Feeling Good: The New Mood Therapy (65 page)

Is this serious? Well, there are three potential problems. First, desipramine is not effective at excessively high blood levels. Second, there will be many more side effects at high levels. And third, in rare instances, excessive blood levels of desipramine can trigger abnormal heart rhythms and occasionally even cause death.

Is this type of drug interaction rare? No. The levels of antidepressants can sometimes increase or decrease quite dramatically when combined with common prescription or over-the-counter drugs you might take without thinking twice. The tables in Chapter 20 will delineate the interactions most important to any antidepressant you might be taking.

Finally, some toxic and dangerous drug interactions do not necessarily depend on doses or blood levels. For example, many of the newer antidepressants such as Prozac have powerful effects on the serotonin systems in the brain. The monoamine oxidase inhibitors (MAOIs) also affect the serotonin systems in the brain, but through a different mechanism. The antidepressant tranylcypromine (trade name Parnate) is an example of one of these MAOI drugs. If you take Prozac and Parnate at the same time, the combination could trigger an extremely dangerous reaction known as the “serotonin syndrome.” The symptoms can
include fever, muscle rigidity, and rapid changes in blood pressure, along with agitation, delirium, seizures, coma, and death. Obviously, this combination of drugs should not be given!

You will see in Chapter 20 that many medications can be dangerous if you are taking an MAOI. The list of forbidden drugs includes many antidepressants, some decongestants (especially if they contain dextromethorphan, a common ingredient of cold preparations), antihistamines, local anesthetics, some anticonvulsants, some painkillers such as meperidine (Demerol), antispasmodics including cyclobenzaprine (Flexeril) and weight-loss preparations. Some of these drugs will cause the serotonin syndrome described above, and some of them will cause another dangerous reaction known as a “hypertensive crisis.” In extreme cases, the symptoms of a hypertensive crisis include brain hemorrhage, paralysis, coma, and death. Certain common foods such as cheese are also on the “forbidden” list if you are taking one of the MAOIs, because they can cause a hypertensive crisis as well.

Many doctors do not prescribe the MAOIs because of concerns about these toxic interactions. You may also think: “Well, I will just take a safer drug so I won’t have to worry.” This makes good sense, since many safer medications are available. However, many commonly prescribed antidepressants can cause dangerous interactions. For example, two common antidepressants, nefazodone (trade name Serzone) and fluvoxamine (trade name Luvox) should not be combined with several commonly prescribed drugs because these particular combinations can trigger an abnormal heart rhythm that may result in sudden death. The drugs include terfenadine (trade name Seldane and used for allergies), astemizole (trade name Hismanal and used for allergies), or cisapride (trade name Propulsid, a stimulant for the gastrointestinal tract).

I do not mean to give the impression that it is dangerous to take antidepressant drugs. To the contrary, they are usually quite safe and effective, and the catastrophic drug interactions
I have described are fortunately rare. In addition, most psychiatrists go to great lengths to educate themselves about recent developments and try to keep up with new information about side effects and drug interactions. But in the real world we live in, no doctor is perfect and no doctor can have comprehensive knowledge about all possible drug interactions. For example, your primary care physician may not be familiar with some new antidepressant your psychiatrist has prescribed. And so a little research on your part will be helpful. As an enlightened consumer, you can read about any antidepressant medicine you are taking in Chapter 20 and in other readily available references such as the
Physician’s Desk Reference
(
PDR
). You can find these books at any library, bookstore, or pharmacy. You can also find the
PDR
at your doctor’s office. You can also review the drug insert that comes with the medication. It doesn’t take more than five or ten minutes to review this information. Then you can ask informed questions and bring out the best in your physician. The teamwork can give you a safer and better experience with your antidepressant. This is definitely one case where an ounce of prevention can be worth more than a pound of cure.

(
Notes and References appear on pages 682–687.
)

In this chapter I will give you practical information about the costs, doses, side effects, and drug interactions for all the currently available antidepressant and mood-stabilizing drugs. I would recommend you use this chapter as a reference source rather than trying to read it all at once—there is just too much detailed information to digest at one sitting. If you want to learn about a particular drug that you or a family member may be taking, the Table of Antidepressants on pages 514–515 will help you locate the information you need in this chapter. Let’s assume, for example, that you are taking fluoxetine (Prozac). You can read the section on the SSRI antidepressants starting on page 547. In addition, the section on drug costs starting on this page, as well as the information starting on page 659, should be of general interest to all readers.

Table of Antidepressants

^a
Many of the antidepressants are now available as generic brands (see Table 20–1). Only the trade names of the original brands are listed in this table.

We often think that more expensive means better, but this is not always the case with antidepressants. As it turns out, there are some very dramatic differences in the costs of the different antidepressants that do not reflect differences in effectiveness. In other words, sometimes a drug that is much cheaper will be just as effective, or even more effective, than another drug that costs more than forty times more. Therefore, if the cost of the medication is a concern for you, then a little education may save you a great deal of money.

The costs and doses of the most commonly prescribed antidepressants and mood stabilizing agents are listed in Table 20–1 on pages 518–523. Note that I am quoting
the cheapest wholesale price
for each antidepressant drug in Table 20–1. The retail price you pay for the same medication at the drug store will probably be higher. If you choose a different brand of the same medication, it may be higher yet. Please keep this in mind in all of the following discussions of drug costs.

If you compare the costs of the different types of drugs
and the different doses, it will provide you with some interesting information. You will see, for example, that many of the older tricyclic and tetracyclic drugs are now available generically. When a drug is first manufactured, the drug company gets a seventeen-year patent so it can market the drug exclusively. The relatively high cost of the newer drugs that are still protected by patents helps to cover the costs of the research, development, and testing. After the patent expires, other companies can compete and manufacture the drug, and so the price goes down drastically.

You will see in Table 20–1 that these so-called “generic” medications are much less costly than the newer drugs that are still under patent. Let’s assume that your doctor prescribes a dose of 150 mg per day of imipramine for your depression. The cost of the three 50-mg pills you will take will be less than 10 cents per day, or roughly $3 per month. This is because imipramine is now available generically. In contrast, if your doctor prescribes two 20-mg Prozac pills per day, your cost will be nearly $4.50 per day or $135 per month—over forty times more than the imipramine. And if she or he prescribes four Prozac pills—the maximum dose—your cost will be $270 per month. This is a steep price for many people. Don’t forget these are
wholesale
prices—you may pay even more.

Is Prozac forty to a hundred times more effective than imipramine? Definitely not. As you will learn below, most of the antidepressants tend to be comparably effective. Research studies have not confirmed that Prozac is any more effective than imipramine—in fact it may be slightly less effective for severe depressions. However, the big advantage of Prozac is that it has fewer side effects (such as dry mouth or sleepiness) than imipramine. This may be quite important to some people and may make the price difference worthwhile. On the other hand, you will learn that Prozac has some side effects of its own, such as problems with sexual functioning (difficulty achieving orgasm) in as many as 30 percent to 40 percent of patients, and possibly more. People who don’t like this particular side effect might actually prefer the cheaper medication.

You will also see in Table 20–1 that pills which contain a larger quantity of a particular drug are not necessarily more expensive than pills which contain a smaller quantity. This is especially true if you are taking one of the newer drugs that is still under patent, so you may be able to save money by buying pills containing a larger dose. For example, you will see in Table 20–1 that the cost of a hundred nefazodone (Serzone) tablets is $83.14 for the 100-mg size. The price for a hundred tablets of the larger sizes (150 mg to 250 mg) is exactly the same. So if you are taking a large dose, say 500 mg per day, you could either take five of the 100-mg pills (cost of $4.16 per day) or two of the 250-mg pills (cost of $1.66 per day).

In addition, you can often save money by buying a larger size of a medication and breaking a pill in half. So to continue with the same example, if you are taking 250-mg pills, it will cost you approximately half as much if you purchase 500-mg pills and break them in half.

For the generic drugs, things are different. On the average, the costs are low overall and depend on the dose, and the savings at higher doses are not so drastic. In addition, because so many different companies manufacture these drugs, the prices for the different doses are not always entirely consistent—sometimes a smaller dose will actually cost more than a larger dose. For example, look at the pricing structure for the tricyclic antidepressant, desipramine (trade name Norpramin) on page 518. You will see that a hundred of the 10-mg pills cost $15.75, while a hundred of the 25-mg pills costs only $7.14. So the larger pill is actually cheaper. This is because different companies manufacture the two sizes.