Igor Locatelli

Comparative efficacy and acceptability of atomoxetine, lisdexamfetamine, bupropion and methylphenidate in treatment of attention deficit hyperactivity disorder in children and adolescents: A meta-analysis with focus on bupropion

OBJECTIVES There is a lack of comparative effectiveness research among attention deficit hyperactivity disorder (ADHD) drugs in terms of efficacy and acceptability, where bupropion is compared with atomoxetine, lisdexamfetamine and methylphenidate. The main aim of this work was to compare the efficacy and acceptability of these drugs in children and adolescents using a metaanalysis. METHODS A literature search was conducted to identify double-blind, placebo-controlled, noncrossover studies of ADHD. PubMed/Medline and Clinicaltrials.gov were searched. Comparative drug efficacy to placebo was calculated based on the standardized mean difference (SMD), while the comparative drug acceptability (all cause discontinuation) to placebo was estimated on the odds ratio (OR). RESULTS In total 28 trials were included in the meta-analysis. Efficacy in reducing ADHD symptoms compared to placebo was small for bupropion (SMD=-0.32, 95% CI; -0.69, 0.05), while modest efficacy was shown for atomoxetine (SMD=-0.68, 95% CI; -0.76, -0.59) and methylphenidate (SMD=-0.75, 95% CI; -0.98, -0.52) and high efficacy was observed for lisdexamfetamine (SMD=-1.28, 95% CI; -1.84, -0.71). Compared to placebo treatment discontinuation was statistically significantly lower for methylphenidate (OR=0.35, 95% CI; 0.24, 0.52), while it was not significantly different for atomoxetine (OR=0.91, 95% CI; 0.66, 1.24), lisdexamfetamine (OR=0.60, 95% CI, 0.22, 1.65), and bupropion (OR=1.64, 95% CI; 0.5, 5.43). LIMITATIONS The heterogeneity was high, except in atomoxetine trials. The crossover studies were excluded. The effect sizes at specific time points were not computed. Studies with comorbid conditions, except those reporting on oppositional defiant disorder, were also excluded. All studies involving MPH were combined. CONCLUSIONS The results suggest that lisdexamfetamine has the best benefit risk balance and has promising potential for treating children and adolescents with ADHD. More research is needed for a better clinical evaluation of bupropion.

MDR1 gene polymorphisms and response to acute risperidone treatment

Polymorphic multidrug resistant protein 1 (MDR1) transports drugs against a concentration gradient across the blood-brain barrier and reduces their accumulation in the brain. MDR1 may therefore influence antipsychotic brain availability contributing to inter-individual differences in treatment response and adverse effects, regardless of plasma concentrations. In the present study we investigated the influence of two common MDR1 polymorphisms on the improvement of psychopathological symptoms and occurrence of extrapyramidal side effects (EPS) in Slovenian schizophrenia patients acutely treated with risperidone. A total of 59 clinically well defined patients with first episode schizophrenia spectrum disorders or after tapering their maintenance treatment were genotyped for MDR1 C3435T and G2677T/A. Steady-state plasma concentrations of risperidone active moiety (sum of risperidone and the 9-hydroxyrisperidone) were determined. G2677T/A and C3435T genotypes were not associated to psychopathological symptoms, efficacy of treatment and risk for parkinsonism. Marginal associations with akathisia (p=0.039 and p=0.042, respectively) and dystonia (p=0.013 and p=0.034, respectively) were observed for both G2677T/A and C3435T genotypes. However, higher AIMS and BARS scores were observed only in heterozygous carriers of G2677T/A and C3435T polymorphisms and there was no tendency of gene-dose effect. The present study does not suggest a major influence of MDR1 G2677T/A and C3435T polymorphisms on treatment response during short-term risperidone therapy in patients with schizophrenia or schizoaffective disorder.

A population pharmacokinetic evaluation of the influence of CYP2D6 genotype on risperidone metabolism in patients with acute episode of schizophrenia

The objective of this prospective study was to characterize the metabolism of risperidone to (+)- and (-)-9-hydroxyrisperidone in vivo and to evaluate the influence of CYP2D6 genotype. A population pharmacokinetic modeling approach was used to estimate the interindividual variability of the pharmacokinetic parameters in 50 hospitalized patients with acute episode of schizophrenia. CYP2D6 genotype remarkably influenced the formation clearances of the risperidone metabolites, while creatinine clearance was related to the plasma clearance of 9-hydroxyrisperidone. CYP2D6 genotype was also associated with the average plasma concentration of risperidone active moiety (a sum of all three active compounds). In comparison to the patients with CYP2D6*1/*1 genotype, average steady-state plasma concentration of risperidone active moiety was 3.3- and 1.6-fold higher in poor metabolizers (both alleles nonfunctional; CYP2D6*3 or *4) and intermediate metabolizers (one nonfunctional allele and one allele for diminished enzyme activity; CYP2D6*10 or *41), respectively. Additionally, average plasma concentration of risperidone active moiety was higher in the patients with dystonia (p=0.0066) and parkinsonism (p=0.046). The results of this study imply the potential role of CYP2D6 genotyping in personalizing risperidone therapy in patients with schizophrenia to reduce the incidence of adverse extrapyramidal symptoms.

Simultaneous determination of risperidone and 9-hydroxyrisperidone enantiomers in human blood plasma by liquid chromatography with electrochemical detection

Risperidone is a commonly prescribed antipsychotic drug. An enantioselective HPLC method with electrochemical detection was developed and validated for simultaneous determination of plasma concentrations of risperidone and its active metabolites, 9-hydroxyrisperidone enantiomers. Following solid phase extraction of 1.0 mL blood plasma, a baseline separation of the analytes was achieved on an AGP (alpha1 acid glycoprotein) column using isocratic mobile phase consisting of methanol-phosphate buffer (pH 6.2; 0.1 M) (15:85, v/v). Total analysis run time was 11 min. For the detection of the analytes analytical cell potentials were set at 500, 650, 950, and 950 mV. The method linearity was attained in the range from 1.0 to 100 ng/mL for risperidone and both 9-hydroxyrisperidone enantiomers. The limit of detection was 0.5 ng/mL for all three analytes. The method was precise and accurate and was successfully applied in a clinical study investigating the stereoselectivity of risperidone 9-hydroxylation.

Gastric emptying of non-disintegrating solid drug delivery systems in fasted state: relevance to drug dissolution

Importance of the field: Knowledge of gastric emptying (GE) of solid drug delivery systems (DDS) is meaningful for the development of new DDS as it enables the design of in vitro dissolution experiments with conditions close to those in vivo in order to predict drug plasma concentration profiles with high reliability. Areas covered in this review: Gastric emptying of non-disintegrating pellets, tablets and mini-tablets in the fasted state is described on the basis of various studies performed in the last 30 years, which have evaluated the emptying process mostly by gamma scintigraphy. Different influences on GE and mathematical models describing GE kinetics of single and multiunit dosage forms are represented. A discussion on the implementation of these data in the development of drug dissolution testing procedures is given. What the reader will gain: Readers will gain an insight into the kinetics and mechanisms of GE processes. Some suggestions on the use of the obtained knowledge in biopharmaceutical testing of DDS are also given. Take home message: Gastric emptying of non-disintegrating solid DDS is a very important process, which might influence drug dissolution, bioavailability and the plasma concentration profile. It is reasonable to consider this process in biopharmaceutical testing of these DDS.

The role of individual gastric emptying of pellets in the prediction of diclofenac in vivo dissolution.

The objective of the present study was to check for the possibility to successfully predict individual in vivo dissolution/absorption profiles resulting from fasted administration of a diclofenac extended release pellet formulation. For this purpose dissolution profiles were generated with different dissolution setups using a set of media reflecting pH-conditions in the different segments of the gastrointestinal tract. Since gastric emptying of pellets seemed to be a critical factor for in vivo drug release, a set of different gastric residence times was screened in in vitro studies. Subsequently, in vitro release profiles were first directly compared with the individual in vivo absorption profiles and in a second step a mathematical model, which had been developed in a previous study, was applied to calculate predicted individual in vivo release profiles based on in vitro release profiles and individual gastric emptying. The comparison of predicted individual in vivo release profiles and individual in vivo absorption profiles showed a high degree of similarity, thus confirming the suitability of a set of different gastric residence times used in in vitro drug release testing. Additionally, obtained results indicated that a substantial part of variability of diclofenac absorption profiles can be explained by the variability of pellet gastric emptying kinetics.

Effects of synbiotic fermented milk containing Lactobacillus acidophilus La-5 and Bifidobacterium animalis ssp. lactis BB-12 on the fecal microbiota of adults with irritable bowel syndrome: A randomized double-blind, placebo-controlled trial

We conducted a randomized double-blind, placebo-controlled multicentric study to investigate the influence of a synbiotic fermented milk on the fecal microbiota composition of 30 adults with irritable bowel syndrome (IBS). The synbiotic product contained Lactobacillus acidophilus La-5, Bifidobacterium animalis ssp. lactis BB-12, Streptococcus thermophilus, and dietary fiber (90% inulin, 10% oligofructose), and a heat-treated fermented milk without probiotic bacteria or dietary fiber served as placebo. Stool samples were collected after a run-in period, a 4-wk consumption period, and a 1-wk follow-up period, and were subjected to real-time PCR and 16S rDNA profiling by next-generation sequencing. After 4wk of synbiotic (11 subjects) or placebo (19 subjects) consumption, a greater increase in DNA specific for L. acidophilus La-5 and Bifidobacterium animalis ssp. lactis was detected in the feces of the synbiotic group compared with the placebo group by quantitative real-time PCR. After 1wk of follow-up, the content of L. acidophilus La-5 and B. animalis ssp. lactis decreased to levels close to initial levels. No significant changes with time or differences between the groups were observed for Lactobacillus, Enterobacteriaceae, Bifidobacterium, or all bacteria. The presence of viable BB-12- and La-5-like bacteria in the feces resulting from the intake of synbiotic product was confirmed by random amplification of polymorphic DNA (RAPD)-PCR. At the end of consumption period, the feces of all subjects assigned to the synbiotic group contained viable bacteria with a BB-12-like RAPD profile, and after 1wk of follow-up, BB-12-like bacteria remained in the feces of 87.5% of these subjects. The presence of La-5-like colonies was observed less frequently (37.5 and 25% of subjects, respectively). Next-generation sequencing of 16S rDNA amplicons revealed that only the percentage of sequences assigned to Strep. thermophilus was temporarily increased in both groups, whereas the global profile of the fecal microbiota of patients was not altered by consumption of the synbiotic or placebo. In conclusion, daily consumption of a synbiotic fermented milk had a short-term effect on the amount and proportion of La-5-like strains and B. animalis ssp. lactis in the fecal microbiome of IBS patients. Furthermore, both synbiotic and placebo products caused a temporary increase in fecal Strep. thermophilus.

Physicochemical and preclinical pharmacokinetic and toxicological evaluation of LK-423—a new phthalimido-desmuramyl-dipeptide derivative with immunomodulating activity

Introduction: LK-423 is a new phthalimido-desmuramyl-dipeptide derivative with immunomodulating activity. As optimized delivery to the site of action appears crucial for further preclinical development of LK-423, the aim of this study was to perform a physicochemical and preclinical pharmacokinetic and toxicological evaluation. Methods: The solubility, partition coefficient, permeability, and stability profile were determined. Pharmacokinetics were evaluated in rats following intravenous and oral application of LK-423, and in dogs after intravenous administration and oral administration of microcapsules, designed for colon-specific delivery of LK-423 based on pH-, time-, and enzyme-controlled release mechanisms. Additionally, the acute and subchronic toxicity was examined. Results and discussion: LK-423 is hydrophilic, sparingly to slightly soluble, and poorly permeable. Stability profile in aqueous solution is pH dependent. A pharmacokinetic study following intravenous application to rats and dogs revealed that LK-423 is rapidly eliminated with a short terminal phase half-life, and high plasma clearance, as well as a limited distribution to the peripheral tissue. Oral bioavailability of LK-423 is low, presumably due to low permeability. Debris of insoluble microcapsule coating in feces and obtained plasma concentration profiles confirm that LK-423 microcapsules are a promising approach for local treatment of inflammatory diseases of the large intestine. Acute and a subchronic toxicity results indicate that LK-423 is a safe and nontoxic drug under the applied experimental conditions.

Clinically relevant potential drug–drug interactions among outpatients: A nationwide database study

Background Adverse drug events due to drug‐drug interactions (DDIs) represent a considerable public health burden, also in Slovenia. A better understanding of the most frequently occurring potential DDIs may enable safer pharmacotherapy and minimize drug‐related problems. Objectives The aim of this study was to evaluate the prevalence and predictors of potential DDIs among outpatients in Slovenia. Methods An analysis of potential DDIs was performed using health claims data on prescription drugs from a nationwide database. The Lexi‐Interact Module was used as the reference source of interactions. The influence of patient‐specific predictors on the risk of potential clinically relevant DDIs was evaluated using logistic regression model. Results The study population included 1,179,803 outpatients who received 15,811,979 prescriptions. The total number of potential DDI cases identified was 3,974,994, of which 15.6% were potentially clinically relevant. Altogether, 9.3% (N = 191,213) of the total population in Slovenia is exposed to clinically relevant potential DDIs, and the proportion is higher among women and the elderly. After adjustment for cofactors, higher number of medications and older age are associated with higher odds of clinically relevant potential DDIs. The burden of DDIs is highest with drug combinations that increase risk of bleeding, enhance CNS depression or anticholinergic effects or cause cardiovascular complications. Conclusion The current study revealed that 1 in 10 individuals in the total Slovenian population is exposed to clinically relevant potential DDIs yearly. Taking into account the literature based conservative estimate that approximately 1% of potential DDIs result in negative health outcomes, roughly 1800 individuals in Slovenia experience an adverse health outcome each year as a result of clinically relevant potential interactions alone. Highlights1 in 10 individuals in the total Slovenian population is exposed to clinically relevant potential DDIs.Outpatients with higher number of medications and elderly have higher odds of clinically relevant potential DDIs.Roughly 1800 individuals in Slovenia experience an adverse health outcome each year as a result of clinically relevant DDIs.

Criterion validity of 8-item Morisky Medication Adherence Scale in patients with asthma

The 8-item Morisky Medication Adherence Scale (MMAS-8) is reliable and valid in patients with hypertension, but to our knowledge validity has not been established for patients with asthma. The aim of the study was to determine the criterion validity of the MMAS-8 in patients with asthma. In the cross-sectional study patients older than 12 year were recruited when dispensed asthma medications in community pharmacies. Criterion validity of the scale was assessed through associations with asthma control and quality of life. Asthma control was assessed by the Asthma Control Test (ACT) and quality of life was evaluated by the Saint George Respiratory Questionnaire (SGRQ). A total of 208 patients (mean age 56 years, 59% female) were included in the study. Almost all patients were prescribed inhaled corticosteroids (96%). Asthma was not controlled in 37% of the patients and 22% experienced at least one exacerbation requiring emergency room visit, hospitalization or treatment with oral corticosteroid therapy in the previous year. The 8-item MMAS was significantly associated with asthma control and quality of life. Patients who scored 8 points, <8 to >6 points and ≤6 points on the scale were considered to have high, medium and low adherence, respectively. High, medium and low adherence was found in 53%, 23% and 24% of the patients, respectively. As adherence improved from low to medium or from medium to high, the odds of asthma control increased by 1.7 times (OR 1.65, p = 0.027). Patients with high and medium adherence had SGRQ scores that were 6.1 and 5.3 points lower, respectively, compared with patients with low adherence. The MMAS-8 was found to be valid for assessing medication adherence and predicting health outcomes in patients with asthma.