Simultaneous quantitation of buspirone and its major metabolite 1-(2-pyrimidinyl)piperazine in human plasma by high-performance liquid chromatography with coulometric detection

Buspirone is a member of the azapirone group of anxiolytic drugs and has one major metabolite, 1-(2-pyrimidinyl)piperazine (1-PP). The analyte, its metabolite and the internal standard were extracted from plasma utilizing solid-phase extraction columns. Chromatography was performed using isocratic reversed-phase high-performance liquid chromatography with coulometric end-point detection. The calibration graph was linear over the range 0-50 ng ml-1 of plasma. The lower limits of quantitation for buspirone and 1-PP were 0.5 and 2 ng ml-1, respectively, when 1 ml of plasma was extracted. The intra-assay relative standard deviations (RSD) over the range of the calibration graph varied from 4 to 12.5% for buspirone and 1-PP. The inter-assay RSD was 6.9% for 1-PP and 9.6% for buspirone. The recovery averaged 96% for buspirone and 66% for 1-PP. Plasma profiles of buspirone and 1-PP following oral dosing are presented.

Evaluation of the alpha 2-adrenoceptor blocking properties of buspirone and ipsapirone in healthy subjects. Relationship with the plasma concentration of the common metabolite 1-(2-pyrimidinyl)-piperazine

1. Because the 5-HT1A agonist anxiolytic azapirones have a common alpha 2-adrenoceptor antagonist metabolite, 1-(2-pyrimidinyl)-piperazine (1PP), we measured central and peripheral alpha 2-adrenoceptor dependent responses before and after intravenous administration of 0.15 mg clonidine when healthy subjects were taking buspirone (30 mg day-1 for 4 days and 10 mg on day 5), ipsapirone (15 mg day-1 for 4 days and 5 mg on day 5) or placebo. 2. Clonidine decreased blood pressure, heart rate, oral body temperature, salivary excretion, plasma noradrenaline, 3,4-dihydroxyphenylglycol (DHPG) concentrations, increased plasma growth hormone but did not modify plasma insulin and C-peptide concentrations. Treatments tended to modify only the effect of clonidine on growth hormone (P = 0.07). 3. The azapirones reduced clonidine induced prolongation of choice reaction time (P = 0.015) and tended to antagonise clonidine induced fall in critical flicker fusion frequency (P = 0.066). 4. Only buspirone reduced total reaction time and increased critical flicker fusion threshold measured 12 h after the evening dose and these effects were correlated with the residual plasma 1PP concentration which was higher on buspirone than on ipsapirone (2.76 micrograms l-1, 95% CI:1.3-4.22 vs 0.65 microgram l-1, 95% CI: 0.32-0.98, P = 0.006). 5. Mean AUC of the 1PP plasma concentrations after the last dose of treatments were 3.7 times greater with buspirone than with ipsapirone (P = 0.0011). The AUC ipsapirone/AUC 1PP ratio was 6.45 and the AUC buspirone/AUC 1PP ratio was 0.076.(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonin and impulsive/aggressive behavior in cocaine dependent subjects

1. 10 male cocaine dependent patients and 10 sex matched controls were administered several behavioral measures of aggression including the Buss-Durkee Hostility Inventory, and The Brown-Goodwin Life History of Aggression. 2. All subjects were also administered a buspirone neuroendocrine challenge as a measure of serotonin function. 3. The cocaine dependent subjects were significantly more aggressive than the controls. 4. There was a significant correlation between the growth hormone response to buspirone and behavioral measures of aggression in the cocaine dependent subjects, but not in the controls. 5. There was no difference in the overall growth hormone response between the controls and cocaine dependent subjects, possibly due to differences in metabolism of buspirone. 6. This study supports a role for serotonin in aggression in cocaine dependent subjects.

Distinguishing a benzodiazepine agonist (triazolam) from a nonagonist anxiolytic (buspirone) by electroencephalography: kinetic-dynamic studies

BACKGROUND AND OBJECTIVES

Benzodiazepine agonists and azaperone derivatives are used clinically as anxiolytics but have different neuroreceptor mechanisms of action. This study evaluated clinical pharmacodynamic approaches to distinguishing these two classes of compounds.

METHODS

Healthy volunteers received single oral doses of placebo, the benzodiazepine agonist triazolam (0.25 mg) or the azaperone anxiolytic buspirone (20 mg), in a double-blind, three-way crossover study. Ratings of mood and sedation, performance on the digit symbol substitution test (DSST), and quantitative measures of electroencephalographic (EEG) beta activity (13 to 31.75 cycles/sec) determined by fast-Fourier transform were obtained at multiple times after dosage.

RESULTS

Triazolam significantly increased self- and observer-rated sedation, impaired DSST performance, impaired recall, and increased EEG beta activity. Pharmacodynamic changes were significantly intercorrelated; all effects were maximal 1 to 2 hours after dosage but were indistinguishable from placebo by 8 hours. Buspirone did not alter the EEG or DSST performance but did increase self-ratings of sedation and feeling "spacey" and impaired memory function; these effects generally were quantitatively less than with triazolam. Peak plasma triazolam concentrations preceded maximum pharmacodynamic effects; the mean plasma effect site equilibration half-life was 9.4 minutes. Kinetic-dynamic modeling procedures yielded significant relationships between hypothetical effect site triazolam concentrations and pharmacodynamic changes.

CONCLUSIONS

Quantitative analysis of the EEG clearly distinguishes a typical benzodiazepine agonist from a nonagonist anxiolytic, in clinically relevant dosage, whose pharmacodynamic actions do not involve benzodiazepine receptor occupancy. EEG effects associated with triazolam are intercorrelated with other pharmacodynamic measures.

Disposition kinetics of buspirone in patients with renal or hepatic impairment after administration of single and multiple doses

The single dose and steady-state pharmacokinetics of buspirone and its metabolite 1-pyrimidinyl piperazine (1-PP) have been evaluated in normal volunteers and patients with renal or hepatic impairment, using a parallel group design, with assignment of patients to study group on the basis of the degree of renal (mild, moderate, severe) or hepatic (compensated or decompensated) impairment. Each healthy volunteer or patient received a single dose of 10 mg buspirone on Day 1 of the study, and starting 36 h after the first dose, healthy volunteers and patients received 10 mg doses of buspirone every 12 hours for 9 days. On the morning of Day 10 they received the last dose. Serial blood samples were collected on Days 1, 5 and 10 and plasma was analysed for buspirone and 1-PP. The plasma concentrations of buspirone and 1-PP were highly variable regardless of the renal or hepatic function. The peak concentrations (Cmax) and area under the curves (AUC) of buspirone and 1-PP on Days D5 and 10 were higher than on Day D1. The trough levels (Cmin) and AUCs (D5 and 10) of buspirone and 1-PP indicated, that, regardless of renal or hepatic function, steady state was reached after 3 to 5 days of dosing. At steady-state, patients with renal or hepatic impairment had significantly higher Cmax and AUC values of buspirone than in normal volunteers. However, the intensity and frequency of adverse experiences in patients with renal or hepatic impairment were not significantly different from those observed in normal volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of pharmacokinetic interaction between buspirone and alprazolam at steady state

The steady-state pharmacokinetic interaction between buspirone and alprazolam was evaluated in a parallel study with two groups of 12 male volunteers each. On days 1 to 7, group I subjects received a 1-mg alprazolam tablet every 8 hours (q8h) (TRT 1) and group II subjects received 2 x 5-mg buspirone tablets q8h (TRT 2). On days 8 through 14, all subjects received a combination of 1-mg alprazolam and 2 x 5-mg buspirone tablets q8h (TRT 3). Plasma samples, collected 0 to 8 hours after the morning dose on days 7 and 14, were analyzed for buspirone, alprazolam and their metabolites, 1-PP, and alpha-HO-alprazolam, respectively. Additional samples were collected before the morning dose on days 5 and 6 of each session to monitor the attainment of steady state. Steady-state pharmacokinetic parameters Cmax, Tmax, AUC0-8, and Cmin were calculated. The results indicated that for alprazolam, there was a small (< 10%) increase in Cmax and AUC when coadministered with buspirone. For buspirone, there was a 10% and 29% increase in Cmax and AUC, when coadministered with alprazolam. These values were within the normal variability observed with this class of drugs. Except for a 14% decrease in Cmin for alpha-HO-alprazolam, coadministration of buspirone and alprazolam did not affect the parameters for the metabolites. The results of this study suggest that coadministration of buspirone and alprazolam did not markedly affect the steady-state pharmacokinetics of either drug.

Effect of food on the bioavailability of gepirone in humans

A randomized two-period crossover study was conducted in 20 healthy male volunteers to assess the effect of food on the pharmacokinetics of gepirone (BMY-13805) and its metabolite, 1-(2-pyrimidinyl)-piperazine (1-PP) after a single 20-mg dose of gepirone either after fasting or after consumption of a standard high-fat breakfast. There was a 1-week washout period between treatments. Plasma samples were obtained predose and at specified time points after dosing and analyzed for gepirone and 1-PP content by a specific gas chromatographic-mass spectrometric method. Food did not significantly affect gepirone maximum peak plasma concentration (Cmax) and half-life (t1/2). The mean gepirone Cmax was 16.98 +/- 8.12 ng/mL (fed) and 18.73 +/- 10.30 ng/mL (fasted), with mean t1/2 of 3.32 +/- 1.84 hours (fed) and 2.94 +/- 0.90 hours (fasted). Food significantly increased the mean area under the curveinf (AUCinf) from 55.26 +/- 35.74 ng.hour/mL (fasted) to 75.69 +/- 42.79 ng.hour/mL (fed), and the mean residence timeinf (MRTinf) from 4.31 +/- 0.78 hours (fasted) to 5.37 +/- 1.21 hours (fed). The median time to maximum plasma concentration (tmax) for gepirone was also significantly increased in the presence of food, 2.0 hours, versus 0.75 hours in the absence of food. For 1-PP, food had no affect on Cmax, t1/2, or AUCinf. Mean t1/2 for 1-PP in the presence and absence of food was 6.06 +/- 1.75 and 5.76 +/- 1.75 hours, respectively. MRTinf, however, was increased significantly from 9.32 +/- 2.68 hours (fasted) to 10.53 +/- 2.89 hours (fed).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of anxiolytics in children

Anxiety disorders are among the most frequent of childhood psychiatric disorders. These disorders can persist from childhood and adolescence into adulthood, resulting in impaired functioning at home, school or work. Some anxiety disorders like generalized or separation anxiety are acute requiring urgent, short-term treatment. Others like fears or inhibitions are chronic resulting in longterm handicaps. Other psychiatric disorders may be concurrent with, or misdiagnosed as, anxiety disorder. Anxiety can be associated with mood or behavioral disorders. When anxiety is symptomatic of another disorder, the primary disorder should be treated first. The pharmacology of childhood anxiety has been hindered by the lack of reliable quantitative evaluations, and the changes in the manifestations of anxiety. Various types of drugs have been used to treat anxiety and related disorders. The use of different drugs is reviewed. The results of a controlled clinical trial with alprazolam and two trials with buspirone in the treatment of child and adolescent anxiety are presented. While these results are promising, further clinical trials are a priority.

Kinetics, brain uptake, and receptor binding of tandospirone and its metabolite 1-(2-pyrimidinyl)-piperazine

Tandospirone is an azaspirodecanedione derivative under investigation as an antidepressant. Metabolism of tandospirone in humans and rodents leads to 1-(2-pyrimidinyl)-piperazine (1-PP), presumed to have pharmacologic activity. To determine the relative contributions of tandospirone and 1-PP after tandospirone administration, we evaluated open-field activity, pharmacokinetics, and receptor binding of tandospirone and 1-PP in a mouse model. Tandospirone significantly reduced open-field activity during 30 minutes at doses of 1-20 mg/kg. 1-PP had no significant effect on activity except for a trend toward reduction at 20 mg/kg. At 30 minutes after administration, plasma and cortex concentrations of tandospirone and 1-PP increased in proportion to dose. Plasma protein binding (free fraction) for tandospirone was 30.4%, and for 1-PP, 87.5%. Receptor binding studies indicated that tandospirone bound with high affinity to serotonin1A sites, and with low affinity to serotonin2, alpha 1, alpha 2, and benzodiazepine sites. 1-PP bound with high affinity to alpha 2 sites and with low affinity to the other sites evaluated. A "receptor occupancy index" of tandospirone cortex concentrations divided by receptor affinity suggests that after acute administration of tandospirone, effects are likely to be due to the parent compound rather than to the metabolite. Similar conclusions are likely to be correct for other azaspirodecanediones, including buspirone.

Therapeutic effects and effects on actual driving performance of chronically administered buspirone and diazepam in anxious outpatients

Two groups of 12 outpatients each (six men and six women) with generalized anxiety disorder, participated in this study. Each patient was treated single-blind with placebo during the first 7 days (baseline), followed by a double-blind drug treatment period of 4 consecutive weeks (active) and ending again with 7 days single-blind placebo treatment (washout). One group received buspirone 5 mg three times a day in the first week and continued with 10 mg in the morning, 5 mg in the afternoon, and 5 mg in the evening during the second, third, and fourth weeks. The other group received diazepam 5 mg three times a day in all 4 weeks. On the evening of the seventh day of each treatment week the Hamilton Rating Scale for Anxiety and the Symptom Check List (90 items) were applied to assess the therapeutic effects, followed by an on-the-road driving test that started 1.5 hours after the last drug or placebo intake. The test consisted of operating an instrumented vehicle over a 100 kilometer highway circuit while attempting to maintain a constant speed and a steady lateral position within the right traffic lane. Two patients in the diazepam group were unable to complete their test after the first and second treatment week, respectively, because of serious sedative reactions. Both buspirone and diazepam were equally effective in reducing overall anxiety symptoms. The specific profiles showed that buspirone also reduced concomitant depressive symptoms and symptoms of interpersonal sensitivity and anger-hostility. In contrast, diazepam was found to be slightly more effective in reducing somatic symptoms and to positively affect sleep disturbances. Moreover, abrupt discontinuation of diazepam resulted in a relapse of psychic anxiety symptoms comparable with the placebo-baseline level and a partial relapse of somatic anxiety symptoms. Chronic treatment with buspirone had no significant effects on lateral position and speed control. In contrast, diazepam significantly impaired control of lateral position in the first 3 weeks of treatment. There was no significant impairment in the fourth treatment week and the placebo-washout week. Speed control was significantly impaired only in the first week. The relevance of the trend toward decreasing performance impairment during chronic treatment remains to be established.

Sensitive determination of buspirone in serum by solid-phase extraction and two-dimensional high-performance liquid chromatography

A selective and sensitive determination of buspirone in serum by high-performance liquid chromatography is described. The procedure is based on separation on a C18 column. A solid-phase extraction procedure is used for sample clean-up. The retention on the first column is based on the hydrophobic interaction of buspirone with the stationary phase, and the retention on the second column is based on ionic interactions due to the presence of sodium lauryl sulphate in the mobile phase as well as hydrophobic interaction. This allows for good separation of buspirone from impurities and consequently allows lower detection limits than previously reported for liquid chromatographic methods. Detection by ultraviolet absorbance gives a detection limit of 0.2 ng/ml.

[Buspirone: a new non-benzodiazepine anxiolytic drug]

Buspirone is a new drug with ansiolitic properties which chemical structure and mechanism of action is different from the classical drugs traditionally used for this symptom. Its farmacokinetic characteristics make it a convenient drug to be used for oral administration. Buspirone's double-blind controlled clinical studies contrasted with benzodiazepines have shown that buspirone has an ansiolitic effect close to them but without sedation or relaxation. Other secondary effects appear with a smaller incidence with buspirone. These properties make buspirone very efficient in anxiety treatment.

Pharmacokinetics of buspirone in elderly subjects

Twenty-four men and 24 women ages 20-77 years received a single 15 mg oral dose of buspirone followed by 4 days of 15 mg tid administration. Plasma concentrations of buspirone and 1-pyrimidinylpiperazine following both single and multiple dosing were determined by RIA and GCMS, respectively. There were no significant differences between the young and elderly of either gender with regard to buspirone AUC, Cmax, Tmax and half-life values. The 1-PP AUC values were higher for young of either gender compared to the corresponding group of elderly subjects and the 1-PP Cmax values were higher for women than men. These differences are unlikely to be of clinical significance. The buspirone and 1-PP AUC values for a dosing interval during multiple dosing are not significantly different than the respective single dose AUC values. Buspirone treatment was well-tolerated by all subjects even though the 45 mg/day dose was 3 times the recommended starting dose in clinical practice. Overall, the lack of marked or consistent differences in buspirone or 1-PP pharmacokinetics in elderly subjects compared to younger subjects of the same gender suggest there is no need to alter the initial dose of buspirone based solely on patient age.

Phase I study of a new antianxiety drug, buspirone

1. A phase I study of buspirone was conducted in 7 healthy male volunteers. 2. Diazepam was selected as the control drug and administered in equipotent doses to buspirone. Dosage was initiated at 2.5mg and doubled until a maximum dosage of 20mg was attained. Subsequently, 10mg was administered once a day for three consecutive days. 3. Clinico-pharmacologically both drugs produced sleepiness/drowsiness, but dizziness, light-headed feeling and feeling of drunkenness were marked only in the diazepam group. 4. No drug-related abnormalities were observed in clinical laboratory test values, endocrinological tests and ECG. 5. On the Uchida-Kraepelin test, no change with the control values was observed under buspirone but subjects administered diazepam exhibited marked deterioration during the latter half of the test. Moreover, in the tapping test, significant impairment was observed in the diazepam group whereas buspirone had no effect. 6. On the EEG some fast waves were observed with diazepam whereas buspirone exhibited slow waves.

Clinical pharmacokinetics of oral buspirone in patients with impaired renal function

12 patients with mild to moderate impairment of renal function and 12 healthy subjects each received 20mg buspirone as a single dose in this acute study. Six anuric patients with chronic renal failure were given two 20mg doses of buspirone, the first 2 days before haemodialysis (between dialyses) and the second during hemodialysis (2 hours before dialysis began). The differences between the median pharmacokinetic values of buspirone for healthy subjects, patients with mild to moderate renal impairment, and anuric patients were not statistically significant. Similarly, there were no significant differences between values in mild to moderate renal failure vs healthy subjects. Some of the median pharmacokinetic values for the active buspirone metabolite 1-(2-pyrimidinyl)-piperazine (1-PP), however, differed significantly for anuric patients, compared with healthy subjects or patients with mild to moderate renal impairment. When assessed between and during haemodialysis, the anuric patients had significantly (p less than 0.05) greater pharmacokinetic median values: half-life (t 1/2) = 15.2 vs 9.8 hours; area under the concentration-time curve (AUC) = 604 vs 404 nmol/L.h; and mean residence time (MRT) = 9.28 vs 6.96 hours. No firm recommendation for specific dosage can be made based on the present data. However, it does appear that in patients with mild to moderate renal impairment, the pharmacokinetics of buspirone and its active metabolite 1-PP are similar to those in individuals with normal renal function. For anuric patients higher concentrations of the 1-PP metabolite are attained while they are not undergoing haemodialysis. A dosage reduction of 25 to 50% might be necessary when buspirone is given to anuric patients.

[Buspirone: pharmacological and clinical properties of the first member of a new anxiolytic drug family]

Buspirone is a new anxiolytic agent with an original chemical structure. Its activity in doses of 15 to 30 mg per day has been demonstrated in patients presenting with manifestations of generalized anxiety. Its mode of action is still imperfectly known; in animals, it influences several neuromediator systems but does not act on benzodiazepine receptors. Its main pharmacokinetic features are: complete absorption when given orally, short half-life (4 to 8 h), reduced plasma clearance in patients with hepatic cirrhosis or renal impairment and no major interaction with most of the other psychotropic drugs. Controlled clinical studies have provided evidence of its anxiolytic properties; against anxiety symptoms buspirone has proved more effective than placebo and as effective as several reference benzodiazepine derivatives, with a lesser incidence of sedative effects. However, it is not effective in the treatment of benzodiazepine withdrawal. Gastrointestinal disorders and moderate headache have been reported in less than 10 p. 100 of the patients treated. Administered acutely, buspirone does not seem to alter cognitive mechanisms. Unlike benzodiazepines, it does not potentiate the effects of alcohol and does not lead to drug-dependence. Its usefulness in panic disorders, anxious-depressive states and obsessional symptoms remains to be determined.

Pharmacokinetics of buspirone as determined by ex vivo (3H)-DPAT binding

Ex vivo (3H)-8-hydroxy-2-(di-n-propylamino)-tetraline ((3H)-DPAT) binding to the hippocampus has been utilized to determine the pharmacokinetic parameters of buspirone after i.v. (30 mumol/kg) and oral (100 mumol/kg) administration of this drug to rats. Intravenous buspirone rapidly penetrated the brain as demonstrated by a maximum inhibition of (3H)-DPAT binding at 1 min. Elimination of drug from the brain was biphasic, with a first component half-life of 24.8 min and a second component half-life of 96 min. Oral buspirone at 3 times the i.v. dose produced less than one-third the maximum inhibition of (3H)-DPAT binding compared to that observed with i.v. buspirone. The pharmacokinetic parameters of buspirone observed in the present study are in agreement with those reported previously. Thus, the ex vivo binding assay could be utilized to determine the bioavailability of the drug to the brain, and its duration of action.

Buspirone pharmacokinetics in patients with cirrhosis

The pharmacokinetics of a single oral dose of buspirone (20 mg) were determined in 12 patients with cirrhosis and 12 normal subjects. The mean AUC of buspirone was 55 +/- 38 s.d. ng ml-1 h in cirrhotics and 3.5 +/- 2.4 s.d. ng ml-1 h in normals. The time until maximum concentration (tmax) attained was similar in the two groups (0.6 vs 0.7 h), but mean maximum concentration Cmax was higher in patients (18.8 +/- 16.3 s.d. ng ml-1) than in normals (1.2 +/- 0.8 s.d. ng ml-1). Mean elimination half-life of buspirone was greater in cirrhotics, but this difference was marginally significant statistically (cirrhotics, 6.1 +/- 3.5 s.d. h, normals 3.2 +/- 1.5 s.d. h, P = 0.05). Eight of 12 patients and seven of 12 normal subjects had a second peak in the plasma concentrations of buspirone. In patients this occurred at 10.8 +/- 7.4 s.d. h after the dose, and its mean concentration was 3.1 +/- 6.6 ng ml-1. In normal subjects the second peak occurred at 4.3 +/- 2.1 h after the dose and its mean concentration was 0.5 +/- 0.3 ng ml-1. On the kinetic evidence buspirone should be used with caution in liver disease.