Venlafaxine Health Dictionary

These widely used drugs include a range of different preparations which relieve DEPRESSION. All the antidepressants available at the time of writing are more or less equally e?ective. In studies where patients agree to take either antidepressants or identical dummy PLACEBO pills (without knowing which), at least two-thirds of those who receive antidepressants feel much better within three months, while fewer than one-third of those on placebos recover naturally in the same period. In general these drugs are useful for severe and moderate depression including postnatal illness; they are not e?ective in milder forms of depression although they may be tried for a short time if other therapies have failed.

The most widely prescribed type of antidepressants are the tricyclics, so-called because their molecular structure includes three rings. The other commonly used types are named after the actions they have on chemicals in the brain: the SELECTIVE SEROTONIN-REUPTAKE INHIBITORS (SSRIS) and the MONOAMINE OXIDASE INHIBITORS (MAOIS) – see also below. All types of antidepressant work in similar ways. Tricyclic antidepressants have cured depression in millions of people, but they can cause unpleasant side-effects, particularly in the ?rst couple of weeks. These include SEDATION, dry mouth, excessive sweating, CONSTIPATION, urinary problems, and impotence (inability to get an erection). Up to half of all people prescribed tricyclic drugs cannot tolerate the side-effects and stop treatment before their depression is properly treated. More seriously, tricyclics can upset the rhythm of the heart in susceptible people and should never be given in the presence of heart disease.

The SSRIs are newer, coming into wide use in the late 1980s. They increase the levels in the brain of the chemical messenger SEROTONIN, which is thought to be depleted in depression. Indeed, the SSRIs are as e?ective as tricyclics and, although they can cause nausea and excessive sweating at ?rst, they generally have fewer side-effects. Their main disadvantage, however, is that they cost much more than the most commonly used tricyclic, amitriptyline. On the other hand, they are more acceptable to many patients and they cause fewer drop-outs from treatment – up to a quarter rather than a half. The money saved by completed, successful treatment may outweigh the prescribing costs. SSRIs have been reported as associated with an increased risk of suicide.

Another group of antidepressants, the MAOIs, have been in use since the late 1950s.

They are stimulants, rather than sedatives, and are particularly helpful for people who are physically and mentally slowed by depression. They work well but have one big disadvantage – a dangerous interaction with certain foods and other drugs, causing a sudden and very dangerous increase in blood pressure. People taking them must carry an information card explaining the risk and listing the things that they should avoid. Because of this risk, MAOIs are not used much now, except when other treatments have failed. A new MAOI, moclobemide, which is less likely to interact and so cause high blood pressure, is now available.

LITHIUM CARBONATE is a powerful antidepressant used for intractable depression. It should be used under specialist supervision as the gap between an e?ective dose and a toxic one is narrow.

St John’s Wort is a popular herbal remedy which may be e?ective, but which is handicapped by di?erences of strength between di?erent preparations or batches. It can interact with a number of conventional drugs and so needs to be used cautiously and with advice.

In general, antidepressants work by restoring the balance of chemicals in the brain. Improved sleep and reduced anxiety are usually the ?rst signs of improvement, particularly among people taking the more sedative tricyclic drugs. Improvement in other symptoms follow, with the mood starting to lift after about two weeks of treatment. Most people feel well by three months, although a few residual symptoms, such as slowness in the mornings, may take longer to clear up. People taking antidepressants usually want to stop them as soon as they feel better; however, the risk of relapse is high for up to a year and most doctors recommend continuing the drugs for around 4–6 months after recovery, with gradual reduction of the dose after that.

Withdrawal reactions may occur including nausea, vomiting, headache, giddiness, panic or anxiety and restlessness. The drugs should be withdrawn gradually over about a month or longer (up to six months in those who have been on maintenance treatment).

A wide range of antidepressant drugs is described in the British National Formulary. Examples include:

Tricyclics: amitryptyline, imipramine, doxepin.

MAOIs: phenelzine, isocarboxazid.

SSRIs: citalopram, ?uoxetine, paraxtene. (Antidepressant drugs not in these three

groups include ?upenthixol, mertazapine and venlafaxine.)... antidepressant drugs

n. a drug designed to alleviate the symptoms of *depression. Most antidepressants act by altering the availability of *serotonin and *noradrenaline in the brain; they are also likely to influence synaptic transmission regulation and postsynaptic conduction. There are four main classes of antidepressants. The selective serotonin reuptake inhibitors, such as fluoxetine, sertraline, escitalopram, and citalopram (see SSRI), are recommended as first-line treatment for depression and anxiety by current NICE guidelines. Their mode of action is entirely on serotonin. Side-effects include gastrointestinal problems and nausea. Tricyclic antidepressants, such as *imipramine, *doxepin, *lofepramine, *clomipramine, and *amitriptyline, are also widely used. They act on noradrenaline as well as serotonin, although most of them primarily have a noradrenergic action. They are also used in chronic pain management. Their side-effect profile varies from that of SSRIs; on the whole they have more *antimuscarinic effects and are more sedative. They are more dangerous in overdose than SSRIs and cause more weight gain. Other side-effects include postural hypotension. Serotonin and noradrenaline reuptake inhibitors), such as venlafaxine and duloxetine (see SNRI), are a common second-line choice in the treatment of depression and anxiety. Monoamine oxidase inhibitors (MAOIs), such as the reversible moclobemide and the irreversible phenelzine (see MAO inhibitor), are older antidepressants. They are now less used because of significant side-effects and interactions with other drugs. The irreversible MAOIs also require certain dietary restrictions. Antidepressants are not addictive, but depending on their half-life they show a varying prevalence of *discontinuation syndrome. Antidepressants have consistently been shown to be more effective than placebo. Their efficacy is lower in mild depression but moderate to good in moderate and severe depression. They are part of the gold-standard treatment for depression and anxiety.... antidepressant

a painful disorder of the cornea of the eye due to excessive exposure to ultraviolet light reflected from the snow. Recovery usually follows within 24 hours of covering the eyes.

SNRI (selective serotonin and noradrenaline reuptake inhibitor) any one of a class of *antidepressant drugs that increase the availability of *serotonin and *noradrenaline by blocking the reabsorption of these neurotransmitters by nerve endings in the brain. Side-effects include gastrointestinal disturbances, giddiness, nausea, and sweating. The group includes venlafaxine (also licensed for the treatment of *generalized anxiety disorder) and duloxetine (also licensed for treating generalized anxiety disorder, diabetic neuropathy, and stress *incontinence in women).... snow blindness