A Genome-Wide Association Study of Oxypurinol Concentrations in Patients Treated with Allopurinol.

Cohort studies have identified several genetic determinants that could predict the clinical response to allopurinol. However, they have not been commonly used for genome-wide investigations to identify genetic determinants on allopurinol metabolism and concentrations. We conducted a genome-wide association study of a prior cross-sectional investigation of patients from the Montreal Heart Institute Biobank undergoing allopurinol therapy. Four endpoints were investigated, namely plasma concentrations of oxypurinol, the active metabolite of allopurinol, allopurinol, and allopurinol-riboside, as well as allopurinol daily dosing. A total of 439 participants (mean age 69.4 years; 86.4% male) taking allopurinol (mean daily dose 194.5 mg) and who had quantifiable oxypurinol concentrations were included in the genome-wide analyses. Participants presented with multiple comorbidities and received concomitant cardiovascular medications. No association achieved the predefined genome-wide threshold values for any of the endpoints (all p > 5 × 10-8). Our results are consistent with prior findings regarding the difficulty in identifying genetic determinants of drug concentrations or pharmacokinetics of allopurinol and its metabolites, as well as allopurinol daily dosing. Given the size of this genome-wide study, collaborative investigations involving larger and diverse cohorts may be required to further identify pharmacogenomic determinants of allopurinol and measure their clinical relevance to personalize allopurinol therapy.

Stability Evaluation of Bracketed Diclofenac Sodium USP in VersaPro™ Cream Base, VersaPro™ Gel Base and PLO Gel Mediflo™ 30 Compound Kit.

Diclofenac Sodium is a nonsteroidal anti-inflammatory drug (NSAID) that has analgesic, anti-inflammatory, and antipyretic properties, and has been found to be effective in treating a variety of acute and chronic pain and inflammatory conditions. A stability study was designed to assess the physical, chemical, and antimicrobial stability of three extemporaneously compounded bracketed Diclofenac Sodium formulations over time using a validated, stability indicating HPLC method. Diclofenac Sodium 1% and 15% were compounded in Medisca VersaPro™ Cream Base, VersaPro™ Gel Base and PLO Gel Mediflo™30 Compound Kit and stored at room temperature, in tightly closed, light resistant, plastic containers for 180 days. The organoleptic properties, pH, viscosity, and Diclofenac Sodium concentration of each formulation were evaluated at predetermined time points. Antimicrobial effectiveness testing of the compounded formulation according to USP <51> was also evaluated at the initial time point and after 180 days. The results demonstrated that all formulations remained within the specified stability criteria for the duration of the study. Therefore, an extended beyond-use-date of 180 days may be assigned to these compounded formulations under the studied conditions.

Impact of amiodarone use on metoprolol concentrations, α-OH-metoprolol concentrations, metoprolol dosing and heart rate: A cross-sectional study.

Small studies suggest that amiodarone is a weak inhibitor of cytochrome P450 (CYP) 2D6. Inhibition of CYP2D6 leads to increases in concentrations of drugs metabolized by the enzyme, such as metoprolol. Considering that both metoprolol and amiodarone have ß-adrenergic blocking properties and that the modest interaction between the two drugs would result in increased metoprolol concentrations, this could lead to a higher risk of bradycardia and atrioventricular block. The primary objective of this study was to evaluate whether metoprolol plasma concentrations collected at random timepoints from patients enrolled in the Montreal Heart Institute Hospital Cohort could be useful in identifying the modest pharmacokinetic interaction between amiodarone and metoprolol. We performed an analysis of a cross-sectional study, conducted as part of the Montreal Heart Institute Hospital Cohort. All participants were self-described "White" adults with metoprolol being a part of their daily pharmacotherapy regimen. Of the 999 patients being treated with metoprolol, 36 were also taking amiodarone. Amiodarone use was associated with higher metoprolol concentrations following adjustment for different covariates (p = .0132). Consistently, the association between amiodarone use and lower heart rate was apparent and significant after adjustment for all covariates under study (p = .0001). Our results highlight that single randomly collected blood samples can be leveraged to detect modest pharmacokinetic interactions.

Y-site simulation compatibility study of 10% calcium salts with various injectable solutions during toxicological resuscitation.

PURPOSE: To determine the physical compatibility of 10% calcium chloride and 10% calcium gluconate in combination with injectable solutions, administered in the paediatric and adult intensive care unit setting during toxicological resuscitation involving calcium channel blockers and beta-blockers. METHODS: Forty-eight combinations were prepared at room temperature, including the following products: calcium chloride, calcium gluconate, insulin, epinephrine, norepinephrine, highly concentrated dextrose solution, sodium chloride, Plasma-Lyte A and Ringer's lactate. A visual evaluation at times 0, 1, 4, 24, 48 and 72 hours and a particle count test with the LS-20 particle counter at times 0, 4, 24 and 72 hours were performed. The admixtures were considered incompatible if there was a precipitate, a colour change, turbidity, viscosity or a gas formation. The stability of calcium salts was also tested in empty IV bags and syringes by the particle count test. RESULTS: All drug mixtures were found to be compatible by visual evaluation and using the particle counter based on United States Pharmacopoeia chapter 788 (USP<788>) specifications. Calcium salts were compatible with insulin and vasopressors in the tested combinations. The stability of 10% calcium salts in empty IV bags and polypropylene syringes was demonstrated for up to 48 hours at room temperature. CONCLUSION: All the combinations tested were physically compatible for up to 72 hours at room temperature. Clinical use of calcium salt infusions, at an undiluted concentration, in combination with these injectable solutions in a toxicological resuscitation context is considered clinically acceptable.

Pharmacogenomic markers of metoprolol and α-OH-metoprolol concentrations: a genome-wide association study.

Aim: Few genome-wide association studies (GWASs) have been conducted to identify predictors of drug concentrations. The authors therefore sought to discover the pharmacogenomic markers involved in metoprolol pharmacokinetics. Patients & methods: The authors performed a GWAS of a cross-sectional study of 993 patients from the Montreal Heart Institute Biobank taking metoprolol. Results: A total of 391 and 444 SNPs reached the significance threshold of 5 × 10-8 for metoprolol and α-OH-metoprolol concentrations, respectively. All were located on chromosome 22 at or near the CYP2D6 gene, encoding CYP450 2D6, metoprolol's main metabolizing enzyme. Conclusion: The results reinforce previous findings of the importance of the CYP2D6 locus for metoprolol concentrations and confirm that large biobanks can be used to identify genetic determinants of drug pharmacokinetics at a GWAS significance level.

Transfer of Mexiletine into Breast Milk: A Case Report.

Background: Mexiletine is a class 1B antiarrhythmic agent, used to treat ventricular arrhythmias, and noncardiac-related problems such as myotonia. Limited safety data are available on the transfer of this drug into breast milk. Case Report: We report the case of a woman diagnosed with myotonia congenita who breastfed two children after two consecutive pregnancies. During the breastfeeding of the first and the second infant, she collected, respectively, five and seven samples at 0, 2, 4, 6, and 8 hours and 0, 1, 2, 3, 4, 6, and 8 hours after taking 200 mg of mexiletine thrice daily for seven doses. One week after the collection, samples were analyzed with a validated liquid chromatography tandem mass spectrometry method. No side effect was observed in either child according to the mother. Results: Using the mean milk concentrations, it is estimated that an exclusively breastfed infant would receive a maximum of 5.14% of the initial pediatric mexiletine dosage. We calculated a maximum of 2.67% for the first infant in our case, considering a nonexclusive breastfeeding. Maximal concentrations were observed 1-2 hours after the dose of mexiletine. Results seem to be in accordance with the two cases previously published. Conclusions: Mexiletine transfers into breast milk in low levels. However, results are obtained from only one woman. Therefore, caution should be used when mexiletine is prescribed to breastfeeding women. More cases are needed to evaluate the interindividual variability and to guide women regarding breastfeeding with mexiletine.

Females present higher dose-adjusted drug concentrations of metoprolol and allopurinol/oxypurinol than males.

Females present a higher risk of adverse drug reactions. Sex-related differences in drug concentrations may contribute to these observations but they remain understudied given the underrepresentation of females in clinical trials. The aim of this study was to investigate whether anthropometric and socioeconomic factors and comorbidities could explain sex-related differences in concentrations and dosing for metoprolol and oxypurinol, the active metabolite of allopurinol. We conducted an analysis of two cross-sectional studies. Participants were self-described "White" adults taking metoprolol or allopurinol selected from the Montreal Heart Institute Hospital Cohort. A total of 1007 participants were included in the metoprolol subpopulation and 459 participants in the allopurinol subpopulation; 73% and 86% of the participants from the metoprolol and allopurinol subpopulations were males, respectively. Females presented higher age- and dose-adjusted concentrations of both metoprolol and oxypurinol (both p < 0.03). Accordingly, females presented higher unadjusted and age-adjusted concentration:dose ratio of both metoprolol and allopurinol/oxypurinol compared to males (all p < 3.0 × 10-4 ). Sex remained an independent predictor of metoprolol concentrations (p < 0.01), but not of oxypurinol concentrations, after adjusting for other predictors. In addition to sex, age, daily dose, use of moderate to strong CYP2D6 inhibitors, weight, and CYP2D6 genotype-inferred phenotype were associated with concentrations of metoprolol (all p < 0.01). Daily dose, weight, estimated glomerular filtration rate (eGFR), and employment status were associated with oxypurinol concentrations (all p < 0.01). Females present higher dose-adjusted concentrations of metoprolol and oxypurinol than males. This suggests the need for sex-specific dosing requirements for these drugs, although this hypothesis should be validated in prospective studies.

Visual compatibility and particle counter evaluations of syringes of intramuscular psychotropic coadministered solutions.

BACKGROUND: Patients in the acute phase of agitation can require the administration of multiple drugs by intramuscular injection in order to temporarily stabilise their condition. Administration of multiple psychotropic medications in a single syringe can be beneficial to both the patient and healthcare professionals. However, there are very little data in the literature regarding psychotropic drug compatibility in syringes for acute agitation. OBJECTIVE: The aim of this study was to assess the visual compatibility of various combinations of 12 intramuscular psychotropic medications in syringes, and to validate compatibility with the use of a particle counter. The medications evaluated were benztropine mesylate, diazepam, dimenhydrinate, diphenhydramine hydrochloride, haloperidol lactate, hydroxyzine, lorazepam, loxapine, methotrimeprazine, midazolam, olanzapine and zuclopenthixol acetate. METHODS: Compounded solutions of medication combinations underwent visual inspection initially and after 0.25, 0.5, 1, 2 and 4 hours using a white background and a black background. In order to validate the compatibility results, the presence of particulate matter was determined by light obscuration. RESULTS: This study identified 35 combinations that were visually compatible and 35 that were visually incompatible. We chose eight highly clinically relevant combinations to test using the requirements of the United States Pharmacopoeia (USP) chapter 788 (Particulate Matter in Injections). Of those eight, six were physically compatible, including the triple combinations of lorazepam and haloperidol with either benztropine or diphenhydramine. CONCLUSION: These physical compatibility results will give healthcare professionals an idea of the possible compatible combinations of psychotropic drugs in syringes, and thus complete some of the missing data in the literature.

Pharmacokinetics of Cannabis and Its Derivatives in Animals and Humans During Pregnancy and Breastfeeding.

Cannabis is one of the most widely used illicit drugs during pregnancy and lactation. With the recent legalization of cannabis in many countries, health professionals are increasingly exposed to pregnant and breastfeeding women who are consuming cannabis on a regular basis as a solution for depression, anxiety, nausea, and pain. Cannabis consumption during pregnancy can induce negative birth outcomes such as reduced birth weight and increased risk of prematurity and admission to the neonatal intensive care unit. Yet, limited information is available regarding the pharmacokinetics of cannabis in the fetus and newborn exposed during pregnancy and lactation. Indeed, the official recommendations regarding the use of cannabis during these two critical development periods lack robust pharmacokinetics data and make it difficult for health professionals to guide their patients. Many clinical studies are currently evaluating the effects of cannabis on the brain development and base their groups mostly on questionnaires. These studies should be associated with pharmacokinetics studies to assess correlations between the infant brain development and the exposure to cannabis during pregnancy and breastfeeding. Our project aims to review the available data on the pharmacokinetics of cannabinoids in adults, neonates, and animals. If the available literature is abundant in adult humans and animals, there is still a lack of published data on the exposure of pregnant and lactating women and neonates. However, some of the published information causes concerns on the exposure and the potential effects of cannabis on fetuses and neonates. The safety of cannabis use for non-medical purpose during pregnancy and breastfeeding needs to be further characterized with proper pharmacokinetic studies in humans feasible in regions where cannabis has been legalized. Given the available data, significant transfer occurs to the fetus and the breastfed newborn with a theoretical risk of accumulation of products known to be biologically active.

An association study of ABCG2 rs2231142 on the concentrations of allopurinol and its metabolites.

ABCG2 is a gene that codes for the human breast cancer resistance protein (BCRP). It is established that rs2231142 G>T, a single nucleotide polymorphism of the ABCG2 gene, is associated with gout and poor response to allopurinol, a uric acid-lowering agent used to treat this condition. It has also been suggested that oxypurinol, the primary active metabolite of allopurinol, is a substrate of the BCRP. We thus hypothesized that carrying the rs2231142 variant would be associated with decreased oxypurinol concentrations, which would explain the lower reduction in uric acid. We performed a cross-sectional study to investigate the association between the ABCG2 rs2231142 variant and oxypurinol, allopurinol, and allopurinol riboside concentrations in 459 participants from the Montreal Heart Institute Hospital Cohort. Age, sex, weight, use of diuretics, and estimated glomerular filtration rate were all significantly associated with oxypurinol plasma concentration. No association was found between rs2231142 and oxypurinol, allopurinol and allopurinol riboside plasma concentrations. Rs2231142 was not significantly associated with daily allopurinol dose in the overall population, but an association was observed in men, with T carriers receiving higher doses. Our results do not support a major role of ABCG2 in the pharmacokinetics of allopurinol or its metabolites. The underlying mechanism of the association between rs2231142 and allopurinol efficacy requires further investigation.

Stability evaluation of compounded hydroxyurea 100 mg/mL oral liquids using a novel analytical method involving chemical derivatization.

This study assessed the stability of six extemporaneously compounded hydroxyurea oral liquids stored at room temperature. Hydroxyurea oral liquids (100 mg/mL) were prepared using three different mixing methods (mortar, mixer or QuartetRx) from either bulk powder, capsule content, or whole capsules. Two brands of capsules were tested in this study. All formulations were stored at room temperature (25°C / 60% RH) in amber plastic bottles for 90 days and amber plastic syringes for 14 days. Physical stability was assessed visually, while chemical stability was evaluated using a stability-indicating high-performance liquid chromatography method. Chemical derivatization with xanthydrol allowed the retention of hydroxyurea on a reverse-phase column. At least 93.9% and 97.0% of the initial concentration of hydroxyurea remained after 90 days in bottles and 14 days in syringes, respectively. There were no visual changes in formulations over the study period. Changes in pH up to 1.6 units were observed after 90 days of storage and were explained most likely by an ammonium generating degradation pathway. Ammonium was quantified and remained within safe levels in each HU 100 mg/mL oral preparations. Hydroxyurea oral liquids were all stable for 90 days in amber plastic bottles and 14 days in amber plastic syringes.

Stability of Compounded Digoxin Solution 0.05 mg/mL for Injection.

Background: In 2015, commercial pediatric digoxin injection 0.05 mg/mL was discontinued, leaving only one adult concentration (0.25 mg/mL) for injection on the Canadian market. No published studies have documented the chemical stability over a long period of time of a diluted solution of digoxin for injection. Objective: The aim of this study was to assess the chemical stability of 2 digoxin injection formulations 0.05 mg/mL diluted in 2 vehicles stored at 5°C or a 25°C. Methods: The compounded solution of digoxin 0.05 mg/mL for injection was prepared with digoxin 0.25 mg/mL after dilution in 2 different vehicles, normal saline, and a compounding of the commercial vehicle. Half of the compounding products were stored in 2 mL transparent glass vials at 25°C and the other half at 5°C. Chemical stability was evaluated by HPLC-UV analysis on days 0, 14, 30, 60, 90, 120, 150, 180 for each temperature conditions. In addition, samples were tested for organoleptic change, presence of particular matter as well as sterility. Results: For all tested preparations, the concentration of digoxin remained above 90.0% of the initial concentration throughout the 180-day study. Furthermore, no organoleptic change was observed; particulate matter assessment was in acceptable range; and sterility specifications were met. Conclusions: Digoxin 0.05 mg/mL obtained with a dilution of digoxin 0.25 mg/mL by normal saline or a copy of the commercial vehicle remained stable for at least 180 days at 5°C and 25°C.

Evaluation of uptake of the cytostatic methotrexate in Elliptio complanata mussels by LC-MS/MS.

Aquatic organisms are continuously exposed to emerging contaminants coming from urban effluents of wastewater treatment plants. The contamination of surface water by those effluents poses a number of environmental risks, and pharmaceuticals are part of this class of effluent contaminants. Various classes of pharmaceuticals are not treated by wastewater treatment plants and anticancer drugs are part of them. The chemotherapy drug methotrexate (MTX) is an emerging contaminant and its growing use with the increase in cancer cases worldwide raises potential risk to aquatic organisms exposed to effluent discharges. However, chemical analyses in exposed freshwater aquatic organisms for ecotoxicological studies are rarely available and no studies have been done yet to accompany ecotoxicological data of exposed filter-feeding organisms. The purpose of this study was to develop a specific and sensitive analytical LC-MS/MS method for the quantification of methotrexate uptake in mussels exposed at different concentrations of the drug. A solid/liquid extraction followed by solid phase extraction (SPE) using an MCX phase purification scheme was optimized. The optimal recovery of 65% and matrix effect of 38% allowed to achieve a limit of quantification of 0.25 ng g-1, with an accuracy of 99-106%, a precision of no more than 3% RSD, and linearity ranging from 0.25 to 25 ng g-1. This methodology was tested with mussels exposed for 96 h at different concentrations (4 to 100 µg L-1) of MTX. The data revealed tissue uptake at concentrations ranging from 0 to 2.53 ng g-1. This suggests that this drug has low uptake potential and this methodology could be used to examine tissue levels of this drug in organisms continuously exposed to urban pollution.

Leveraging large observational studies to discover genetic determinants of drug concentrations: A proof-of-concept study.

Large, observational genetic studies are commonly used to identify genetic factors associated with diseases and disease-related traits. Such cohorts have not been commonly used to identify genetic predictors of drug dosing or concentrations, perhaps because of the heterogeneity in drug dosing and formulation, and the random timing of blood sampling. We hypothesized that large sample sizes relative to traditional pharmacokinetic studies would compensate for this variability and enable the identification of pharmacogenetic predictors of drug concentrations. We performed a cross-sectional, proof-of-concept association study to replicate the well-established association between metoprolol concentrations and CYP2D6 genotype-inferred metabolizer phenotypes in participants from the Montreal Heart Institute Hospital Cohort undergoing metoprolol therapy. Plasma concentrations of metoprolol and α-hydroxymetoprolol (α-OH-metoprolol) were measured in samples collected randomly regarding the previous metoprolol dose. A total of 999 individuals were included. The metoprolol daily dose ranged from 6.25 to 400 mg (mean 84.3 ± 57.1 mg). CYP2D6-inferred phenotype was significantly associated with both metoprolol and α-OH-metoprolol in unadjusted and adjusted models (all p < 10-14 ). Models for metoprolol daily dose showed consistent results. Our study suggests that randomly drawn blood samples from biobanks can serve as a new approach to discover genetic associations related to drug concentrations and dosing, with potentially broader implications for genomewide association studies on the pharmacogenomics of drug metabolism.

Stability evaluation of compounded clonidine hydrochloride oral liquids based on a solid-phase extraction HPLC-UV method.

The present study aimed to assess the stability of clonidine hydrochloride oral liquids (20-µg/mL) prepared from two different generic tablets in Ora-Blend and stored in amber plastic bottles. Physical and chemical stabilities were evaluated over a period of 90 days at 25°C. Analytical challenges were overcome with the development of a new extraction procedure based on solid phase extraction to ensure efficient clonidine hydrochloride quantification. The absence of physical instabilities, evaluated by qualitative and quantitative measurements (static multiple light scattering), as well as the absence of chemical instabilities, evidenced by a stability-indicating HPLC-UV method, confirmed that a beyond-use date of 90 days was appropriate for these compounded oral liquids.

Stability of Extemporaneously Compounded Suspensions of Trimethoprim and Sulfamethoxazole in Amber Plastic Bottles and Amber Plastic Syringes.

BACKGROUND: Trimethoprim (TMP) and sulfamethoxazole (SMX) are widely used, in combination, to treat or prevent various infections. Unfortunately, no liquid oral formulation is currently available in Canada for patients who are unable to swallow tablets. OBJECTIVE: To evaluate the stability of suspensions of TMP and SMX (8 and 40 mg/mL, respectively) prepared in Oral Mix or Oral Mix SF vehicle (Medisca Pharmaceutique Inc) and stored for up to 90 days in amber plastic bottles or amber plastic syringes at 5°C or 25°C. METHODS: Suspensions were prepared from bulk powder and from tablets in Oral Mix and Oral Mix SF vehicles, then transferred to amber plastic (polyethylene terephthalate glycol) bottles and plastic oral syringes and stored at 5°C and 25°C. Samples were collected on predetermined study days (0, 7, 14, 23, 45, 60, 75, and 90 days) and analyzed using a validated high-performance liquid chromatography - ultraviolet detection method. A suspension was considered stable if it maintained at least 90% of its initial concentration with 95% confidence. Observations of organoleptic characteristics such as colour and odour, as well as pH, were used to assess physical stability. RESULTS: Suspensions prepared from bulk powder maintained concentrations of TMP and SMX of at least 97% of the initial concentration over the 90-day study period. No obvious changes in colour, odour, or pH were observed. However, acceptable suspensions could not be prepared from the commercial tablets. A persistent foam that developed at the surface of all suspensions prepared from tablets could result in inconsistent dosing. CONCLUSIONS: Extemporaneously compounded oral suspensions of TMP and SMX (8 and 40 mg/mL, respectively) prepared from bulk powder in Oral Mix and Oral Mix SF vehicles and stored in amber plastic bottles or syringes at 5°C or 25°C remained stable for at least 90 days. Suspensions made from tablets produced unacceptable formulations.

CONTEXTE: Le triméthoprime (TMP) et le sulfaméthoxazole (SMX) sont largement utilisés conjointement pour traiter ou prévenir diverses infections. Malheureusement, aucune formulation liquide orale n'est actuellement disponible au Canada pour les patients incapables d'avaler des comprimés. OBJECTIF: Évaluer la stabilité des suspensions de TMP et de SMX (respectivement 8 et 40 mg/mL) préparées dans un véhicule Oral Mix ou Oral Mix SF (Medisca Pharmaceutique Inc.) et stockées pendant 90 jours dans des flacons ou des seringues en plastique ambré à 5 °C ou 25 °C. MÉTHODES: Les suspensions ont été préparées à partir de poudre en vrac et de comprimés dans les véhicules Oral Mix et Oral Mix SF, puis transférées dans des flacons en plastique ambré (polyéthylène téréphtalate glycol) et dans des seringues orales en plastique et stockées à 5 °C et 25 °C. Des échantillons ont été recueillis à des jours prédéterminés (0, 7, 14, 23, 45, 60, 75 et 90 jours) et analysés à l'aide d'une méthode de détection par ultraviolet validée de chromatographie en phase liquide à haute performance. La suspension était jugée stable si elle préservait au moins 90 % de sa concentration initiale avec un seuil de confiance de 95 %. Les observations des caractéristiques organoleptiques, comme la couleur et l'odeur, ainsi que le pH, ont été faites pour évaluer la stabilité physique. RÉSULTATS: Les suspensions préparées à partir de poudre en vrac préservaient au moins 97 % de la concentration initiale de TMP et de SMX pendant la période d'étude de 90 jours. Aucun changement manifeste de couleur, d'odeur ou de pH n'a été observé. Cependant, les suspensions acceptables n'ont pas pu être préparées à partir des comprimés commerciaux. Une mousse homogène se formait à la surface de ces suspensions, ce qui pourrait entraîner un dosage incohérent. CONCLUSIONS: Les suspensions orales composées extemporanées de TMP et SMX (respectivement 8 et 40 mg/mL) préparées à partir de poudre en vrac dans des véhicules Oral Mix et Oral Mix SF et stockées dans des flacons ou des seringues en plastique ambré à 5 °C ou 25°C sont restées stables pendant au moins 90 jours. Les suspensions préparées à partir de comprimés ont donné des formulations inacceptables.

Stability of N-Acetylcysteine 60 mg/mL in Extemporaneously Compounded Injectable Solutions.

BACKGROUND: N-Acetylcysteine (NAC) administered by the IV route is the current treatment of choice for acetaminophen overdose. However, the protocol approved by health authorities in most countries has a complex dosing regimen, which leads to dosage errors in one-third of cases. Therefore, the Canadian Antidote Guide in Acute Care Toxicology and individual poison centres have begun to recommend a simplified regimen using continuous IV infusion. Unfortunately, no study has demonstrated the stability of IV solutions of NAC at concentrations above 30 mg/mL or in solutions other than 5% dextrose. OBJECTIVE: To evaluate the stability of solutions of NAC 60 mg/mL in 0.9% sodium chloride, 0.45% sodium chloride, or 5% dextrose, stored for up to 72 hours in polyvinyl chloride (PVC) bags at 25°C. METHODS: Solutions of the desired concentration were prepared from a commercial solution of NAC 200 mg/mL, with dilution in 0.9% sodium chloride, 0.45% sodium chloride, or 5% dextrose, and were then stored at room temperature in PVC bags for up to 72 hours. At predetermined time points (0, 16, 24, 40, 48 and 72 h), samples were collected and analyzed using a stability-indicating high-performance liquid chromatography method. A solution was considered stable if it maintained at least 90.0% of its initial concentration. Particulate matter count was also evaluated to confirm chemical stability. Finally, organoleptic properties, such as odour and colour, were evaluated to assess the stability of the solutions. RESULTS: All solutions maintained at least 98.7% of their initial concentration. No obvious changes in odour or colour were observed. Moreover, particle counts remained acceptable throughout the study, according to the criteria specified in United States Pharmacopeia (USP) General Chapter <788>. CONCLUSIONS: NAC 60 mg/mL, diluted in 0.9% sodium chloride, 0.45% sodium chloride, or 5% dextrose and stored in PVC bags at 25°C, was chemically and physically stable for a period of at least 72 hours.

CONTEXTE: La N-acétylcystéine (NAC) administrée par IV est actuellement le traitement de choix en cas de surdose d'acétaminophène. Cependant, le protocole approuvé par les autorités sanitaires de la plupart des pays s'accompagne d'un schéma posologique complexe qui entraîne des erreurs de dosage dans un tiers des cas. C'est pourquoi, le Guide canadien des antidotes en toxicologie d'urgence et les centres antipoison ont commencé à recommander un schéma simplifié utilisant des perfusions IV. Malheureusement, aucune étude n'a permis de démontrer la stabilité des solutions IV de NAC à des concentrations supérieures à 30 mg/mL ou dans des solutions autres que 5 % de dextrose. OBJECTIF: Évaluer la stabilité des solutions de 60 mg/mL de NAC dans 0,9 % de chlorure de sodium, 0,45 % de chlorure de sodium ou 5 % de dextrose, stockées jusqu'à 72 heures dans des pochettes de chlorure de polyvinyle (PVC) à 25 °C. MÉTHODES: Les solutions ont été préparées à partir d'une solution commerciale de 200 mg/mL de NAC, avec une dilution dans 0,9 % de chlorure de sodium, dans 0,45 % de chlorure de sodium ou dans 5 % de dextrose. Elles ont ensuite été stockées à température ambiante dans des pochettes en PVC pendant une période allant jusqu'à 72 h. À des instants prédéterminés (0, 16, 24, 40, 48 et 72 h), des échantillons étaient recueillis et analysés à l'aide d'une méthode de chromatographie en phase liquide à haute performance indiquant la stabilité. Si la solution préservait au moins 90 % de sa concentration initiale, elle était jugée stable. Un comptage de particules a aussi permis de confirmer la stabilité chimique. Finalement, les propriétés organoleptiques, comme l'odeur et la couleur, ont été examinées pour évaluer la stabilité des solutions de NAC. RÉSULTATS: Toutes les solutions préservaient au moins 98,7 % de leur concentration initiale. Aucun changement manifeste d'odeur ou de couleur n'a été observé. De plus, le nombre de particules est resté acceptable pendant toute la durée de l'étude selon les critères indiqués dans le chapitre général de la Pharmacopée américaine (USP) <788>. CONCLUSIONS: La solution de 60 mg/mL de NAC, diluée dans 0,9 % de chlorure de sodium, dans 0,45 % de chlorure de sodium ou dans 5 % de dextrose et stockée dans des pochettes en PVC à 25 °C était chimiquement et physiquement stable pendant au moins 72 h.

Compatibility of Lactated Ringer's Injection With 94 Selected Intravenous Drugs During Simulated Y-site Administration.

Objective: To test the compatibility of intravenous (IV) lactated Ringer's injection (LR) with 94 injectable (IV) drugs during simulated Y-site administration. Methods: Ninety-four IV drugs were investigated for compatibility with LR (Baxter). Each sample was prepared in duplicate and performed at room temperature. Two observers performed visual evaluation independently immediately upon mixing and then 15 minutes, 1 hour, 2 hours, 3 hours, and 4 hours after admixture. Another observer performed a particle counting test on 1 of the 2 duplicates of each admixture that did not immediately show incompatibility and then after 4 hours by a light obscuration particle count test. Results: Of the 94 tested drugs, 86 were found to be compatible with LR. A total of 8 drugs were found to be physically incompatible. Of these incompatible drugs, 7 were directly identified visually and 1 was confirmed by the light obscuration particle count test. Conclusion: Lactated Ringer's injection was physically compatible for 4 hours with 86 tested drugs during simulated Y-site administration. Eight drugs, ciprofloxacin, cyclosporine, diazepam, ketamine, lorazepam, nitroglycerin, phenytoin, and propofol, were found to be incompatible and should not be administered with LR.

Simultaneous quantification of 19 analytes in breast milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

A bioanalytical method by high performance liquid chromatography coupled to mass spectrometry (HPLC-MS/MS) for the simultaneous quantification of 17 drugs and 2 major active metabolites in breast milk was developed and validated. Breast milk samples (100 µL) were submitted to a simple protein precipitation for the extraction of the analytes after the addition of deuterated internal standards (10 µL). A Kinetex C8 column was used for the separation of analytes with mobile phases composed of acetonitrile with 0.1 % formic acid and water with 0.1 % formic acid in gradient elution mode. Analytes were detected using an AB/SCIEX 4000 QTRAP instrument with positive electrospray ionization and operating in scheduled multiple reaction monitoring mode. Validation covered a large range of concentrations (0.5-500 ng/mL) for most of the analytes except bisoprolol, lacosamide, vilazodone (1-500 ng/mL), acid mycophenolic, letrozole, clomiphene (2-500 ng/mL) and hydroxy-melatonin (10-500 ng/mL). Within-run and between-run accuracy and precision for 4 levels of quality controls (QC) spiked at the lower limit of quantification (LLOQ), at 3 times the LLOQ, 50 % of the upper limit of quantification (ULOQ) and 80 % of the ULOQ were in agreement with the criteria from international guidelines. Matrix effect and extraction recovery ranged from 40.7 to 106.5 % and 87.3 to 110.8 %, respectively with relative standard deviations less than 15 %. Furthermore, all analytes were stable in breast milk at room temperature for 24 h, at -20 °C for two weeks, at -80 °C for 1 month, and after 3 freeze-thaw cycles. Finally, the method was successfully applied to nursing women samples collected from an ongoing feasibility study on drug quantification in breast milk.

Isocyanate derivatization coupled with phospholipid removal microelution-solid phase extraction for the simultaneous quantification of (S)-metoprolol and (S)-α-hydroxymetoprolol in human plasma with LC-MS/MS.

A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed and validated for the quantification of (S)-metoprolol (MET) and its main metabolite, (S)-α-hydroxymetoprolol (OH-MET). Human plasma samples (50 µL) were spiked with both analytes and their deuterated internal standards (IS) (S)-MET-(d7) and α-OH-MET-(d5). Phospholipid removal microelution-solid phase extraction (PRM-SPE) was performed using a 4-step protocol with Oasis PRiME MCX µElution 96-well cartridges. The eluates were reconstituted in 100 µL of acetonitrile with 50 µg/mL (S)-α-methylbenzyl isocyanate (MBIC) for chiral derivatization. After 60 min at room temperature, the reaction was quenched using 100 µL of water 2 % formic acid. Chromatographic separation of the derivatized analytes was performed on a Kinetex phenyl-hexyl core-shell stationary phase with an elution gradient. Mobile phases were composed of a mixture of water and methanol, with ammonium formate and formic acid as buffers. Total runtime was 15 min. Analyte detection was performed by an AB/SCIEX 4000 QTRAP mass spectrometer with multiple reaction monitoring. Chromatograms showed MBIC successfully reacted with racemic MET, α-OH-MET, and their respective IS. Detection by positive electrospray ionization did not reveal derivatized by-products. Quantification ranges were validated for (S)-MET and (S)-α-OH-MET between 0.5-500 and 1.25-500 ng/mL, respectively, with correlation coefficients (r2) >0.9906. The PRM-SPE assay showed low matrix effects (86.9-104.0 %) and reproducible recoveries (69.4-78.7 %) at low, medium, and high quality control (QC) levels. Precision and accuracy were all comprised between 85-115 % for all three QCs, and between 80-120 % for the lower limit of quantification, for intra- and inter-day values (n = 6, 3 consecutive days). Non-derivatized analytes were stable at room temperature, after 3 freeze-thaw cycles, and stored for 30 days at -80 °C (n = 4). Reinjection reproducibility of a previously validated batch was achieved after 8 days under auto-sampler conditions, indicating the stability of (S)-MET and (S)-α-OH-MET derivatives. Its clinical use was established in a cohort of 50 patients and could be used to further investigate the clinical impact of (S)-MET concentrations.