Clinical Pharmacology of Phentermine
Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, the amphetamines. Actions include central nervous system stimulation and elevation of blood pressure. Tachyphylaxis and tolerance have been demonstrated with all drugs of this class in which the sephenomena have been looked for. Phentermine used in obesity are commonly known as anorecticsor anorexigenics It has not been established that the action of such drugs in treating obesity is primarily one of appetite suppression. Other central nervous system actions, or metabolic effects, may be involved, for example. Adult obese subjects instructed in dietary management and treated with anorecticdrugs lose more weight on the average than those treated with placebo and diet, as determined in relatively short-term clinical trials.

Uses of Phentermine
Oral Phentermine hydrochloride is used as an appetite suppressant used for short-term treatment of exogenous obesity. Phentermine is used in conjunction with an overall diet plan to reduce weight.

How Phentermine Works
Phentermine works by stimulating a gland, called the hypothalamus, and affecting certain neurotransmitters to decrease appetite. Because Phentermine hydrochloride is similar chemically to amphetamines, it has the potential for psychological dependency. Phentermine should be used with caution.

How to Take Phentermine
Phentermine is best taken on an empty stomach one half-hour before breakfast. Because Phentermine may cause sleeplessness, avoid taking a dose late in the day. Take Phentermine as prescribed. Do not take it more often or longer than directed.

Side Effects of Phentermine
Dry mouth, sleeplessness, irritability, stomach upset or constipation may occur the first few days as your body adjusts to Phentermine. If these effects persist or become bothersome, inform your doctor.

Phentermine Dosage
Adults Under 60: Capsules: Phentermine 15 to 37.5 mg every morning before breakfast or 1 to 2 hours after breakfast. Tablets: Phentermine 15 to 37.5 mg every morning before breakfast or 1 to 2 hours after breakfast. Alternatively, take Phentermine 15 to 37.5 mg in divided doses one-half hour before meals.
Adults 60 and Over: Reduced Phentermine dosage may be necessary. Consult your physician. Infants and Children: Use is not recommended.
Maximum Dosage Recommendations: Do not exceed the recommended Phentermine doses, unless deemed necessary by your doctor.
If You Miss a Dose: Take as soon as possible. If close to the next dose, skip and take the next dose. Do not double the dose.

Precautions for Phentermine
Tell your doctor your complete medical history especially if you have high blood pressure, an over-active thyroid, glaucoma, diabetes or emotional problems. Consult with your doctor if you think you are pregnant or before breast-feeding. Alcohol can increase unwanted side effects of dizziness. Limit alcohol use. Phentermine is not recommended for use in children. Consult your doctor or pharmacist for further information.

Drug Interactions with Phentermine
Inform your doctor about all the medicines you use, (prescription and nonprescription) especially if you take high blood pressure medicine or MAO inhibitors (e.g., furazolidone, phenelzine, selegiline, tranylcypromine) or any other weight loss medicine. Decongestants are commonly found in over-the-counter cough and cold medicine.

Drug Abuse and Dependence of Phentermine
Phentermine is related chemically and pharmacologically to the amphetamines. Amphetamines and related stimulant drugs have been extensively abused, and the possibility of abuse of Phentermine should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program.

Abuse of amphetamines and related drugs may be associated with intense psychological dependence and severe social dysfunction. There are reports of patients who have increased the dosage to many times that recommended. Abrupt cessation following prolonged high dosage administration results in extreme fatigue and mental depression; changes are also noted on the sleep EEG.

Manifestations of chronic intoxication with anorectic drugs include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The most severe manifestation of chronic intoxications is psychosis, often clinically indistinguishable from schizophrenia.

Warnings for Phentermine
Tolerance to the anorectic effect usually develops within a few weeks. When this occurs, the recommended Phentermine dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued. Phentermine hydrochloride may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.

Usage in Pregnancy: Safe use in pregnancy has not been established. Use of Phentermine hydrochloride by women who are or who may become pregnant, and those in the first trimester of pregnancy, requires that the potential benefit be weighed against the possible hazard to mother and infant.
Usage in Children: Phentermine hydrochloride is not recommended for use in children under 12 years of age.

Overdosage with Phentermine
Manifestations of acute overdosage with Phentermine include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, panic states. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include arrhythmias, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea, and abdominal cramps. Fatal poisoning usually terminates in convulsions and coma.

Management of acute Phentermine intoxication is largely symptomatic and includes lavage and sedation with a barbiturate. Experience with hemodialysis or peritoneal dialysis is inadequate to permit recommendations in this regard. Acidification of the urine increases Phentermine excretion. Intravenous phentolamine (Regitine) has been suggested for possible acute, severe hypertension, if this complicates Phentermine overdosage.

Notes for Phentermine
Phentermine appetite suppressants are not a substitute for proper diet. For maximum effects, this must be used in conjunction with a diet and exercise program. Do not share Phentermine with others.

Storage of Phentermine
Store Phentermine at room temperature away from sunlight and moisture. Keep this and all medications out of the reach of children

What is Phentermine?
Phentermine is a sympathomimetic amine, which is similar to an amphetamine. It is also known as an "anorectic" or "anorexigenic" drug. Phentermine stimulates the central nervous system (nerves and brain), which increases your heart rate and blood pressure and decreases your appetite. Phentermine is used as a short-term supplement to diet and exercise in the treatment of obesity. Phentermine may also be used for purposes other than those listed in this medication guide.

Who should not take Phentermine?
You cannot take Phentermine if you
· have heart disease or high blood pressure;
· have arteriosclerosis (hardening of the arteries)
· have glaucoma
· have taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), tranylcypromine (Parnate), or phenelzine (Nardil) in the last 14 days; or
· have a history of drug or alcohol abuse.

 •  Before taking Phentermine, tell your doctor if you have
· problems with your thyroid
· an anxiety disorder
· epilepsy or another seizure disorder
· diabetes.
You may not be able to take Phentermine, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.
 •  It is not known whether Phentermine hydrochloride will harm an unborn baby. Do not take Phentermine without first talking to your doctor if you are pregnant.
 •  It is also not known whether Phentermine passes into breast milk. Do not take Phentermine without first talking to your doctor if you are breast-feeding a baby.

How should I take Phentermine?
 •  Take Phentermine hydrochloride exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
 •  Take each Phentermine dose with a full glass of water.
 •  Phentermine is usually taken once or twice a day before a meal on an empty stomach.
 •  Do not take Phentermine in the evening because it may cause insomnia.
 •  Do not crush, chew or open any "once-daily" Phentermine tablets or capsules. Swallow them whole.
 •  Never take more Phentermine than is prescribed for you. Too much Phentermine could be very dangerous to your health.
 •  Store Phentermine at room temperature away from moisture and heat.  •  Take the missed Phentermine dose as soon as you remember. However, if it is almost time for your next dose or if it is already evening, skip the missed dose and take only your next regularly scheduled dose. A dose taken too late in the day will cause insomnia. Do not take a double dose of Phentermine hydrochloride.

What happens if I overdose?
 •  Seek emergency medical attention.
 •  Symptoms of a Phentermine overdose include restlessness, tremor, rapid breathing, confusion, hallucinations, panic, aggressiveness, nausea, vomiting, diarrhea, an irregular heartbeat, and seizures.

What should I avoid while taking Phentermine?
 •  Use caution when driving, operating machinery, or performing other hazardous activities. Phentermine hydrochloride may cause dizziness, blurred vision, or restlessness, and it may hide the symptoms of extreme tiredness. If you experience these effects, avoid hazardous activities.
 •  Do not take Phentermine late in the day. A dose taken too late in the day can cause insomnia.

What are the possible side effects of Phentermine?
 •  If you experience any of the following serious side effects, stop taking Phentermine and seek emergency medical attention:
· an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
· an irregular heartbeat or very high blood pressure (severe headache, blurred vision); or
· hallucinations, abnormal behavior, or confusion.
 •  Other, less serious side effects may be more likely to occur. Continue to take Phentermine and talk to your doctor if you experience
· restlessness or tremor,
· nervousness or anxiety,
· headache or dizziness,
· insomnia,
· dry mouth or an unpleasant taste in your mouth,
· diarrhea or constipation, or
· impotence or changes in your sex drive.
 •  Phentermine is habit forming. You can become physically and psychologically dependent on Phentermine, and withdrawal effects may occur if you stop taking it suddenly after several weeks of continuous use. Talk to your doctor about stopping Phentermine gradually.
 •  Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

Where can I get more information?
 •  Your pharmacist has more information about Phentermine written for health professionals that you may read.