Adipex helps in four ways:

• Prevent overeating by reducing your appetite
• Boost your metabolism
• Burn calories and fat 24 hours a day
• Achieve rapid weight loss results

Phentermine is a phenethylamine, more importantly a derivative of amphetamine, primarily used as an appetite suppressant. It is typically prescribed for individuals who are at increased medical risk because of their weight, as opposed to cosmetic weight loss. Phentermine is sold either as an immediate-release formulation (Adipex®) or as a slow-release resin (Ionamin®, Duromine® in Australia and New Zealand).

Mechanism of action

Phentermine, like many other prescription drugs, works with neurotransmitters in the brain. It is a centrally-acting stimulant and is a constitutional isomer of methamphetamine. It stimulates neuron bundles to release a particular group of neurotransmitters known as catecholamines; these include dopamine, epinephrine (also known as adrenalin), and norepinephrine (noradrenaline). The anorectic activity seen with these compounds would thus seem likely due to this effect on the central nervous system, which is consistent with current knowledge about central nervous system systems and feeding behavior. This is the same mechanism of action as other stimulant appetite suppressants such as diethylpropion, and phendimetrazine. The neurotransmitters signal a fight-or-flight response in the body which, in turn, puts a halt to the hunger signal. As a result, it causes a loss in appetite because the brain does not receive the hunger message.

Phentermine HCL is available in these FDA-approved doses:

• Phentermine HCL 8mg tablet
• Phentermine HCL 15mg capsule
• Phentermine HCL 18.75mg capsule
• Phentermine HCL 30mg capsule
• Phentermine HCL 37.5mg capsule
• Phentermine HCL 37.5mg tablet

Clinical use

Generally, it is recommended by the Food and Drug Administration (FDA) that phentermine should be used short-term (usually interpreted as up to 12 weeks), while following nonpharmacological approaches to weight loss such as healthy dieting and exercise. However, recommendations limiting its use for short-term treatment may be controversial. One reason given behind limiting its use to 12 weeks is drug tolerance, whereby phentermine loses its appetite-suppressing effects after the body adjusts to the drug. On the contrary, it has been shown that phentermine did not lose effectiveness in a 36-week trial. Due to the risk of insomnia, it is generally recommended that the drug be taken either before breakfast or 1-2 hours after breakfast.