Chemical stability and physical compatibility of meropenem in admixtures for continuous and extended intravenous infusions / Estabilidad química y compatibilidad física de meropenem en mezclas para infusión intravenosa continua y extendida

Introduction: Prolonged intravenous infusion of beta-lactams increase the clinical cure rate compared to conventional administration in critical or septic patients. This study aimed to determine chemical stability and physical compatibility of meropenem at conditions used in clinical practice to evaluate the stability of the preparation during its administration and the possibility of anticipated preparation. Methods: Admixtures in study were: (i) meropenem 6g in 0.9% sodium chloride (NS) in infusor of 2mL/h 50mL or 10mL/h 240mL; (ii) meropenem 1 or 2g in NS in infusion bag of 250mL. Temperatures of study were: (i) infusor: 4.5°C, 32°C or 12h at 4.5°C followed by 32°C; (ii) Infusion bag: 4.5°C, 24.5°C or 6h at 4.5°C followed by 24.5°C. Time of study was 5–6 days in infusor and 1 day in infusion bag. Chemical stability was evaluated by high performance liquid chromatography and physical compatibility by measuring pH and visual inspection. Results: Chemical stability and physical compatibility of meropenem in admixtures in infusors were reduced at high meropenem concentration and high temperature. Admixtures in infusion bag show chemical stability and physical compatibility for at least 1 day. Conclusion: Administration of meropenem 6g in infusion of 24h in 240mL of 0.9% NaCl in infusor of 10mL/h could be possible if the admixture is infused at 4.5°C. Extended infusion of meropenem 1 or 2g in 0.9% NaCl in infusion bag (250mL) in 3–4h is also feasible. Anticipated preparation of the admixtures in infusion bag is possible with a stability of 24h.(AU)

Introducción: La infusión intravenosa prolongada de beta-lactámicos aumenta la velocidad de curación clínica comparada con la administración convencional en pacientes críticos o sépticos. Este estudio tiene como objetivo determinar la estabilidad química y la compatibilidad física de meropenem en condiciones utilizadas en la práctica clínica para evaluar la estabilidad de la preparación durante su administración y la posibilidad de la preparación anticipada. Métodos: Las mezclas en estudio fueron: (I) meropenem 6g en cloruro sódico 0,9% (SN) en infusor de 2mL/h 50 mL o 10mL/h 240mL; (iii) meropenem 1 o 2g en SN en bolsa de infusión de 250mL. Las temperaturas de estudio fueron: (i) infusor: 4,5°C, 32°C o 12h a 4,5°c seguido de 32°C; (ii) bolsa de infusión: 4,5°C, 24,5°C o 6h a 4,5°c seguido de 24,5°C. El tiempo de estudio fue de 5-6 días en infusor y 1 día en bolsa de infusión. Se evaluó la estabilidad química mediante cromatografía líquida de alta resolución y la compatibilidad física por medida de pH e inspección visual. Resultados: La estabilidad química y la compatibilidad física de meropenem en las mezclas en infusores disminuyeron al aumentar la concentración de meropenem y la temperatura. Las mezclas en bolsas de infusión mostraron estabilidad química y compatibilidad física durante al menos 1 día. Conclusión: La administración de meropenem 6g en infusión de 24h en 240 mL de cloruro sódico 0,9% en infusor de 10ml/h podría ser posible si la mezcla es administrada a 4,5°C. La infusión extendida de 1 o 2g en cloruro sódico 0,9% en bolsa de infusión (250 mL) en 3-4h es también viable. Puede realizarse la preparación anticipada de mezclas de meropenem en bolsas de infusión con una estabilidad de 1 día.(AU)

Chemical stability and physical compatibility of meropenem in admixtures for continuous and extended intravenous infusions.

INTRODUCTION: Prolonged intravenous infusion of beta-lactams increase the clinical cure rate compared to conventional administration in critical or septic patients. This study aimed to determine chemical stability and physical compatibility of meropenem at conditions used in clinical practice to evaluate the stability of the preparation during its administration and the possibility of anticipated preparation. METHODS: Admixtures in study were: (i) meropenem 6g in 0.9% sodium chloride (NS) in infusor of 2mL/h 50mL or 10mL/h 240mL; (ii) meropenem 1 or 2g in NS in infusion bag of 250mL. Temperatures of study were: (i) infusor: 4.5°C, 32°C or 12h at 4.5°C followed by 32°C; (ii) Infusion bag: 4.5°C, 24.5°C or 6h at 4.5°C followed by 24.5°C. Time of study was 5-6 days in infusor and 1 day in infusion bag. Chemical stability was evaluated by high performance liquid chromatography and physical compatibility by measuring pH and visual inspection. RESULTS: Chemical stability and physical compatibility of meropenem in admixtures in infusors were reduced at high meropenem concentration and high temperature. Admixtures in infusion bag show chemical stability and physical compatibility for at least 1 day. CONCLUSION: Administration of meropenem 6g in infusion of 24h in 240mL of 0.9% NaCl in infusor of 10mL/h could be possible if the admixture is infused at 4.5°C. Extended infusion of meropenem 1 or 2g in 0.9% NaCl in infusion bag (250mL) in 3-4h is also feasible. Anticipated preparation of the admixtures in infusion bag is possible with a stability of 24h.

Quantitative assessment of the exposure-efficacy relationship of glucocerebrosidase using Markovian elements in Gaucher patients treated with enzyme replacement therapy.

AIMS: The aims of this study are (i) to develop a population pharmacokinetic model of enzyme activity in Gaucher-type 1 (GD1) patients after intravenous administration of enzyme replacement therapy (ERT), and (ii) to establish an exposure-efficacy relationship for bone marrow infiltration to propose dose adjustments according to patient covariate values. METHODS: A prospective follow-up, semi-experimental multi-centre study was conducted in four hospitals to evaluate the pharmacokinetics, efficacy and safety of ERT in GD1 patients. Twenty-five individuals with 266 glucocerebrosidase (GCase) observations in plasma and leukocytes and 14 individuals with 68 Spanish magnetic resonance imaging (S-MRI) observations were enrolled. RESULTS: A two concatenated compartment model with zero-order endogenous production and first-order distribution (CL1 = 3.85 × 10-1 L/d) and elimination (CL2 = 1.25 L/d) allowed GCase observations in plasma and leukocytes to be described, respectively. An exponential time dependency (kT = 6.14 × 10-1 d-1 ) effect on CL1 was incorporated. The final exposure-efficacy model was a longitudinal logistic regression model with a first-order Markov element. An Emax function (EC50 = 15.73 U/L and Emax = 2.33) linked steady-state concentrations of GCase in leukocytes to the probability of transition across the different S-MRI stages. CONCLUSION: A population pharmacokinetic model successfully characterized the leukocyte activity-time profiles of GCase following intravenous administration of ERT in GD1 patients together with an exposure-efficacy relationship in bone marrow using Markovian elements. The information obtained from this study could be of high clinical relevance in individualization of ERT in GD1 patients, as this could lead to anticipative decision-making regarding clinical response in bone and optimal dosing strategy.

Topical rapamycin in the treatment of facial angiofibromas in tuberous sclerosis: a systematic review based on evidence.

INTRODUCTION: facial angiofibromas of tuberous sclerosis are the most prevalent cutaneous manifestation, affecting 80% of patients, which cause facial lesions with negative psychosocial consequences. Newly, topical rapamycin has been established as an effective and safe therapy for this skin condition. PURPOSE: to analyze the available scientific evidence about the effectiveness and safety of topical sirolimus in the treatment of facial angiofibromas in tuberous sclerosis. METHODS: a literature search was conducted in PubMed and Cochrane. Effectiveness and safety were analyzed along with the main characteristics of each formulation in all included studies. RESULTS: thirty studies were included involving a total of 508 patients, developed in the last 20 years. Four randomized clinical trial, 17 case series and 9 single case reports were founded. Multiple topical rapamycin concentrations (0.003-1%) and formulations (gel, ointment, solution) were found in literature. Rapamycin demonstrated its effectiveness in all studies included, except for 5 patients in a 1 b study. Rapamycin was shown to be safe for the treatment of FA. CONCLUSIONS: Topical sirolimus can be considered an effective and safety option for the treatment of facial angiofibromas in tuberous sclerosis. However, further long-term studies need to establish an evidence-based therapeutic protocol.KEY MESSAGEUpdated review to date in topical rapamycin for facial angiofibromas, allowing support in therapeutic decisions.

Physico-Chemical Stability of Admixtures of Vinflunine Used in Clinical Practice.

Procedure of administration of vinflunine is complex and consists of an Y-site injection with fluid at different speeds. Dose is diluted with 100 mL of 0.9% sodium chloride or 5% glucose and infused with half of the 500 mL bag of the fluid over 20 min; after that, the remaining fluid is administered at 300 mL/h. In this study, chemical stability and physical compatibility of vinflunine diluted with in 500 mL of both fluids were evaluated to simplify the administration procedure (infusion of mixture on 20 min followed by 250 mL of fluid at 300 mL/h). Physical compatibility and chemical stability were evaluated at two temperatures and protected from and exposed to light. Physical compatibility was evaluated by visual inspection, gravimetric control and measure of pH. A chromatographic method was developed to evaluate chemical stability. The dilution of vinflunine with 500 mL of fluid to final concentrations of 0.75 and 1.54 mg/mL is viable at doses used in clinical practice since admixtures are stable for 2 days at room temperature and at least 7 days under refrigeration. These results extend the expiration date of mixtures of vinflunine administered by the usual procedure and confirm the viability of the proposed procedure since administration is simplified and stability of vinflunine is guaranteed.

Physicochemical stability of binary admixtures of paracetamol and dexketoprofen-trometamol for patient-controlled analgesia use.

BACKGROUND: Intravenous admixtures of dexketoprofen-trometamol and paracetamol are frequently used in clinical practice due to synergism obtained administering both drugs concomitantly. Physicochemical stability of binary admixture containing both drugs is currently unknown. OBJECTIVE: To determine physicochemical stability of binary admixture containing dexketoprofen-trometamol 50 mg and paracetamol 1000 mg in a low-density polyethylene bottle at different storage conditions of light and temperature for advanced preparation. METHODS: Eight mixtures containing dexketoprofen-trometamol (Enantyum ampule 2 mL) 50 mg and paracetamol (Paracetamol B. Braun bottle 100 mL) 1000 mg were prepared and stored at: room temperature and exposed to light; room temperature and protected from light; refrigerated and exposed to light; and refrigerated and protected from light. From each mixture, aliquots were extracted at different times for 15 days. For physical compatibility, pH measure, gravimetric analysis and visual inspection were carried out. For chemical stability, concentrations of dexketoprofen-trometamol and paracetamol were simultaneously measured by high performance liquid chromatography. RESULTS: Only refrigerated mixtures showed incompatibility since white precipitation appeared at day 6, possibly due to paracetamol instability. Remaining drugs concentrations were in all cases≥90% after 15 days. CONCLUSION: Binary mixture containing paracetamol (100 mL) 1000 mg and dexketoprofen-trometamol (2 mL) 50 mg in a low-density polyethylene bottle is physicochemically stable for 5 days under refrigeration and 15 days at room temperature. By considering also microbial contamination, this mixture can be prepared in advance, 5 days stored refrigerated and 2 days stored at room temperature, being unnecessary protection from light.

Relationship Between Glucocerebrosidase Activity and Clinical Response to Enzyme Replacement Therapy in Patients With Gaucher Disease Type I.

The quantification of enzyme activity in the patient treated with enzyme replacement therapy (ERT) has been suggested as a tool for dosage individualization, so we conducted a study to evaluate the relationship between glucocerebrosidase activity and clinical response in patients with Gaucher disease type I (GD1) to ERT. The study included patients diagnosed with GD1, who were being treated with ERT, and healthy individuals. Markers based on glucocerebrosidase activity measurement in patients' leucocytes were studied: enzyme activity at 15 min. post-infusion (Act75 ) reflects the amount of enzyme that is distributed in the body post-ERT infusion, and accumulated glucocerebrosidase activity during ERT infusion (Act75-0 ) indicates the total drug exposure during infusion. The clinical response was evaluated based on criteria established by Pastores et al. and Gaucher Severity Score Index. Statistical analysis included ROC analysis and area under the curve test. Act75 and Act75-0 were found to be moderate predictive markers of an optimal clinical response (area under the ROC of Act75 was 0.733 and Act75-0 was 0.817). Act75-0 showed statistical significance in its discriminative capacity (p < 0.05) for obtaining an optimal response to ERT. The cut-off point was 58% (RR = 1.800; 95% CI: 1.003-3.229; p < 0.05). Moreover, Act75 showed a significant and inverse correlation with the Gaucher Severity Score Index, and Act75 and Act75-0 presented a significant correlation with residual enzyme activity at diagnosis. Markers based on glucocerebrosidase activity have a good correlation with clinical response to ERT. Therefore, it could provide supporting clinical data for dose management in GD1 patients.

Cellular Uptake of Glucocerebrosidase in Gaucher Patients Receiving Enzyme Replacement Treatment.

BACKGROUND: Enzyme replacement therapy (ERT) is currently the standard treatment for patients with Gaucher disease type I (GD1), but the pharmacokinetics have hardly been studied. This study aimed to quantify in vivo enzyme activity in peripheral leukocytes from patients receiving long-term treatment with imiglucerase or velaglucerase for GD1, and set out to assess the process of enzymatic uptake by peripheral leukocytes. METHODS: A prospective semi-experimental study was conducted. Four time points for blood withdrawal were planned per patient to quantify the intra-leukocyte enzymatic activity. In order to assess the uptake process, the rate of enzyme uptake by leukocytes (Rupt) and the rate of enzyme disappearance from the plasma (Rdis) were estimated. RESULTS: Eight GD1 patients were included. Intra-leukocyte activity was 24.31 mU/mL [standard deviation (SD) 6.32 mU/mL; coefficient of variation (CV) 25.96 %] at baseline and 27.14 mU/mL (SD  6.96 mU/mL; CV 25.65 %) at 15 min post-perfusion. The relationships with the administered dose were linear. The Rupt value was 37.73 mU/mL/min [95 % confidence interval (CI) 25.63-49.84] and showed a linear correlation with the administered enzyme dose (p < 0.05), and the Rdis value was 189.43 mU/mL/min (95 % CI 80.31-298.55) and also showed a linear correlation with the dose (p < 0.05). CONCLUSION: This was the first in vivo study to quantify the accumulated enzymatic activity in patients receiving ERT for GD1. It showed that intra-leukocyte activity at baseline and at 15 min post-perfusion could be used as a possible marker for therapeutic individualization in patients receiving ERT for GD1.

A Wide Linearity Range Method for the Determination of Lenalidomide in Plasma by High-Performance Liquid Chromatography: Application to Pharmacokinetic Studies.

A wide linearity range analytical method for the determination of lenalidomide in patients with multiple myeloma for pharmacokinetic studies is required. Plasma samples were ultrasonicated for protein precipitation. A solid-phase extraction was performed. The eluted samples were evaporated to dryness under vacuum, and the solid obtained was diluted and injected into the high-performance liquid chromatography (HPLC) system. Separation of lenalidomide was performed on an Xterra RP C18 (250 mm length × 4.6 mm i.d., 5 µm) using a mobile phase consisting of phosphate buffer/acetonitrile (85:15, v/v, pH 3.2) at a flow rate of 0.5 mL · min-1 The samples were monitored at a wavelength of 311 nm. A linear relationship with good correlation coefficient (r = 0.997, n = 9) was found between the peak area and lenalidomide concentrations in the range of 100 to 950 ng · mL-1 The limits of detection and quantitation were 28 and 100 ng · mL-1, respectively. The intra- and interassay precisions were satisfactory, and the accuracy of the method was proved. In conclusion, the proposed method is suitable for the accurate quantification of lenalidomide in human plasma with a wide linear range, from 100 to 950 ng · mL-1 This is a valuable method for pharmacokinetic studies of lenalidomide in human subjects.

Evaluation of enantioselective binding of propanocaine to human serum albumin by ultrafiltration and electrokinetic chromatography under intermediate precision conditions.

Stereoselectivity in protein binding can have a significant effect on the pharmacokinetic and pharmacodynamic properties of chiral drugs. In this paper, the enantioselective binding of propanocaine (PRO) enantiomers to human serum albumin (HSA), the most relevant plasmatic protein in view of stereoselectivity, has been evaluated by incubation and ultrafiltration of racemic PRO-HSA mixtures and chiral analysis of the bound and unbound fractions by electrokinetic chromatography using HSA as chiral selector. Experimental conditions for the separation of PRO enantiomers using HSA as chiral selector and electrokinetic chromatography have been optimised. Affinity constants and protein binding in percentage (PB) were obtained for both enantiomers of PRO, as well as the enantioselectivity (ES) to HSA. Data were obtained in two independent working sessions (days). The influence of the session and fraction processed factors were examined. A univariate direct-estimation approach was used facilitating outliers' identification and statistical comparison. Non-linear fitting of data was used to verify the stoichiometry and affinity estimations obtained by the direct approach. Robust statistics were applied to obtain reliable estimations of uncertainty, accounting for the factors (day and processed fraction), thus representing intermediate precision conditions. Mimicking in vivo experimental conditions, information unapproachable by in vivo experiments was obtained for PRO enantiomers interacting with HSA. For the first (E1) and the second (E2) eluted PRO enantiomers the results were: 1:1 stoichiometry, medium affinity constants, logK(E1)=3.20±0.16 and log K(E2)=3.40±0.14, medium protein binding percentage, PB=48.7 and 60.1% for E1 and E2, respectively, and moderate but significant enantioselectivity, ES=K(E2)/K(E1)=1.5±0.3.

Microseparation techniques for the study of the enantioselectivity of drug-plasma protein binding.

Stereoselectivity in protein binding can have a significant effect on the pharmacokinetic and pharmacodynamic properties of chiral drugs. The investigation of enantioselectivity of drugs in their binding with human plasma proteins and the identification of the molecular mechanisms involved in the stereodiscrimination by the proteins represent a great challenge for clinical pharmacology. In this review, the separation techniques used for enantioselective protein binding experiments are described and compared. An overview of studies on enantiomer-protein interactions, enantiomer-enantiomer interactions as well as chiral drug-drug interactions, including allosteric effects, is presented. The contribution of individual plasma proteins to the overall enantioselective binding and the animal species variability in drug-plasma protein binding stereoselectivity are reviewed.

Enantioseparation of nuarimol by affinity electrokinetic chromatography-partial filling technique using human serum albumin as chiral selector.

The present paper deals with the enantiomeric separation of nuarimol enantiomers by affinity EKC-partial filling technique using HSA as chiral selector. Firstly, a study of nuarimol interactions with HSA by CE-frontal analysis was performed. The binding parameters obtained for the first site of interaction were n(1) = 0.84; K(1) = 9.7 +/- 0.3x10(3 )M(-1) and the protein binding percentage of nuarimol at physiological concentration of HSA was 75.2 +/- 0.2%. Due to the moderate affinity of nuarimol towards HSA the possibility of using this protein as chiral selector for the separation of nuarimol using the partial filling technique was evaluated. A multivariate optimization approach of the most critical experimental variables in enantioresolution, running pH, HSA concentration and plug length was carried out. Separation of nuarimol enantiomers was obtained under the following selected conditions: electrophoretic buffer composed of 50 mM Tris at pH 7.3; 160 muM HSA solution applied at 50 mbar for 156 s as chiral selector; nuarimol solutions in the range of 2-8x10(-4) M injected hydrodynamically at 30 mbar for 2 s and the electrophoretic runs performed at 30 degrees C applying 15 kV voltage. Resolution, accuracy, reproducibility speed and cost of the proposed method make it suitable for quality control of the enantiomeric composition of nuarimol in formulations and for further toxicological studies. The results showed a different affinity between nuarimol enantiomers towards HSA.

Evaluation of enantioselective binding of basic drugs to plasma by ACE.

The present paper deals with the evaluation of the stereoselective binding of antihistamines (brompheniramine, chlorpheniramine, hydroxyzine, orphenadrine and phenindamine), phenothiazines (promethazine and trimeprazine) and a local anesthetic (bupivacaine) to human plasma proteins. Since all of them are drugs highly bound to proteins, a methodology to determine the bound fraction of each drug enantiomer was proposed. This methodology includes the incubation of samples containing plasma and racemic drug, ultrafiltration of the mixture and the chiral separation of enantiomers in the bound drug fraction using affinity EKC (AEKC)-partial filling technique and HSA as chiral selector. The results shown in this paper represent the first evidence of the enantioselective binding of some antihistamines such as brompheniramine, hydroxyzine, orphenadrine and phenindamine and the phenothiazines, promethazine and trimeprazine, to human plasma proteins. The binding of phenindamine to plasma presented the highest enantioselectivity (ES) (ES = 2.5) followed by trimeprazine (ES = 1.5) and promethazine (ES = 1.4).

Evaluation of enantioselective binding of antihistamines to human serum albumin by ACE.

The drug binding to plasma and tissue proteins is a fundamental factor in determining the overall pharmacological activity of a drug. HSA, together with alpha(1)-acid glycoprotein, are the most important plasma proteins, which act as drug carriers, with implications on the pharmacokinetic of drugs. Among plasma proteins, HSA possesses the highest enantioselectivity. In this paper, a new methodology for the study of enantiodifferentiation of chiral drugs with HSA is developed and applied to evaluate the possible enantioselective binding of four antihistamines: brompheniramine, chlorpheniramine, hydroxyzine and orphenadrine to HSA. This study includes the determination of affinity constants of drug enantiomers to HSA and the evaluation of the binding sites of antihistamines on the HSA molecule. The developed methodology includes the ultrafiltration of samples containing HSA and racemic antihistaminic drugs and the analysis of the free or bound drug fraction using the affinity EKC-partial filling technique and HSA as chiral selector. The results shown in this paper represent the first evidence of the enantioselective binding of antihistamines to HSA, the major plasmatic protein.

Enantioseparation of phenotiazines by affinity electrokinetic chromatography using human serum albumin as chiral selector: application to enantiomeric quality control in pharmaceutical formulations.

Nowadays, there is a special interest within the pharmaceutical laboratories to develop single enantiomer formulations and consequently a need for analytical methods to determine the enantiomeric purity of drugs. The present paper deals with the enantiomeric separation of promethazine and trimeprazine enantiomers by affinity electrokinetic chromatography (AEKC)-partial filling technique using human serum albumin (HSA) as chiral selector. A multivariate optimization of the most critical experimental variables in enantioresolution, running pH, HSA concentration and plug length, is carried out to obtain enantioresolution of promethazine and trimeprazine. The estimated maximum and optimum resolution of trimeprazine and prometazine enantiomers (Rs=1.74 and 2.01, respectively) corresponded to the following experimental conditions: pH 7.5; [HSA] 170 microM and plug length 190 s and pH 7.6; [HSA] 170 microM and plug length 170 s, for trimeprazine and prometazine, respectively. The developed methodologies were applied for the enantiomeric quality control of promethazine and trimeprazine enantiomers in commercially available pharmaceutical formulations. Resolution, accuracy, reproducibility, cost and sample throughput of the proposed methodologies make it suitable for quality control of the enantiomeric composition of promethazine and trimeprazine in pharmaceutical preparations.