Phentermine

1 INDICATIONS AND USAGE 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. BODY MASS INDEX (BMI), kg/m 2 The limited usefulness of agents of this class, including phentermine hydrochloride tablets, [ see Clinical Pharmacology (12.1 , 12.2) ] should be measured against possible risk factors inherent in their use such as those described below. Phentermine hydrochloride is a sympathomimetic amine anorectic indicated as a short-term adjunct (a few weeks) 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). ( 1 ) The limited usefulness of agents of this class, including phentermine hydrochloride, should be measured against possible risk factors inherent in their use. ( 1 ) Figure

12.1 Mechanism of Action Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and d / l-amphetamine). Drugs of this class used in obesity are commonly known as "anorectics" or "anorexigenics." It has not been established that the primary action of such drugs in treating obesity is one of appetite suppression since other central nervous system actions, or metabolic effects, may also be involved.

2 DOSAGE AND ADMINISTRATION Dosage should be individualized to obtain an adequate response with the lowest effective dose. (2.1) Late evening administration should be avoided (risk of insomnia). (2.1) Phentermine hydrochloride tablets can be taken with or without food. (2.1) Limit the dosage to 15 mg daily for patients with severe renal impairment (eGFR 15 to 29 mL/min/1.73 m 2 ) (2.2) 2.1 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. 2.2 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 (8.6) and Clinical Pharmacology (12.3)].

6 ADVERSE REACTIONS 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. Central Nervous System Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache, psychosis. Gastrointestinal Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances. Allergic Urticaria. Endocrine Impotence, changes in libido. Adverse events have been reported in the cardiovascular, central nervous, gastrointestinal, allergic, and endocrine systems. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Sun Pharmaceutical Industries, Inc. at 1-800-406-7984 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

5 WARNINGS AND PRECAUTIONS 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. ( 5.4 ) Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle. ( 5.5 ) Risk of abuse and dependence. The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage. ( 5.6 ) Concomitant alcohol use may result in an adverse drug reaction. ( 5.7 ) Use caution in patients with even mild hypertension (risk of increase in blood pressure). ( 5.8 ) A reduction in dose of insulin or oral hypoglycemic medication may be required in some patients. ( 5.9 ) 5.1 Coadministration With Other Drug Products for Weight Loss Phentermine hydrochloride tablets are indicated only as short-term (a few weeks) monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss including prescribed drugs, over-the-counter preparations, and herbal products, or serotonergic agents such as selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of phentermine and these drug products is not recommended. 5.2 Primary Pulmonary Hypertension Primary Pulmonary Hypertension (PPH) – a rare, frequently fatal disease of the lungs has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken phentermine alone. The initial symptom of PPH is usually dyspnea. Other initial symptoms may include angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema, and patients should be evaluated for the possible presence of pulmonary hypertension. 5.3 Valvular Heart Disease Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss. The possible role of phentermine in the etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone. 5.4 Development of Tolerance, Discontinuation in Case of Tolerance When tolerance to the anorectant effect develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued. 5.5 Effect on the Ability to Engage in Potentially Hazardous Tasks Phentermine 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. 5.6 Risk of Abuse and Dependence Phentermine is related chemically and

4 CONTRAINDICATIONS 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., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension) ( 4 ) During or within 14 days following the administration of monoamine oxidase inhibitors ( 4 ) Hyperthyroidism ( 4 ) Glaucoma ( 4 ) Agitated states ( 4 ) History of drug abuse ( 4 ) Pregnancy ( 4 , 8.1 ) Nursing ( 4 , 8.3 ) Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines ( 4 )

10 OVERDOSAGE 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. Overdosage of pharmacologically similar compounds has resulted in fatal poisoning usually terminates in convulsions and coma. Management of acute phentermine hydrochloride 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 ® , CIBA) has been suggested on pharmacologic grounds for possible acute, severe hypertension, if this complicates overdosage. 10.2 Chronic Intoxication 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. See Drug Abuse and Dependence (9.3) .