Bayer Offers Moxifloxacin, a Promising New Antibiotic in the Fight
against TB and AIDS
By
Donald G. McNeil Jr.
Reprinted with permission from The New York Times
Dr. Wafaa El-Sadr,
who treats tuberculosis
patients in central Harlem and in Durban,
South Africa,
believes that a new drug for tuberculosis is needed "absolutely
desperately." No new medication has been registered for 40
years, she points out. And one of the four drugs she prescribes
for new patients clashes with an important HIV
drug, meaning that patients who have both HIV and
tuberculosis - as more than half of her New York patients and 80
percent of her African
patients do - cannot fight both at the same time.
"Every
new TB drug is precious," Dr. El-Sadr
said. "That's why what Bayer is doing is a big deal."
In an unusual
step, Bayer Healthcare announced yesterday that it had agreed
to allow its most promising new antibiotic,
moxifloxacin (Avelox), be tested
against tuberculosis, a disease that kills 5,000 people a day
and is the immediate cause of death
for a third of the world's AIDS victims. If the antibiotic substantially
shortens TB treatment, which now typically lasts six months, the
company will make millions of doses and sell them at low prices
to poor countries.
Bayer's decision
is unusual because major drug companies rarely test their best-selling
patented antibiotics against diseases of the poor - and virtually
never test them against tuberculosis - for fear of hurting sales
in rich countries. Bayer makes about $500 million a year from
moxifloxacin, which it sells in the
United States
as Avelox and elsewhere as Avalox,
Avelon, Megaxin,
Actira and Izilox.
The company
hopes to have $1 billion in annual sales of the drug soon, according
to Dr. Wolfgang Plischke, head of Bayer's pharmaceutical division. First marketed
in 1999, moxifloxacin the company's
heir apparent to ciprofloxacin (Cipro),
a related antibiotic that, sold as Cipro
and other names, has earned billions of dollars but its patent
will soon expire.
Bayer's decision
is part of a contract with the Global Alliance for TB Drug Development,
a public-private partnership. The clinical trials of moxifloxacin,
involving thousands of patients in eight countries including Brazil and Zambia, will be paid for by the Bill
and Melinda Gates Foundation and by the Centers for Disease Control
and Prevention, the new European and Developing Countries Clinical
Trials Partnership and the Food and Drug Administration.
"As someone
who's been working on TB for 12 years, this is one of the most
exciting advances I've seen," said Dr. Kenneth G. Castro,
director of TB elimination at the C.D.C.
 |
|
In South Africa, a traditional medicine healer holds prescription
pills used to fight tuberculosis. The healers are being
used as distributors of such medicines.
|
Even Doctors
without Borders, the Nobel Prize-winning medical charity that
is often harshly critical of the pharmaceutical industry, praised
Bayer.
"Moxi
is a very promising drug for TB, so it's very good news,"
said Dr. Tido von Schoen-Angerer, research
chief of the charity's global campaign for cheaper drugs. He questioned
only why the decision took nearly three years, saying, "valuable
time has been lost."
Dr. Plischke
said in a telephone interview that Bayer had "an underlying
commitment to TB" and pointed out that isoniazid,
a 50-year-old drug that is one of the mainstays of TB treatment,
is a Bayer drug. The company also works on low-profit-margin drugs
for tropical diseases like sleeping sickness and Chagas'
disease, he said.
Many powerful
antibiotics made by many companies can kill the Mycobacterium
tuberculosis germ that causes tuberculosis.
But the more
lucrative antibiotic sales lie in curing the ills of the relatively
wealthy residents of North America, Europe and Japan:
pills for infections of the ears, sinuses, lungs and urinary tracts,
and intravenous infusions for dangerous hospital infections.
Beside the small
profits made serving poor countries, there are other risks to
registering a drug for TB. For example, the cheaper pills may
be shipped back to rich countries for "gray market"
sale.
In nations with
broken-down health systems, the drug may be sold openly and overused,
leading to drug-resistant germs that make their way to rich countries
and render the company's best-seller useless. And when millions
use a drug for months, rare side effects can emerge, forcing its
withdrawal, much as unexpected reports of heart attacks forced
Merck to pull Vioxx, its best-selling
painkiller, from the market.
"Companies
are much more likely to offer drugs that have no commercial value,
or to piggyback a drug from the veterinary sector and give it
a human application," said Dr. Mary Moran, an expert on drugs
for neglected diseases at the London School of Economics. "Big
companies say 'TB muddies the water.' If it works, governments
may try to restrict it for TB use. And if you get a side effect,
you've just trashed your best commercial antibiotic."
Dr. Plischke
said he believed that new side effects were unlikely because moxifloxacin had already been taken by 40 million people.
Overuse leading to resistance
and gray-market sales were unlikely, he said,
because the drug would be mixed into a four-drug pill.
Four old antibiotics
with expired patents - isoniazid, ethambutol,
rifampicin and pyrazinamide
- are the mainstays of first-line tuberculosis treatment. A typical
patient takes cocktails of them for six months.
In tests in
mice with tuberculosis, the substitution of moxifloxacin
for one of them cuts treatment time to four months, Dr. Castro
said.
Also, he said,
moxifloxacin's close chemical relatives ciprofloxacin and
levofloxacin have been used for a decade to treat multidrug-resistant strains of TB. Ideally, tuberculosis specialists
want to get treatment down to a few weeks, because many patients
stop taking their pills when they stop coughing up blood and start
feeling better. Ending treatment early encourages drug-resistant
strains.
To prevent that,
patients are put on "directly observed therapy," or
D.O.T., meaning a nurse or someone else who will not let the patient
slip up must watch them take their pills every other day.
Six months of
that, Dr. El-Sadr said, is very taxing for patients in New York who have to get to jobs, as well as
for those who are homeless or have drug problems. It is equally
hard, she said, for her African patients many miles from clinics.
In the last
few years, several pharmaceutical companies have begun drug-donation
programs, though they often limit them to drugs without lucrative
Western markets or limit which diseases the drugs may be used
against.
Pfizer, for
example, donates millions of doses of its best-selling antibiotic
Zithromax to programs fighting trachoma,
an eyelid infection common in rural Africa that slowly causes blindness. Merck and GlaxoSmithKline
donate their veterinary deworming pills
to poor countries to treat human worm diseases.
10/19/05
Source
D
G McNeil Jr. Bayer Offers New
Antibiotic with Promise in Fight on TB. The New York Times. October 18, 2005.
