Fluoxetine and sertraline, antidepressants in the SSRI family. SSRIs are antidepressants whose mechanism of action is selective inhibition of serotonin reuptake. The first antidepressants in this family hit the market in the late 1980s. The advantage over previous antidepressants is that they have a lower incidence of side effects and they are milder.
Sertraline is sold under different trade names in Spain. Aremis ® And Besitran ® are the best known.
Fluoxetine is also sold under various trade names, such as Adofen ® Or Reneuron ®. However, the brand name Prozac®, Is by far the most representative.
Similarities between fluoxetine and sertraline
Sertraline and fluoxetine are, as we said, two of the SNRI antidepressants. Therefore, since they belong to the same family of antidepressants, they will have a lot in common with each other.
Fluoxetine and sertraline have in common that they are indicated, according to the data sheet, for the treatment of major depression and obsessive-compulsive disorder (OCD). As we will see later, in addition to these two indications, they can also improve symptoms of other conditions. Both drugs are considered to be activating antidepressants because they do not cause sleepiness and may cause insomnia and nervousness in the first days of treatment. For this reason, both drugs are preferably taken in the morning and in single doses, given their high half-life. When using high doses, both drugs can be split between breakfast and lunch. Fluoxetine and sertraline reduce appetite for carbohydrates, so they usually help people lose weight. Neither of these drugs usually causes drowsiness, although yawning may occur. They are widely used medications that have been on the market for many years: their safety has been proven by millions of people around the world who have taken them.
Differences between fluoxetine and sertraline
When choosing between sertraline and fluoxetine, psychiatrists pay attention to the differences between the two drugs. Although they are very similar and belong to the same family, they are not identical. We should not forget that we have a much wider selection of antidepressants. Let's focus on the aspects that are most important to our patients.
Differences between Fluoxetine and Sertraline: drowsiness
As for the drowsiness that sertraline and fluoxetine can cause, indeed, they are not very different in this aspect. Neither of these two drugs usually causes drowsiness, so they are usually prescribed in the morning. They are considered to be activating antidepressants: increase energy. On the other hand, activation can be unpleasant, leading to agitation and anxiety, especially at the beginning of treatment. Moreover, if taken at night, they can cause insomnia. Indeed, especially fluoxetine can cause yawning, but it is unusual for it to cause drowsiness.
Differences between fluoxetine and sertraline: appetite
Again, they will differ very little in this regard. Both drugs tend to reduce appetite, especially appetite for carbohydrates. This tends to lead to weight loss more often than weight gain. This effect makes them very useful in cases where depression or anxiety has led to increased appetite and weight gain.
Interestingly, fluoxetine reduces appetite to such an extent that it is prescribed for bulimia nervosa and overeating syndrome. Sertraline can also be used in these cases, especially as an alternative to fluoxetine when it is poorly tolerated.
Differences between fluoxetine and sertraline: sexual dysfunction
Antidepressant-induced sexual dysfunction affects both women and men. In addition, it exacerbates the dysfunction already caused by depression or anxiety itself. In men, this often translates into erectile dysfunction, delayed ejaculation, and decreased sexual desire. In women, however, they tend to cause decreased sexual libido and difficulty achieving orgasm.
In this regard, sertraline causes less sexual dysfunction than fluoxetine.
The difference between fluoxetine and sertraline: the risk of addiction
Very often our patients ask us about the fear of addiction to antidepressants. Antidepressants are not addictive. However, benzodiazepines, which are often prescribed along with antidepressants, cause sexual dysfunction. If we name some benzodiazepines, we get: Lorazepam, Orfidal ®, Lexatin ®, Bromazepam, Rivotril ®, Clonazepam, etc.
Differences between Fluoxetine and Sertraline: therapeutic indications
The therapeutic indications of the drug are diseases for which it has been approved for use because it has been shown to be effective. Fluoxetine for adults is indicated in Spain according to the datasheet for the treatment of major depression, OCD, and bulimia nervosa. However, Fluoxetine has indications in other countries and is commonly prescribed for other disorders such as: panic disorder, social anxiety disorder, binge eating disorder, post-traumatic stress disorder, and premenstrual dysphoric disorder.
When we commented on the similarities between the two drugs, we saw that both are indicated for the treatment of major depressive disorder and OCD (obsessive-compulsive disorder). Sertraline is also indicated for the treatment of anxiety disorder, post-traumatic stress disorder, and social anxiety disorder (social phobia). Sertraline is also widely used for generalized anxiety disorder.
Differences between fluoxetine and sertraline: mechanism of action
As mentioned above, both drugs belong to the family of selective serotonin reuptake inhibitors (SSRIs). Thus, the primary mechanism of action of sertraline and fluoxetine is, as the name implies, inhibition of serotonin reuptake. This effect is achieved by blocking the serotonin reuptake pump located in the presynaptic terminal axon and in the somatodendritic region. This blockade results in the release of serotonin at the axon terminal and the subsequent downregulation (or desensitization) of postsynaptic serotonin receptors. This mechanism, common to all SSRIs, explains the antidepressant, anxiolytic, and antiobesity properties of both drugs.
Blockade of the serotonin transporter is the common mechanism of action of all six SSRIs. However, each of the six SSRIs has other secondary pharmacological actions that explain why one antidepressant works well in one person and fails in another. Every antidepressant is different, and no two are alike.
As a secondary mechanism of action, fluoxetine has the ability to antagonize serotonin 5HT2c receptors. This effect promotes the release of norepinephrine and dopamine. This explains Fluoxetine's activating effects: it increases energy, reduces fatigue, and improves attention and concentration. These actions make Fluoxetine more suitable for the treatment of depression, in which apathy, lack of interest and pleasure, excessive sleepiness, lethargy, and fatigue prevail. However, Fluoxetine may be less suitable because of its activating effect in depression with anxiety, insomnia, or agitation. 5HT2c antagonism may explain Fluoxetine's anti-bulimic effect. Fluoxetine may also cause a weak blockade of norepinephrine reuptake.
Sertraline has two secondary mechanisms, in addition to blocking the serotonin transporter. On the one hand, it can inhibit the dopamine transporter and, on the other hand, it binds to the Sigma 1 receptor. Dopamine transporter inhibition, although weak, is likely to improve symptoms such as motivation, energy, and concentration. The effects of sertraline on the Sigma 1 receptor are not yet fully understood. It is thought to contribute to the anxiolytic effects of the drug and its effect on psychotic and delusional depression.
Differences between fluoxetine and sertraline: panic attacks
Both sertraline and fluoxetine have an activating effect and should be taken with caution in patients with panic disorder (anxiety attacks). Starting treatment with these drugs can trigger an anxiety attack. The way to avoid a panic attack is to first prescribe a very low dose of the drug and gradually increase it so that the drug does not cause anxiety. In any case, it is possible that in cases where a patient has significant anxiety, neither Fluoxetine nor Sertraline is the most indicated medication. It is not uncommon for benzodiazepines to be prescribed in combination with these two drugs. In this case, it is advisable to explain to the patient that benzodiazepine treatment is limited in time and that it will be withdrawn when the patient is accustomed to the effects of the antidepressant.
Differences between fluoxetine and sertraline: schedule of taking
As mentioned above, sertraline and fluoxetine are activating antidepressants. For this reason, there is a tendency to prescribe Fluoxetine or Sertraline in the morning during breakfast. In principle, they are administered in a single dose unless very high doses are used or side effects occur, and it is preferable to spread them over two doses.
Differences between fluoxetine and sertraline: dosages
The difference between sertraline and fluoxetine in terms of dosage is very important. Approximately 20 mg of fluoxetine is equivalent to 50 mg of sertraline. The recommended daily dose of sertraline is 50 to 200 mg per day. While the recommended daily dose of fluoxetine is between 20 and 80 mg per day. This dosage difference does not mean that Fluoxetine is stronger than Sertraline, and vice versa.
The starting dose of Fluoxetine for depression is 20 mg per day, but it is preferable to start with 5 or 10 mg per day for anxiety. Sertraline is usually started at 50 mg per day, or 25 mg for the first few days if you have anxiety.
OCD and overeating usually require higher doses than anxiety or depression. For this reason we recommend that a psychiatrist prescribe medication for these disorders. GPs or other specialists are often reluctant to prescribe high doses and so treatment is not effective.
Differences between fluoxetine and sertraline: presentations
Fluoxetine is available as capsules, tablets, and oral solution. Tablets and capsules are available in single doses of 20 mg.
Sertraline is available in 50 mg and 100 mg tablets and as an oral solution.
Oral solution is used in people who have difficulty swallowing, mostly in pregnant women.
Differences between fluoxetine and sertraline: use in pregnant women
Antidepressants during pregnancy are not risk-free and should always be prescribed by doctors aware of a woman's condition. Given the vulnerability of the embryo during pregnancy to any external agent, a detailed and individualized benefit-risk assessment should be performed with the patient and her partner. Both fluoxetine and sertraline are very safe during pregnancy, both drugs are category C. Fluoxetine is chosen because it has been on the market for many years and has few problems, and sertraline because of its safety and in breastfeeding. Some authors note that it is preferable to avoid fluoxetine because of its long half-life.
Fluoxetine or sertraline: which is better?
Fluoxetine and sertraline are two well-known and versatile antidepressants. The truth is that they have a lot in common and there are some differences. Some people do well with one, while others do well with the other.
If you ask me: which is better, sertraline or fluoxetine? I cannot give a definite answer, since both drugs are good antidepressants and antipsychotics. These are probably the two medications that are more appropriate for depressions in which fatigue, apathy, lack of interest and motivation prevail. Whereas for depression with anxiety, agitation, and insomnia, they are less recommended.
To summarize the most important specific qualities, I would choose Fluoxetine's ability to reduce bouts of overeating and uncontrolled eating. Of sertraline, I would choose its low frequency of side effects, as well as its usefulness for obsessive symptoms and psychotic depression.