ANTIDEPRESSANTS – INTRODUCTION
Antidepressants are the most prescribed therapy for depression. The exact mechanism of action of antidepressants is unknown. The prevailing theory is that antidepressants increase the concentration of one or more brain chemicals (neurotransmitters) that nerves in the brain use to communicate with one another. The neurotransmitters affected by antidepressants are norepinephrine, serotonin, and dopamine. The different classes of antidepressants differ in the neurotransmitters they affect. This determines some of their side effects and potential drug interactions. All available antidepressants are effective, and for most cases of depression there is no good evidence that any antidepressant is more effective than another.
ANTIDEPRESSANTS – INDICATION
Antidepressants are a type of medication used to treat clinical depression or prevent it recurring.
The main use for antidepressants is treating clinical depression in adults. They’re also used for other mental health conditions and treatment of long-term pain.
ANTIDEPRESSANTS – INFORMATION
Antidepressants are a class of drugs that reduce symptoms of depressive disorders by correcting chemical imbalances of neurotransmitters in the brain. Chemical imbalances may be responsible for changes in mood and behavior.
Neurotransmitters are vital, as they are the communication link between nerve cells in the brain. Neurotransmitters reside within vesicles found in nerve cells, which are released by one nerve and taken up by other nerves. Neurotransmitters not taken up by other nerves are taken up by the same nerves that released them. This process is called “reuptake.” The prevalent neurotransmitters in the brain specific to depression are serotonin, dopamine and norepinephrine (also called noradrenaline).
In general, antidepressants work by inhibiting the reuptake of specific neurotransmitters, hence increasing their levels around the nerves within the brain, such as selective serotonin reuptake inhibitors (SSRIs), antidepressants that will affect serotonin levels in the brain.
Side Effects Of Antidepressants
The side effects of antidepressants can cause problems at first, but then generally improve with time.
It’s important to continue treatment, even if you’re affected by side effects, as it will take several weeks before you begin to benefit from treatment. With time, you should find that the benefits of treatment outweigh any problems from side effects.
During the first few months of treatment, you’ll usually see your doctor or a specialist nurse at least once every two to four weeks to see how well the medication is working.
Some of the more common side effects of the main types of antidepressants are outlined below. For more information about your specific medication, see the patient information leaflet that comes with it.
SSRIs and SNRIs
Common side effects of selective serotonin reuptake inhibitors (SSRIs) and serotonin-noradrenaline reuptake inhibitors (SNRIs) can include:
- feeling agitated, shaky or anxious
- feeling and being sick
- indigestion and stomach aches
- diarrhoea or constipation
- loss of appetite
- not sleeping well (insomnia), or feeling very sleepy
- low sex drive
- difficulties achieving orgasm during sex or masturbation
- in men, difficulties obtaining or maintaining an erection (erectile dysfunction)
These side effects should improve within a few weeks, although some can occasionally persist.
Tricyclic Antidepressants (Tcas)
Common side effects of TCAs can include:
- dry mouth
- slight blurring of vision
- problems passing urine
- weight gain
- excessive sweating (especially at night)
- heart rhythm problems, such as noticeable palpitations or a fast heartbeat (tachycardia)
The side effects should ease after a couple of weeks as your body begins to get used to the medication.