Phendimetrazine Tartrate Ext-rel

  • Obesity

Phendimetrazine Tartrate Ext-rel Generic Name & Formulations

General Description

Phendimetrazine tartrate 105mg; ext-rel caps.

Pharmacological Class

Phenylalkylamine sympathomimetic amine.

How Supplied

Caps—100, 1000

How Supplied

Phendimetrazine tartrate is supplied as brown/clear extended-release capsules imprinted with E 5254 in:

  • Bottles of 30
  • Bottles of 1000


Store at 20° to 25° C (68° to 77° F).

Protect from moisture.

Phendimetrazine Tartrate Ext-rel Indications


Management of exogenous obesity as a short term adjunct (a few weeks) in a regimen of weight reduction based on caloric restriction in patients with an initial body mass index (BMI) of ≥30kg/m2 or ≥27kg/m2 in the presence of other risk factors (eg, controlled hypertension, diabetes, hyperlipidemia) who have not responded to appropriate weight reducing regimen (diet and/or exercise) alone.

Phendimetrazine Tartrate Ext-rel Dosage and Administration


≥17yrs: 1 cap in the AM (30–60mins before morning meal).


<17yrs: not recommended.

Phendimetrazine Tartrate Ext-rel Contraindications


History of cardiovascular disease (eg, coronary artery disease, stroke, arrhythmias, CHF, uncontrolled hypertension, pulmonary hypertension). Hyperthyroidism. Glaucoma. Agitated states. History of drug abuse. Pregnancy. Nursing mothers. Concomitant other CNS stimulants, anorectic agents. During or within 14 days of MAOIs.

Phendimetrazine Tartrate Ext-rel Boxed Warnings

Not Applicable

Phendimetrazine Tartrate Ext-rel Warnings/Precautions


Increased risk of pulmonary hypertension with repeated courses. Heart murmer, valvular heart disease: not recommended. Do not exceed max recommended dose. Obtain baseline cardiac evaluation prior to initiating therapy to detect pre-existing valvular heart disease or pulmonary hypertension. Mild hypertension. Diabetes. Prescribe minimal supply to avoid overdose. Renal impairment. Elderly.


In a case-control epidemiological study, the use of anorectic agents, including phendimetrazine tartrate, was associated with an increased risk of developing pulmonary hypertension, a rare, but often fatal disorder. The use of anorectic agents for longer than three months was associated with a 23-fold increase in the risk of developing pulmonary hypertension. Increased risk of pulmonary hypertension with repeated courses of therapy cannot be excluded.

The onset or aggravation of exertional dyspnea, or unexplained symptoms of angina pectoris, syncope, or lower extremity edema suggest the possibility of occurrence of pulmonary hypertension. Under these circumstances, phendimetrazine tartrate should be immediately discontinued, and the patient should be evaluated for the possible presence of pulmonary hypertension.

Valvular heart disease associated with the use of some anorectic agents such as fenfluramine and dexfenfluramine has been reported. Possible contributing factors include use for extended periods of time, higher than recommended dose, and/or use in combination with other anorectic drugs.

The potential risk of possible serious adverse effects such as valvular heart disease and pulmonary hypertension should be assessed carefully against the potential benefit of weight loss. Baseline cardiac evaluation should be considered to detect preexisting valvular heart diseases or pulmonary hypertension prior to initiation of phendimetrazine treatment. Phendimetrazine tartrate is not recommended in patients with known heart murmur or valvular heart disease. Echocardiogram during and after treatment could be useful for detecting any valvular disorders which may occur. Tolerance to the anorectic effect of phendimetrazine develops within a few weeks. When this occurs, its use should be discontinued; the maximum recommended dose should not be exceeded. Use of phendimetrazine tartrate within 14 days following the administration of monoamine oxidase inhibitors may result in a hypertensive crisis. 

Abrupt cessation of administration following prolonged high dosage results in extreme fatigue and depression. 

Because of the effect on the central nervous system, phendimetrazine 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.

Caution is to be exercised in prescribing phendimetrazine tartrate for patients with even mild hypertension.

Insulin or oral hypoglycemic medication requirements in diabetes mellitus may be altered in association with the use of phendimetrazine and the concomitant dietary regimen.

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

Phendimetrazine tartrate is related chemically and pharmacologically to the amphetamines. Amphetamines and related stimulant drugs have been extensively abused and the possibility of abuse of phendimetrazine 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. 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.

Pregnancy Considerations

Phendimetrazine tartrate 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.

Animal reproduction studies have not been conducted in phendimetrazine tartrate. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus.

Nursing Mother Considerations

It is not known if phendimetrazine tartrate is excreted in human milk. Phendimetrazine tartrate, a phenylalkylamine sympathomimetic amine, has pharmacological activity similar to the amphetamines, and other amphetamines are present in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Considerations

Safety and effectiveness in pediatric patients have not been established. Because pediatric obesity is a chronic condition requiring long-term treatment, the use of phendimetrazine tartrate ER approved for short-term therapy, is not recommended in patients <17 years of age.

Geriatric Considerations

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.

The major route of elimination is via the kidney where most of the drug and metabolites are excreted. The risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Renal Impairment Considerations

Phendimetrazine tartrate extended-release capsules were not studied in patients with renal impairment. As phendimetrazine tartrate is excreted in urine, exposure increases can be expected in patients with renal impairment. Use caution when administering phendimetrazine tartrate to patients with renal impairment.

Phendimetrazine Tartrate Ext-rel Pharmacokinetics


The major route of elimination is via the kidneys where most of the drug and metabolites are excreted. Some of the drug is metabolized to phenmetrazine and also phendimetrazine-N-oxide.

The average half-life of elimination is about 3.7 hours for both the extended-release and immediate release forms. 

Phendimetrazine Tartrate Ext-rel Interactions


See Contraindications. Hypertensive crisis with MAOIs. Anorectic agents use within prior year: not recommended. Insulin and oral hyperglycemic requirements may be altered. May decrease hypotensive effect of guanethidine, adrenergic neuron blocking drugs. Concomitant alcohol may result in adverse drug reaction.


Use of phendimetrazine tartrate is contraindicated during or within 14 days following the administration of monoamine oxidase inhibitors because of the risk of hypertensive crisis.

Phendimetrazine tartrate should not be used in combination with other anorectic agents, including prescribed drugs, over-the-counter preparations and herbal products.

Phendimetrazine Tartrate Ext-rel Adverse Reactions

Adverse Reactions

Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevated BP, ischemic events, overstimulation, restlessness, insomnia, agitation, flushing, tremor, sweating, dizziness, headache, psychotic state, blurred vision, dry mouth, GI upset, constipation, stomach pain, urinary frequency, dysuria, changes in libido; tolerance (discontinue when occurs), withdrawal effects (w. prolonged use).

Phendimetrazine Tartrate Ext-rel Clinical Trials

See Literature

Phendimetrazine Tartrate Ext-rel Note


Formerly known under the brand name Bontril.

Phendimetrazine Tartrate Ext-rel Patient Counseling

See Literature