Drug-related problems and pharmacy interventions in non-prescription medication, with a focus on high-risk over-the-counter medications

Background The risks associated with over-the-counter medication are often underestimated by consumers. The incorrect use of certain medications can lead to significant patient harm. Inappropriate use can be prevented by pharmaceutical counselling. Objective To determine the number and nature of drug-related problems in over-the-counter medication with a special emphasis on high-risk over-the-counter medications. Setting Fifty-two community pharmacies in Finland. Method This observational study was conducted as a questionnaire survey. The pharmacists working in participating pharmacies documented the observed drug-related problems and pharmacy interventions in over-the-counter medication during 1 week using an electronic study form based on the Westerlund drug-related problem classification system. Main outcome measure The prevalence of drug-related problems and problem types in different medication categories. Results The 52 community pharmacies documented 339 drug-related problems in 0.6% of over-the-counter customers, the most common problem being "Uncertainty about the indication for the drug" (39.2%). A significant proportion of the documented problems (26.3%) concerned high-risk over-the-counter medications, and the majority of these cases were associated with non-steroidal anti-inflammatory drugs (21.8%). In total, pharmacies made 641 interventions to resolve the drug-related problems. For majority of drug-related problems (87%), pharmacist's intervention involved counselling. In more than half of the problem cases, the pharmacy intervention was precautionary. Conclusion Pharmacists intervene in and prevent problems related to over-the-counter medications, including high-risk medications like analgesics, in which inappropriate use due to consumers' lack of knowledge can lead to severe consequences. As the selection and use of over-the-counter medications is continuously increasing, pharmaceutical counselling should be readily available and actively provided for consumers to achieve safer self-medication.Peer reviewe

Defining new criteria for selection of cell-based intestinal models using publicly available databases

Peer reviewe

Imeytymisvaiheen lääkeainemetabolian ja effluksin tutkiminen Caco-2-solulinjalla

Preclinical prediction of intestinal drug absorption is a continuous challenge in drug development. The absorption of a drug from the gastrointestinal tract is a complicated process, involving passive membrane permeability parameters as well as many active transport and metabolism components. Therefore, well characterised and reliable in vitro methods for studying drug absorption are constantly devised and under refinement. In this work, the Caco-2 cell line, a widely used model for intestinal drug absorption, was assessed as a platform to study the interplay of phase II metabolism and MRP (multidrug resistance associated protein) -mediated efflux. Expression and function of several metabolic enzymes and efflux proteins have been observed in the intestine and many drug conjugates produced by UDP-glucunorosyltransferases (UGTs) and sulfotransferases (SULTs) are substrates for the apical MRP2 and/or the basolateral MRPs. The kinetics of these interactions is complex, but the human origin and intestinal-like differentiation under appropriate culture conditions appoint Caco-2 cells as a potential platform for these studies. The Caco-2 cell line studied was thoroughly characterised with regards to different efflux proteins and UGT enzymes. The expression and functionality of MDR1 (multidrug resistance protein 1, P-glycoprotein) and several MRP proteins as well as UGT enzymes were observed in the studied cells, while the expression of SULTs and GSTs (glutathione-S-transferases) have been previously reported by other groups working with Caco-2. In fully differentiated Caco-2 monolayers the expression of most MRPs and UGTs was significantly higher compared to less differentiated cells grown for shorter periods or in flasks, an important observation with direct implications for the sensitivity and specificity of higher throughput cell-based screening assays. Other factors such as the passage number of the cells and the use of inducers also affected the mRNA expression levels. Based on the observed efflux and phase II metabolism activities, a Caco-2 based screening method was developed for compounds interacting with MRP2, either directly or via their phase II metabolites. The kinetics of these interactions were investigated more closely in permeability experiments, where conjugation of model compounds and the efflux of their metabolites (indomethacin glucuronide, paracetamol sulfate and naphthol glucuronide) were detected. Substrate or product inhibition of the UGT enzyme(s) was evident at higher 1-naphthol concentrations, whereas the complementary role of basolateral efflux proteins was observed at the highest indomethacin concentration as the apical efflux was saturated. Pharmacokinetic modelling could be utilized as a tool for further interpretation of the results. The combined results of these studies go a long way in improving our understanding of the Caco-2 cell line and its suitability as a model system for drug absorption and metabolism in the intestine.Lääkeaineen imeytymisen ennustaminen on yksi lääkekehityksen suurimmista haasteista. Siksi tarvitaan menetelmiä, joiden avulla voidaan seuloa lääkeainekandidaateista imeytymisominaisuuksiltaan sopivimmat jo mahdollisimman varhaisessa vaiheessa kallista lääkekehitysprojektia. Perinteisesti alkuvaiheen imeytymistutkimuksia on tehty eläinkokein, mutta koe-eläinten elimistö poikkeaa ihmisen elimistöstä ja koe-eläinten käyttöä pyritään vähentämään myös eettisin perustein. Caco-2-solumallia on hyödynnetty imeytymistutkimuksissa laajalti jo vuosikymmenien ajan. Soluja voidaan kasvattaa puoliläpäisevillä kalvoilla, jolloin ne muodostavat ohutsuolen seinämää muistuttavan yksisolukerroksen ja niillä voidaan tehdä imeytymistutkimuksia laboratorio-olosuhteissa. Ohutsuolen sisällön erottaa verenkierrosta vain yhden solun paksuinen solukerros. Tämä yksisolukerros paitsi vastaa tarvittavien ravinto- ym. aineiden imeytymisestä, myös toimii suojana suun kautta elimistöön päässeitä vierasaineita vastaan. Tästä syystä ohutsuolen seinämässä on monia aktiivisia puolustusmekanismeja, kuten vierasainemolekyylejä vesiliukoisemmaksi muokkaavia metaboliaentsyymejä sekä effluksiproteiineja, jotka suojaavat soluja kuljettamalla soluun päässeitä aineita joko takaisin suoleen tai edelleen verenkiertoon. Usein nämä mekanismit toimivat keskenään yhteistyössä esimerkiksi siten, että ensin entsyymit muokkaavat molekyylejä ja sen jälkeen effluksiproteiinit poistavat syntyneet metaboliatuotteet soluista. Tässä väitöskirjatyössä selvitettiin Caco-2-yksisolukerrosten soveltuvuutta eräiden ohutsuolen seinämän aktiivisten puolustusmekanismien tutkimiseen. Effluksiproteiinien sekä tiettyjen vierasaineiden metaboliaan osallistuvien entsyymien ilmentymistä ja toiminnallisuutta tutkittaessa havaittiin, että näitä puolustusmekanismeja on selvästi enemmän valmiiksi yksisolukerrokseksi erilaistuneissa soluissa. Lisäksi työssä kehitettiin seulontamenetelmä effluksiproteiinille sekä tutkittiin effluksiproteiinien ja entsyymien yhteistoimintaa Caco-2-soluissa. Malliaineilla tehdyissä kokeissa muodostuikin metaboliatuotteita, joita effluksiproteiinit poistivat soluista sekä suolta että verenkiertoa mallittavalle puolelle yksisolukerrosta. Työssä saavutettujen tulosten perusteella Caco-2-solulinja on erittäin lupaava malli imeytymisvaiheen metabolian ja effluksin yhteistoiminnan tutkimiseen. Havaitut ilmiöt lisäävät myös tietoa paljon käytetyn Caco-2-solumallin ominaisuuksista ja toiminnasta, tehostaen sitä kautta rutiini-imeytymiskokeista saatujen tulosten tulkintaa

In Vitro Methods to Study the Interplay of Drug Metabolism and Efflux in the Intestine

This review provides an overview of the in vitro methods currently used in studies of intestinal drug metabolism and active efflux with a special emphasis on the efflux-metabolism interplay. These methods include e. g. expressed enzymes or efflux transporters, fractionated intestinal cells, cell lines, primary cells, intestinal segments and other tissue preparations. Pharmacokinetics of efflux-metabolism interplay is often very complicated, possibly involving saturation, stimulation and/or inhibition of one or both of these mechanisms. Parent drug and/or metabolite(s) can be substrates for several enzymes and/or efflux proteins. These detoxifying proteins may alter the exposure of drugs to each other and, consequently, their contributions to the overall drug elimination. Depending on the complexity of the in vitro system used, different kinds of information can be extracted from the results. Simple methods concentrating on single mechanisms provide easily interpretable information, but neglect the interplay between various mechanisms influencing the kinetics in a whole organism. More complex experimental systems mimic the mechanistic complexity of in vivo setting better, but at the same time the interpretation and utilization of the results becomes more challenging. Advantages and limitations of various in vitro systems are addressed and consideration is given to the physiological relevance of the results obtained and there is discussion of approaches for in vitro - in vivo translation of the data

The Consequence of Drug–Drug Interactions Influencing the Interplay between P-Glycoprotein and Cytochrome P450 3a:An Ex Vivo Study with Rat Precision-Cut Intestinal Slices

P-glycoprotein (P-gp) and cytochrome P450 3A (CYP3A) are differentially expressed along the intestine and work coordinately to reduce the intracellular concentration of xenobiotics and the absorption of orally taken drugs. Drug–drug interactions (DDIs) based on P-gp/CYP3A interplay are of clinical importance and require preclinical investigation. We investigated the P-gp/Cyp3a interplay and related DDIs with different P-gp inhibitors in the various regions of the rat intestine ex vivo using precision-cut intestinal slices (PCIS) with quinidine (Qi), a dual substrate of P-gp and Cyp3a, as the probe. The results showed that P-gp efflux was the main factor limiting the intracellular Qi content at concentrations below 5 µM, whereas both efflux and metabolism were saturated at [Qi] > 50 µM. The selective P-gp inhibitors CP100356 [N-(3,4-dimethoxyphenethyl)-4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2[1H]-yl)-6,7-dimethoxyquinazolin-2-amine] and PSC833 [valspodar, 6-[(2S,4R,6E)-4-methyl-2-(methylamino)-3-oxo-6-octenoic acid]-7-l-valine-cyclosporin A] enhanced the Qi accumulation in slices in line with the different P-gp expression in the intestinal regions and, as a result, also enhanced metabolism in the jejunum and ileum. Dual inhibitors of both P-gp and Cyp3a (verapamil and ketoconazole) increased the concentration of Qi in the jejunum and ileum, but less 3-hydroxy-quinidine was produced due to inhibition of Cyp3a. The results indicate that the P-gp/Cyp3a interplay depends on the concentration of the drug and on the intestinal region under study. Furthermore, due to the P-gp/Cyp3a interplay, DDIs can lead to remarkable changes in the intracellular concentration of both the parent drug and the metabolite, which varies among the intestinal regions and depends on the selectivity of the inhibitors, with potentially important implications for disposition and toxicity of drugs and their metabolites

Nanoparticle formulation of a poorly soluble cannabinoid receptor 1 antagonist improves absorption by rat and human intestine

The inclusion of nanoparticles dispersed in a hydrophilic matrix is one of the formulation strategies to improve the bioavailability of orally administered Biopharmaceutics Classification System (BCS) class II and IV drugs by increasing their dissolution rate in the intestine. To confirm that the increased dissolution rate results in increased bioavailability, in vitro and in vivo animal experiments are performed, however, translation to the human situation is hazardous. In this study, we used a range of in vitro and ex vivo methods, including methods applying human tissue, to predict the in vivo oral bioavailability of a model BCS class II CB-1 antagonist, formulated as a nanoparticle solid dispersion. The enhanced dissolution rate from the nanoparticle formulation resulted in an increased metabolite formation in both rat and human precision-cut intestinal slices, suggesting increased uptake and intracellular drug concentration in the enterocytes. In Ussing chamber experiments with human tissue, both the metabolite formation and apical efflux of the metabolite were increased for the nanoparticulate solid dispersion compared with a physical mixture, in line with the results in intestinal slices. The pharmacokinetics of the different formulations was studied in rats in vivo. The nanoparticle formulation indeed improved the absorption of the cannabinoid receptor 1 (CB-1) antagonist and the delivery into the brain compared with the physical mixture. In conclusion, the combined approach provides a valuable set of tools to investigate the effects of formulation on the absorption of poorly soluble compounds in human intestine and may provide relevant information on the oral bioavailability in humans early in the development process. Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics