Plasma interleukin-1 beta concentrations in panic disorder

Plasma interleukin-1 beta (IL-1 beta) concentrations were measured in 10 outpatients with panic disorder before and on days 30 and 32 of treatment with alprazolam (2-2.5 mg/day). IL-1 beta concentrations were found to be significantly higher in patients than in control subjects both before and during therapy. Thus, IL-1 beta levels may be a marker of panic disorder that is not related to the current level of symptomatology.

A review of GHRH stimulation test in psychiatry

We critically reviewed controlled investigations of the growth hormone releasing hormone (GHRH) stimulation test in depression, anorexia nervosa, bulimia, panic disorder, schizophrenia, and Alzheimer's disease. Comparisons of GH responsiveness between patients and controls within each diagnostic category were equivocal and in some cases contradictory. Factors that may contribute substantially to the inconsistent findings within diagnostic categories include (1) the variability of GHRH-simulated GH among control groups; (2) the lack of uniformity in test procedures and outcome measures; and (3) the age and gender of subjects. In addition, the individual reproducibility of the GHRH stimulation test has not been adequately investigated and until the test's stability within subjects can be determined, the validity of interpretations resulting from the GHRH simulation test are in question.

The relationship of alprazolam and clonazepam dose to steady-state concentration in plasma

This report addresses the correlation between dose and concentration of both alprazolam and clonazepam in plasma. Patients were 43 participants in a double-blind, placebo-controlled study of alprazolam and clonazepam for the treatment of panic disorder. The concentration of clonazepam in plasma was linearly related with dose, measured as milligrams per day (R = 0.724; F = 24.2; p = 0.0001) or milligrams per kilogram per day (R = 0.863; F = 58.3; p = 0.0001). The correlation between drug concentration and daily dose of alprazolam was also significant (R = 0.60; F = 9.5; p = 0.007), although the correlation between dose measured as milligrams per kilogram per day and drug level was not significant (R = 0.361; F = 2.4; p = 0.14). This replicates previous findings that, for each additional milligram per day dose of alprazolam, there is a corresponding increase of approximately 10 ng/ml in the plasma and presents preliminary data that, for each added 1 mg/day dose of clonazepam, there is approximately an increase of 12 ng/ml in the plasma. For both drugs, however, there may be considerable variation in level in plasma for a given dose. Weight-adjusted clonazepam concentration may be more predictable than weight-adjusted alprazolam concentration.

Serotonergic function in panic disorder: endocrine responses to D-fenfluramine

1. Prolactin and cortisol responses to d-fenfluramine were measured in 16 patients with DSM-III-R panic disorder and 14 normal controls. 2. Patients showed a greater mean prolactin response than controls but the difference between groups was not statistically significant (P > 0.05, MANOVA). 3. No consistent differences were observed between patients and controls with respect to cortisol responses (P > 0.05, MANOVA). 4. The results do not support the hypothesis of hypersensitive post-synaptic serotonin receptors in patients with panic disorder. 5. Studies in larger groups are necessary to confirm the trend and to explore receptor subtype sensitivity.

Relationship between concentrations of adinazolam and its primary metabolite in plasma and therapeutic/untoward effects in the treatment of panic disorder

Adinazolam mesylate, a triazolobenzodiazepine with antidepressant and anxiolytic activity, has been shown in several studies to treat panic disorder effectively. This report presents the results of analysis of concentrations in plasma of adinazolam and its primary metabolite, N-desmethyladinazolam (NDMAD), determined as a part of a flexible-dose, double-blind study of the efficacy of adinazolam mesylate sustained release tablets in the treatment of panic disorder with agoraphobia. Dosages administered in the study were titrated from 30 mg/day up to a maximum of 120 mg/day. Concentrations in plasma were determined by high-performance liquid chromatography at clinical evaluations at the end of treatment weeks 1, 2, and 4. The concentrations of both compounds were proportional to the administered dose. An inverted U-shaped concentration-response curve was apparent, where response was based on a priori definitions contained in the study protocol. However, this was probably a result of the flexible-dose study design used. By use of the post hoc definitions of response, as measured by the Clinician's Global Improvement Scale and the total panic attack frequency, logistic regression analysis resulted in more adequate predictions of actual response frequencies. Results indicate that NDMAD contributes to the therapeutic effects of adinazolam mesylate sustained release tablets in the treatment of panic disorder. The exact contributions of adinazolam and NDMAD to response in panic disorder could not be determined, because of the correlation between adinazolam and NDMAD concentrations on multiple dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

Preliminary application of magnetic resonance spectroscopy to investigate lactate-induced panic

OBJECTIVE

To characterize changes associated with lactate-induced panic, proton magnetic resonance spectroscopy (MRS) was used to measure brain lactate during intravenous infusion of 0.5-M sodium lactate in panic disorder patients and comparison subjects.

METHOD

Eight panic disorder subjects, five medicated and three unmedicated, and eight healthy comparison subjects were studied at baseline, during lactate infusion (5 meq/kg over 20 minutes), and after infusion. Localized proton MRS was used to acquire averaged spectra every 5 minutes from a 27-ml sampling volume in the insular cortex and adjacent regions. Brain lactate levels, quantitatively estimated in relationship to N-acetyl aspartate, were compared to blood lactate levels.

RESULTS

The procedure was generally well tolerated; one panic subject requested early termination before lactate infusion. Significant rises in brain lactate levels occurred for all subjects during infusion. The panic patients who responded to lactate (N = 3) had significantly higher brain lactate levels before, during, and after infusion than did the comparison subjects (N = 8) and medicated patients who were lactate nonresponders (N = 4). After infusion the panic patients with lactate-induced panic exhibited a striking dissociation between decreasing blood lactate and further increases in brain lactate levels.

CONCLUSIONS

These preliminary observations indicate that brain lactate increases during a standard lactate infusion. Lactate-induced panic is associated with greater increases than in comparison subjects and with prolonged elevations in brain lactate that are decoupled from falling blood lactate levels after completion of lactate infusion. Further investigation is necessary to clarify the mechanism(s) responsible for these findings and establish whether a causal relationship to the occurrence of lactate-induced panic exists.

Growth hormone response to intravenous clonidine in social phobia: comparison to patients with panic disorder and healthy volunteers

The growth hormone (GH) response to intravenous administration of clonidine hydrochloride (2 micrograms/kg) was assessed in 16 patients with DSM-III-R social phobia, 13 patients with DSM-III-R panic disorder, and 31 healthy controls. Compared to the healthy volunteers, both social phobic and panic-disorder patients had significantly blunted GH increments after clonidine. The social phobic patients demonstrated a similar degree of GH "blunting" to clonidine as did the patients with panic disorder.

Noradrenergic response to intravenous yohimbine in patients with depression and comorbidity of depression and panic

Adrenergic response following infusions of yohimbine or normal saline was evaluated in 9 control subjects, 8 patients suffering from a major depressive episode (MDE), and 12 patients suffering from concurrent MDE and panic disorder (MDE + P). Blood was drawn at -20, 0, 5, 10, 20, 45, and 90 min following the infusions, and assayed for norepinephrine (NE) and 3-methoxy-4-hydroxy-phenyl glycol (MHPG). Although the patient groups exhibited higher baseline NE concentrations, and a greater NE area under the plasma concentration versus time curve (AUC0-90) during the yohimbine infusion, the differences were not statistically significant. Baseline NE was significantly correlated with the NE AUC0-90 in all three groups, suggesting that, although the NE system may be dysregulated in the MDE and MDE + P patients, the NE system still appears to respond somewhat predictably following a challenge, even though the actual magnitude of response may vary.

Decreased lymphocyte beta-adrenoreceptor function correlates with less agoraphobia and better outcome in panic disorder

Previous studies have demonstrated reduced function of peripheral beta-adrenoreceptors in panic disorder with agoraphobia (PDA). We recently reported that decreased lymphocyte beta-receptor function was associated with milder agoraphobia and better treatment response in PDA. We now report on lymphocyte beta-receptor function in 12 additional patients with PDA. Lower cyclic AMP responses to isoproterenol were significantly correlated with milder agoraphobia and better response to naturalistic treatment. Lower beta-receptor density tended to correlate similarly with agoraphobia and treatment response. These findings further support the hypothesis that decreased peripheral beta-receptor function in PDA reflects an adaptive process associated with greater resistance to agoraphobia and greater capacity for recovery with treatment.

Plasma alprazolam concentrations. Relation to efficacy and side effects in the treatment of panic disorder

A series of 237 patients with DSM-III-diagnosed panic disorder, or agoraphobia with panic attacks, received alprazolam as part of the placebo-controlled Cross-National Collaborative Panic Study. After a 1-week drug-free period, alprazolam dosage was titrated upward with the objective of reaching 6.0 mg/d in all patients. At week 3 of treatment, alprazolam plasma levels were significantly correlated with daily dosage (regression slope: 11.7 ng/mL per milligram per day) but with considerable individual variation. Among patients with spontaneous panic attacks, 70% of those with plasma alprazolam levels greater than 20 ng/mL achieved complete remission vs 31% of those with levels less than 20 ng/mL. Situational panic attack remission increased in frequency with increasing plasma levels, but the relationship was not significant. Patient- and physician-rated global improvement and Hamilton Anxiety and Depression Scale score reductions were maximal at 20 to 39 ng/mL, with no further benefit at higher levels. Central nervous system-depressant side effects increased in frequency with higher plasma levels. Between weeks 3 and 8 of treatment, physicians were permitted to adjust dosage (maximum: 10 mg/d) to optimize response. At week 8, the dose-concentration relationship was essentially identical (regression slope: 10.8 ng/mL per milligram per day), but plasma levels were no longer related to efficacy or side effects. Thus, monitoring of plasma alprazolam concentrations may have a clinically useful role during short-term treatment of panic disorder.

Evidence that decreased function of lymphocyte beta adrenoreceptors reflects regulatory and adaptive processes in panic disorder with agoraphobia

OBJECTIVE

This study was designed to clarify the nature of the reduced function of the peripheral beta adrenoceptor system observed in panic disorder with agoraphobia. The authors hypothesized that this phenomenon reflected a regulatory and adaptive process.

METHODS

Lymphocyte beta adrenoreceptor density and affinity, basal lymphocyte cAMP level, and isoproterenol-stimulated cAMP generation were measured in 27 untreated outpatients with panic disorder with agoraphobia and 24 healthy comparison subjects. Lymphocyte beta receptor attributes were again assessed in patients after 4 weeks of double-blind treatment with adinazolam (slow-release form) or placebo. Panic frequency, agoraphobic symptoms, overall anxiety, and improvement with treatment were assessed with standard rating instruments.

RESULTS

Multivariate statistics revealed significantly lower beta receptor density and isoproterenol-stimulated cAMP generation in patients than in comparison subjects. beta receptor density tended to normalize after adinazolam but not after placebo. Pretreatment beta receptor density was lower in treatment responders than nonresponders. Patients with mild agoraphobia had lower cAMP responsivity than patients with moderate or severe agoraphobia.

CONCLUSIONS

Decreased function of lymphocyte beta receptors in panic disorder with agoraphobia is expressed as both decreased density and decreased cAMP responsivity. This pattern of changes, and the tendency for receptor density to normalize with treatment, is consistent with an active, regulatory process rather than a structural deficit in the beta receptor system. Preliminary clinical findings suggest that these changes may reflect adaptive processes associated with a favorable clinical course in panic disorder with agoraphobia.

Lymphocyte cholecystokinin concentrations in panic disorder

Since cholecystokinin (CCK) is known to be anxiogenic in experimental animals and to induce panic attacks in humans, lymphocyte CCK-8 concentrations were measured in 15 patients with panic disorder and 15 age- and sex-matched healthy subjects. The patients' levels were measured again after a 30-day course of alprazolam therapy, 1.5 mg/day. The CCK-8 concentrations were significantly lower in the patients than in the control subjects and did not change after alprazolam therapy. There was no correlation between the peptide values and levels of anxiety or frequency and severity of panic attacks.

Relationships between thyroid indices and symptoms of anxiety in depressed outpatients

Scores on rating scales measuring symptoms of depression, panic anxiety, state anxiety, trait anxiety, and agoraphobic avoidance were correlated, using multivariate statistics, with total thyroxine- and thyrotropin-releasing hormone concentrations in outpatients with major depression. A significant inverse relationship was demonstrated between agoraphobic avoidance and total thyroxine concentrations in female patients. No other symptom ratings were significantly associated with these thyroid indices. The depressed patients scored in the clinically significant range for agoraphobic symptoms. Assessment of agoraphobic avoidance may help identify a clinically and biologically distinct subgroup of depressed patients.

Blunted growth hormone responses to growth hormone-releasing factor and to clonidine in panic disorder

Blunted growth hormone (GH) responses to growth hormone-releasing factor (GH-RF) and clonidine have been reported in patients with panic disorder. In this study GH-RF and clonidine were administered to 13 patients with panic disorder and 20 healthy volunteers. Compared to the normal subjects, the patients with panic disorder had significantly blunted GH responses after both GH-RF and clonidine.

Hypertonic saline infusion increases plasma norepinephrine concentrations in normal men

We recently demonstrated in patients with panic disorder that hypertonic saline infusion induces acute panic with the same frequency and intensity as the standard hypertonic sodium lactate infusion. We now report the effects in normal men of hypertonic saline infusion on neuroendocrine systems possibly relevant to panic and anxiety. We administered a 150-min infusion of hypertonic saline (5% sodium chloride) which increased plasma osmolality from 288 +/- 1 to 303 +/- 2 mOsm/kg and produced the appropriate increase of plasma arginine vasopressin (AVP). Plasma norepinephrine (NE) increased substantially during hypertonic saline infusion compared to a normal saline infusion of equal volume and duration. Mean arterial pressure (MAP) also increased and there were significant positive correlations between MAP and NE, but not between MAP and AVP during hypertonic saline infusion. Plasma epinephrine and cortisol did not differ between conditions. Although the pattern of plasma adrenocorticotrophic hormone (ACTH) response differed between hypertonic saline and normal saline conditions, ACTH concentrations did not increase compared to baseline in either condition. These data suggest that hypertonic saline infusion increases sympathetic nervous system activity in normal men.

Alprazolam plasma concentrations and treatment response in panic disorder and agoraphobia

OBJECTIVE

The authors' goal was to evaluate the relationship between plasma concentrations of alprazolam and both treatment response and side effects in patients with panic disorder and agoraphobia.

METHOD

Ninety-six patients with panic disorder and agoraphobia were treated at three sites in a 6-week, fixed-dose, double-blind, placebo-controlled, dose-response study of 2 mg/day or 6 mg/day of alprazolam. Assessments were made of panic attacks, avoidance behavior, generalized anxiety, and global response. Blood samples were collected throughout the study and analyzed for alprazolam and other benzodiazepines.

RESULTS

Patient compliance with the protocol was judged to be good on the basis of plasma concentrations. According to logistic regression analysis, the relationships between plasma alprazolam concentration and response, as reflected by number of panic attacks reported, phobia ratings, physicians' and patients' ratings of global improvement, and the emergence of side effects, were significant. However, there was no significant relationship between plasma alprazolam concentration and the degree of generalized anxiety symptoms.

CONCLUSIONS

The authors conclude that plasma concentration of alprazolam is related to treatment response, particularly in panic attacks. The alprazolam concentration associated with treatment response or with emergence of a given side effect varied widely among individuals, highlighting the necessity for individualized dose adjustment to obtain optimal treatment response while minimizing side effects.

Growth hormone response to clonidine in male patients with panic disorder untreated by antidepressants

We report a non-significantly higher growth hormone (GH) response to intravenous clonidine administration (150 micrograms) in 10 male patients with panic disorder who had never received antidepressant therapy than in 10 matched controls. These results are consistent with data suggesting a normal or increased adrenergic receptor sensitivity in panic disorder patients.

Cortisol response during different anxiogenic challenges in panic disorder patients

The present study assessed the relation of cortisol response to anxiogenic reactivity during intravenous lactate infusion and oral fenfluramine in 12 panic disorder (PD) patients who responded positively to both challenges and in eight non-reactive control subjects. There was no significant cortisol response difference between the PD patients and the controls during lactate infusion, but there was s significant difference at 120 min during the fenfluramine challenge. These findings are consistent with the possibility that these challenges stimulate different neurobiologic mechanisms and that fenfluramine-precipitated anxiety is more akin to anticipatory or generalized anxiety than to true panic anxiety.

Functional interrelationship of serotonin and norepinephrine: cortisol response to MCPP and DMI in patients with panic disorder, patients with depression, and normal control subjects

The relationship between norepinephrine (NE) and serotonin (5-hydroxytryptamine; 5HT) functioning was explored in a neuroendocrine challenge paradigm. Ten normal control subjects, 17 patients with major depression, and 22 patients with panic disorder volunteered to participate in this study. Each subject received a challenge with meta-chlorophenylpiperazine (MCPP; 0.25 mg/kg, p.o.), a 5HT agonist, and desmethylimipramine (DMI; 75 mg, i.m.), an indirect NE agonist, in randomized order. The peak-minus-baseline cortisol response to MCPP was used as an indicator of 5HT function, and cortisol response at 75 minutes-minus-baseline to DMI was used as an indicator of NE function. The cortisol responses to DMI and MCPP were found to be highly negatively correlated in the total sample, in particular in the patients with major depression and panic disorder. This finding suggests that the functions (or dysfunctions) of the NE and 5HT systems may not be separate as is usually believed, and that the NE and 5HT disturbances observed in major depression and panic disorder may not be independent. Rather, there may be a joint disturbance of NE-5HT in these disorders.

Tricyclic antidepressant-induced seizures and plasma drug concentration

BACKGROUND

This study identifies eight patients who during routine therapy with conventional doses of tricyclic antidepressants (TCAs) experienced elevated plasma concentrations and suffered a grand mal seizure. We correlate the incidence of TCA-induced seizures with TCA plasma level and suggest that the incidence of TCA-induced seizures can be significantly reduced with the judicious use of therapeutic drug monitoring.

METHOD

Seven of the eight cases of TCA-induced seizures during routine pharmacotherapy represent all the cases known to the authors during their careers. Histories were evaluated for factors that would predispose patients to suffer seizures. The following data were also recorded: (1) duration of treatment with the dose that was associated with the seizure, (2) the time between last dose and the seizure, (3) a plasma TCA level obtained at the time of seizure, and (4) presence or absence of other manifestations of TCA toxicity. In addition, a MEDLINE search was conducted using the key phrases "tricyclic antidepressants" and "seizures" to obtain all English language articles published since 1966 on the occurrence of TCA-induced seizures.

RESULTS

The mean +/- SD daily TCA dose was 250 +/- 80 mg/day. The mean +/- SD total plasma TCA concentration was 734 +/- 249 ng/mL (range, 438-1200 ng/mL). The only risk factor that emerged for experiencing seizures was an elevated plasma TCA concentration. Three patients presented with no other manifestations of TCA toxicity prior to seizure.

CONCLUSION

The incidence of TCA-induced seizures for our inpatient population in which therapeutic drug monitoring is routinely used is 0.4%. This incidence is less than that reported in earlier inpatient series (1% to 4%). Our finding is consistent with the conclusion that therapeutic drug monitoring reduces the incidence of TCA-induced seizures by allowing for rational dose adjustment.

Heart rate and plasma norepinephrine responsivity to orthostatic challenge in anxiety disorders. Comparison of patients with panic disorder and social phobia and normal control subjects

Heart rate and plasma norepinephrine responsivity to a physiologic challenge, ie, orthostasis, were measured in 20 patients with panic disorder (PD) and 20 age- and sex-matched normal control subjects. While the two groups exhibited similar supine heart rates, patients with PD had a significantly greater heart rate response to orthostatic challenge. Plasma norepinephrine responses did not differ between patients with PD and normal control subjects. In a matched subgroup of 14 patients with PD, 14 normal control subjects, and 14 patients with social phobia, the patients with social phobia exhibited supine and upright plasma norepinephrine levels that were significantly higher than those of the other two diagnostic groups. Taken together, and in the context of findings from other studies, these preliminary observations suggest that the anxiety disorders may demonstrate differing patterns of autonomic dysfunction.

A fixed-dose study of alprazolam 2 mg, alprazolam 6 mg, and placebo in panic disorder

A recently reported multinational, 8-week double-blind, placebo-controlled study assessing the efficacy of alprazolam versus placebo in the treatment of panic disorder indicated significant differences favoring alprazolam. We now report the results of a three-site, 6-week, double-blind, fixed-dose study comparing alprazolam 2 mg, alprazolam 6 mg, and placebo in 94 patients with panic disorder with or without agoraphobia. Both alprazolam treatment groups (6 mg and 2 mg) improved significantly more than did the placebo treatment group on most outcome measures. Only a few statistically significant differences between the 6 mg and 2 mg alprazolam groups were discerned, although the pattern of treatment response across measures suggested a dose effect. Dropouts in the placebo group were primarily due to lack of efficacy and in the alprazolam 6 mg group were due to side effects, which may have contributed to the limited differences between groups at study end. The findings suggest that many patients may require less than 6 mg of alprazolam per day for effective treatment of panic disorder.