Combinations of QTc-prolonging drugs: towards disentangling pharmacokinetic and pharmacodynamic effects in their potentially additive nature

Whether arrhythmia risks will increase if drugs with electrocardiographic (ECG) QT-prolonging properties are combined is generally supposed but not well studied. Based on available evidence, the Arizona Center for Education and Research on Therapeutics (AZCERT) classification defines the risk of QT prolongation for exposure to single drugs. We aimed to investigate how combining AZCERT drug categories impacts QT duration and how relative drug exposure affects the extent of pharmacodynamic drug-drug interactions

Antipsychotic dose mediates the association between polypharmacy and corrected QT interval

Antipsychotic (AP) drugs have the potential to cause prolongation of the QT interval corrected for heart rate (QTc). As this risk is dose-dependent, it may be associated with the number of AP drugs concurrently prescribed, which is known to be associated with increased cumulative equivalent AP dosage. This study analysed whether AP dose mediates the relationship between polypharmacy and QTc interval. We used data from a cross-sectional survey that investigated the prevalence of QTc lengthening among people with psychiatric illnesses in Italy. AP polypharmacy was tested for evidence of association with AP dose and QTc interval using the Baron and Kenny mediational model. A total of 725 patients were included in this analysis. Of these, 186 (26%) were treated with two or more AP drugs (AP polypharmacy). The mean cumulative AP dose was significantly higher in those receiving AP polypharmacy (prescribed daily dose/defined daily dose = 2.93, standard deviation 1.31) than monotherapy (prescribed daily dose/defined daily dose = 0.82, standard deviation 0.77) (z = 1212.62, p < 0.001). Similarly, the mean QTc interval was significantly longer in those receiving AP polypharmacy (mean = 420.86 milliseconds, standard deviation 27.16) than monotherapy (mean = 413.42 milliseconds, standard deviation 31.54) (z = 122.70, p = 0.006). The Baron and Kenny mediational analysis showed that, after adjustment for confounding variables, AP dose mediates the association between polypharmacy and QTc interval. The present study found that AP polypharmacy is associated with QTc interval, and this effect is mediated by AP dose. Given the high prevalence of AP polypharmacy in real-world clinical practice, clinicians should consider not only the myriad risk factors for QTc prolongation in their patients, but also that adding a second AP drug may further increase risk as compared with monotherapy

Effectiveness of lithium in subjects with treatment-resistant depression and suicide risk: a protocol for a randomised, independent, pragmatic, multicentre, parallel-group, superiority clinical trial.

BACKGROUND: Data on therapeutic interventions following deliberate self harm (DSH) in patients with treatment-resistant depression (TRD) are very scant and there is no unanimous consensus on the best pharmacological option for these patients. There is some evidence that lithium treatment might be effective in reducing the risk of completed suicide in adult patients with unipolar affective disorders, however no clear cut results have been found so far. The primary aim of the present study is to assess whether adding lithium to standard therapy is an effective treatment strategy to reduce the risk of suicidal behaviour in long term treatment of people with TRD and previous history of DSH. METHODS/DESIGN: We will carry out a randomised, parallel group, assessor-blinded superiority clinical trial. Adults with a diagnosis of major depression, an episode of DSH in the previous 12 months and inadequate response to at least two antidepressants given sequentially at an adequate dose for an adequate time for the current depressive episode will be allocated to add lithium to current therapy (intervention arm) or not (control arm). Following randomisation, treatment is to be taken daily for 1 year unless some clear reason to stop develops. Suicide completion and acts of DSH during the 12 months of follow-up will constitute the composite primary outcome. To preserve outcome assessor blindness, an independent adjudicating committee, blind to treatment allocation, will anonymously review all outcome events. DISCUSSION: The results of this study should indicate whether lithium treatment is associated with lower risk of completed suicide and DSH in adult patients with treatment resistant unipolar depression, who recently attempted suicide. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00927550

Factors Associated with Medication Adherence to Long-Acting Injectable Antipsychotics: Results from the STAR Network Depot Study

Introduction Long-acting injectable (LAI) antipsychotics are prescribed to people with severe psychiatric disorders who show poor adherence to oral medication. The present paper examined factors potentially associated with medication adherence to LAI treatment.Methods The STAR (Servizi Territoriali Associati per la Ricerca) Network Depot Study was a multicenter, observational, prospective study that enrolled 461 subjects initiating a LAI from 32 Italian centers. After 6 and 12 months of treatment, we evaluated differences between participants with high ( >= 5 points) and low ( < 5 points) medication adherence using Kemp's 7-point scale in sociodemographic, clinical, psychopathological, and drug-related variables. Factors that differed significantly between the two groups were entered for multivariate logistic regression.Results Six months after enrollment, participants with high medication adherence were younger, living with other people, had lower Brief Psychiatric Rating Scale ( BPRS) total scores, lower adverse events, and a more positive attitude toward medication than participants with low adherence. Multivariate regression confirmed lower BPRS resistance and activation scores, absence of adverse events, and positive attitude toward medication as factors significantly associated with good adherence. After 12 months, all BPRS subscales were significantly lower in the high adherence group, which also showed a more positive attitude toward medication. BPRS resistance and attitude toward medication were confirmed as factors associated with medication adherence.Discussion Our findings suggest that adherence to LAI is principally related to attitude toward medication and traits of suspiciousness/hostility. Quality of patient- clinician relationship and tailored psychoeducational strategies may positively affect adherence in people undergoing psychopharmacological treatment, including LAI