Antidepressants
What is an antidepressant? And why are they seen as such terrible drugs to be on? When I first started taking medication for my depression, the split of opinion was about 50:50 as to whether they were ok, or terrible. So how do they work, and are they a wholly unnatural and harmful group of drugs, or are they, in fact, invaluable?
Firstly, there are many, many types of anti-depressants, and they fall into a number of broad groups, defined by their mode of action. But before I describe them, you all need a little bit of Biology revision.
The brain is essentially, a whole group of nerve cells. These cells communicate with one another using electrical impulses. These impulses can move very easily and quickly through a single cell, but to be passed on to another cell, it must cross the gap between the two cells, called a synapse. The process by which this occurs uses a group of chemicals known as neurotransmitters. When an impulse reaches the boundary of a cell, small pockets in the cell wall open up, and release a neurotransmitter into the gap between the two cells. The chemical diffuses across the gap, and is detected by a chemical receiver on the outside of the cell wall of the opposite cell. When the transmitter binds to the receptor, an electrical impulse is induced in the second cell, and the whole process starts again.
Depression, in a purely chemical sense, is characterised by an imbalance of chemicals in the brain; the neurotransmitters are there in too low a concentration. This can be for a number of reasons, including a lower than normal production rate of the chemicals, or an over active removal process for after the impulse has been transmitted. In this case, the transmitter is removed before it has the chance to transmit the impulse. Antidepressants work by increasing the levels of various neurotransmitters within the brain. The most common of these to be acted upon are norepinephrine, serotonin and dopamine, and less commonly, noradrenalin.
The first group of AD’s to be used for the treatment of depression, are the Tricyclic Antidepressants (TCAs), so called because of their chemical structure. It is not entirely understood how these drugs achieve their therapeutic effects, but it is known that they act to increase the levels of norepinephrine and serotonin found in the brain. They were introduced in the 1950’s, and are still used today. However, being the older drugs that they are, they have some side effects. They tend to be very sedative drugs which make you very drowsy and reduce concentration span. Obviously, you can’t drive in this state, and this can be a huge problem, depending on the life style of the patient. They also cause a large weight gain in most patients. This is one of the side effects of AD’s which is not understood, although it is believed that the increase in weight may be due to an increased carbohydrate craving, induced by the drugs. However, the main reason that Tricyclics are very rarely prescribed any more, is that they are exceptionally dangerous when taken in excess, i.e. as an overdose. Since they treat depression, the drawbacks of this problem are obvious.
Tricyclics are sometimes prescribed though, because they can often be effective in cases where the patient does not respond to any of the other kinds of drugs available.
Another largely out of date group of AD’s, is MAOI’s. This stands for Monoamine Oxidase inhibitors, which refers to their mode of operation. Monoamine Oxidase is an enzyme found both in the brain, and the liver. In the brain, it’s purpose is to mop up excess neurotransmitters, namely, serotonin, norepinephrine and dopamine. All of these neurotransmitters are monoamine’s, and as such are broken down by monoamine oxidase. MAOI’s act by inhibiting (interfering with) the action of monoamine oxidase. A decrease in the amount of the working enzyme present in the brain clearly causes an increase in neurotransmitter levels, causing a mood increase.
However, monoamine oxidase is not only active in the brain – it also breaks down the monoamine tyramine, a molecule involved in regulating blood pressure. If there is to much tyramine present in the blood stream (as would occur if its break down is inhibited), it leads to dangerously high blood pressure, which can cause very severe strokes, or death. Tyramine is an amino-acid found in many foods, such as yeast, cheese, some meats etc. If a patient is taking a MAOI, they must avoid these foods, which means they are limited to a fairly restricted diet. MAOI’s also react with many other prescription drugs, so MAOI’s are far from ideal.
Again, they are still prescribed to some patients, if they have shown no response to any of the other AD’s. In these cases, MAOI’s are usually administered in an inpatient set up.
By far the most commonly prescribed group of AD’s these days, are the SSRI’s (Selective Serotonin Reuptake Inhibitors). These drugs work specifically on serotonin, which is often referred to as the feel good factor in the human brain. These drugs have a lot of advantages over their older relations. Firstly, they are a lot safer to take, in that they are much less dangerous when taken in excess. Patients also get put straight onto a therapeutically effective dose, rather than having to slowly increase the dose over a few weeks to cope with the side effects.
SSRI’s are not without their own side effects though. Most patients will suffer drowsiness or insomnia, some nausea, and a greater chance of developing headaches/migraine. These usually only last for the first couple of weeks of treatment, and then clear up. The most problematic side effect of this type of drugs is that 1/10 patients will suffer increased agitation and anxiety for the first 7-10 days of treatment. In these cases, patients are usually swapped to an alternative drug, as patients suffering a depressive illness do not need to feel increased agitation!
The only side effect which lasts the full course of the tablets, is sexual dysfunction. More than half the patients who take SSRI’s suffer this, although some tablets are worse than others. In these patients, there is a reduced sex drive, and either an inability to reach orgasm, or a greatly delayed orgasm. Interestingly, SSRI’s are sometimes prescribed as a treatment for premature ejaculation in men… but this is obviously not a desirable side effect for depressed patients.
Prozac (fluoxetine) was the first drug of this type to be put on the market, and as such has gained itself quite a reputation. However, there are many others including Seroxat (paroxetine), Cipramil (citalopram) and Cipralex (escitalopram).
The final type of AD’s that I’m going to describe to you are a slightly less defined group. They are the newest of the AD’s on the market, and have been developed in response to problems encountered by some patients. In most patients, a drug working on the serotonin levels alone causes an automatic rise in noradrenalin levels. However, this does not always occur, and to treat these cases, a new group of AD’s have been developed, which work either on both serotonin and noradrenalin, or purely on noradrenalin. Tricyclics would fit this brief, but they have too many side effects. These new generation AD’s have fewer side effects, and are less dangerous in excess/overdose.
Effexor (venlafaxine) and Zispin (mirtazapine) work on both serotonin and noradrenalin systems. Edronax (reboxetine) works powerfully on noradrenalin alone.
So, there you have it. The antidepressant drugs available for prescription in the UK. I have not listed every drug within each category. But what’s my point? Why have I thrown all that science and information at you? Because I am willing to bet that most of you weren’t even aware that there were different kinds of antidepressants, let alone their pros and cons.
Personally, I believe that AD’s are a totally invaluable group of drugs. With one in three people suffering a depressive episode at some point in their lives, they are some of the most widely used drugs on the market. So why do they still have such a stigma attached to them? Depression is as much a physical illness as is cancer, but no one would consider ridiculing someone for having chemotherapy. I put it to you that AD’s are not addictive, no matter what anyone tells you. They are not happy pills. They do not make the person taking them into some kind of freak to be avoided. And they are most certainly not a mind control drug. They merely make life bearable for those people with depression, just as a typical analgesic is used to relieve physical pain.
Of course, it is up to you to make your own opinions about AD’s and the people who take them. But it is my opinion that if you have a problem with people taking AD’s, then it is you with the problem, and not the patient.
The main source of information used is a fantastic little book, called “Depressive Illness, The curse of the strong”, by. Dr Tim Cantopher. If you’re at all interested in depression, my family has a number of copies of this book, which we would be happy to lend to you. I learnt a lot from it.
I have just realised quite how long this is. I’m sorry!