As of 2009 there are two prescription weight loss medications approved by the Food and Drug Administration. One is an appetite suppressant that reduces the desire to eat by maintaining brain levels of a neurotransmitter called serotonin. The other medication works by blocking a percentage of dietary fat from being absorbed. A third medication suppresses appetite by blocking a specific hunger receptor, but has suspended clinical trials due to side effects and is currently not available in the United States.
Meridia
Meridia is the trade name for the drug sibutramine. Neurologist Anjali Shah explains that meridia works by maintaining higher circulating levels of a neurotransmitter called serotonin. This chemical signals the brain with feelings of satiety and reduces the urge to eat. Usage is recommended for people who have a body mass index (BMI) of 30 or greater. The most notable side effect of meridia is elevated blood pressure, which may require discontinuation of the drug. Medline reports other symptoms can occur such as anxiety, dizziness or headache and encourages contacting a physician to report these. The amount of weight loss achieved in the use of meridia averages 5 to 10 percent of initial body weight. Most of the weight is lost in the first six months of use. People who stop using meridia are likely to regain the weight, as the drug does not provoke lasting lifestyle changes.
Orlistat
Xenical is the trade name of this weight loss drug, known as a fat blocker. It is taken with meals and works by binding to lipase, the enzyme that digests fat. The manufacturers report approximately 30 percent of fat eaten at each meal continues along the intestine and is excreted undigested. People who take this prescription weight loss drug should have a BMI of 30 or greater and stand to gain health benefits from using the drug.
The side effects of orlistat are a result of undigested fats in the body. Since absorption of fats is reduced, so is absorption of fat soluble vitamins. These vitamins need to be supplemented between meals to prevent deficiency. An unpleasant, but not harmful side effect is from the excretion of undigested fat. Fecal incontinence and oily stools occur especially when higher amounts of dietary fat are ingested. If the person taking orlistat is not able to limit dietary fat intake, the amount of oily bowel movements can be bothersome enough to discontinue using the drug.
Orlistat promotes a 5 to 10 percent loss of original body weight in the average patient, mostly occurring in the first six months of use.
Rimonabant
A third prescription weight loss medication is currently not available in the United States. This drug called acomplia works by blocking cannabinoid receptors in the brain. Normally these receptors stimulate hunger, so the drug reduces the desire to eat. The same receptors also induce feelings of relaxation and calm mood, so blocking them resulted in depression and nausea in some study subjects. The occurrence of these side effects was significant enough to prevent further drug trials as of 2008.
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