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Bupropion vs Buspirone

by egpat         02 May 2024

The names of bupropion and buspirone are somewhat confusing; they start with similar letters, and both are ketone derivatives, which can be observed in their suffixes. Interestingly, both of these drugs act on the CNS to treat a few mental conditions. But these two drugs are not equivalent, and they are classified into different categories. Bupropion is well known by the brand name Wellbutrin, whereas buspirone is well known by the brand name Buspar. Even though both of these drugs are somewhat different, they can show a few similarities.

1. Clinical uses

Bupropion is classified as an atypical antidepressant. Here, the term atypical indicates that this drug is a new-generation anti-depressant that works by a unique mechanism with somewhat fewer side effects compared with old-generation anti-depressants. And this drug is particularly indicated for the treatment of major depressive disorder, commonly known as MDD, which is a type of mental illness associated with depressive symptoms. In such conditions, bupropion can be used as an atypical antidepressant.

On the other hand, buspirone is not an antidepressant; it is classified as anxiolytic, so it can be used to treat anxiety, and it is particularly indicated for the treatment of generalized anxiety disorder (GAD). This is one of the anxiety conditions that, without any proper reason, can be observed for long periods of time. In such conditions, buspirone can be given to control the anxiety.

So both of these drugs have different clinical indications, and particularly bupropion can be given when people are having depressive symptoms such as low mood, no initiation, lack of interest, feeling of guilt, pessimism, and negative thinking. If all these symptoms are observed, then bupropion can be given as an atypical anti-depressant to elevate the mood and relieve the symptoms.

On the other hand, buspirone can be given to people who are having anxiety symptoms like anger, irritability, and a feeling of worry, which further increase the anxiety. If these symptoms are observed in people, then buspirone can be given as an anxiolytic. So now we can see the clear difference between bupropion and buspirone.

Bupropion can be given to control those symptoms that are associated with central depression. It can particularly control negative thinking and negative thoughts. whereas buspirone is particularly used to calm the patient's agitation and irritability and improve their lifestyle. So this is the first difference between bupropion and buspirone; both are used in different clinical conditions.

Apart from these clinical uses, bupropion can also be used for other conditions. It can also be used for smoking cessation. Similarly, bupropion can be combined with another drug, naltrexone. It can be used to control excess weight, so it is used as a weight-loss medication along with naltrexone.

These are the other clinical indications of bupropion, whereas buspirone does not have any other indication, but this drug is tested for the treatment of unipolar depression. This is a condition where we can always observe depressive symptoms in people, and they are not shifted to the manic phase; that's why it's called unipolar depression.

Buspirone is tested for treatment in unipolar depression, but its efficacy is not clear, and it is not approved by the FDA. That's why, right now, buspirone is not used as an anti-depressant; it is only indicated for the treatment of anxiety.

2. When are they avoided?

What are the contraindications to these two drugs? Bupropion is particularly contraindicated for people with a history of seizures since it can induce seizures. For people with any history of seizure induction, bupropion should be avoided. Similarly, those drugs that increase the risk of seizure induction should be avoided with bupropion.

Similarly, another contraindication is anorexia nervosa. This is a condition where people have excessive eating habits, which can increase their risk of seizure induction. So in these conditions, bupropion is contraindicated. On the other hand, buspirone does not have any significant contraindications, but it should be avoided by those who have hypersensitivity and allergies to the use of buspirone.

3. Time to show their effect

At this point, both bupropion and buspirone show similar effects; both of these drugs are acting centrally, but they can show some delayed pharmacological actions, which means they cannot produce the therapeutic effect immediately after administration; it takes a few days of treatment in order to show their therapeutic effect.

For instance, bupropion cannot reduce the depressive symptoms immediately after the administration, but it can take around 2 to 4 weeks to elevate the mood and reduce the symptoms of depression. Sometimes it can also take more time, such as around 4 to 8 weeks, to produce beneficial effects.

Similarly, buspirone can also take 2–4 weeks to show its anxiolytic effect. So at this point, both of these drugs have similarities: they produce delayed pharmacological actions.

4. How do they work?

At this point, bupropion and buspirone somewhat differ. Bupropion can affect two types of neurotransmitters: norepinephrine and dopamine. This drug can bind to the norepinephrine transporter, thereby increasing the release of norepinephrine, so this drug increases the norepinephrine transmission within the CNS.

Similarly, it can block another transporter, DAT, the dopamine transporter, thereby increasing the release of dopamine, which can increase dopamine levels within the CNS. In this way, bupropion mainly acts by increasing norepinephrine and dopamine levels within the CNS.

On the other hand, buspirone affects serotonin transmission. This drug can block the 5HT-1A receptors, which are autoinhibitory receptors. By blocking these receptors, initially buspirone can reduce the release of 5HT, so serotonin release is initially inhibited, but after a few days of treatment, the 5HT-1A receptors are desensitized because of their repeated activation with buspirone. So this results in decreased activity of 5HT-1A receptors, thereby increasing 5HT release.

In this way, buspirone initially reduces the 5-HT release, but later it can increase the serotonin release. This requires some time; that's why buspirone shows delayed pharmacological actions. Again, at this point, bupropion and buspirone differ; that's why they are used for different clinical indications.

5. Dosage

Bupropion is available as a tablet, which is of two types: the immediate release tablet, where the drug is immediately released within the stomach, and the extended release tablet, which is a formulation from which the drug is slowly released in an extended way. These two formulations are available for bupropion, and this drug is initially started at 150 mg given once daily. The dose can be increased to a maximum of 400 mg or 300 mg based on the clinical indication and the patient's conditions. But the starting dose of bupropion is 150 mg given once daily.

On the other hand, buspirone is available as an immediate-release tablet, and it is given at a dose of 7.5 mg given twice daily, so the total daily dose is 15 mg. This 15 mg dose can also be given in another way, as 5mg tablets thrice daily. So we can clearly observe that buspirone is given at a very low dose compared with bupropion.

6. Side effects

Both of these drugs, bupropion and buspirone, act on the CNS, so they can produce some central side effects, which are somewhat similar since they act on the CNS. They can produce some dizziness, lightheadedness, insomnia, and lack of sleep. Similarly, they can produce other central side effects like headaches and drowsiness, but they can also show a few of the specific side effects.

Bupropion can increase anxiety in people, whereas buspirone can increase restlessness in people. These are the specific side effects produced by bupropion and buspirone, respectively. So few of the side effects are similar, but a few of the side effects are specific to these two drugs.

7. Effects of MAO inhibitors

At this point again, bupropion and buspirone show similarity; MAO is one of the cleavage enzymes of monoamine oxidase. This monoamine oxidase can produce a metabolism of catecholamines like norepinephrine, dopamine, and 5HT. So when MAO inhibitors are used along with these two drugs, they can show a few of the drug interactions. So drugs like phenelzine, tranylcypromine, isocarboxazid, and even antibiotics like linezolid have MAO inhibitory activity.

When they are combined with bupropion and buspirone, they can produce serotonin syndrome, resulting in a few of the symptoms like agitation,confusion, insomnia, and hypertension; all of these are collectively called serotonin syndrome. So these two drugs should be avoided with MAO inhibitors, and there should be at least a 14-day gap between the administration of these drugs and MAO inhibitors.

8. Effects of alcohol

Since both bupropion and buspirone act centrally, they can also affect the activity of alcohol. Alcohol is a CNS depressant, so when it is combined with bupropion, it can increase seizure induction. Similarly, when it is combined with buspirone, it can increase drowsiness. Because of these effects of alcohol, it is recommended that alcohol not be taken along with bupropion and buspirone.

9. Drug interactions

Interestingly, both bupropion and buspirone are metabolized by the CYP3A4 enzyme, one of the metabolic enzymes within the liver, so CYP3A4 inhibitors like ketoconazole, fluconazole, clarithromycin, and diltiazem can affect the metabolism of these drugs, so CYP3A4 inhibitors should be carefully combined with either bupropion or buspirone. At this point again, both of these drugs are somewhat similar.

10. Effect on liver

Here we can find another difference between bupropion and buspirone. Bupropion can increase the risk of hepatic damage, so it can produce some hepatic impairment, whereas buspirone does not show such activity; instead, it can improve hepatic function, so hepatic impairment is more pronounced with the use of bupropion.

In this way, bupropion and buspirone are the two drugs that look somewhat similar but are somewhat different. Bupropion is an anti-depressant, whereas buspirone is an anxiolytic. Even though both of these drugs have similarities, they are indicated for different purposes, and they are not at all equivalent.