In general, when a medication goes off patent, marketing for it significantly slows down or comes to a halt. Studies have shown that physicians’ prescribing habits are influenced by pharmaceutical representatives and companies.1 This phenomenon may have an unforeseen adverse effect: once an effective and inexpensive medication “goes generic,” its use may fall out of favor. Additionally, physicians may have concerns about prescribing generic medications, such as perceiving them as less effective and conferring more adverse effects compared with brand-name formulations.2 One such generic medication is buspirone, which originally was branded as BuSpar.
Anxiety disorders are the most common psychiatric diagnoses, and at times are the most challenging to treat.3 Anecdotally, we often see benzodiazepines prescribed as first-line monotherapy for acute and chronic anxiety, but because these agents can cause physical dependence and a withdrawal reaction, alternative anxiolytic medications should be strongly considered. Despite its age, buspirone still plays a role in the treatment of anxiety, and its off-label use can also be useful in certain populations and scenarios. In this article, we delve into buspirone’s mechanism of action, discuss its advantages and challenges, and what you need to know when prescribing it.
How buspirone works
Buspirone was originally described as an anxiolytic agent that was pharmacologically unrelated to traditional anxiety-reducing medications (ie, benzodiazepines and barbiturates).4 It has a high affinity for the 5-hydroxytryptamine 1A (5HT1A) receptor and may also act as a central dopamine antagonist at D2 receptors.4,5 It is FDA-approved only for the treatment of generalized anxiety disorder (GAD).4 Buspirone also is commonly used as an augmenting agent to selective serotonin reuptake inhibitors (SSRIs) in the treatment of medication-resistant or partially treated depression.6 When a patient who is depressed appears to have marginal to no response to an adequate trial of a first-line agent, buspirone is thought to replenish depleted stores and/or increase synthesis of serotonin. Additionally, it acts directly on 5HT1A autoreceptors to achieve the desired desensitization of those receptors. All of these proposed mechanisms are thought to improve symptoms of depression.6
The antidepressants vortioxetine and vilazodone exhibit dual-action at both serotonin reuptake transporters and 5HT1A receptors; thus, they work like an SSRI and buspirone combined.6 Although some patients may find it more convenient to take a dual-action pill over 2 separate ones, some insurance companies do not cover these newer agents. Additionally, prescribing buspirone separately allows for more precise dosing, which may lower the risk of adverse effects.
Buspirone is a major substrate for cytochrome P450 (CYP) 3A4 and a minor for CYP2D6, so caution must be advised if considering buspirone for a patient receiving any CYP3A4 inducers and/or inhibitors,7 including grapefruit juice.8
Dose adjustments are not necessary for age and sex, which allows for highly consistent dosing.4 However, as with prescribing medications in any geriatric population, lower starting doses and slower titration of buspirone may be necessary to avoid potential adverse effects due to the alterations of pharmacodynamic and pharmacokinetic processes that occur as patients age.9
Advantages of buspirone
Works well as an add-on to other medications. While buspirone in adequate doses may be helpful as monotherapy in GAD, it can also be helpful in other, more complex psychiatric scenarios. Sumiyoshi et al10 observed improvement in scores on the Digit Symbol Substitution Test when buspirone was added to a second-generation antipsychotic (SGA), which suggests buspirone may help improve attention in patients with schizophrenia. It has been postulated that buspirone may also be helpful for cognitive dysfunction in patients with Alzheimer’s disease.11 Buspirone has been used to treat comorbid anxiety and alcohol use disorder, resulting in reduced anxiety, longer latency to relapse, and fewer drinking days during a 12-week treatment program.12 Buspirone has been more effective than placebo for treating post-stroke anxiety.13
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