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Buspirone
General information
Buspirone, an azapirone drug, similar to its analogues ipsaperone and tandospirone, is chemically and pharmacologically dissimilar to the benzodiazepines and is useful in both generalized anxiety and depression [ ]. In contrast to benzodiazepines, buspirone has an antidepressant-like therapeutic latency [ ], and for this reason it needs to be given with considerable education and encouragement. It is effective in children with anxiety disorders [ ] and as an antidepressant adjuvant in refractory depression with [ ] and without [ ] obsessive-compulsive symptoms. Buspirone is also effective in treating anxious alcoholics, and in patients with agitation or aggression associated with organic brain disease [ ].
Originally thought to act through a dopaminergic mechanism, buspirone is now regarded as acting as a 5-HT 1A receptor (partial) agonist [ ] and produces dose-related adverse effects similar to those of the SSRIs (nausea, headache, insomnia, dizziness, and sexual dysfunction) [ ]. Like them, it interacts with monoamine oxidase inhibitors and can produce the serotonin syndrome [ ]. An uncommon association with extrapyramidal movement disorders [ , ] may reflect its structural relation to some dopamine receptor antagonists.
Compared with benzodiazepines, buspirone causes less sedation and memory impairment [ ], has little interaction with alcohol [ , ], and is essentially devoid of problems of abuse, disinhibition, tolerance, and dependence.
These advantages are important in treating particular groups of patients, including patients with brain injury, elderly people, forensic populations, and the medically ill [ , ]. On the other hand, over 50% of patients with cerebellar ataxia reported significant adverse effects, as described above [ ].
Buspirone may also have advantages in treating individuals who are susceptible to problems with alcohol [ ] or other hypnosedatives [ ], although habitual users of benzodiazepines are often unwilling to persist with buspirone long enough for it to have a therapeutic effect [ ].
Unlike carbamazepine or tricyclic antidepressants, buspirone is not helpful in the management of benzodiazepine withdrawal [ ].
Drug studies
Observational studies
Buspirone (40 mg/day for 4 weeks) has been used as an alternative treatment in eight psychiatric outpatients with attention deficit disorder [ ]. The results suggested that buspirone might be useful in attention deficit disorders, reducing hyperactive behavior and enabling greater attention with few adverse effects. There were no clinically significant changes in blood pressure. There was mild transient tiredness, which lasted about 2 weeks. In one case, there was an initial trend toward a reduced appetite, but that generally stabilized. Headaches and stomach aches occurred in two patients during the first 2 weeks and one of them continued to have mild episodes.
The effects of hydroxyzine 50 mg/day, buspirone 20 mg/day, and placebo have been studied in 244 patients with generalized anxiety disorder in a double-blind placebo-controlled study [ ]. Hydroxyzine (n = 81) was considerably better than placebo (n = 81), and buspirone (n = 82) was intermediate. The main adverse effects were headache and migraine with buspirone (6.1% versus 4.9% with hydroxyzine and 1.2% with placebo). Somnolence occurred in 9.9% with hydroxyzine, 4.9% with buspirone, and none with placebo. Dizziness occurred in 6.1% with buspirone, none with hydroxyzine, and 2.5% with placebo.
In a 21-day, open, multicenter, dose-escalation study, 13 children and 12 adolescents with anxiety disorder and 14 healthy adults took buspirone 5–30 mg bd titrated over 3 weeks [ ]. Buspirone was generally safe and well-tolerated at doses up to 30 mg in adolescents and adults and in most of the children. The most common adverse events in children and adolescents were light-headedness (68%), headache (48%), and dyspepsia (20%); two children withdrew from the study at the higher doses (15 mg and 30 mg bd) owing to adverse effects. In adults, the most common adverse event was somnolence (21%); mild light-headedness, nausea, and diarrhea were also reported.
Placebo-controlled studies
Symptoms of anxiety are common among opioid-dependent individuals. Although buspirone has been used successfully for the treatment of anxiety in alcoholic patients, its efficacy in opioid-dependent patients had not been previously examined. In a 12-week, randomized, placebo-controlled trial of buspirone in 36 subjects receiving methadone maintenance treatment who presented with symptoms of anxiety, buspirone did not significantly reduce anxiety symptoms [ ]. However, buspirone was associated with trends toward reduction in depression scale scores and a slower return to substance use.
Systematic reviews
The safety results from two comparisons of buspirone 15 mg bd and buspirone 10 mg tds in patients with persistent anxiety have been subjected to meta-analysis [ ]. The incidences of adverse events were similar, except for a significantly higher incidence of bouts of palpitation in patients taking buspirone bd (5%) compared with tds (1%). The most frequently reported adverse events with both regimens were dizziness, headache, and nausea. There were no appreciable differences between treatments in vital signs, physical examination, electrocardiography, or clinical laboratory results. A change to twice-daily dosing with buspirone may offer convenience and possibly greater adherence to therapy in patients with persistent anxiety, without compromising the safety and tolerability profile of the drug.
Organs and systems
Respiratory
Because of its virtual absence of respiratory depressant effects compared with benzodiazepines [ ], buspirone may be especially useful in treating anxious patients with lung disease [ ].
Nervous system
The efficacy and safety of buspirone have been evaluated in the management of anxiety and irritability in 22 children with pervasive developmental disorders. One child developed abnormal involuntary movements of the mouth, cheeks, and tongue after having taken buspirone 20 mg/day for 10 months. No other drugs were prescribed. The abnormal movements disappeared completely within 2 weeks of withdrawal of buspirone. Other adverse effects in other children were minimal and included initial sedation, slight agitation, and initial nausea [ ].
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