Phentermine and Alcohol/Food Interactions

GENERALLY AVOID: Alcohol may potentiate the central nervous system and cardiovascular effects of centrally-acting appetite suppressants. In one study, concurrent administration of methamphetamine (30 mg intravenously) and ethanol (1 gm/kg orally over 30 minutes) increased heart rate by 24 beats/minute compared to methamphetamine alone. This increases cardiac work and myocardial oxygen consumption, which may lead to more adverse cardiovascular effects than either agent alone. Subjective effects of ethanol were diminished in the eight study subjects, but those of methamphetamine were not affected. The pharmacokinetics of methamphetamine were also unaffected except for a decrease in the apparent volume of distribution at steady state.

MANAGEMENT: Concomitant use of centrally-acting appetite suppressants and alcohol should be avoided if possible, especially in patients with a history of cardiovascular disease. Patients should be counselled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

CNS stimulants - cardiac disease

Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.

CNS stimulants - hypertension

CNS stimulants increase blood pressure and heart rate; the use of some agents may be contraindicated in patients with severe/uncontrolled hypertension. Caution should be used when administering to patients with preexisting high blood pressure (even mild hypertension) and other cardiovascular conditions. All patients under treatment should be regularly monitored for potential tachycardia and hypertension.