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PubMed2000

Buspirone, a 5-HT(1A) receptor agonist, dilates the perfused rat uterine vascular bed through alpha(1)-adrenoceptor blockade.

In the perfused rat uterine vascular bed, 5-hydroxytryptamine (5-HT) produced dose-dependent vasoconstrictor responses. Buspirone, a selective 5-HT(1A) receptor agonist, was not effective at low doses but produced a response at high doses. When perfusion pressure was raised with phenylephrine, responses to 5-HT were enhanced while buspirone produced dose-dependent vasodilator responses. Buspirone did not produce vasodilation when perfusion pressure was raised with vasopressin or U46619. Buspirone-induced vasodilator responses were not affected by selective 5-HT(1A) receptor antagonists, 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]-decane-7,9-dione (BMY 7378) and N-tert-butyl-3-(4-[2-methoxyphenyl]piperazin-1-yl)-2-phenylpropanamide (WAY 100478), indicating that specific 5-HT(1A) receptors might not be involved in buspirone-induced vasodilation. Buspirone (3 x 10 (-5) M) and prazosin (3 x 10(-9) M) antagonized noradrenaline-induced constriction with dose ratios of 19.1+/-2.9 and 11.7+/-2.1, respectively. The dose ratio of these antagonists in combination was 46.6+/-8.1. Since the combination ratio is closer to the sum of their individual dose ratios less 2 (i.e. DR(p)+DR(b)-2) than it is to the product of their individual dose ratios, our data suggest an interaction of buspirone with alpha(1)-adrenoceptors. Buspirone also protected adrenoceptors against inactivation by phenoxybenzamine confirming that buspirone interacted with alpha(1)-adrenoceptors. We concluded that buspirone-induced vasodilation of the perfused rat uterine vascular bed is mediated through blockade of alpha(1)-adrenoceptors rather than through 5-HT(1A) receptors.

Animals↗
PubMed1998

Concentrations and effects of buspirone are considerably reduced by rifampicin.

AIMS: The effects of rifampicin on the pharmacokinetics and pharmacodynamics of buspirone, a non-benzodiazepine anxiolytic agent, were investigated. METHODS: In a randomized, placebo-controlled cross-over study with two phases, 10 young healthy volunteers took either 600 mg rifampicin or matched placebo once daily for 5 days. On day 6, 30 mg buspirone was administered orally. Plasma buspirone concentrations and effects of buspirone were measured up to 10 h. RESULTS: The total area under the plasma buspirone concentration-time curve after rifampicin was 10.4% (95% CI, 6.3-14.5%) of that after placebo (1.64+/-0.35 ng ml(-1) h vs 22.0+/-15.1 ng ml(-1) h (mean+/-s.d.); P< 0.01). Rifampicin decreased the peak plasma concentration of buspirone from 6.6+/-3.7 ng ml(-1) to 0.84+/-0.23 ng ml(-1) (P< 0.01) and the half-life from 2.8+/-0.7 h to 1.3+/-0.5 h (P< 0.01). A significant (P<0.05) reduction in the effects of buspirone was observed in three of the six psychomotor tests employed (postural sway test with eyes closed, subjective drowsiness and overall drug effect) after rifampicin pretreatment. CONCLUSIONS: The strong interaction between rifampicin and buspirone is probably mostly due to enhanced CYP3A4-mediated first-pass metabolism of buspirone. Buspirone will most likely show a greatly reduced anxiolytic effect when used together with rifampicin or other potent inducers of CYP3A4 such as phenytoin and carbamazepine.

Adolescent↗
PubMed1999

Stability-indicating high-performance liquid chromatographic assay of buspirone HCl.

The United States Pharmacopoeia high-performance liquid chromatographic (HPLC) assay method of buspirone is not able to discriminate buspirone from its degradation products. The purpose of this work is to develop a sensitive, selective, and validated stability-indicating HPLC assay for the analysis of a buspirone hydrochloride in a bulk drug. Buspirone HCI and its potential impurities and degradation products are analyzed on an Ultrasphere C18 column heated to 40 degrees C using a gradient program that contains monobasic potassium phosphate buffer solution (pH 6.9) and acetonitrile-methanol mixture (13:17) of 35% for 5 minutes, then increased to 54% in 5.5 minutes. The samples are monitored using a photo-diode array detector and integrated at 244 and 210 nm. The stress testing of buspirone HCI shows that buspirone acid hydrochloride is the major degradation product. The developed method shows a separation of buspirone degradation product and its potential impurities in one run. The stability of buspirone HCI is studied under accelerated conditions in order to provide a rapid indication of differences that might result from a change in the manufacturing process or source of the sample. The forced degradation conditions include the effect of heat, moisture, light, acid-base hydrolysis, sonication, and oxidation. The compatibility of buspirone HCI with some pharmaceutical excipients is studied under stress conditions. The linear range of buspirone HCI is between 5 and 200 ng/microL with a limit of quantitation of 2.5 ng/microL. The intraassay percentage deviation is not more than 0.38%, and the day-to-day variation was not more than 0.80%. The selectivity, repeatability, linearity, range, accuracy, sample solution stability, ruggedness, and robustness show acceptable values.

Buspirone↗
PubMed1991

Pharmacodynamic effects of buspirone and clobazam.

1. The pharmacodynamic effects of buspirone and clobazam were compared in two volunteer studies. Acute doses of buspirone 5 mg, 10 mg and clobazam 10 mg were contrasted with placebo and a verum (lorazepam 1 mg), in a repeated measures design with 10 subjects assessed on a battery of psychometric tests at 1.5, 3.5, and 5.5 h post dose. For the combined results clobazam and the lower dose of buspirone (5 mg) were significantly contrasted with lorazepam on measures of subjective sedation, memory and choice reaction time (CRT). The higher dose of buspirone was not statistically different from lorazepam for all measures except memory; whilst contrasting significantly with placebo and clobazam on movement and total reaction time components respectively. Though failing to achieve significance, a similar trend was seen for critical flicker fusion (CFF) with buspirone 10 mg and lorazepam producing the lowest scores indicative of increased sedation. 2. Repeated doses of buspirone 5 mg twice daily, clobazam 10 mg twice daily, or placebo twice daily for 8 consecutive days were compared on the same battery of psychometric tests in a repeated measures design. Nine subjects were assessed on days 1, 3, and 8 of the study. Overall, memory performance significantly decreased with buspirone 5 mg in contrast to both clobazam and placebo whilst the opposite trend was seen with CFF. Clobazam significantly improved TRT in contrast to both placebo and buspirone. 3. These results indicate improved reaction time and memory performance with repeated dosing of clobazam in contrast to buspirone. Impairment following acute administration of buspirone appears limited to the higher (10 mg) dose.

Adult↗
PubMed2005

Cytochrome P450 3A-mediated metabolism of buspirone in human liver microsomes.

This study was carried out to determine the metabolic pathways of buspirone and cytochrome P450 (P450) isoform(s) responsible for buspirone metabolism in human liver microsomes (HLMs). Buspirone mainly underwent N-dealkylation to 1-pyrimidinylpiperazine (1-PP), N-oxidation on the piperazine ring to buspirone N-oxide (Bu N-oxide), and hydroxylation to 3'-hydroxybuspirone (3'-OH-Bu), 5-hydroxybuspirone (5-OH-Bu), and 6'-hydroxybuspirone (6'-OH-Bu) in HLMs. The apparent K(m) values for buspirone metabolite formation in pooled HLMs were 8.7 (1-PP), 34.0 (Bu N-oxide), 4.3 (3'-OH-Bu), 11.4/514 (5-OH-Bu), and 8.8 microM (6'-OH-Bu). CYP3A inhibitor ketoconazole (1 microM) completely inhibited the formation of all major metabolites in HLMs (0-16% of control), whereas the chemical inhibitor selective to other P450 isoforms had little or no inhibitory effect. Recombinant CYP3A4, CYP3A5, and CYP2D6 exhibited buspirone oxidation activities among nine P450 isoforms tested. The overall metabolism rate of 5 microM buspirone by CYP3A4 was 18-fold greater than that by CYP2D6 and 35-fold greater than that by CYP3A5. In a panel of HLMs from 16 donors, buspirone metabolism correlated well CYP3A activity (r2 = 0.85-0.96, rho < 0.0005), but not the activities of other P450 isoforms. The metabolism rates of buspirone in CYP2D6 poor-metabolizer genotype HLMs were comparable to those in pooled HLMs. Taken together, these data suggest that CYP3A, mostly likely CYP3A4, is primarily responsible for the metabolism of buspirone in HLMs.

Animals↗
PubMed2001

A comparative multidose pharmacokinetic study of buspirone extended-release tablets with a reference immediate-release product.

Buspirone is disclosed in U.S. Patent No. 3,717,634 as a pharmaceutically active compound that has been found to be effective for the treatment of anxiety disorders and depression. In this randomized, two-treatment, two-period, multidose crossover study, the pharmacokinetics of a once-daily extended-release (ER)formulation of buspirone was compared with that of an immediate-release (IR) formulation of commercially available buspirone. A total of 30 mg of the ER formulation was administered to 36 healthy volunteers once daily for 7 days, and 15 mg of the IR formulation was administered twice daily for 7 days. Pharmacokinetic profiles of buspirone and its metabolite, 1-pyrimidinylpiperazine (1-PP), were obtained at steady state. The bioavailability of buspirone from the ER formulation was more than three times higher than that from the IR formulation at steady state, and that of 1-PP was about 25% less. The mean steady-state Cmax of buspirone from the ER formulation was 46% higher than that from the IR formulation (p < 0.05), and that for 1-PP was lower by 29% (p < 0.05). The mean apparent half-life of buspirone from the ER formulation (9.04 hours) was considerably longer than that observed for the IR formulation (3.06 hours). The median 1-PP/buspirone AUC ratio was much higher for the IR formulation at steady state (24.4) than for the ER formulation (6.44). There were no significant differences in average pharmacokinetic metrics observed in men and women. Based on these observations of the potential benefits of once-daily dosing with the ER product in terms of prolonged buspirone plasma concentrations, a significant increase in the ratio of buspirone to 1-PP concentration with a lower intersubject variation could be achieved that should provide an improvement in the desired therapeutic effects of buspirone.

Anti-Anxiety Agents↗
PubMed1999

Pharmacokinetics of buspirone following oral administration to rhesus monkeys.

Pharmacokinetics of buspirone and its active metabolite, 1-pyrimidinyl piperazine (1-PP) following oral administration were assessed in rhesus monkeys at doses used in chronic toxicology studies. The study was conducted over four periods in three male and three female rhesus monkeys. In the first three periods, buspirone hydrochloride solution was administered in a randomized manner by oral gavage at doses (expressed as buspirone free base) of 12.5, 25 and 50 mg kg(-1) once a day on days 1 and 7 and twice a day on days 2-6. In the last period, all monkeys received 25 mg kg(-1) buspirone as a single daily dose for 7 days. Serial plasma samples were collected for analysis of buspirone and 1-PP on days 1 and 7 in the first three periods and on day 7 in the last period for assessment of single dose and steady-state pharmacokinetics. Inter-animal variability in the pharmacokinetics of buspirone was high. Examination of Cmin vs time plots revealed that the steady state was attained by day 7 except for one monkey who demonstrated much higher Cmin values. For buspirone, dose proportionality was concluded for both Cmax and AUC on day 1 but not on day 7. The accumulation factor on day 7 for buspirone was nearly 5 for Cmax and 7 for AUC when compared with day 1. For 1-PP, dose proportionality was concluded except for Cmax in male monkeys on day 7. In contrast to buspirone, 1-PP showed less than 2-fold accumulation in Cmax and AUC values on day 7 compared with those on day 1. Exposure at a dose of 25 mg kg(-1) once daily was in between the 125 mg kg(-1) and 25 mg kg(-1) twice-a-day regimens. These results document dose-dependency in the steady-state pharmacokinetics of buspirone in rhesus monkeys.

Administration, Oral↗
PubMed1990

Buspirone in the management of major depression: a placebo-controlled comparison.

One hundred forty outpatients with major depression were admitted to an 8-week, placebo-controlled, double-blind study of buspirone. Entry criteria included a Hamilton Rating Scale for Depression (25-item [HAM-D]) score of greater than or equal to 18 and a Hamilton Rating Scale for Anxiety (HAM-A), score of greater than or equal to 18. A flexible dose schedule ranging from 5-90 mg/day was employed. The mean dose of buspirone was 41-54 mg/day from Week 2 to the end of the study. Sixty-four percent of buspirone patients and 50% of placebo patients were melancholic; 64% of buspirone patients and 74% of placebo patients discontinued treatment before the end of the study. Extender data analysis showed that buspirone patients had significant (p less than .05) HAM-D score reductions compared with the placebo group at Weeks 2, 3, 4, and 6. The HAM-D retardation factor trended toward significance over placebo at Weeks 3, 4, and 6. HAM-D change scores for the subgroup of melancholic patients taking buspirone were significantly (p less than .02) better than those of the placebo-treated melancholic subjects at Weeks 2, 3, 4, and 6. Most other efficacy parameters also favored the buspirone-treated group over the placebo-treated group. The most common adverse experiences for the buspirone group were CNS effects (74% in the buspirone group vs. 21% in the placebo group) and gastrointestinal effects (55% in the buspirone group vs. 37% in the placebo group). Side effects consisted of dizziness, light-headedness, nausea, and headache. No serious or unexpected adverse effects occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Discriminative stimulus effects of the novel anxiolytic buspirone.

Separate groups of Long-Evans rats were trained to discriminate either 0.56 or 1.0mg/kg buspirone i.p. in a two-lever, drug vs no-drug discrimination procedure. Training took twice as long for the lower versus the higher training-dose group. Generalization tests were conducted with buspirone (0.1-1.8mg/kg, i.p., 0.32-10mg/kg, p.o.), pentylenetetrazole (1-18mg/kg, i.p.), meprobamate (3.2-180mg/kg, p.o.), haloperidol (0.01-0.32mg/kg, i.p.), and 8-OH-DPAT (0.01-0.32mg/kg, i.p.). Buspirone p.o. was 0.5-1.0 log(10) units less potent than buspirone i.p. in producing dose-dependent generalization (i.e. > 80% buspirone-lever responding). Dose-effect functions for the 1.0 training-dose group were to the right of those for the 0.56 group. Partial generalization to meprobamate occurred in both groups, representing the first report of overlap of the buspirone discriminative stimulus with that of another anxiolytic. Complete generalization to 8-OH-DPAT occurred, consistent with buspirone's prominent 5HT(1A)-receptor activity and replicating findings in the pigeon. Partial generalization to haloperidol was concluded: every rat generalized to haloperidol, but the gradients did not increase monotonically and drug-lever responding at a given dose was inconsistent within and across rats. The haloperidol results suggest a stronger influence of the dopaminergic component in the buspirone discriminative stimulus in rats than was found with pigeons. Although a previous study found generalization to buspirone from pentylenetetrazole in baboons, there was no generalization to pentylenetetrazole from buspirone in the present study.

Journal Article↗
PubMed1985

Comparative chronic effects of buspirone or neuroleptics on rat brain dopaminergic neurotransmission.

Buspirone is a novel anti-anxiety drug which has neither a benzodiazepine structure nor any other benzodiazepine-like properties. Since buspirone is known to block dopamine autoreceptors and increase dopamine metabolism, it was compared to classical antipsychotic drugs for subchronic and chronic effects on dopaminergic function. When continuously infused into rats at 1.0 mg/kg/day s.c. for 2 weeks there was a small diminution of striatal dopamine metabolism response to acute injection of buspirone, but haloperidol produced a normal increase in DOPAC concentrations. In contrast, infusion of 0.3 mg/kg/day of haloperidol caused a marked subsensitivity to both acute buspirone and haloperidol challenge. The data from 3 months of treatment with buspirone or trifluoperazine (3.0 or 1.0 mg/kg/day, respectively) added to the rats' drinking water yielded similar results. Also, there was no alteration of dopamine autoreceptor sensitivity or postsynaptic D2 receptor sensitivity in 3 month buspirone treated rats. Three months of trifluoperazine produced a 45% increase in striatal binding of 3H-spiperone, which was reversed by simultaneous administration of buspirone during the final 2 weeks of trifluoperazine treatment. These data indicate that buspirone in moderate doses, such as used for treating anxiety, should be free of extrapyramidal side-effects. The modulation of neuroleptic-induced increased D2 receptor binding reinforces the hypothesis that buspirone has a modulatory effect at an unknown site within the extrapyramidal system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

Preference for diazepam, but not buspirone, in moderate drinkers.

The purpose of the present study was to determine the preference for buspirone, an anxiolytic predicted to have minimal abuse potential, in comparison with diazepam in moderate drinkers. Preference for diazepam and buspirone was assessed in 55 moderate drinkers using a seven-session procedure consisting of four sampling sessions followed by three choice sessions. On each sampling session subjects ingested five capsules, one every 30 min. Color-coded capsules contained placebo on two sessions and drug on two sessions. Each drug capsule contained diazepam (4 mg) for 30 subjects and buspirone (5 mg) for 25 subjects. On choice sessions subjects chose whichever of the two color-coded capsules, i.e., drug or placebo, they wished to take. After ingesting one capsule, every 30 min they had the option of ingesting another capsule of the same color and content, for a maximum of seven capsules over the session (maximum of 28 mg diazepam or 35 mg buspirone). In the diazepam group 70% of subjects chose diazepam over placebo on at least two of the three choice sessions, whereas in the buspirone group only 24% of subjects chose buspirone over placebo on at least two sessions. Both diazepam and buspirone increased measures of sedation. Only diazepam increased ratings of liking and impaired performance, whereas only buspirone decreased ratings of feeling Friendly. These results replicate previous findings indicating that diazepam has reinforcing effects in moderate drinkers. Further, these results demonstrate the pharmacological specificity of this effect by showing that buspirone did not function as a reinforcer under these same conditions.

Adult↗
PubMed1993

Effects of buspirone and ipsapirone on schedule induced polydipsia: comparison with 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and raclopride.

In the present experiments, the effects of the azapirone anxiolytics, buspirone and ipsapirone, on excessive drinking induced by a FT-60 schedule of food delivery (schedule induced polydipsia, SIP) were investigated. Because buspirone is known to block dopamine receptors and both buspirone and ipsapirone act as agonists at the 5-HT1A receptor, their effects on polydipsia were compared to raclopride, an antagonist at D2 receptors, and 8-OH-DPAT, an agonist at the 5-HT1A receptor, thus providing information about the relative importance of the serotonergic and/or dopaminergic systems for the maintenance of polydipsia. The effects of all four drugs were investigated both acutely, and following repeated treatment. The doses employed were as follows: buspirone, 1.0, 3.0, and 10.0 mg/kg; raclopride, 0.05, 0.15, and 0.5 mg/kg; 8-OH-DPAT, 0.1, and 1.0 mg/kg and ipsapirone, 1.0, 3.0, 10.0 mg/kg. Administered acutely, the lowest doses of buspirone and raclopride did not alter drinking, whilst the low dose of 8-OH-DPAT significantly reduced polydipsia. These effects were reversed following repeated treatment over 16 successive days. Buspirone 1.0 mg/kg and 0.05 mg/kg raclopride reduced drinking, whilst tolerance developed to the effects of 0.1 mg/kg 8-OH-DPAT. Ipsapirone, at low doses, was without effect on drinking. At high doses, all four drugs reduced drinking both acutely and chronically. Repeated treatment with buspirone (3.0, and 10.0 mg/kg) reduced licking and panel entries, but induced a selective decrease in licking at the low dose (1.0 mg/kg). Similar effects were seen following raclopride treatment, although the effects were less selective. 8-OH-DPAT and ipsapirone, in contrast reduced licking only at the highest dose, and both drugs increased panel entries as testing continued. The effects of buspirone resembled those of raclopride whereas the effects of ipsapirone resembled those of 8-OH-DPAT. Buspirone appears to act as a dopamine antagonist in this test. The effects of the drugs suggest that SIP depends upon motivational and performance factors which may be more sensitive to drug manipulation than potential underlying psychological factors such as anxiety or stress.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2004

Social instability in female rats: effects on anxiety and buspirone efficacy.

RATIONALE: Buspirone produces inconsistent effects in laboratory rodents. Individual housing increases the efficacy of buspirone in male rats, suggesting that the effects of this (and other) compounds become conspicuous in animals showing anxiety-like states. The effect of individual housing was, however, weak, and evident only when the locomotor suppressive effects of buspirone dissipated (i.e. 4 h after treatment). OBJECTIVES: The effects of social instability, a recently developed model of social stress in female rats, was investigated on both anxiety and the anxiolytic efficacy of buspirone. METHODS: Female rats were exposed to alternate days of isolation and moderate crowding for 2 weeks. Group composition was changed for each crowding phase. Basal anxiety and the anxiolytic efficacy of buspirone were assessed by the social interaction test of anxiety 24 h after the last crowding phase. RESULTS: Crowding appeared stressful, as it increased plasma glucocorticoid levels in less than 1 h. Anxiety-like behaviours were increased by social instability compared with stable group housing. In group housed controls, buspirone markedly suppressed locomotion, without clear effects on anxiety-related behaviours. Social instability attenuated the locomotor suppressive effects of buspirone, but made the anxiolytic effects of the compound more conspicuous. The effects of individual housing (assessed earlier) and social instability (assessed here) on buspirone efficacy appear qualitatively different. CONCLUSIONS: Buspirone abolishes stress-induced anxiety, but has no anxiolytic effects in controls. This is consistent with clinical findings, as the drug decreases anxiety in anxious patients but not in healthy humans. Laboratory models involving stress-induced anxiety-like states can improve our understanding of drug effects and efficacy.

Animals↗
PubMed2001

Compounds with affinity for serotonergic receptors in the treatment of premenstrual dysphoria: a comparison of buspirone, nefazodone and placebo.

RATIONALE: It is well established that serotonin reuptake inhibitors (SRIs) are effective for the treatment of premenstrual dysphoria (PMD), but the receptor subtype(s) mediating this effect of serotonin have yet not been identified. OBJECTIVE: In this trial, the possible efficacy of buspirone, a partial 5HT1A receptor agonist, and nefazodone, a combined SRI and 5HT2 receptor antagonist, was evaluated in women with PMD. METHODS: After a three-menstrual-cycle screening phase, patients were randomised to buspirone (n=19), nefazodone (n=22) or placebo (n=22). During the first two treatment cycles, patients were taking the drug during the luteal phase only (mean +/- SD daily dose of buspirone: 21 +/- 6 mg; nefazodone: 228 +/- 54 mg). During the subsequent two cycles, the medication was taken each day of the menstrual cycle (mean daily dose of buspirone: 27 +/- 10 mg; nefazodone: 304 +/- 95 mg). RESULTS: With respect to self-rated global improvement, buspirone (P<0.001) but not nefazodone was significantly superior to placebo. While buspirone appeared to reduce self-rated irritability (visual analogue scale) more effectively than placebo, other self-rated symptoms did not differ markedly between the groups. The side-effects were mild, and sexual dysfunction was not significantly more common in patients given buspirone or nefazodone than in those given placebo. CONCLUSION: It is suggested that buspirone is mildly effective for premenstrual irritability. In patients experiencing sexual dysfunction when treated with an SRI, buspirone may be a useful alternative.

Adult↗
PubMed1986

Buspirone: review of its pharmacology and current perspectives on its mechanism of action.

Buspirone is a novel anxiolytic agent unrelated to the benzodiazepines in structure or pharmacologic properties. Extensive clinical studies have shown buspirone to be effective in the treatment of anxiety, with efficacy comparable to diazepam or clorazepate. Buspirone exhibits a unique pharmacologic profile in that it alleviates anxiety without causing sedation or functional impairment and does not promote abuse or physical dependence. Furthermore, preclinical studies have shown that buspirone does not possess anticonvulsant or muscle relaxant properties and does not interact significantly with central nervous system depressants. Biochemical and electrophysiologic studies indicate that buspirone alters monoaminergic and GABAergic systems in a manner different from that of the benzodiazepines. The uniform depressant action of the benzodiazepines upon serotonergic, noradrenergic, and dopaminergic cell firing may result from their facilitatory effect on gamma-aminobutyric acid and its known inhibitory influence in these monoaminergic areas. Unlike the benzodiazepines, buspirone exerts a differential influence upon monoaminergic neuronal activity, suppressing serotonergic activity while enhancing dopaminergic and noradrenergic cell firing. The mechanism of action of buspirone challenges the notion that only one neurotransmitter mediates anxiety. The interaction with multiple neurotransmitters at multiple brain sites suggests that buspirone may alter diverse activities within a "neural matrix of anxiety." In contrast to the benzodiazepines, buspirone orchestrates activity within this neural matrix to achieve effective treatment of anxiety while preserving arousal and attentional processes.

Animals↗
PubMed1985

Pharmacological and clinical effects of buspirone.

Clinical trials have demonstrated that buspirone (BuSpar) is effective in the treatment of anxiety with efficacy and dosage comparable to diazepam or chlorazepate. Buspirone has a unique structure and a pharmacologic profile which distinguishes it from the benzodiazepines. Because it lacks the anticonvulsant, sedative, and muscle-relaxant properties associated with other anxiolytics, buspirone has been termed "anxioselective." Animal studies suggest that it lacks potential for abuse, and this finding is supported by clinical investigations. Further preclinical work supports the contention that buspirone lacks liability to produce physical dependence or to significantly interact with central nervous system depressants such as ethanol. Moreover, biochemical investigations have not identified any direct interaction of buspirone with the benzodiazepine-gamma-aminobutyric acid-chloride ionophore complex. Pharmacologic studies on the molecular level indicate that buspirone interacts with dopamine and serotonin receptors. Recent behavioral, electrophysiological, and biochemical studies have clearly demonstrated that early hypotheses that buspirone might be considered a neuroleptic are no longer tenable. Recent evidence indicates that other neurotransmitter systems (serotonin, norepinephrine, acetylcholine) mediate buspirone's effects. It is hoped that future studies can define the mechanism by which buspirone alleviates the clinical manifestations of anxiety.

Animals↗
PubMed1986

Interaction of buspirone and dopaminergic agents on punished behavior of pigeons.

The non-benzodiazepine anxiolytic buspirone was studied alone and in combination with either haloperidol or apomorphine. Drug effects were evaluated under a baseline of punished and unpunished keypeck responses of pigeons; every 30th response produced food (no punishment) in the presence of a white keylight and, when the keylight was red in alternate 3 min periods, every 30th response produced both food and a brief electric shock (punishment). Buspirone (0.03-3 mg/kg, IM) increased the low rates of punished responding to a maximum of 1000% of control at doses of 0.1-1 mg/kg. Unpunished responding was only marginally affected at lower doses and dose-dependent decreases were obtained from 1 to 10 mg/kg. Although less potent, chlordiazepoxide (1-100 mg/kg IM) produced effects which were similar to those of buspirone, a finding which contrasts with the greater efficacy of benzodiazepines for increasing punished behavior in mammals. Dose-effect functions for buspirone were unchanged by haloperidol administration (0.01 and 0.03 mg/kg, IM, 5 min prior) or by concurrent treatment with a behaviorally-ineffective dose of apomorphine (0.003 mg/kg, IM). Rate-decreasing doses of apomorphine (0.01-0.1 mg/kg) reversed the increases in punished responding produced by lower doses of buspirone (0.03 and 0.1 mg/kg) and the apomorphine-induced decreases in unpunished responding were antagonized by buspirone at doses which had little affect when given alone. The ability of buspirone to reverse the rate-decreasing effects of apomorphine on unpunished responding suggests that buspirone does exhibit dopaminergic antagonist properties in vivo. However, effects of buspirone on punished responding of pigeons do not appear to be due to dopaminergic mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Role of alpha-adrenoceptors in the effects of buspirone and 5-carboxamidotryptamine in rabbit isolated thoracic aorta.

1. The role of alpha-adrenoceptors in the vascular effects of buspirone (BUS) and 5-carboxamidotryptamine (5-CT) was investigated in rabbit thoracic aorta. 2. Buspirone produced a concentration-dependent contraction. The non-selective 5-HT1 and 5-HT2-receptor antagonist methysergide and the 5-HT2 receptor antagonist ketanserin did not alter the contractile effect of buspirone. However, the competitive antagonist of alpha 1-adrenoceptors, prazosin, shifted the concentration-response curve of buspirone to the right without changing the maximal response. 3. Benextramine tetrahydrochloride monohydrate (BHC), a noncompetitive antagonist of alpha 1-adrenoceptors, inhibited the contraction induced by buspirone in a noncompetitive manner. After pretreatment with two different concentrations of BHC, the estimated apparent dissociation constants of buspirone were found to be identical. 4. In addition, buspirone antagonized the concentration-response curve of phenylephrine again showing a similar dissociation constant, suggesting a partial agonistic action of buspirone at the level of alpha 1-adrenoceptors. 5. The concentration-response curve of 5-HT showed two components in the thoracic aorta obtained from reserpine treated and untreated animals as verified by different pD2 values. The second component was observed with relatively higher concentrations of 5-CT and could be blocked by prazosin or BHC. Neither of these compounds altered the first component. After Pretreatment with BHC, the first component of 5-CT was competitively antagonized by methysergide and ketanserin, having pA2 values of 8.81 and 9.1 respectively. 6. These results suggest that the contraction induced by buspirone is mainly mediated by alpha 1-adrenoceptors, while the higher concentrations of 5-CT caused contraction via alpha 1-adrenoceptor stimulation in addition to its 5-HT2 agonistic effect.

Adrenergic alpha-Antagonists↗