Meridia and orlistat have two different mechanisms of action. Their effects and side effects when used in combination have not been investigated, but some experts predict that the two drugs are likely to be prescribed in combination. Phenylpropanolamine is the only weight loss drug available without a prescription. It works by increasing the level of catecholamine, a nervous system chemical that revs up the body. It can also increase heart rate, blood pressure and glucose levels.
Preliminary studies indicate that taking leptin produces modest weight loss.
But the drug, even if proven safe and effective, is at least a year away from FDA approval. Cholecystokinin boosters Cholecystokinin is a brain chemical believed to produce the feeling of fullness. If drugs could be manufactured to boost cholecystokinin's effect, people who take the medication would feel full quicker and presumably eat less. Risks of drug therapy Before taking any appetite suppressant medication, ask your doctor or pharmacist about all the known risks and side effects. Taking more than one diet drug at the same time can be dangerous.