Drugs for Weight Loss
There are three medications
approved by the FDA for weight loss:
• Phentermine (suppresses
appetite)
• Sibutramine (suppresses
appetite)
• Orlistat (causes a
malabsorption of fats)
• Rimonabant (suppresses
appetite;)
In general, medications for
weight loss are only modestly effective, and their main use is in conjunction with diet and exercise weight-loss
interventions. The current experience suggests that the weight is regained once the drugs are stopped; in other
words, the medications do not change the body, and continued use may be necessary for maintenance of weight
loss.
PHENTERMINE (ADIPEX-P,
ANOXINE-AM, FASTIN, IONAMIN, OBEPHEN, OBERMINE, OBESTIN-30, PHENTROL, TERAMINE)
Phentermine works on the
brain—it is chemically related to amphetamine, and it helps weight loss by reducing appetite and increasing
metabolism. It increases heart rate and blood pressure because it stimulates the sympathetic system. Therefore,
it should not be used by people who have heart disease or high blood pressure or an overactive thyroid. Its
other side effects include dry mouth, anxiety, and constipation. It has been approved for weight-loss use for
up to a maximum of three months, in conjunction with diet and exercise, in people with a BMI of 27 or more who
also have diabetes. The dose is 8 mg half an hour before each meal, three times a day. There are also
long-acting forms given as a single dose in the morning (15 to 37.5 mg).
Despite the fact that the
medication has been available for almost fi fty years, long- term safety studies are lacking. The longest study
was for six months, and the average weight-loss effect in combination with lifestyle changes was about eight
pounds.
SIBUTRAMINE
(MERIDIA)
This medication works in the
brain to reduce appetite by its effect on nerve terminals that release serotonin and noradrenaline. Its side
effects include insomnia, dry mouth, and increased heart rate and blood pressure. The usual starting dose is 10
mg once a day, increased to 15 mg at four weeks if the weight loss is less than four pounds. In a two-year
study, people taking sibutramine were better able to keep off their weight than those taking placebo (43 percent
versus 16 percent). There is no information regarding safety and benefits beyond two years.
ORLISTAT(XENICAL,TETRAHYDROLIPOSTATIN)
Orlistat blocks the activity
of a pancreatic enzyme called lipase, which breaks down many fats so they can be absorbed. A 120 mg capsule is
given three times a day with each main meal, and it blocks the absorption of 30 percent of ingested fat. It can
cause oily stool and occasionally fecal incontinence and increased stool frequency. These unpleasant effects are
the main reason why patients stop the medication—in a large two-year clinical trial about a quarter of the
subjects dropped out within the first four weeks of the study. Those individuals who continued on the drug had
lost seven pounds on average at one year. By the end of the second year there was regaining of some of the
weight, but it was clearly better than the placebo group— the average weight loss was about five pounds. Only
about one-third of the people who entered the study were still participating at the end of the two years.
Orlistat does appear to have a favorable effect on lipids: it lowers triglycerides, total cholesterol, and LDL
cholesterol.
Orlistat can impair the
absorption of fat-soluble vitamins A, D, E, and K, so if you take Orlistat, take a vitamin supplement containing
these vitamins.
RIMONABANT
(ACOMPLIA)
Rimonabant is an antagonist;
that is, it prevents the CB1 receptor from being stimulated and reduces appetite. Over a one-year period,
patients on 20 mg of rimonabant had an eleven-pound weight loss, and when followed for a second year maintained
the weight loss, whereas those who came off the drug regained the weight. The main side effects were nausea,
anxiety, and depression. About 40 percent of the subjects did not complete the trial. It is too early to say how
useful this medication will be in helping weight control.
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