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Bupropion – Mechanism, precautions & side effects

by egpat         22 May 2024

Bupropion is one of the drugs that is classified as an atypical antidepressant. This drug is particularly used in the treatment of major depressive disorder, which is associated with a few of the depressive symptoms like insomnia, lack of sleep, and either an increase or decrease in appetite. Few people may lose weight because of a loss of appetite. However, a few people may experience unexpected weight gain.

Depression is also associated with a few other symptoms, like agitation and mental retardation. Another important symptom is pessimism—the negative thoughts in people. Loss of libido, fatigue, feeling of guilt, apathy, lack of initiation, and suicidal initiation are a few other symptoms of depressive disorder. Bupropion is one of the atypical antidepressants with a somewhat better profile compared with the typical antidepressants. It can relieve a few symptoms of depression.

Apart from this antidepressant action, bupropion can also be used to stop smoking. So for the cessation of smoking, bupropion can be used.

Mechanism of action

Bupropion is thought to inhibit the reuptake of two important mediators within the CNS: one is norepinephrine, and the other is dopamine. From the pre-synaptic nerve terminal, norepinephrine can be released, and it can act on the post-synaptic neurons, which are equipped with either alpha or beta adrenergic receptors. When the calcium enters the presynaptic neural terminal due to the reach of the action potential, the neurotransmitters are going to be released by exocytosis.

The released norepinephrine can act on either the alpha or beta receptors, which results in post-synaptic action. In this way, the signal can be transmitted from the presynaptic neurons to the postsynaptic neurons within the CNS through the norepinephrine neurotransmitter. But the action of this norepinephrine is controlled by its reuptake into the nerve terminal. So here, one of the transporters is the NET, or norepinephrine transporter. This is a reuptake transporter that can take the norepinephrine again back into the nerve terminal, such that the action of norepinephrine is going to be terminated.

Similarly, few of the presynaptic neurons store dopamine. Now again, by exocytosis, this dopamine can be released, and the dopamine molecule can bind to dopamine receptors on the postsynaptic neuron, leading to their activation. But just like the norepinephrine again on the dopaminergic neurons, one type of transporter is present, and that is the dopamine transporter, which can bring about dopamine reuptake into the nerve terminal. In this way, the action of both the mediators, norepinephrine and dopamine, is controlled by their reuptake into the nerve terminal.

Bupropion can bind to this norepinephrine transporter as well as the dopamine transporter, such that it can inhibit the activity of these two transporters. When these two transporters are inhibited, it results in increased levels of norepinephrine as well as dopamine within the synaptic cleft. In this way, bupropion can increase the transmission of both norepinephrine and dopamine, and when the levels of these neurotransmitters are increased within the CNS, it results in an elevation of the mood in the patients.


One of the important precautions with bupropion is the psychotic symptoms. This bupropion, when used for treatment, can cause a few of the psychotic symptoms, like hallucinations, delusions, and even mild confusion. Impaired concentration can also be observed in the patients. When this drug is given for bipolar depression, it can increase the manic phase.

What is mania? Mania is a condition of hyperexcitability where we can observe the irritability in the patients, hyperactivity, poor judgment, and even easy distractions. All this can be observed in mania, which is quite opposite to depression. When this bupropion is given in bipolar depressive disorder, it can increase the manic phase. So in these two conditions, such as psychosis and mania, bupropion should be carefully given.

Another important precaution is that bupropion can increase suicidal risk. That's why the treatment should be carefully monitored, and it can also produce a few allergic reactions that may cause fever, rashes, and a few painful conditions like arthritis and myalgia. Joint and muscle pains can also be observed with bupropion. So these are the delayed, hypersensitive reactions that can be observed with this drug.

Another important precaution of this drug is that bupropion can increase weight loss as well as increase agitation in patients. Many of the antidepressants produce a variety of side effects, but one of the most important side effects of bupropion is weight loss. This weight loss produced by bupropion can be attributed to the activation of the POMC neurons, pre-opiomelanocortin neurons, which are going to control the appetite. So by activating these POMC neurons, appetite is going to be reduced, which results in the loss of weight.

Side effects

The important side effects include dry mouth, constipation, nausea, vomiting, and headaches. Another important thing is that this drug can increase agitation and can also produce tremors in patients. Similarly, this drug can also produce a disturbance in sleep, resulting in insomnia and dizziness. It can increase the blood pressure, resulting in hypertension. However, in a few of the patients, it can also reduce the blood pressure.

Palpitations—awareness of the heartbeat—can also be observed. Another important side effect is weight loss. This weight loss is because of its action on pre-opiomelanocortin activation, which may result in weight loss. A few of the allergy reactions, like skin rashes and arthritis, can also be observed with bupropion. This medication can also produce sedation.

Dosage forms

This drug is available as a tablet at different strengths, like 100 mg and 200 mg, and these tablets are particularly used for the treatment of depression. This drug is also available as a SR tablet, which is available at a dose of 150 mg. The SR tablet is nothing but a sustained-release tablet, which has an outer coat, and this outer coat makes the drug be released slowly for a prolonged period of time. Particularly, this formulation is used for the cessation of smoking in patients.


In this way, bupropion is one of the drugs that is used to treat depression as well as for the cessation of smoking, but it is mainly approved for the treatment of depression because it can control the depressive symptoms in patients. But this can increase the weight loss and the agitation and psychotic symptoms. Even so, it can increase suicidal initiation. With these precautions, bupropion should be carefully given, and since it is an atypical antidepressant, this drug shows a better therapeutic profile compared with typical antipsychotics.