Tenuate (Diethylpropion) Interactions
Antidiabetic Agents
Antihypertensive Agents
Halogenated anesthetics
Monoamine oxidase inhibitors (MAOIs)
Phenothiazines
Psychostimulants
Radiopaque Contrast Agents
Sympathomimetics
Thyroid hormones
Tricyclic antidepressants
Tenuate (Diethylpropion) Interactions
Diethylpropion has vasopressor effects and may limit the benefit of antihypertensive agents particularly sympatholytic agents such as guanadrel, guanethidine, methyldopa or reserpine. Diethylpropion may displace guanethidine from the neuron and antagonize the neuronal blockade caused by guanethidine. Concomitant use of diethylpropion with methyldopa or reserpine may antagonize the antihypertensive effects of these agents. Although leading drug interaction texts differ in the potential for an interaction between diethylpropion and this group of antihypertensive agents, these effects are likely to be clinically significant and have been described in hypertensive patients on these medications.
All sympathomimetics and psychostimulants, including other anorexiants, should be used cautiously or avoided in patients receiving diethylpropion. The efficacy of diethylpropion when used with other anorexiants such as amphetamine, dexfenfluramine, fenfluramine, phendimetrazine, or phentermine has not been studied. The combined use of these agents may have the potential for serious cardiac adverse effects such as hypertensive crisis and cardiac arrhythmias. Similarly, diethylpropion should not be used in combination with OTC preparations and herbal products that may contain caffeine, ephedrine, ephedra alkaloids or Ma huang.
Atomoxetine, an inhibitor of norepinephrine reuptake used for treatment of ADHD, has been shown to increase heart rate and blood pressure. Diethylpropion also inhibits norepinephrine reuptake. The combination of atomoxetine with diethylpropion should be used extremely cautiously, if at all, due to the potential for serious increases in blood pressure and/or heart rate. If these agents must be used concomitantly, consider monitoring blood pressure and heart rate at baseline and regularly throughout treatment.
Sibutramine is contraindicated in patients taking other centrally-acting appetite suppressant drugs, including diethylpropion.
Diabetic patients may have decreased insulin requirements in association with the use of diethylpropion and the concomitant dietary regimen and weight loss. Diethylpropion enhances the hypoglycemic activity of insulin by increasing the uptake of glucose by skeletal muscle cells. Diethylpropion also exhibits intrinsic hypoglycemic activity and can lower postprandial blood glucose concentrations. Diethylpropion should be used cautiously in diabetic patients who are stabilized on insulin, sulfonylureas, or other antidiabetic agents or on diet alone.
Interactions between sympathomimetics and MAOIs can be severe. Monoamine oxidase inhibitors (MAOIs) or other drugs that possess MAO-inhibiting activity such as furazolidone , linezolid , or procarbazine, can prolong and intensify the cardiac stimulation and vasopressor effects of diethylpropion. In the presence of MAOIs, diethylpropion and other drugs that cause release of norepinephrine induce severe cardiovascular and cerebrovascular responses. Cases have been documented where seizures and pyrexia have occurred. Diethylpropion should not be administered during, or within 14 days following the use of MAOIs, or drugs with MAO-inhibiting activity.
Concurrent use of diethylpropion and phenothiazines may antagonize the anorectic effects of diethylpropion. In addition, psychostimulants can aggravate psychotic states.
Administration of tricyclic antidepressants with diethylpropion and other amphetamine derivatives has been reported to result in enhanced amphetamine effects from the release of norepinephrine. Acute increases in blood pressure have been noted. Conversely, tricyclic antidepressants may decrease the effects of anorexiants.
Phentermine and diethylpropion have a similar mechanism of action. When phentermine was given with fluoxetine, adrenergic excess and dyskinesia were observed. Thus, diethylpropion may interact with fluoxetine similarly. It is unclear, however, if all SSRIs would be affected as fluoxetine has the longest half-life of the group.
Halogenated anesthetics sensitize the myocardium to the effects of the sympathomimetics. Because of this, and its effects on blood pressure, diethylpropion should be discontinued several days prior to surgery.
Diethylproprion has CNS depressant properties. Although not studied, the concomitant use of ethanol and diethylproprion may result in an adverse reaction. The manufacturer recommends that alcohol should be avoided during diethylproprion therapy.
Caution is advised when using thyroid hormones in combination with diethylpropion; co-administration of sympathomimetics and thyroid hormones can enhance the cardiovascular effects of both agents. Patients with coronary artery disease have an increased risk of developing coronary insufficiency from either agent. Use of these agents concomitantly may increase this risk even further.
Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Diethylpropion should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
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