Phentermine vs. Sibutramine: Which Is Better?

Nowadays, excess weight is a widespread problem which is growing due to the quality of food and contemporary tendency in nutrition characterized by irregular and improper meals. A lot of medicines supporting weight loss achieved by physical exercises and diets have been created to solve the problem more efficiently. Their main aim is to improve and keep the result, but still there are some differences. Here we are going to consider Phentermine and Sibutramine – two weight loss drugs, which are rather popular and often prescribed by dietitians.

Reasons for Prescription

benefits-exercisePhentermine and Sibutramine are prescribed when a patient has an abnormal body mass index (more than 30) in some cases accompanied by health problems which may affect the result of diet and physical activities. Thus, in case of exogenous obesity a patient may get a prescription with one of these drugs. The difference is that Phentermine is strictly limited in the time of usage and shouldn’t be taken for more than three months, and the possible term for Sibutramine usage is much longer – up to a year.

There is age limit for taking both of these drugs. Usually, a patient must be older than 18 and younger than 65. If you don’t belong to the age group from 18 to 65, these medicines are contraindicated. Other contraindications include the following:

  • Pregnancy;
  • Lactation;
  • Cardiovascular diseases;
  • Hypertension;
  • Drug and alcohol abuse;
  • Depressive disorders;
  • Hypersensitivity to any ingredient.

Mechanism of Action

Although Phentermine and Sibutramine are alike in their effect, the principles they work on are different.

Sibutramine reduces the appetite by intensifying neuromediators’ influence on the satiety centre of ventromedial area of hypothalamus, increasing the metabolic rate and thermogenesis which hastens weight loss. Sibutramine reduces the secondary usage of serotonin, dopamine and norepinaphrine.

On the contrary, Phentermine stimulates the release of norepinaphrine and dopamine in nerve-endings, thus, decreasing the food intake and increasing resting energy expenditure.

Rules of Usage

Both Phentermine and Sibutramine are addictive substances, so it’s necessary to follow the prescription given by your doctor. It’s strictly forbidden to increase the dose, take it more often than your doctor tells you or continue taking the medicine after the end of your course.

Phentermine is produced in tablets and extended-release capsules, while Sibutramine exists in capsules exclusively.

Phentremine is tightly bound with meals and may be taken either once a day in the morning or three times a day half an hour before your meals; while Sibutramine is not so sensitive in relation to food and must be taken once a day either during your meals or without it.

Side Effects

Like most of drugs, Phentermine and Sibutramine have some side effects, and it’s necessary to be aware of what the medicination’s action may be accompanied with. There are some possible common side effects for Phentermine and Sibutramine:

  • Dry mouth;
  • Constipation;
  • Drowsiness;
  • Insomnia;
  • Vomiting;
  • Tremor;
  • Dizziness;
  • Swelling of the legs and ankles;
  • Restlessness;
  • Weakness;
  • Heart palpitation;
  • Chest pain.

Moreover, there are some individual side effects for each drug, which are caused by difference in the nature of their action. For example, Phentermine may lead to diarrhea, while Sibutramine may cause itching, eyepain, fever and headache. In general, the number of side effects for Sibutramine is much bigger than that for Phentermine. Moreover, cardiovascular diseases initiated by Sibutramine are highly frequent and in some cases have already led to fatal outcomes. That’s why being less effective for weight loss, Phentermine is more preferable in treatment of obesity.

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