Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2016 Publisher: Actavis UK Limited (Trading styles: Actavis), Whiddon Valley, BARNSTAPLE, N Devon EX32 8NS
ATC code: NO5BE01
Buspirone is an azaspirodecanedione. The exact mechanism of Buspirone anxioselective action is not fully known. It does not act on benzodiazepine receptor sites and lacks sedative, anticonvulsant and muscle relaxant properties. From animal studies it is known to interact with serotonin, noradrenaline (norepinephrine), acetylcholine and dopamine systems of the brain. Buspirone enhances the activity of specific noradrenergic and dopaminergic pathways, whereas the activity of serotonin and acetylcholine are reduced.
Buspirone hydrochloride is rapidly absorbed from the gastrointestinal tract reaching peak plasma concentrations within 40 to 90 minutes after administration by mouth. Systemic bioavailability is low because of extensive first-pass metabolism.
Buspirone is about 95% bound to plasma proteins.
Metabolism in the liver is extensive via the cytochrome P450 isoenzyme CYP3A4. The elimination half-life of buspirone is usually about 2 to 4 hours but half-lives of up to 11 hours have been reported.
Buspirone is excreted mainly as metabolites in the urine, and also the faeces.
At steady state, the following doses of buspirone in children aged 6–12 years resulted in increases in Cmax (maximum concentration) and AUC (area under the curve), compared with adults, as shown in the table:
| Dosage | Cmax | AUC |
|---|---|---|
| 7.5mg b.i.d | 2.9–fold | 1.8-fold |
| 15mg b.i.d | 2.1-fold | 1.5–fold |
Across the dose range studied, the Cmax and AUC of 1-PP (the active metabolite of buspirone, 1-pyrimidinylpiperazine) in children were approximately double those in adults.
There are no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.
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