Phentermine (Page 2 of 4)


2.1 Exogenous Obesity

Dosage should be individualized to obtain an adequate response with the lowest effective dose.
The usual adult dose is 15 mg to 30 mg as prescribed by the physician, at approximately 2 hours after breakfast for appetite control. Administration of one 30 mg capsule daily has been found to be adequate in depression of the appetite for 12 to 14 hours. Phentermine is not recommended for use in pediatric patient’s≤16 years of age.
Late evening medication should be avoided because of the possibility of resulting insomnia.
With dry hands, gently remove the Phentermine Hydrochloride Capsule from the bottle. Immediately place the Phentermine Hydrochloride Capsule on top of the tongue where it will dissolve, then swallow with or without water.

2.2 Dosage in Patients with Renal Impairment

The recommended maximum dosage of Phentermine Hydrochloride Capsule is 15 mg daily for patients with severe renal impairment (eGFR 15 to 29 mL/min/1.73m2). Avoid use of Phentermine Hydrochloride Capsule in patients with eGFR less than 15 mL/min/1.73m2 or end-stage renal disease requiring dialysis [see Use in Specific Populations (8.6)and Clinical Pharmacology (12.3)]


Capsules containing 15 mg or 30 mg phentermine hydrochloride (equivalent to 12 mg or 24 mg phentermine base respectively)

15 mg Capsules: white to off-white powder filled in Size ‘3’ gray opaque/yellow opaque capsules, imprinted with “U47” on cap and body in black ink.

30 mg Capsules: white to off-white powder filled in Size ‘3’ yellow opaque/yellow opaque capsules, imprinted with “U48” on cap and body in black ink.


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
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


5.1 Coadministration with Other Drug Products for Weight Loss

Phentermine hydrochloride Capsules 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, syncopeor lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment shouldbe 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 pharmacologically to amphetamine (d- and d/ l-amphetamine) and other related stimulant drugs that have been extensively abused. 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. See Drug Abuse and Dependence (9) and Overdosage (10)].

The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.

5.7 Usage with Alcohol

Concomitant use of alcohol with phentermine may result in an adverse drug reaction.

5.8 Use in Patients with Hypertension

Use caution in prescribing phentermine for patients with even mild hypertension (risk of increase in blood pressure).

5.9 Use in Patients on Insulin or Oral Hypoglycemic Medications for Diabetes Mellitus

A reduction in insulin or oral hypoglycemic medications in patients with diabetes mellitus may be required.

5.10 Risk of Allergic Reactions

This product contains FD&C Yellow No. 5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons. Although the overall incidence of FD&C Yellow No. 5 (tartrazine) sensitivity in the general population is low, it is frequently seen in patients who also have aspirin hypersensitivity.


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:


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.


Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances.




Impotence, changes in libido.

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