Quetiapine extended-release augmentation has not been found to be beneficial , in comparison to placebo , in non-responders to previously recommended pharmacotherapy .
In non-responders to cognitive behavioral therapy ( CBT ) , switching to paroxetine/citalopram has been found to be more effective than continuing CBT .
Acceptance and commitment therapy ( ACT ) has shown some improvement in patients ’ resistance to previous psychological/pharmacological interventions compared with a waiting-list condition .
Prolonged pharmacotherapy may produce significant improvement in patients with unsatisfactory response to short-term pharmacotherapy  , while switching to pharmacotherapy may help non-responders to CBT .
Purpose of Review Purpose of Review Management of treatment-resistant ( TR ) panic disorder ( PD ) is an unresolved issue .
In this paper , we provide a brief summary of previous findings , an up date d ( 2015–2017 ) systematic review of pharmacological/non-pharmacological studies , and our personal perspective on this topic .
Modulation by muscarinic antagonists of the response to carbon dioxide challenge in panic disorder.
BACKGROUND Panic attacks can be induced in persons with panic disorder by inhalation of carbon dioxide . Hypercapnia also elicits a reflex hyperventilation , which is controlled in part by cholinergic mechanisms . This study investigated whether the exaggerated response to carbon dioxide in panic disorder ( PD ) can be modulated by antagonists of muscarinic cholinergic receptors . METHODS Twelve patients with PD received biperiden hydrochloride ( a muscarinic antagonist that crosses the blood-brain barrier ) , pirenzepine hydrochloride ( a muscarinic antagonist that does not cross the blood-brain barrier ) , or placebo 2 hours before a 35 % carbon dioxide-65 % oxygen respiratory challenge ( vs air as a placebo ) on 3 separate days , in a double-blind , r and om crossover design . RESULTS According to patients ' self-ratings of subjective anxiety , inhalation of the carbon dioxide/oxygen mixture provoked a significant and intense response after treatment with pirenzepine and placebo . After biperiden treatment , however , hypercapnia elicited a response profile similar to that elicited by air , whereby subjective anxiety remained similar to preinhalation levels . CONCLUSIONS Consistent with the hypothesis of the study , a central ly active muscarinic antagonist can block the response to carbon dioxide commonly observed in subjects with PD
Quetiapine extended-release augmentation has not been found to be beneficial , in comparison to placebo , in non-responders to previously recommended pharmacotherapy .
In non-responders to cognitive behavioral therapy ( CBT ) , switching to paroxetine/citalopram has been found to be more effective than continuing CBT .
Acceptance and commitment therapy ( ACT ) has shown some improvement in patients ’ resistance to previous psychological/pharmacological interventions compared with a waiting-list condition .
Prolonged pharmacotherapy may produce significant improvement in patients with unsatisfactory response to short-term pharmacotherapy  , while switching to pharmacotherapy may help non-responders to CBT .
Purpose of Review Purpose of Review Management of treatment-resistant ( TR ) panic disorder ( PD ) is an unresolved issue .
In this paper , we provide a brief summary of previous findings , an up date d ( 2015–2017 ) systematic review of pharmacological/non-pharmacological studies , and our personal perspective on this topic .