A Critical Assessment of Extemporaneous Formulations for Proton Pump Inhibitors: The Importance of Proper Vehicle Selection.

OBJECTIVE: To examine the influence of vehicles on the stability of extemporaneous suspensions of proton pump inhibitors (PPIs), to single out the formulation most suitable for children, providing appropriate evidence and arguments. METHODS: A review was performed of data identified from Medline, Embase, Science Direct, as well as public digital archive PubMed, including reference texts, related to the field of stability testing of extemporaneous PPI suspensions. RESULTS: Fourteen selected formulations of extemporaneous suspensions are presented and discussed. Depending on the vehicle and its composition, which was analyzed and explained in detail, the suspensions had various beyond-use dates (BUDs). CONCLUSIONS: Selected vehicles and the process of preparation had great influence on the stability of extemporaneous PPI suspensions. The suspension with the longest BUD has been singled out, which is especially suitable for use in newborns. Because an explanation is provided for the influence of individual vehicle components on the stability of the mentioned suspensions, this can aid not only in the selection of an adequate formulation, but also in the development of new ones, which will be suited to individual patients.

Application of direct peptide reactivity assay for assessing the skin sensitization potential of essential oils.

Plant-derived products are frequently found as ingredients in cosmetics. However, the current data show non-neglectable skin sensitizing potential of these preparations suggesting an urgent need for data regarding their health safety profile. The aim of this study was to assess the skin sensitization potential of commercial essential oils by selected Lamiaceae species (Lavandula angustifolia, Melissa officinalis, Mentha longifolia, Thymus vulgaris, Salvia officinalis, and Rosmarinus officinalis) using a chemistry-based Direct Peptide Reactivity Assay (DPRA) in order to predict their potential allergic properties. In the DPRA assay, nucleophile-containing synthetic peptides (cysteine peptide and lysine peptide) were incubated with the test substance for 24 h. Depletion of the peptide in the reaction mixture was measured by high-pressure liquid chromatography (HPLC) using UV detection and the average peptide depletion data for cysteine and lysine was then calculated. Menthae longifoliae aetheroleum showed no or minimal reactivity with 4.48% cysteine depletion, Rosmarini aetheroleum and Salviae aetheroleum showed low reactivity with the 12.79% and 15.34% of cysteine depletion, respectively, while the other analyzed essential oils showed moderate reactivity with the cysteine depletion between 23.21 and 48.43%. According to DPRA predictive analysis, only Menthae longifoliae aetheroleum can be classified as negative, while all other essential oils may be classified as positive, thus having the potential to cause skin sensitization.

Interaction between Omeprazole and Gliclazide in Relation to CYP2C19 Phenotype.

The antidiabetic drug gliclazide is partly metabolized by CYP2C19, the main enzyme involved in omeprazole metabolism. The aim of the study was to explore the interaction between omeprazole and gliclazide in relation to CYP2C19 phenotype using physiologically based pharmacokinetic (PBPK) modeling approach. Developed PBPK models were verified using in vivo pharmacokinetic profiles obtained from a clinical trial on omeprazole-gliclazide interaction in healthy volunteers, CYP2C19 normal/rapid/ultrarapid metabolizers (NM/RM/UM). In addition, the association of omeprazole cotreatment with gliclazide-induced hypoglycemia was explored in 267 patients with type 2 diabetes (T2D) from the GoDARTS cohort, Scotland. The PBPK simulations predicted 1.4-1.6-fold higher gliclazide area under the curve (AUC) after 5-day treatment with 20 mg omeprazole in all CYP2C19 phenotype groups except in poor metabolizers. The predicted gliclazide AUC increased 2.1 and 2.5-fold in intermediate metabolizers, and 2.6- and 3.8-fold in NM/RM/UM group, after simulated 20-day dosing with 40 mg omeprazole once and twice daily, respectively. The predicted results were corroborated by findings in patients with T2D which demonstrated 3.3-fold higher odds of severe gliclazide-induced hypoglycemia in NM/RM/UM patients concomitantly treated with omeprazole. Our results indicate that omeprazole may increase exposure to gliclazide and thus increase the risk of gliclazide-associated hypoglycemia in the majority of patients.

In vitro pH dependent passive transport of ketoprofen and metformin.

The kinetics of passive transport of ketoprofen and metformin, as model substances for high and low permeability, respectively, across the artificial membrane under the influence of the pH of donor solution was investigated. There was an upward trend in the apparent permeation coefficient (P app) of ketoprofen with the decrease in pH to a value close to pKa. At the pH value below pKa the permeation coefficient had lower value, due to the higher retention of ketoprofen in the artificial membrane. Metformin is a low permeable compound, and the highest permeation values were recorded at pH 7.4. Two dissociation constants determine that metformin at physiological pH exists as a hydrophilic cationic molecule, i.e. predominantly in ionized form. At pH values below 2.8, metformin mainly exists in diprotonated form, and it was, thus, very poorly permeable. The highest retention, i.e. affinity of both ketoprofen and metformin to the membrane, was at the lowest pH values, which is explained by different mechanisms. At higher pH values of donor compartment the substances showed significantly less affinity to the membrane. The obtained values of apparent permeation coefficients at studied pH values showed good correlation with the obtained experimental values by other in vitro methods.

Stability of suspensions: theoretical and practical considerations before compounding.

Suspension stability can be theoretically estimated prior to the beginning of the formulating process based on the solid phase particle size, liquid phase density, and viscosity. Stokes equation can be used to predict suspension stability in order to save time and resources. The examples of these calculations for the assessment of suspension physical characteristics are given in this article. One parameter that cannot be theoretically estimated with precision is flocculation/deflocculation. Flocculation can be experimentally determined using the "jar test," and it is a critical parameter for the substances showing inclination toward caking. Suspensions will sediment in time; however, it is their key feature to be able to redisperse in order to preserve the efficacy and proper dosage. Bismuth subnitrate is practically insoluble in water, which makes it convenient for oral pharmaceutical suspensions, rather than the other pharmaceutical forms. Like the other bismuth compounds, it tends to cake in aqueous medium. In order to prevent formation of the solid sediment, controlled flocculation of the suspended bismuth subnitrate particles is recommended. The effect of the excipients (sodium citrate, Tween 20, propylene glycol, microcrystalline cellulose) on the transmittance of the prepared suspensions and the quantity and characteristics of the formed sediment were evaluated. Suspensions containing sodium citrate, as well as the formulations with sodium citrate and microcrystalline cellulose, based on their transmittance characteristics, were determined to be flocculating suspensions, regardless of the sodium citrate concentration used. The highest affinity towards formation of flocculating suspensions, with the highest transmittance value had microcrystalline cellulose with 15% (w/w) sodium citrate.