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.

Dosage of Phentermine
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 of 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 of 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.