Regulatory agencies encourage computer modeling and simulation to reduce the time and cost of clinical trials. Although still not classified in formal guidelines, system biology-based models represent a powerful tool for generating hypotheses with great molecular detail. Herein, we have applied a mechanistic head-to-head in silico clinical trial (ISCT) between two treatments for attention-deficit/hyperactivity disorder, to wit lisdexamfetamine (LDX) and methylphenidate (MPH). The ISCT was generated through three phases comprising (i) the molecular characterization of drugs and pathologies, (ii) the generation of adult and children virtual populations (vPOPs) totaling 2,600 individuals and the creation of physiologically based pharmacokinetic (PBPK) and quantitative systems pharmacology (QSP) models, and (iii) data analysis with artificial intelligence methods. The characteristics of our vPOPs were in close agreement with real reference populations extracted from clinical trials, as did our PBPK models with in vivo parameters. The mechanisms of action of LDX and MPH were obtained from QSP models combining PBPK modeling of dosing schemes and systems biology-based modeling technology, i.e., therapeutic performance mapping system. The step-by-step process described here to undertake a head-to-head ISCT would allow obtaining mechanistic conclusions that could be extrapolated or used for predictions to a certain extent at the clinical level. Altogether, these computational techniques are proven an excellent tool for hypothesis-generation and would help reach a personalized medicine.

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Attention-deficit/hyperactivity disorder (ADHD) is a common childhood-onset neurodevelopmental disorder characterised by persistent inattention, hyperactivity and impulsivity. Moreover, ADHD is commonly associated with other comorbid diseases (depression, anxiety, bipolar disorder, etc.). The ADHD symptomatology interferes with subject function and development. The treatment of ADHD requires a multidisciplinary approach based on a combination of non-pharmacological and pharmacological treatments with the aim of ameliorating the symptomatology; among first-line pharmacological treatments are stimulants [such as methylphenidate (MPH) and lisdexamfetamine dimesylate (LDX)]. In this review we explored recent ADHD- and stimulants-related literature, with the aim of compiling available descriptions of molecular pathways altered in ADHD, and molecular mechanisms of current first-line stimulants MPH and LDX. While conducting the narrative review, we applied structured search strategies covering PubMed/MEDLINE database and performed handsearching of reference lists on the results of those searches. The aetiology and pathophysiology of ADHD are incompletely understood; both genetic and environmental factors have been associated with the disorder and its grade of burden, and also the relationship between the molecular mechanisms of pharmacological treatments and their clinical implications. The lack of comprehensive understanding of the underlying molecular pathology makes both the diagnosis and treatment difficult. Few published studies evaluating molecular data on the mechanism of action (MoA) of MPH and LDX on ADHD are available and most of them are based on animal models. Further studies are necessary to improve the knowledge of ADHD pathophysiology and how the MoAs of MPH and LDX differentially modulate ADHD pathophysiology and control ADHD symptomatology.

Aim: To assess the degree of compliance and adherence to treatment during the follow-up of schizophrenic outpatients after a new therapeutic strategy had been initiated.Methods: A multicenter, retrospective, prospective, observational study of 1,848 outpatients with schizophrenia or schizoaffective disorders (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria) was conducted. Patients were treated either with oral or injectable conventional or second generation antipsychotics, and were followed up for 3 months at mental health centers. Patient compliance with the pharmacological treatment was assessed by the use of questionnaires, scales, medication accountability, and the Medication Event Monitoring System. Patients were considered compliant if they reported a high compliance rate (≥80%).Results: At baseline only 29% of patients on oral medication were compliant compared with 79% of patients on injectable medication (injection counting) (OR= 9.11; 95% CI 6.02-13.77; P<.0001). At the 3 month visit, 84% of patients had changed their treatment and in these, the compliance rate of those on injectable medication was 94% versus 87% of patients taking oral medication (OR= 2.47; 95% CI 1.21-5.05; P=.022).Conclusion: The use of long-acting injectable antipsychotics, which improves compliance rates and patient follow-up, should facilitate the management of Spanish patients with schizophrenia in mental health centers.

In Spanish patients with schizophrenia, activities of daily living and anxiety/depression were more relevant reported problems. Risperidone LAI was associated with better quality-of-life outcomes and lower caregiver burden compared to other types of antipsychotic.