Drugs may be used in the short term that is up to 3 months for obesity treatment as an adjunct to the dietary regimen, but they are not substitute for strict dieting.
Indication for anti obesity drugs.
Adjuvant treatment with drugs are indicated in
1.Patients with a BMI >30 kg/m 2.
2.Patients with BMI >27 kg/m 2 with concomitant obesity related diseases.
3.Patients with BMI >27 kg/m 2 who do not get satisfactory weight reduction with dietary and physical activity therapy.
Significance of lifestyle program with drugs.
Patients should be engaged in a lifestyle program when an antiobesity drug is prescribed. The life style program will provides them the strategies and skills which are needed to use these antiobesity drug efficiently because this support increases total weight loss.
Targets of drug therapy for obesity.
Suppression of appetite via centrally active drugs which alter monoamine neurotransmitters is the most thoroughly explored treatment.
A second strategy is to decrease the absorption of selective macronutrients from the gut such a fat.
Type of antiobesity drugs.
Centrally acting drugs
They are appetite-suppressing drugs, or anorexiants, affect satiety and hunger.
Satiety is the absence of hunger after eating.
Hunger is a sensation which initiates eating.
These agents increase the satiety and decrease hunger, thus help to reduce the intake of calories without a feeling of deprivation of food.
Example of centrally acting drug is sibutramine (Meridia).
Peripherally acting drugs
Example of peripherally acting drugs is Orlistat.
It is a lipase inhibitor, inhibit the hydrolysis of dietary fat the essential step required for their absorption. Thus Orlistat blocks the digestion and absorption of 30% of dietary fat and help to achieve weight loss. Weight regain will occurs once the drug is stopped. Studies have shown that Orlistat produces a weight loss of about 9 - 10% at the end of one year. Orlistat has minimal gut absorption so it is devoid of systemic side effects. Tolerability to Orlistat is related to the malabsorption of dietary fat and passage of fat in the feces. About 10 percentage of people treated with this drug experience gut side effect. They are flatus with discharge, fecal urgency, increased defecation and oily stool. These side effects of Orlistat is seen early in the course of treatment. The side effect can be reduced if the patient controls the dietary fat intake.Psyllium mucilloid if taken along with orlistat will helps to reduce the gut side effects. There is decreased concentration of fat-soluble vitamins D, E and ß-carotene is seen in patients treated with Orlistat.Vitamin supplements are necessary to prevent deficiency disease.
The Endocannabinoid System
Rimonabant is the first selective cannabinoid CB 1 receptor antagonist, used for treatment of obesity. This drug antagonizes the orexigenic effect of endocannabinoid system and suppresses appetite. Rimonabant is a weight-loss agent which shows improvement in waist circumference and reduce the heart problems. However increased risk of certain side effect such as seizures, depression, aggressiveness and suicidal thoughts anxiety, insomnia are seen. Even though the drug was available in 56 countries in 2008, European Medicines Agency (EMEA) has officially withdrawn this drug in January 2009, due to increased side effect compared to its benefits.