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.

In Aldosterone Targeted Neurohormonal Combined with Natriuresis Therapy in Heart Failure (ATHENA-HF), high-dose spironolactone (100 mg daily) did not improve efficacy endpoints over usual care [placebo or continued low-dose spironolactone (25 mg daily) in patients already receiving spironolactone] in the treatment of acute heart failure (HF). We hypothesized that low concentrations of the long-acting active metabolites of spironolactone [canrenone and 7-thiomethylspironolactone (7-TMS)] in the high-dose group could have contributed to these neutral results.

Drugs and proteins with poor intestinal permeability have a limited oral bioavailability. To remediate this problem, a receptor-mediated endocytosis and transcytosis approach was explored. Indeed, the non-toxic β subunit of cholera toxin (CTB) can cross the intestinal barrier by binding to receptor GM1. In this study, we explored the use of GM1-binding peptides and CTB as potential covalent carriers of poorly permeable molecules. GM1-binding peptides (G23, P3) and CTB were conjugated to poorly permeable fluorescent probes such as FITC and albumin-FITC using triethylene glycol spacers and click chemistry.The affinity of the peptide conjugates with receptor GM1 was confirmed by isothermal titration calorimetry or microscale thermophoresis and the results suggested the involvement of non-specific interactions. Conjugating the model drugs to G23 and P3 improved the internalization into Caco-2 and T84 cells, although the process was not dependent of the amount of GM1 receptor. However, conjugation of BSA-FITC to CTB increased the internalization in the same cells in a GM1-dependent pathway.Peptides conjugates demonstrated a limited permeability through a Caco-2 monolayer, whereas G23-and CTB-conjugates slightly enhanced permeability through a T84 cell monolayer compared to model drugs alone. Since CTB can improve the permeability of large macromolecules such as albumin, it is an interesting carrier for the improvement of oral bioavailability of various other macromolecules such as heparins, proteins and siRNAs.

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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. RÉSUMÉ 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.