Phentermine Contraindications and Precautions
- angina
- anorexia nervosa
- arteriosclerosis
- cardiac arrhythmias
- cardiac disease
- glaucoma
- hypertension
- hyperthyroidism
- pulmonary hypertension
- valvular heart disease
- abrupt discontinuation
- alcoholism
- breast-feeding
- children
- depression
- diabetes mellitus
- driving or operating machinery
- elderly
- pregnancy
- substance abuse
- suicidal ideation
- surgery
- thyroid disease
Phentermine Contraindications and Precautions
Phentermine is contraindicated in patients with advanced arteriosclerosis, agitated states, moderate to severe hypertension, glaucoma, or symptomatic cardiovascular disease including cardiac arrhythmias. Phentermine is not recommended for use in patients with cardiac disease including valvular heart disease. Valvular heart disease has been reported in women receiving the combination of fenfluramine and phentermine (FDA Public Health Advisory, July 8, 1997). The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss, including selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of these drug products for weight loss is not recommended. Further, primary pulmonary hypertension (PPH) has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between the use of phentermine alone and PPH or valvular heart disease cannot be ruled out. The initial symptom of PPH is usually dyspnea. Other initial symptoms 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.
Because phentermine is a sympathomimetic agent, it is contraindicated in thyroid disease patients with hyperthyroidism.
Phentermine should not be administered during or within 14 days following the use of MAOIs or drugs with MAO-inhibiting activity. Monoamine oxidase inhibitors (MAOIs), or drugs that possess MAO-inhibiting activity such as furazolidone or procarbazine, can prolong and intensify the cardiac stimulation and vasopressor effects of phentermine.
Abrupt discontinuation of phentermine after prolonged high doses may result in severe mental depression or extreme fatigue; sleep EEG changes have also been noted. Gradual withdrawal of therapy is recommended.
Phentermine is chemically and pharmacologically related to the amphetamines which have been extensively abused. Obesity treatment with phentermine should be tried only in weight reduction programs for whom alternative therapies, including repeated dietary reduction, exercise. Physiological dependence can occur with prolonged administration of phentermine. The appetite suppressant is not recommend for use in those patients with a history of anorexia nervosa or other eating disorders. Use should be avoided in patients with a known history of substance abuse. Risk versus benefit should be weighed in patients with a history of alcoholism, major depression, or suicidal ideation. Symptoms of chronic intoxication include insomnia, irritability, change in personality, and psychotic symptoms that may be clinically indistinguishable from other psychotic disorders, like schizophrenia. The least amount reasonable should be prescribed or dispensed at one time in order to limit the potential for overuse or drug diversion.
Phentermine is classified pregnancy category C. Safe use of phentermine during pregnancy has not been established. Phentermine should not be taken by pregnant women or by women who may become pregnant unless, in the opinion of the physician, the potential benefits outweigh the possible hazards.
It is not known whether phentermine and its metabolites are excreted in breast milk. Because of the potential for serious adverse effects in the nursing infants, breast-feeding while taking phentermine is not recommended.
Safety and effectiveness of phentermine in children have not been established. Phentermine is not recommended for patients under 16 years of age.
Use phentermine cautiously in patients with diabetes mellitus. Insulin requirements may be altered in these patients when using phentermine and changing dietary regimens.
The use of phentermine may cause dizziness, mask signs of fatigue or the need for rest, or impair the ability of a patient to participate in activities that require mental alertness. Patients should not perform such tasks, including driving or operating machinery, until they are aware of how this medication affects them. Debilitated patients or the elderly may be more susceptible to the CNS and sympathomimetic side effects of the phentermine; use with caution in elderly patients.
The use of inhalational anesthetics during surgery may sensitize the myocardium to the effects of sympathomimetic drugs. Because of this, and its effects on blood pressure, phentermine should be discontinued several days prior to surgery.
[ Last revised: 1/27/2004 3:53:00 PM ]
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