Drug Interactions between atorvastatin and Xadago

GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of atorvastatin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. When a single 40 mg dose of atorvastatin was coadministered with 240 mL of grapefruit juice, atorvastatin peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 16% and 37%, respectively. Greater increases in Cmax (up to 71%) and/or AUC (up to 2.5 fold) have been reported with excessive consumption of grapefruit juice (>=750 mL to 1.2 liters per day). Clinically, high levels of HMG-CoA reductase inhibitory activity in plasma is associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death.

ADJUST DOSING INTERVAL: Fibres such as oat bran and pectin may diminish the pharmacologic effects of HMG-CoA reductase inhibitors by interfering with their absorption from the gastrointestinal tract.

MANAGEMENT: Patients receiving therapy with atorvastatin should limit their consumption of grapefruit juice to no more than 1 liter per day. Patients should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. In addition, patients should either refrain from the use of oat bran and pectin or, if concurrent use cannot be avoided, to separate the administration times by at least 2 to 4 hours.

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GENERALLY AVOID: Foods that contain large amounts of tyramine may precipitate a hypertensive crisis in patients treated with safinamide. The proposed mechanism involves potentiation of the tyramine pressor effect due to inhibition of monoamine oxidase (MAO) by safinamide. Monoamine oxidase in the gastrointestinal tract and liver, primarily type A (MAO-A), is the enzyme responsible for metabolizing exogenous amines such as tyramine and preventing them from being absorbed intact. Once absorbed, tyramine is metabolized to octopamine, a substance that is believed to displace norepinephrine from storage granules causing a rise in blood pressure. In vitro, safinamide inhibits MAO-B with greater than 1000-fold selectivity over MAO-A, and neither safinamide nor its major metabolites inhibit MAO-A at clinically relevant concentrations. Results from an oral tyramine challenge study also suggest that safinamide is a selective inhibitor of MAO-B at the recommended dosages of 50 or 100 mg/day. However, this selectivity is not absolute and may diminish in a dose-related manner above the maximum recommended daily dosage. In clinical trials, the incidence of hypertension was 7% and 5% for safinamide 50 mg and 100 mg, respectively, versus 4% for placebo. There were no reported cases of hypertensive crisis.

Administration of safinamide following intake of a high-fat, high-caloric breakfast resulted in a slight delay in the absorption of safinamide, but had no effects on safinamide peak plasma concentration (Cmax) and systemic exposure (AUC) compared to administration under fasted conditions.

MANAGEMENT: Dietary restriction is not ordinarily required during safinamide treatment with respect to most foods and beverages that contain tyramine, which usually include aged, fermented, cured, smoked, or pickled foods (e.g., air-dried and fermented meats or fish, aged cheeses, most soybean products, yeast extracts, red wine, beer, sauerkraut). However, certain foods like some of the aged cheeses (e.g., Boursault, Liederkrantz, Mycella, Stilton) and pickled herring may contain very high amounts of tyramine and could potentially cause a hypertensive reaction in patients taking safinamide, even at recommended dosages, due to increased sensitivity to tyramine. Patients should be advised to avoid the intake of very high levels of tyramine (e.g., greater than 150 mg) and to promptly seek medical attention if they experience potential signs and symptoms of a hypertensive crisis such as severe headache, visual disturbances, confusion, stupor, seizures, chest pain, unexplained nausea or vomiting, and stroke-like symptoms. Blood pressure should be regularly monitored and managed accordingly. Medication adjustment may be necessary if blood pressure elevations are sustained or not adequately controlled. Safinamide should not be used at dosages exceeding 100 mg/day, or 50 mg/day in patients with moderate hepatic impairment (Child-Pugh B, 7-9), as it may increase the risk of hypertensive crisis and other adverse reactions associated with nonselective inhibition of MAO. Safinamide can be administered with or without food.

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