Phentermine

Phentermine hydrochloride is indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index ≥ 30 kg/m 2 , or ≥ 27 kg/m 2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia). Below is a chart of body mass index (BMI) based on various heights and weights. BMI is calculated by taking the patient's weight, in kilograms (kg), divided by the patient's height, in meters (m), squared. Metric conversions are as follows: pounds ÷ 2.2 = kg; inches × 0.0254 = meters. …

• Dosage should be individualized to obtain an adequate response with the lowest effective dose
• Late evening administration should be avoided (risk of insomnia)
• Phentermine hydrochloride tablets can be taken with or without food
• Limit the dosage to 15 mg daily for patients with severe renal impairment (eGFR 15 to 29 mL/min/1.73 m 2 ) Exogenous Obesity Dosage should be individualized to obtain an adequate response with the lowest effective dose
• The usual adult dose is one tablet (37.5 mg) daily, as prescribed by the physician, administered before breakfast or 1 to 2 hours after breakfast
• The dosage may be adjusted to the patient’s need
• For some patients, half tablet (18.75 mg) daily may be adequate, while in some cases it may be desirable to give half tablets (18.75 mg) two times a day
• Phentermine hydrochloride is not recommended for use
• In pediatric patients ≤ 16 years of age
• Late evening medication should be avoided because of the possibility of resulting insomnia
• Dosage in Patients With Renal Impairment The recommended maximum dosage of phentermine hydrochloride are 15 mg daily for patients with severe renal impairment (eGFR 15 to 29 mL min/1.73m 2 )
• Avoid use of phentermine hydrochloride in patients with eGFR less than 15 mL/min/1.73m 2 or end-stage renal disease requiring dialysis [see Use in Specific Populations and Clinical Pharmacology ]

Tablets containing 37.5 mg phentermine hydrochloride (equivalent to 30 mg phentermine base). Tablets containing 37.5 mg phentermine hydrochloride. ( 3 )

• Safety and effectiveness
• In pediatric patients have not been established
• Because pediatric obesity is a chronic condition requiring long-term treatment, the use of this product, approved for short-term therapy, is not recommended

In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. …

• Patients must be informed that phentermine hydrochloride is a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity, and that coadministration of phentermine with other drugs for weight loss is not recommended [ see Indications and Usage and Warnings and Precautions ]
• Patients must be instructed on how much phentermine to take, and when and how to take it [ see Dosage and Administration ]
• Advise pregnant women and nursing mothers not to use phentermine [ see Use in Specific Populations ]. …

History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension) During or within 14 days following the administration of monoamine oxidase inhibitors Hyperthyroidism Glaucoma Agitated states History of drug abuse Pregnancy [ see Use in Specific Populations (8.1) ] Nursing [ see Use in Specific Populations (8.3) ] Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines History of cardiovascular disease (e.g. …

Monoamine oxidase inhibitors: Risk of hypertensive crisis. ( 4 , 7.1 ) Alcohol: Consider potential interaction. ( 7.2 ) Insulin and oral hypoglycemics: Requirements may be altered. ( 7.3 ) Adrenergic neuron blocking drugs: Hypotensive effect may be decreased by phentermine. ( 7.4 ) 7.1 Monoamine Oxidase Inhibitors Use of phentermine is contraindicated during or within 14 days following the administration of monoamine oxidase inhibitors because of the risk of hypertensive crisis . 7.2 Alcohol Concomitant use of alcohol with phentermine may result in an adverse drug reaction . 7.3 Insulin and Oral Hypoglycemic Medications Requirements may be altered [ see Warnings and Precautions (5.9) ]. …

Coadministration with other drugs for weight loss is not recommended (safety and efficacy of combination not established). ( 5.1 ) Rare cases of primary pulmonary hypertension have been reported. Phentermine should be discontinued in case of new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema. ( 5.2 ) Rare cases of serious regurgitant cardiac valvular disease have been reported. ( 5.3 ) Tolerance to the anorectic effect usually develops within a few weeks. If this occurs, phentermine should be discontinued. The recommended dose should not be exceeded. …

The following adverse reactions are described, or described in greater detail, in other sections: Primary pulmonary hypertension [ see Warnings and Precautions (5.2) ] Valvular heart disease [ see Warnings and Precautions (5.3) ] Effect on the ability to engage in potentially hazardous tasks [ see Warnings and Precautions (5.5) ] Withdrawal effects following prolonged high dosage administration [ see Drug Abuse and Dependence (9.3) ] The following adverse reactions to phentermine have been identified: Cardiovascular Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevation of blood pressure, ischemic events. …

8.1 Pregnancy Pregnancy Category X Phentermine is contraindicated during pregnancy because weight loss offers no potential benefit to a pregnant woman and may result in fetal harm. A minimum weight gain, and no weight loss, is currently recommended for all pregnant women, including those who are already overweight or obese, due to obligatory weight gain that occurs in maternal tissues during pregnancy. …

The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage. 10.1 Acute Overdosage Manifestations of acute overdosage include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, and panic states. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include tachycardia, arrhythmia, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea and abdominal cramps. …

9.1 Controlled Substance Phentermine is a Schedule IV controlled substance. 9.2 Abuse Phentermine is related chemically and pharmacologically to the amphetamines. Amphetamines and other 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. …

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature] DISPENSE IN TIGHT, LIGHT-RESISTANT CONTAINER. Keep out of the reach of children.

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.