Obesity (Weight Loss) (cont.)
What is the role of medication in the treatment of obesity?
Medication treatment of obesity should be used only in patients who have
health risks related to obesity. Medications should be used in patients with a
BMI greater than 30 or in those with a BMI of greater than 27 who have other
medical conditions (such as high blood pressure, diabetes, high blood
cholesterol) that put them at risk for developing heart disease. Medications
should not be used for cosmetic reasons.
Like diet and exercise, the goal of medication treatment has to be realistic.
With successful medication treatment, one can expect an initial weight loss of
at least 5 pounds during the first month of treatment, and a total weight loss
of 10-15% of the initial body weight. It is also important to remember that
these medications only work when they are taken. When they are discontinued,
weight gain can occur.
The first class (category) of medication used for weight control cause
symptoms that mimic the sympathetic nervous system. They cause the body to feel
"under stress" or " nervous". As a result, the major side effect of this
class of medication is high blood pressure. This class of medication includes
sibutramine (Meridia) and phentermine (Fastin, Adipex P). These medications also
decrease appetite and create a sensation of fullness. Hunger and fullness
(satiety) are regulated by brain chemicals called neurotransmitters. Examples of
neurotransmitters include serotonin, norepinephrine, and dopamine. Anti-obesity
medications that suppress appetite do so by increasing the level of these
neurotransmitters at the junction (called synapse) between nerve endings in the
brain.
Phentermine
Phentermine (the other half of fen/phen) suppresses appetite by causing a
release of norepinephrine by the cells. Phentermine alone is still available for
treatment of obesity, but only on a short-term basis (a few weeks). The common
side effects of phentermine include headache, insomnia, irritability and
nervousness. Fenfluramine (the fen of fen/phen) and dexfenfluramine (Redux)
suppress appetite mainly by increasing release of serotonin by the cells.
Unfortunately, both fenfluramine and dexfenfluramine were withdrawn from the
market in September 1997 because of association of these two medications with
pulmonary hypertension (a rare but serious disease of the arteries in the
lungs), and association of fen/phen with damage to the heart valves. Since the
withdrawal of fenfluramine, some have suggested combining phentermine with
fluoxetine (Prozac) - a combination that has been referred to as phen/pro.
However, no clinical trials have been conducted to confirm the safety and
effectiveness of this combination. Therefore, this combination is NOT an
accepted treatment for obesity.
Sibutramine (Meridia)
Sibutramine (Meridia) suppresses appetite by increasing the amount of
neurotransmitters serotonin and norepinephrine in the brain synapses. Unlike
fenfluramine and dexfenfluramine, sibutramine does not increase release of these
neurotransmitters from the cells. Instead, sibutramine inhibits the re-uptake of
these neurotransmitters by the nerve cells. Therefore, the action of sibutramine
is similar to that of anti-depressants that inhibit re-uptake of serotonin such
as fluoxetine (Prozac) - a medication that has been used for years without known
association with pulmonary hypertension or heart valve damage.
In December 1997, the United States Food and Drug Administration (FDA)
approved sibutramine (Meridia) to treat obesity (both in attaining and in
maintaining weight loss). According to FDA guidelines, Meridia should be
considered only for patients with BMI of 30 or higher, or for those with a BMI
of 27 or higher who also have other conditions (such as high blood pressure,
diabetes mellitus, sleep apnea) that can improve with weight loss. Meridia
should be accompanied by regular exercise and reduced-calorie diet.
Meridia is available in 5, 10, and 15mg capsules. The recommended starting
dose is one 10 mg capsule per day. The dose of Meridia can be increased if
weight loss is inadequate. Meridia should always be prescribed by doctors
familiar with the patients' medical condition, and familiar with the use and
side effects of the medicine.
In clinical trials involving 6,000 individuals, Meridia produced
statistically significantly more weight loss when compared to placebo (sugar
pill). Generally, weight loss achieved with Meridia is modest. On average,
patients treated with Meridia lost 5% to 10% of initial weight at various dosage
levels. In two 12-month studies, maximal weight loss was achieved by six months,
and statistically significant weight loss was maintained over 12 months.
Thus far, there are no reported increases in pulmonary hypertension or heart
valve damage associated with the use of Meridia. Like any newly released
medication, however, close monitoring will be necessary to determine the drug's
long-term safety and effectiveness. Certain side effects may not become apparent
until months to years after release.
The known side effects of Meridia are mild and transient. They include dry
mouth, headache, constipation and insomnia. Meridia also causes a small increase
in average blood pressure and heart rate. But in some individuals, the increase
in blood pressure can be more pronounced. Therefore, patients on Meridia should
have regular monitoring of their blood pressure. Meridia should not be used in
patients with uncontrolled high blood pressure, history of stroke, coronary
heart disease, and congestive heart failure. For more, please read the
Meridia
article.
Orlistat (Xenical)
The next class (category) of drugs changes the metabolism of fat. Orlistat
(Xenical) is the only drug of this category that is FDA approved. This s a new
class of anti-obesity drugs called lipase inhibitors, or fat blockers. Fat from
food can only be absorbed into the body after being broken up (a process called
digestion) by digestive enzymes called lipase in the intestines. By inhibiting
the action of lipase enzymes, Xenical prevents the intestinal absorption of fat
by 30%. Drugs in this class do not affect brain chemistry. Theoretically,
Xenical also should have minimal or no systemic side effects (side effects in
other parts of the body) because the major locale of action is inside the gut
lumen and very little of the drug is absorbed.
In clinical trials, Xenical with a moderately reduced calorie diet was found
to be superior to placebo in achieving weight loss. The average patient in the
one-year trial using Xenical lost about 10% of body weight. Many patients who
continued treatment were able to maintain the weight loss. In addition, Xenical
treated patients had statistically significant reductions in total and LDL
cholesterol, blood pressure, and improvements in blood glucose levels after one
year when compared to patients on only placebo and diet.
The clinical trials showed that Xenical was well tolerated. The most common
side effects were gas, cramps and diarrhea. These side effects were believed to
be due to the action of the drug (the unabsorbed fat in the gut can cause cramps
and diarrhea). According to Hoffmann La- Roche, the maker of Xenical, these side
effects generally occurred early in treatment and were of short duration.
Long-term decrease in fat absorption can cause deficiency of fat-soluble
vitamins (such as vitamins A, D, E, K). Therefore, patients on Xenical should
receive adequate vitamin supplementation. For more, please read the Vitamins and
Calcium Supplements and Xenical articles.
In May 1997, the United States FDA Endocrinology and Metabolic Drugs Advisory
Committee recommended the approval of Xenical as an adjunct to diet and exercise
in treating obesity. After a temporary delay, the FDA has approved Xenical.
Next: What about herbal fen/phen? »
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