GABAergic agents and panic disorder

Anticonvulsant and antipsychotic medications in the pharmacotherapy of panic disorder: a structured review

BACKGROUND

As the remission rate of panic disorder (PD) achieved with conventional pharmacotherapy ranges between 20% and 50%, alternative psychopharmacological strategies are needed. We aimed to firstly review data regarding use of antipsychotic and non-benzodiazepine anticonvulsant medication in PD patients with or without comorbidities; secondly, to review data concerning reduction of panic symptoms during treatment of another psychiatric disorder with the same medications; and thirdly, to examine reports of anticonvulsant- or antipsychotic-induced new-onset panic symptomatology.

METHODS

We performed a PubMed search (last day: 28 April 2020) of English-language studies only, combining psychopathological terms (e.g. 'panic disorder') and terms referring either to categories of psychotropic medications (e.g. 'anticonvulsants') or to specific drugs (e.g. 'carbamazepine'). All duplications were eliminated. All studies included in the review met certain inclusion/exclusion criteria. The level of evidence for the efficacy of each drug was defined according to widely accepted criteria.

RESULTS

In treatment-resistant PD, beneficial effects have been reported after treatment (mostly augmentation therapy) with a range of anticonvulsant (carbamazepine, gabapentin, lamotrigine, levetiracetam, oxcarbamazepine, valproate, vigabatrin, tiagabine) and antipsychotic (aripiprazole, olanzapine, risperidone, sulpiride) medications: overall, most medications appear generally well tolerated. Additionally, bipolar patients receiving valproate or quetiapine-XR (but not risperidone or ziprasidone) demonstrated reductions of comorbid panic-related symptoms. There are case reports of new-onset panic symptoms associated with clozapine, haloperidol, olanzapine and topiramate, in patients with conditions other than PD. The small-to-modest sample size, the lack of control groups and the open-label and short-term nature of most of the reviewed studies hinder definitive conclusions regarding either the short-term and long-term efficacy of antipsychotic and anticonvulsant medications or their potential long-term side effects.

CONCLUSION

Some atypical antipsychotic and anticonvulsant medications may have a role in the treatment of some PD patients, mostly when more conventional approaches have not been successful, but the quality of supporting evidence is limited.

The diagnostic value of clinical EEG in detecting abnormal synchronicity in panic disorder

Electroencephalographic (EEG) findings repeatedly reported abnormal synchronous or even epileptiform discharges in panic disorder. Although less frequently occurring in patients with panic disorder, these deviant EEG features during panic attacks were also observed in intracranial EEG. For this purpose, our article reviews the consideration of abnormal synchronous neuronal activity in different neurocircuits, particularly limbic, as a suggested condition of panic attacks. Therapeutic approaches of anticonvulsants have shown reductions of symptoms and frequency of attacks in numerous patients suffering from panic disorder, supporting the presumption of underlying abnormal synchronous neuronal activity. Thus, scalp EEG recordings are still recommended for discovering indications of abnormal synchronous neuronal activity in panic patients.

Valproic acid for the treatment of social anxiety disorder

The aim of the study was to examine the efficacy of valproic acid in participants with social anxiety disorder. Following a 2-week single-blind, placebo run-in period, 17 participants were enrolled in a 12-week open flexible-dose trial of valproic acid (500-2500 mg). The primary outcome measures were the mean change from baseline in the Liebowitz Social Anxiety Scale (LSAS) total score and responder status [defined as a Clinical Global Impression of Improvement score (CGI-I) < or =2]. Social anxiety symptoms as measured by the LSAS and CGI-I scores significantly improved with treatment. The mean reduction in the LSAS was 21.3 points in the last visit carried forward analysis and 19.1 points for the completer analysis, with 41.1% and 46.6% participants, respectively, achieving responder status. The results from this open-label trial suggest the potential efficacy of valproic acid for the treatment of social anxiety disorder. Placebo-controlled trials are indicated to confirm these findings.

Neuroactive steroid changes in response to challenge with the panicogenic agent pentagastrin

BACKGROUND

Female hormones and female hormone derivatives, including neuroactive steroids (NASs) have been suspected to play a role in the pathophysiology of panic disorder (PD). The panicogenic agent CO(2) has been shown to induce a delayed release of NASs in both brain and plasma of rats. In the present study, we measured NASs plasma levels in response to challenge with another panicogenic agent, pentagastrin, and assessed the effect of ethynil estradiol (EE) pretreatment.

METHODS

A double-blind cross-over placebo-controlled design with randomization of the order of a three day pretreatment of EE (50 microg/day) or placebo was used to assess the effect of a 30 microg iv bolus injection of pentagastrin on the release of allopregnanolone (ALLO) and dehydroepiandrosterone (DHEA) into plasma in 15 male PD patients and 10 male healthy volunteers (HV).

RESULTS

After pentagastrin challenge there was a significant release of DHEA and a trend for the release of ALLO. EE pretreatment did not affect the pentagastrin-induced panic response or NAS release.

CONCLUSIONS

Pentagastrin induced release of NASs into plasma, the purpose of which remains to be determined.

Comprehensive review of the psychiatric uses of valproate

The therapeutic effects of valproate in psychiatric conditions are most substantially recognized in bipolar disorder. However, this well-tolerated medication may be beneficial in the treatment of other mental illnesses. In this article, the authors comprehensively review studies of valproate as treatment for psychiatric conditions, including bipolar, depressive, anxiety, and psychotic disorders; alcohol withdrawal and dependence; tardive dyskinesia; agitation associated with dementia; and borderline personality disorder. Valproate shows the most promising efficacy in treating mood and anxiety disorders, with possible efficacy in the treatment of agitation and impulsive aggression, and less convincing therapeutic response in treating psychosis and alcohol withdrawal or dependence. The authors conclude with a brief summary of its mechanism of action and therapeutic spectrum.

Panic attacks, complex partial seizures, and multiple meningiomas

A 39-year-old woman presented with typical panic disorder symptoms of two years duration. Imipramine (IMI) treatment yielded complete remission of her symptoms for three years. At that time, however, her symptoms recurred. Neither increasing the IMI dose nor an adequate trial of fluoxetine controlled her symptoms. Further history revealed subtle changes in her symptoms suggestive of complex partial seizures. Scalp EEG was normal, but an MRI revealed multiple meningiomas. Her symptoms remitted completely on carbamazepine. This case illustrates the phenomenologic overlap between panic attacks and complex partial seizures, and a neuroanatomic overlap between the two syndromes is hypothesized.

Valproate treatment of panic disorder and lactate-induced panic attacks

Several lines of evidence suggest that the anticonvulsant drug valproate may have antipanic properties: (1) It enhances gamma-aminobutyric acid activity in the brain; (2) it has anxiolytic effects in animal models of anxiety; and (3) it has been reported to be effective in panic disorder in several preliminary studies; however, valproate has not been studied in the prevention of lactate-induced panic attacks. Sixteen patients with panic disorder underwent a lactate infusion followed by a 28-day treatment period with valproate and subsequent rechallenge with lactate. Response was measured by change in panic attack frequency and Hamilton Anxiety Scale (HAS) scores and by the ability of valproate to block lactate-induced panic on rechallenge. Of the 14 patients completing the 28-day trial, 10 (71%) experienced a greater than 50% reduction in the weekly frequency of panic attacks. Six (43%) had complete remission. HAS scores dropped significantly from a baseline mean of 30.8 +/- 9.4 (SD) to 12.6 +/- 7 after 4 weeks of treatment. Valproate blocked reinduction of panic symptoms on lactate rechallenge in 10 (83%) of 12 patients who had initially experienced panic symptoms on initial infusion. The significant reduction in spontaneous panic attacks and the blockade of lactate-induced panic symptoms by valproate support earlier studies suggesting that the drug may be an effective treatment for panic disorder.