valvular heart disease
Phendimetrazine Contraindications and Precautions
Phendimetrazine is contraindicated in patients with advanced arteriosclerosis, glaucoma, or who are highly nervous or agitated including those with psychosis or mania. Phendimetrazine 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 can prolong and intensify the cardiac stimulation and vasopressor effects of phendimetrazine (see Drug Interactions).
Because phendimetrazine is a sympathomimetic agent, it is contraindicated in thyroid disease patients with hyperthyroidism.
In a case-control epidemiological study, the use of anorectic agents, including phendimetrazine, was associated with an increased risk of developing pulmonary hypertension, a rare, but often fatal disorder. The use of anorectic agents for longer than 3 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 should be immediately discontinued, and the patient should be evaluated for the possible presence of pulmonary hypertension.
Phendimetrazine is contraindicated in patients with moderate to severe hypertension, symptomatic cardiac disease including cardiac arrhythmias. Caution should also be exercised in patients with even mild hypertension. Valvular heart disease has been associated with the use of some anorectic agents such as fenfluramine and dexfenfluramine. Possible contributing factors include use for extended periods of time, higher than recommended dose, and/or use in combination with other anorectic drugs. Valvulopathy has not been reported with phendimetrazine monotherapy. 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 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.
Abrupt discontinuation of phendimetrazine 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.
Phendimetrazine is chemically and pharmacologically related to the amphetamines which have been extensively abused. Obesity treatment with phendimetrazine 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 phendimetrazine. 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.
Phendimetrazine is not recommended for children and adolescents under 16 years of age. Safe and effective use in pediatric patients has not been established.
Phendimetrazine is classified pregnancy category C. Safe use of phentermine during pregnancy has not been established. Phendimetrazine 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 phendimetrazine and its metabolites are excreted in breast milk. Because of the potential for serious adverse effects in the nursing infants, breast-feeding while taking phendimetrazine is not recommended.
Concurrent use of phendimetrazine with other anorectic agents is contraindicated. Phendimetrazine is not recommended for patients who used any anorectic agent within the prior year.
Use phendimetrazine cautiously in patients with diabetes mellitus. Insulin requirements may be altered in these patients when using phendimetrazine and changing dietary regimens.
The use of phendimetrazine 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 phendimetrazine; 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, phendimetrazine should be discontinued several days prior to surgery.
[ Last revised: 2/1/2002 ]
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