciones y atributos de calidad establecidos. Lafunción del error de cada uno de los métodos validados puedeemplearse como método de ponderación heteroscedástica en laestimación de parámetros mediante regresión no lineal en estudiosde farmacocinética clínica de los antirretrovirales ensayados

Objective: Development, validation and error characterizationof three analytical methods, by high performance liquid chromatography(HPLC), for the quantitative analysis of ritonavir,saquinavir and abacavir in human plasma.Method: Reagents and instrumentation used, preparation ofdifferent standards, sample extraction procedure from biologicmatrix, and analytical conditions assayed were detailed to set upthree analytical methods. In addition, the validation and the determinationof analytical error were also described.Results: The analytical methods developed for ritonavir,saquinavir and abacavir in human plasma were selective, linear(r2 > 0.99), precise (coefficients of variation < 15%) and accurate(relative errors < 15%) over the concentration range selected. Therecovery was more than 95% in all methods. Antiretroviral drugswere stable in the storage conditions assayed according to theroutine laboratory. The error function discriminated for each analyticalmethod validated was linear in saquinavir (SD = 4.84 +7.14·10-2C) and abacavir (SD = -1.072 + 3.70·10-2C), and nonlinearin ritonavir (SD = 39.98 + 2.40·10-5C2).Conclusions: Three analytical methods were developed andsubsequently validated, with validation parameters being withinthe specifications and attributes of quality established. The errorfunction characterized for each validated method can be used as aheteroscedastic weighting method in the parameter estimation bynon-linear regression analysis in clinical pharmacokinetic studiesof antiretroviral drugs assayed

[Development and validation of laboratory methods for antiretroviral quantitation using HPLC]. / Desarrollo y validación de métodos analíticos para la cuantificacion de antirretrovirales por HPLC.

OBJECTIVE: Development, validation and error characterization of three analytical methods, by high performance liquid chromatography (HPLC), for the quantitative analysis of ritonavir, saquinavir and abacavir in human plasma. METHOD: Reagents and instrumentation used, preparation of different standards, sample extraction procedure from biologic matrix, and analytical conditions assayed were detailed to set up three analytical methods. In addition, the validation and the determination of analytical error were also described. RESULTS: The analytical methods developed for ritonavir, saquinavir and abacavir in human plasma were selective, linear (r2>0.99), precise (coefficients of variation<15%) and accurate (relative errors<15%) over the concentration range selected. The recovery was more than 95% in all methods. Antiretroviral drugs were stable in the storage conditions assayed according to the routine laboratory. The error function discriminated for each analytical method validated was linear in saquinavir (SD=4.84+7.14.10(-2)C) and abacavir (SD=-1.072+3.70.10(-2)C), and non-linear in ritonavir (SD=39.98+2.40.10(-5)C2). CONCLUSIONS: Three analytical methods were developed and subsequently validated, with validation parameters being within the specifications and attributes of quality established. The error function characterized for each validated method can be used as a heteroscedastic weighting method in the parameter estimation by non-linear regression analysis in clinical pharmacokinetic studies of antiretroviral drugs assayed.

Pharmacokinetics of ricobendazole in calves.

The pharmacokinetics of ricobendazole (RBZ) and its major metabolite albendazole sulphone (ABZSO2) were studied in six calves, after administration of RBZ (7.5 mg/kg), using a 10% experimental solution by the intravenous (i.v.) route, a 10% commercial solution by the subcutaneous (s.c.) route, and a 10% experimental suspension by the intraruminal (i.r.) route. Blood samples were drawn during a 60-h period. Plasma drug and metabolite concentrations were determined by HPLC. The pharmacokinetic evaluation in each case was prepared by weighted least-squares nonlinear regression analysis. Ricobendazole i.v. data were best fitted by a two-compartment model. The best pharmacokinetic exponents and coefficients were estimated, and the pharmacokinetic variables for RBZ and ABZSO2 were calculated from them. Similar patterns of plasma disposition were found for RBZ after i.r. and s.c. administration, suggesting delayed release from the s.c. site resembling the slow release of the drug from the rumen.

Pharmacokinetics of amoxycillin in normal horses and horses with experimental arthritis.

The serum and synovial pharmacokinetics of amoxycillin (AMX) were studied after i.v. administration at a dosage of 40 mg/kg to normal horses and horses with induced aseptic carpal arthritis. The best estimates of serum and synovial pharmacokinetic parameters were calculated by mono or bivariable non-linear regression analysis. A biexponential equation was used to describe the concentration vs. time profiles in both normal and arthritic horses. There were no serum kinetic differences between normal and arthritic horses. There were, however, major synovial kinetic changes between these groups. The rate of penetration from serum to synovial fluid was larger in arthritic animals, indicating better penetration in this case. On the other hand, the rate of disappearance from synovial fluid was larger in normal horses, indicating more persistence of the drug in the diseased joint. Synovial AMX availability increased from 21% in normal horses to 79% in arthritic horses. These findings support the use of AMX for the treatment of infectious synovial joint disease produced by susceptible organisms in horses.

Análisis y estudio comparativo de la producción científica de los servicios de farmacia de hospital de España y gran bretaña a través del medline (1966-1997) / Analysis and comparative study of the scientific production of the hospital pharmacy services of Spain and Great Britain through the Medline (1966-1997)

En un intento de conocer las aportaciones de los servicios de farmacia de hospital (SFH) localizados en España y Gran Bretaña que pueden favorecer el desarrollo de la práctica basada en la evidencia, se ha realizado un análisis y un estudio comparativo de las líneas de investigación desarrolladas en dichos servicios, a partir de las publicaciones que originan. La base de datos utilizada como fuente de información fue Medline y el período de estudio 1966-1997.Para ello se fijaron tres criterios de inclusión para la selección de un documento indizado en Medline: que se realizara en España o Gran Bretaña, que los autores estuvieran adscritos exclusivamente al SFH y que el tema científico no fuera el económico. El análisis y estudio comparativo se realizó en función del área temática, año y revista de publicación y lugar de realización de los artículos publicados durante el período de estudio. (AU)

Two reproducible and sensitive liquid chromatographic methods to quantify atenolol and propranolol in human plasma and determination of their associated analytical error functions.

Two liquid chromatography (LC) methods with fluorimetric detection have been developed to measure atenolol and propranolol in human plasma. The same 5 microm Nucleosil RP-18 column, extraction procedure and mobile phase (containing acetonitrile, water, triethylamine and phosphoric acid, pH 3) were used. The linearity ranges were 25-800 ng/ml for atenolol and 3.13-100 ng/ml for propranolol. The coefficients of variation for validation assays were lower than 15% at the concentration assayed. The functions of the analytical error were linear: SD (ng/ml)=7.698+0.037C for atenolol and SD (ng/ml)=0.126+0.036C for propranolol.

A comparative in vitro study of percutaneous penetration of beta-blockers in human skin.

In vitro diffusion experiments with propranolol, oxprenolol, metoprolol and atenolol were carried out using excised human abdominal skin. The main permeation parameters (permeability coefficient, flow and lag time) were calculated and compared as measurement of intrinsic permeability across human skin. A long lag time and a low steady-state flow were found for all drugs assayed. Skin permeability predicted at steady state did not reach therapeutic concentrations, which indicated the need for appropriate chemical penetration enhancers or vehicles to overcome limiting factors. The results, including those of celiprolol and bisoprolol reported previously, correlated with physicochemical properties, especially with lipophilicity, one of the main factors in drug permeability prediction through human skin.

Determination of celiprolol and oxprenolol in human plasma by high-performance liquid chromatography and the analytical error function.

Two reversed-phase HPLC methods with UV detection to quantify celiprolol and oxprenolol in human plasma are described. The analytical methods for the determination of both drugs used the same reversed-phase HPLC column, mobile phase and extraction procedure. Linearity was obtained in the ranges 15.63-1000 and 25-800 ng/ml for celiprolol and oxprenolol, respectively. Intra-day and inter-day variation was lower than 14%. After validation of the methods, analytical error functions were established as S.D. (ng/ml)=3.096+0.041C for celiprolol and S.D. (ng/ml)=8.906+8.075x10(-8)C3 for oxprenolol.

Error structure for the HPLC analysis for atenolol, metoprolol and propranolol: a useful weighting method in parameter estimation.

Three reversed-phase high performance liquid chromatography (HPLC) methods with UV detection were developed and fully validated for the quantification of three beta-blockers: atenolol, metoprolol and propranolol. After validation, error structures for the HPLC analysis were established using a convenient and practical procedure. The mean percentage of relative standard deviation (RSD) of the experimental concentrations (C), were less than 4.29% for proportionality and less than 3.68% for precision for any of the drugs, which allowed the quantitation of beta-blockers assayed at concentrations in the range 25-0.78 micrograms.ml-1. The error structures for the HPLC analysis were: SD (micrograms.ml-1) = 5.02 x 10(-2) C for atenolol, SD (micrograms.ml-1) = 4.55 x 10(-2) + 0.63 x 10(-2) C - 7.58 x 10(-6) C3 for metoprolol and SD (micrograms.ml-1) = 2.73 x 10(-2) C - 3.49 x 10(-4) C2 for propranolol. The reciprocal of the square of the SD of the drug concentrations measured within the calibration curve could be used as weighting methods in parameter estimation by non-linear regression.

Comparative study of different weighting methods in non-linear regression analysis: implications in the parametrization of carebastine after intravenous administration in healthy volunteers.

The influence of different weighting methods in non-linear regression analysis was evaluated in the pharmacokinetics of carebastine after a single intravenous dose of 10 mg in 8 healthy volunteers. Plasma concentrations were measured by HPLC using an on-line solid-phase extraction method and automated injection. The analytical method was fully validated and the function of the analytical error subsequently determined. The parametric approach was performed using different weighting methods, including the homoscedastic method (W = 1) and heteroscedastic methods using weights of 1/C, 1/C2, and the inverse of the concentration variance calculated through the analytical error function (1/V), and the results were statistically evaluated according to the normal distribution. Statistically significant differences were observed in the representative parameters of the disposition kinetics of carebastine. The use of a multiple comparison test for statistical analysis of all differences among group means indicated that differences were generated between the homoscedastic method (W = 1) and the heteroscedastic methods (1/C, 1/C2, and 1/V). The results obtained in the present study confirmed the utility of the analytical error function as a weighting method in non-linear regression analysis and reinforced the importance of the correct choice of weights to avoid the estimation of imprecise or erroneous pharmacokinetic parameters.

The effects of the method of calculation on the evaluation of the pharmacokinetic parameters of oxytetracycline after intravenous administration to calves.

The aim of this study was to assess the differences in the values of the pharmacokinetic parameters attributable to the use of either linear or nonlinear regression analysis and to find the effect of weighting schemes on these differences. Six calves received 20 mg/kg oxytetracycline i.v. Blood samples were drawn during 72 h. The assay of the drug was performed microbiologically. A bicompartmental pharmacokinetic model was used, kinetic analysis being carried out by linear regression (LR) and by weighted least-squares nonlinear regression (WLSNLR). Statistical analysis included a test for normality, the Kruskall-Wallis test and ANOVA with log transformation. The A0, alpha and B0 did not show any statistically significant differences attributable to the mathematical method used. On the other hand, the statistically significant differences in the beta values found using the Kruskall-Wallis test and ANOVA with log transformation could be attributed to the different methods employed. ANOVA with log transformation determined statistically significant differences between the parameters obtained by linear analysis and those obtained by WLSNLR when the weighting (w) was 1. When weights were 1/x, 1/x2 or 1/square root of x, no statistically significant differences were found. The optimal weighting scheme was w = 1/x2 because of a more homogeneous scatter and random distribution of residuals about the abcissa axis in a plot of weighted residuals in the ordinate versus time in the abcissa. It was concluded that the use of these different procedures can give major variations in the apparent value of beta, the most important pharmacokinetic parameter. The correct selection of the weighting procedure is therefore fundamental in obtaining the best estimate of this pharmacokinetic parameter in WLSNLR.

Pentoxifylline, ciprofloxacin and prednisone failed to prevent transplant-related toxicities in bone marrow transplant recipients and were associated with an increased incidence of infectious complications.

TNF-alpha (Tumor necrosis factor-alpha) is involved in many immunological and inflammatory processes, and might be expected to play an important role in the development of BMT-related complications. Triple therapy (pentoxifylline, ciprofloxacin and prednisone) with known anti-TNF activity was tested in 37 patients undergoing a hematopoietic progenitor transplant (HPT). A control group of 16 patients with similar characteristics was selected among consecutive patients receiving a HTP in a neighboring center who did not receive anti-TNF prophylaxis. Major transplant-related complications were registered (VOD, acute GVHD, infectious episodes, renal failure and mucositis) and survival status. TNF plasma concentrations were determined by ELISA, and pentoxifylline plasma concentrations were determined by HPLC. Among patients treated with pentoxifylline (PTX), ciprofloxacin and steroids, no difference in the mean survival time was observed compared with the control group. The incidence of procedure-related death up to day +35 was 11% in the study group and 6% in the control group. In spite of a tendency to a lower incidence of mucositis there was a higher incidence of infections (positive blood cultures) in the study group (49%) than in the control group (16.7%) (P = 0.16). This difference achieved statistical significance in patients receiving an allogeneic HPT (P = 0.05). It is likely that the use of steroids in the early period after transplant increases infectious episodes and makes control of GVHD difficult. The combined administration of steroids with pentoxifylline and ciprofloxacin has not proved beneficial in preventing mucositis, renal failure, VOD or GVHD, or in improving patient survival.

Parametrization by nonlinear regression analysis of the active acid metabolite of ebastine using different weighting methods.

The study of the analytical error function has been applied to evaluate the pharmacokinetics of ebastine active acid metabolite after a single oral dose of 10 mg of metabolite in 6 healthy volunteers. Plasma concentrations were measured using an automated solid phase extraction method. The analytical method was fully validated and the function of the analytical error subsequently determined. The parametric approach was performed by nonlinear regression analysis comparing the results obtained after the application of different weighted least square methods including the homoscedastic method (W = 1) and heteroscedastic methods using weights of 1/C, 1/C2 and the inverse of the concentration variance calculated through the function of the analytical error. The results obtained in the study showed no influence of the different weighting methods used on the estimation of the pharmacokinetic parameters of ebastine acid metabolite.

Determination of analytical error function for beta-blockers as a possible weighting method for the estimation of the regression parameters.

Three analytical methods have been developed and validated for the quantification of beta-blockers (celiprolol, bisoprolol and oxprenolol) using high performance liquid chromatography (HPLC) with UV detection. The methods were determined to be linear, precise and accurate (RSDs were lower than 5%), which allowed the quantitation of beta-blockers assayed at concentrations in the range 25-0.78 micrograms ml-1. After validation of reversed-phase HPLC methods, their analytical error functions were established by a rapid, simple and economical procedure. The discrimination of the best function for each active principle was performed by an appropriate polynomial statistical analysis, yielding SD (microgram ml-1) = 0.0295 + 0.0124C - 3.88 x 10(-4)C2 for celiprolol, 0.0199 + 0.011C - 1.27 x 10(-5)C3 for bisoprolol; and 0.0183 + 0.0089C - 9.68 x 10(-6)C3 for oxprenolol. These analytical error functions are an alternative to the weighting methods used in parameter estimation of beta-blockers.

Stability of an oral midazolam solution for premedication in paediatric patients.

The objectives of this study were to assess the stability of a 1 mg/ml oral midazolam solution elaborated by our Hospital Pharmacy Service, and to confirm its clinical effect in presurgical paediatric patients. The solution's stability was tested by determining its pH and its UV-visible absorption spectrum at room temperature for up to 60 days. A high performance liquid chromatography method was used to confirm it. There was no significant change in pH value of either the test or a control solution. No loss of midazolam could be detected during the test. The Anaesthesiology Service assessed the sedation quality (very good, good, bad) and the venous puncture response, 20 minutes after the administration of 0.3 mg/kg of an oral midazolam solution. Twenty children were examined (age: 4-7 years). In addition, the haemodynamic and ventilatory functions were evaluated.

Pharmacokinetic parameters from data relating to the plasma and biliary excretion kinetics of cefmetazole in rats.

The plasma disposition kinetics and the biliary excretion kinetics of cefmetazole after i.v. administration to rats anaesthetized with pentobarbital sodium were studied. Parametric estimation was carried out using non-linear regression methods with uni- and bivariate analyses. On the basis of statistical criteria a two-compartment model was chosen as the most appropriate for fitting the plasma concentration data, establishing a mean half-life value of the slow disposition phase at around 13 min. Analysis of the plasma and biliary data revealed a mean value for the biliary excretion constant of 0.049 l/min and 0.113 l/min for the urinary excretion constant. The cumulative biliary excretion data showed a mean value of 36.25% of the dose administered. The relationship between the biliary excretion rates and plasma concentrations seems to point to a saturable mechanism of excretion.

Open-loop feedback control of serum bentazepam concentrations and Bayesian estimation in multiple dosage regimens in patients.

The time course of serum levels of bentazepam was studied in 10 patients receiving anxiolytic agent orally at a dose of 25 mg on multiple dosage regimens with dosage intervals of 8 and 12 h. Using the methods of "open-loop feedback control", no linear regression programs and Bayesian estimation, it was possible to establish the best estimates of the pharmacokinetic parameters corresponding to the single-compartment model for each patient from all their data relating to the serum levels obtained after the first dose and after multiple dosing with different regimens. The application of the Kruskal Wallis test showed that there were only statistical differences for the absorption constant, determined with and without Bayesian estimation. However, no statistically significant differences were found on comparing the experimentally obtained serum levels with the corresponding theoretical values calculated independently for each patient from the parameters established with and without Bayesian estimation. As population pharmacokinetic parameters of bentazepam, the following were established: Ka = 2.330 +/- 0.665 l/h; Vd = 1.209 +/- 0.546 l/Kg and Ke = 0.160 +/- 0.118 l/h, corresponding to a mean value for the elimination half-life of 4.33 h.