Medications For Anxiety Disorders - Treating Anxiety: Mental Health

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Medications for anxiety disorders

Medications prescribed to treat anxiety disorders fall into several categories (see Table 2). The most commonly prescribed are antidepressants and benzodiazepines. A number of other types of medications — including the azapirone derivative buspirone, atypical antipsychotics, anticonvulsants, and beta blockers — are also used.

This section describes how each class of drug works and which medications within the class are effective for particular anxiety disorders. Side effects are also discussed. In general, newer drugs with fewer or milder side effects are replacing those with more, or more severe, side effects.

Selective serotonin reuptake inhibitors (SSRIs)

This class of antidepressants became a first-line treatment for many anxiety disorders during the 1990s. The serotonin system is active in many regions of the brain, affecting anxiety, mood, arousal, impulses, and aggression. SSRIs work by slowing the reuptake of serotonin, which means they prevent the neurons that release this neurotransmitter from reabsorbing it quickly. This prolongs the time that the serotonin can work at receptor sites (see Figure 6). SSRIs also appear to change the number and sensitivity of receptors and may indirectly influence other neurotransmitters that play a role in anxiety, including norepinephrine and dopamine (see "How neurotransmitters work").

Figure 6: How SSRIs work When neurotransmitters such as serotonin bind with receptors on a neighboring neuron, they carry the impulse to the next cell. But in someone with symptoms of depression, the cell that released the serotonin may reabsorb it too quickly. As a result, there may not be enough serotonin available to bind to the next cell and allow the signal to pass. SSRIs slow the reuptake of serotonin, leaving more of this neurotransmitter in the synapse. This permits it to work for a longer time, improving the transmission of nerve impulses.

The main reason for the popularity of SSRIs is that they have fewer and less severe side effects than do older medications for anxiety. SSRIs are prescribed for generalized anxiety disorder, obsessive-compulsive disorder, social phobia, panic disorder, and post-traumatic stress disorder. There are several kinds of SSRIs, each with a slightly different mode of action.

Although they are usually well-tolerated, SSRIs can have troublesome effects in some people. They can cause sexual dysfunction, weight gain, and insomnia. Sometimes they even temporarily heighten anxiety symptoms. Your doctor should monitor you closely for this reaction and, if necessary, switch your medication. SSRIs can also interact with certain antihistamines, anticonvulsants, or other antidepressants. Reactions to SSRIs vary between different drugs and different people. What induces side effects in one person may not cause any problems in another. Therefore, it may take some trial and error to determine which medication is right for you.

Venlafaxine

Venlafaxine (Effexor) blocks the reuptake of both serotonin and norepinephrine. To a lesser degree, the drug also blocks the reabsorption of dopamine. Venlafaxine is prescribed for generalized anxiety disorder and post-traumatic stress disorder, either initially or when SSRIs aren't effective or cause intolerable side effects. Like SSRIs, however, venlafaxine can exacerbate sleep problems and cause nausea and headache. Effexor XR, the extended-release form of the drug, has fewer side effects than the shorter-acting version. For example, it doesn't cause nausea. And it is taken just once a day.

Tricyclic antidepressants (TCAs)

Tricyclic antidepressants (TCAs) have been used since the 1970s to treat panic disorder and obsessive-compulsive disorder. Their name derives from their three-ring molecular structure. Medications of this class are thought to relieve anxiety and depression mainly by increasing the availability of norepinephrine and serotonin. TCAs do so by slowing the reabsorption of these neurotransmitters by the neurons that released them and by changing the sensitivity of the receptors.

But compared with venlafaxine or the SSRIs, TCAs can cause side effects that are more numerous and more severe, including dizziness, constipation, blurred vision, and trouble urinating. TCAs can also cause weight gain and disturbances in heart rhythm. Thus, people with heart disease should usually avoid these drugs unless they've tried other medications without a good response. Because of their side effects, TCAs are considered second-line treatments for generalized anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and panic disorder. They're sometimes paired with an SSRI when such a drug doesn't work well enough alone. They may also be used as a sleep aid. TCAs are often prescribed as an alternative for people who can't use or tolerate SSRIs. For some people, TCAs actually work better and cause fewer troublesome side effects than SSRIs. A period of trial and error can help determine which drug will work best.

Monoamine oxidase (MAO) inhibitors

The neurotransmitters norepinephrine and serotonin are members of a class of compounds called monoamines, which are normally broken down in the body by the enzyme monoamine oxidase. By blocking monoamine oxidase, these drugs raise the levels of norepinephrine and serotonin in the brain, thus decreasing anxiety and improving mood.

If SSRIs aren't helpful for social phobia and panic disorder, MAO inhibitors are often the next step. Among MAO inhibitors, phenelzine (Nardil) is most commonly prescribed for these disorders, but tranylcypromine (Parnate) and isocarboxazid (Marplan) are also used. Although MAO inhibitors don't have many of the side effects of TCAs, they can cause dizziness and other serious side effects.

People who take MAO inhibitors must avoid certain foods and beverages, including yogurt, aged cheese, pickles, beer or red wine, and other foods containing the amino acid tyramine. Combining tyramine with MAO inhibitors can raise blood pressure to dangerously high levels, possibly resulting in stroke. They must also avoid certain over-the-counter medications, including some cough and cold remedies and weight-loss supplements.

Benzodiazepines

These tranquilizers were the first class of medications used specifically for anxiety. They induce mental and physical relaxation. They enter the brain quickly and bind to receptors for the neurotransmitter GABA, which reduces brain activity. When they bind to GABA receptors, benzodiazepines enhance GABA's calming effects (see Figure 7).

Figure 7: How benzodiazepines work Benzodiazepines encourage calm by entering the brain quickly and binding to receptors for the neurotransmitter gamma-aminobutyric acid (GABA). GABA reduces brain activity. When benzodiazepines bind to GABA receptors, they enhance GABA's calming effects.

The many benzodiazepines include diazepam (Valium), lorazepam (Ativan), and alprazolam (Xanax). These medications are used for generalized anxiety disorder, panic disorder, and specific phobia. They're often paired with a longer-acting drug such as an SSRI, and the dose is gradually reduced once the SSRI starts working. Doctors try to limit the use of benzodiazepines because they can cause tolerance — that is, a need for greater amounts of the drug to produce the same effects. But because these medications are so helpful for generalized anxiety disorder, they're sometimes used alone for extended periods. In such cases, patients should be monitored carefully for signs of tolerance. Benzodiazepines are also prescribed alone, as needed, to treat specific phobia. Someone with a fear of flying, for example, may take a benzodiazepine before getting on a plane to control anxiety immediately before and during the flight.

In addition to tolerance, benzodiazepines can cause drowsiness and cognitive impairment. Older adults and people with a history of substance abuse should avoid them whenever possible because such individuals may be particularly sensitive to their side effects.

Buspirone (BuSpar)

Buspirone (BuSpar) binds to receptors for serotonin and dopamine. The effect is to increase serotonin activity and decrease dopamine activity in the brain. Like the SSRIs, buspirone is used for the long-term treatment of generalized anxiety disorder. But it begins to work faster, after about two weeks. Because it has few side effects and no serious drug interactions, it's a good alternative to benzodiazepines in the treatment of generalized anxiety disorder in older individuals or those with a history of substance abuse. However, this medication isn't effective for most other anxiety disorders.

Atypical antipsychotics

Atypical antipsychotics are most commonly prescribed for schizophrenia. They are also sometimes used in combination with other medications to treat anxiety disorders in cases where SSRIs alone have not proved beneficial. Research suggests atypical antipsychotics may help people with obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, and generalized anxiety disorder. These drugs also have proved to be especially helpful for people with severe anxiety associated with major depressive disorder.

Anticonvulsants

Anticonvulsants are most commonly used to treat epileptic seizures and relapse in people with bipolar depression. Like atypical antipsychotics, they are sometimes used in combination with other drugs to treat anxiety disorders when SSRIs alone are ineffective. Studies find they can be an effective adjunct for treating panic disorder, post-traumatic stress disorder, generalized anxiety, and social phobia.

Beta blockers

Although they're mainly used to treat high blood pressure, beta blockers' ability to slow the heart rate makes them useful in relieving anxiety disorders. For example, they are used to control performance anxiety (stage fright), a type of social phobia that usually occurs when an individual needs to give a speech or perform in front of an audience. They also can help with the physical symptoms of social phobias and panic attacks, such as a pounding heart and shaking hands. In addition, a 2003 study found that people who came to an emergency room after a traffic accident were less likely than average to have symptoms of post-traumatic stress disorder if they took beta blockers for 10 days.

Non-benzodiazepines

These newer drugs are prescribed for insomnia, a common symptom in anxiety disorders. Medications such as zaleplon (Sonata), zolpidem (Ambien), and eszopiclone (Lunesta) have begun replacing the benzodiazepines because they are just as effective, but shorter-acting. This means that they're less likely to cause side effects, such as tolerance or withdrawal symptoms.

Last updated:	September 05, 2008