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In a year of tumbling stock prices, accounting scandals, and shaky consumer spending, the British pharmaceutical giant GlaxoSmithKline has had remarkably good news to report so far. More than eight million prescriptions have been written for Advair, its asthma medication, in the year and a half it has been on the market; Trizivir has become the most frequently prescribed drug for new HIV patients; and despite competition from a new generic version, the antibiotic Augmentin is still selling well.
But it is the antidepressant drug Paxil that seems to be GlaxoSmithKline’s unstoppable star. During the first half of this year, the drug’s sales were up 18 percent in the United States. Every day an estimated 3,000 to 5,000 Americans begin taking Paxil. In 2001 alone, 25 million new scripts were written for the drug. Paxil’s strong sales—$2.1 billion last year—are often cited by Wall Street analysts as one reason GlaxoSmithKline’s stock remains an attractive prospect in an otherwise gloomy market.
Indeed, during the past 15 years the antidepressants known as selective serotonin reuptake inhibitors, or SSRIs, have revolutionized mental health care. And for tens of millions of Americans, Paxil and its pharmaceutical cousins—Prozac, Zoloft, Celexa, and Luvox—have proven a godsend. They boast far fewer side effects than their predecessors and it’s virtually impossible to take a lethal quantity of the new pills. Most people know someone who has been on one of the drugs for years.
The SSRIs have been a boon to the pharmaceutical industry, too, becoming the third most commonly prescribed type of drug, with sales of more than $13 billion a year worldwide. A bonus: Many patients use SSRIs for years, which takes some of the sting out of the cost of bringing a new prescription drug to market.
For years Eli Lilly’s Prozac was the most widely prescribed SSRI. Pfizer’s Zoloft has likewise taken a turn as the top seller. But it’s Paxil that has shone as a marketer’s dream. When the drug was introduced in 1992, the market seemed so saturated with antidepressants that it was hard to imagine Paxil would ever catch up. A decade later, it’s poised to become the world’s best-selling SSRI. GlaxoSmithKline has steadily and energetically added to the list of disorders Paxil can be used to treat, and spent billions of dollars to make sure the buying public knows where to turn in case anxiety or melancholy sets in.
Unfortunately GlaxoSmithKline leaves out one little detail: For thousands of people, it seems that Paxil could well be addictive. The chemical serotonin is present throughout the human body. Among other places, it exists in blood, in the mucous membranes of the gastrointestinal system, and in certain kinds of tumors. Serotonin plays a vital role in regulating sleep, appetite, sensory perception, body temperature, pain, and mood. In the brain, serotonin acts as a neurotransmitter, a chemical messenger that facilitates communication between two nerve cells. Serotonin molecules are released from a “sender” cell into the space between nerve cells known as the synapse. From there, they are scooped back up by a “receiver” cell.
When physicians describe depression as an illness resulting from a chemical imbalance in the brain, one of the possibilities they speak of is an interruption in the supply of serotonin in the synapses. Perhaps too little of the chemical is being manufactured, for instance, or too little of its chemical precursors—the molecules used to make the neurotransmitter. Sometimes there aren’t enough receptor sites, and sometimes serotonin is taken back up before it can get to those sites.
Research into serotonin’s role in mood disorders has been going on for decades. Physicians have long known that in many instances, depression is caused by a lack of another chemical important to brain function, norepinephrine. Perhaps, they posited, a lack of serotonin somehow caused or allowed a dip in norepinephrine. If that were the case, the manipulation of serotonin levels would indirectly raise norepinephrine.
Before Prozac came on the U.S. market in 1988, depression was often treated with a class of drugs known as tricyclic antidepressants. These drugs were quite effective at manipulating both serotonin and norepinephrine but caused a wide range of bothersome side effects. “In the old days, the pre-Prozac days of tricyclic antidepressants, you were told to treat endogenous depressions for six to 12 months and then to taper off,” explains Kevin Turnquist, a psychiatrist with the Hennepin County Mental Health Initiative. “In most cases, it worked well for those people; in fact, the tricyclics worked slightly better. The problem was the side effects. A week’s dose was lethal.”
As a consequence, tricyclics were not widely prescribed. The advent of Prozac, Paxil, and the other selective serotonin reuptake inhibitors changed that. Although each is a slightly different chemical cocktail, the SSRIs all work in roughly the same way: They slow the action of brain cells that take serotonin out of the synapses, raising the amount of the chemical circulating in the brain. And they do it with relatively few side effects. “Plus,” notes Turnquist, “you could just give one dose, start a patient on 20 milligrams and let them stay on it. It’s much easier and safer for the doctor to prescribe.”
To gild the lily, the pharmaceutical industry touted the SSRIs as non-habit-forming. “Paxil is not a controlled substance,” explains GlaxoSmithKline’s promotional literature. “Paxil belongs to a class of medications called SSRIs, which have not been shown to be associated with addiction.” The claim is repeated in all of the ads for Paxil, and in the drug information GlaxoSmithKline gives to doctors. Kevin Murphy found all of this information comforting when he and his wife struggled with the decision to put their 11-year-old daughter Kelly on medication. She’d been having panic attacks for a while and had tried several kinds of therapy. Nothing worked, so the Murphys, who live in Lino Lakes, swallowed their concerns and took Kelly to see a psychiatrist. “He prescribed a couple of medications that didn’t do anything,” Kevin Murphy recalls. “He switched her over to Paxil, and Paxil worked pretty quickly.
“We had talked to the doctor and said what we’d really like to do is have her on it for a year and then take her off of it in the hope that her body would have unlearned the panic response,” he continues. “As we drew near the end of that year, her doctor said very casually that it’s always a good idea to taper off of this very gradually. She was already cracking a 10-milligram tablet in half, then she started cracking that in half, too, to get to 2.5 milligrams.
“Finally, she was off of it altogether for a couple of days and then she started to have panic attacks. Her heart would just race, and then she’d think she was going to be sick—and she hates being sick. So we called the doctor, and he said to put her back on it.” For the next three-plus years, they tried other tactics for weaning her off the drug. They tried switching her to Celexa, another SSRI. That failed. They tried the same tactic, but using Prozac. They tried anti-nausea drugs, acupuncture—”everything,” Murphy says, “but nothing helped.”
In addition to excruciating stomach pain, Kelly was so nauseated she couldn’t sleep or eat. Doctors examined her upper gastrointestinal system. She had a CT scan, an ultrasound, and countless other tests. Each showed her to be healthy. And yet each time she stopped taking Paxil, she found herself homebound. And each time, she went back on Paxil—at a higher dosage. Kelly’s mother, Maureen Murphy, was forced to quit her job to stay home with her. She missed months of school. “We had to get a tutor for her so she wouldn’t fail school,” Kevin Murphy says. “She lost 10 pounds. She would be up until 1:00, 2:00, 3:00 a.m. trying to sleep.
“And all the while her psychiatrist said, ‘This is really weird. I’ll check with the drug company and see what’s going on.’ And they told him that nothing like this happens with this drug,” he recalls. As for Kelly, he adds, “She told me several times she wished she were dead.” Right now she’s trying one more time to taper off Paxil. On the advice of a psychiatrist, she switched to a liquid form of the drug so she could decrease her dose by one milligram each month. Last fall, Murphy became one of 34 named plaintiffs in a class-action lawsuit filed in U.S. District Court in Los Angeles. Since then, some 6,000 people have joined the suit. Several other law firms are pursuing similar suits in the United States. In addition, suits have been filed in Canada (in British Columbia, Ontario, and Quebec) and in England.
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