Drug Interactions between Adderall XR and colchicine

GENERALLY AVOID: Coadministration with grapefruit juice may increase the serum concentrations of colchicine. Clinical toxicity including myopathy, neuropathy, multiorgan failure, and pancytopenia may occur. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism and P-glycoprotein efflux in the gut wall by certain compounds present in grapefruits. A published case report describes an eight-year-old patient with familial Mediterranean fever who developed acute clinical colchicine intoxication after ingesting approximately one liter of grapefruit juice per day for two months prior to hospital admission while being treated with colchicine 2 mg/day. Her condition progressed to circulatory shock and multiorgan failure, but she recovered with supportive therapy after 24 days in the hospital. In a study of 21 healthy volunteers, administration of 240 mL grapefruit juice twice a day for 4 days was found to have no significant effect on the pharmacokinetics of a single 0.6 mg dose of colchicine. However, significant interactions have been reported with other CYP450 3A4 inhibitors such as clarithromycin, diltiazem, erythromycin, ketoconazole, ritonavir, and verapamil.

MANAGEMENT: Patients treated with colchicine should be advised to avoid the consumption of grapefruit and grapefruit juice, and to contact their physician if they experience symptoms of colchicine toxicity such as abdominal pain, nausea, vomiting, diarrhea, fatigue, myalgia, asthenia, hyporeflexia, paresthesia, and numbness.

GENERALLY AVOID: Alcohol may potentiate the cardiovascular effects of amphetamines. The exact mechanism of interaction is unknown. 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. The interaction was suspected in a case report of a 20-year-old male who experienced retrosternal chest pain shortly after drinking alcohol and taking a double dose of his amphetamine/dextroamphetamine medication (Adderall 15 mg X 2) to stay alert. The patient had no family history of cardiovascular diseases, and his past medical history was remarkable only for ADHD. Prior to the episode, the patient had not taken his medication for weeks and had been drinking whiskey the previous three nights before going to bed. The patient was diagnosed with myocardial infarction likely secondary to amphetamine-induced coronary vasospasm.

MANAGEMENT: Concomitant use of amphetamines and alcohol should be avoided if possible, especially in patients with a history of heart disease.

GENERALLY AVOID: Alcohol may potentiate the cardiovascular effects of amphetamines. The exact mechanism of interaction is unknown. 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. The interaction was suspected in a case report of a 20-year-old male who experienced retrosternal chest pain shortly after drinking alcohol and taking a double dose of his amphetamine/dextroamphetamine medication (Adderall 15 mg X 2) to stay alert. The patient had no family history of cardiovascular diseases, and his past medical history was remarkable only for ADHD. Prior to the episode, the patient had not taken his medication for weeks and had been drinking whiskey the previous three nights before going to bed. The patient was diagnosed with myocardial infarction likely secondary to amphetamine-induced coronary vasospasm.

MANAGEMENT: Concomitant use of amphetamines and alcohol should be avoided if possible, especially in patients with a history of heart disease.