Pharmacokinetic Interactions between Antiepileptic and Antidepressant Drugs

The use of antiepileptic drugs (AEDs) for the treatment of psychiatric disorders has reached a new phase of clinical interest. They are commonly used in the therapy of psychoses, mood disorders, aggression and eating disorders. Pharmacotherapy combinations involving AEDs and antidepressant drugs are used to treat co-morbid psychiatric and neurological disorders, to reduce or control the adverse effects of a medication or to increase a medication effect. Therefore, the impact of pharmacokinetic interactions of this class of drugs is quite relevant. In this paper, the available data about the mechanisms of metabolic kinetic interactions between antidepressant and antiepileptic drugs, as well as their clinical significance, has been reviewed.     

Antidepressant-Like Properties of Novel HDAC6-Selective Inhibitors with Improved Brain Bioavailability

HDAC inhibitors have been reported to produce antidepressant and pro-cognitive effects in animal models, however, poor brain bioavailability or lack of isoform selectivity of current probes has limited our understanding of their mode of action. We report the characterization of novel pyrimidine hydroxyl amide small molecule inhibitors of HDAC6, brain bioavailable upon systemic administration. We show that two compounds in this family, ACY-738 and ACY-775, inhibit HDAC6 with low nanomolar potency and a selectivity of 60- to 1500-fold over class I HDACs. In contrast to tubastatin A, a reference HDAC6 inhibitor with similar potency and peripheral activity, but more limited brain bioavailability, ACY-738 and ACY-775 induce dramatic increases in α-tubulin acetylation in brain and stimulate mouse exploratory behaviors in novel, but not familiar environments. Interestingly, despite a lack of detectable effect on histone acetylation, we show that ACY-738 and ACY-775 share the antidepressant-like properties of other HDAC inhibitors, such as SAHA and MS-275, in the tail suspension test and social defeat paradigm. These effects of ACY-738 and ACY-775 are directly attributable to the inhibition of HDAC6 expressed centrally, as they are fully abrogated in mice with a neural-specific loss of function of HDAC6. Furthermore, administered in combination, a behaviorally inactive dose of ACY-738 markedly potentiates the anti-immobility activity of a subactive dose of the selective serotonin reuptake inhibitor citalopram. Our results validate new isoform-selective probes for in vivo pharmacological studies of HDAC6 in the CNS and reinforce the viability of this HDAC isoform as a potential target for antidepressant development.     

Arzneimittelversorgung bei psychischen Erkrankungen

The use of psychotropic drugs has substantially changed during the last two decades. Whereas 1992 the largest amount dispensed with was benzodiazepine-tranquilizing drugs the antidepressants became the most prescribed drug group in 2012, especially due to the increase of selective-serotonine-reuptake-inhibitors (SSRI). The evidence for the treatment of mild depressions compared to placebo is poor. In the treatment of bipolar disorders mainly used are SSRI and lithium.     

Acute Neurofunctional Effects of Escitalopram in Pediatric Anxiety: A Double-Blind,Placebo-Controlled Trial

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Innovations in CNS drug discovery: differentiating strategies to treat depression

Over the past two decades, the clinical management of depression has been revolutionized by the introduction of selective serotonin re-uptake inhibitors and serotonin/noradrenaline re-uptake inhibitors. However, despite this progress, several unmet medical needs remain. These challenges, which collectively represent the next frontier for antidepressant drug discovery, range from improving efficacy in treatment-resistant patients, to accelerating onset of therapeutic activity, to reducing deleterious side effects such as emesis or sexual dysfunction. The present review addresses some of the innovative approaches designed to create novel therapies that improve in one or more of these areas. Additionally, the authors propose that to discover truly novel disease-modifying agents we must improve our appreciation of disease etiology, pathophysiology and genetics. Therefore, while it is still very early in the characterization of these strategies – as well as our general understanding of disease progression – the next several years should allow sufficient time for one (or more) of these approaches to differentiate themselves from current therapies.     

Psychopharmacology and Cardiovascular Disease

This review discusses common mental health disorders and their associations with cardiovascular disease risks. Commonly found mental health disorders include depression, anxiety, and personality types. The link between depression and cardiovascular disease mortality has been established. Depression is also common in patients with heart failure. In addition to discussing psychological disorders, a review of psychotropic drugs is also included. Drugs are described for therapy for depression and anxiety, as well as associations with cardiovascular drug-drug interactions. Drug-drug interactions are more common and potentially dangerous in elderly patients, in whom the conditions often coexist. The most common drug-drug interactions involve the P450 system of enzymes.     

A final common pathway for depression: implications for therapy

Depression in humans and animal models has been found to be accompanied by a hypoactivity of brain regions involved in positively motivated behavior together with a hyperactivity in regions involved in stress responses. Both sets of changes are reversed by diverse antidepressant treatments. It has been proposed that this neural pattern underlies the symptoms common to most forms of depression, which are the loss of positively motivated behavior and the increase in stress. The present paper discusses how this framework can organize diverse findings on the multiple factors associated with this disorder. The hypothesis suggests new therapeutic strategies involving treatment with low-dose corticosteroids to suppress the stress network or with antagonists of α_1A- and agonists of α_1B-adrenoceptors to disinhibit or activate the positive motivational network, respectively.     

Do Adenosine Receptors Play a Role in Amitriptyline‐Induced Cardiovascular Toxicity in Rats?

Objective: The aim of the our study was to investigate the role of adenosine receptors on cardiovascular toxicity induced by amitriptyline, a tricyclic antidepressant agent. Therefore, the hypothesis of this study was that adenosine receptor antagonists would improve and/or prevent amitriptyline‐induced hypotension and conduction abnormalities in an anesthetized rat model of amitriptyline intoxication. Methods: Two separate experimental protocols were performed. Amitriptyline intoxication was induced by the infusion of amitriptyline 0.94 mg/kg/min until 40–45% reduction of mean arterial pressure (MAP). Sodium cromoglycate (10 mg/kg) was injected i.v. to inhibit the A₃ receptor‐mediated activation of mast cells. In protocol 1, after amitriptyline infusion, while control animals (n = 8) were given dextrose solution, treatment groups received a selective adenosine A₁ antagonist DPCPX (8‐cyclopentyl‐1,3‐Dipropylxanthine, 20 µg/kg/min, n = 8) or a selective A_2a antagonist CSC (8‐(3‐chlorostyryl) caffeine, 24 µg/kg/min, n = 8) for 60 minutes. In protocol 2, after the sodium cromoglycate, while control group of rats (n = 8) recevied a dextrose solution, treatment groups of rats were administered DPCPX (20 µg/kg/min, n = 8) or CSC (24 µg/kg/min, n = 8) infusion to block adenosine A₁ and A_2a receptors for 20 minutes before amitriptyline infusion. After pretreatment with adenosine antagonists, all rats were given a dose of 0.94 mg/kg/min of amitriptyline infusion during 60 minutes. Outcome measures were mean arterial pressure (MAP), heart rate (HR), QRS duration and survival rate. Results: In protocol 1, amitriptyline infusion significantly reduced MAP and prolonged QRS within 15 minutes. HR was not changed significantly during the experiments. While dextrose did not improve MAP and QRS prolongation, DPCPX or CSC administration developed a significant improvement in MAP compared to the dextrose group within 10 min (88.5 ± 2.8%, 75.6 ± 4.7% and 50.1 ± 14.7%, p < 0.01, p < 0.05, respectively). Both DPCPX and CSC decreased QRS prolongation (p < 0.05) and increased median survival time significantly (log‐rank test, p < 0.00001). In protocol 2, pretreatment with DPCPX or CSC prevented the reduction in MAP due to amitriptyline toxicity compared to rats administered dextrose infusion (99.5 ± 2.6%, 102.4 ± 2.6%, 81.8 ± 5.4, p < 0.01 at 30 min; 98.0 ± 2.9%, 93.5 ± 6.0%, 64.9 ± 4.7, p < 0.001, p < 0.01 at 40 min, respectively). Pretreatment with DPCPX or CSC also prevented the QRS prolongation (p < 0.05) and increased median survival time significantly (log‐rank test, p < 0.0001). Conclusion: Adenosine antagonists were found to be effective in improving hypotension, QRS prolongation and survival time in our rat model of amitriptyline toxicity. Additionally, amitriptyline‐induced cardiotoxicity was abolished by pretreatment with adenosine receptor antagonists. These results suggest that adenosine receptors may have a role in the pathophysiology of amitriptyline‐induced cardiovascular toxicity. Adenosine A₁ and A_2a receptor antagonists may be promising agents for reversing amitriptyline‐induced cardiovascular toxicity.     

Criticisms of drugs in early development for the treatment of depression: what can be improved?

Major depressive disorder (MDD) is a common and debilitating mental illness, which leads to serious functional impairment in patients, and treatment-wise, there are currently a number of different classes of antidepressants already on the market. However, emerging evidence from numerous clinical trials has confirmed that there is still an unmet need for antidepressant efficacy in terms of response and remission. Approximately only 30% of patients with MDD may remit after adequate treatment with antidepressants in clinical practice. The drawbacks of the currently available antidepressants also include inadequate overall efficacy, safety issues and the lag prior to onset of clinical improvement. The need for new agents with novel mechanisms of action has led to the development of several newer antidepressants including vilazodone, edivoxetine, ketamine, atomoxetine and vortioxetine, which have been approved for the treatment of MDD. However, the efficacy and safety of these next-generation antidepressants, in clinical trials, are still unsatisfactory. This paper provides a brief updated overview of the progress and critical limitations in the development of novel antidepressants.     

Disproportionate Reduction of Serotonin Transporter May Predict the Response and Adherence to Antidepressants in Patients with Major Depressive Disorder: A Positron Emission Tomography Study with 4-[18F]-ADAM

Background:

Many lines of evidence suggest the role of serotonin transporter (SERT)-mediated reuptake of serotonin in the pathophysiology and treatment of major depressive disorder (MDD). This study aimed to examine whether the pretreatment of SERT binding potential or SERT binding ratio between terminal projection regions relative to the midbrain raphe nuclei was associated with treatment outcomes to SERT-targeted antidepressants.

Methods:

We recruited 39 antidepressant-naïve patients with MDD and 39 heathy controls. Positron emission tomography with N,N-dimethyl-2-(2-amino-4-[¹⁸F]fluorophenylthio)benzylamine (4-[¹⁸F]-ADAM) was used to measure in vivo SERT availability prior to antidepressant treatment. The 21-item Hamilton Depression Rating Scale (HDRS) was use to assess the severity of depression from baseline to week 6. All the patients with MDD had HDRS scores of 18 or more.

Results:

Pretreatment SERT binding in the thalamus and striatum positively correlated with an early reduction in HDRS scores at week 3. Nonresponders and dropout patients showed a proportionate reduction in SERT binding in the terminal projection regions and midbrain compared to healthy controls. In contrast, a disproportionate reduction in SERT binding in the terminal projection regions relative to midbrain was observed in responders.

Conclusions:

The results of this study suggested that a disproportionate reduction in SERT binding between terminal projection regions and midbrain may predict better treatment outcomes in patients with MDD.