Complete adverse effect profile including incidence rates and management
Important Safety Information
This is not a complete list of all possible side effects. Contact your healthcare provider if you experience any unexpected symptoms. For serious or life-threatening side effects, seek emergency medical attention immediately.
ADVERSE REACTIONS Central Nervous System Sedation The most common adverse reaction to metyrosine is moderate to severe sedation, which has been observed in almost all patients.
It occurs at both low and high dosages.
Sedative effects begin within the first 24 hours of therapy, are maximal after two to three days, and tend to wane during the next few days.
Sedation usually is not obvious after one week unless the dosage is increased, but at dosages greater than 2000 mg/day some degree of sedation or fatigue may persist.
In most patients who experience sedation, temporary changes in sleep pattern occur following withdrawal of the drug.
Changes consist of insomnia that may last for two or three days and feelings of increased alertness and ambition.
Even patients who do not experience sedation while on metyrosine may report symptoms of psychic stimulation when the drug is discontinued.
Extrapyramidal Signs Extrapyramidal signs such as drooling, speech difficulty, and tremor have been reported in approximately 10% of patients.
These occasionally have been accompanied by trismus and frank parkinsonism.
Anxiety and Psychic Disturbances Anxiety and psychic disturbances such as depression, hallucinations, disorientation, and confusion may occur.
WARNINGS Maintain Fluid Volume During and After Surgery When metyrosine is used preoperatively, alone or especially in combination with alpha-adrenergic blocking drugs, adequate intravascular volume must be maintained intraoperatively (especially after tumor removal) and postoperatively to avoid hypotension and decreased perfusion of vital organs resulting from vasodilatation and expanded volume capacity.
Following tumor removal, large volumes of plasma may be needed to maintain blood pressure and central venous pressure within the normal range.
In addition, life-threatening arrhythmias may occur during anesthesia and surgery, and may require treatment with a beta-blocker or lidocaine.
During surgery, patients should have continuous monitoring of blood pressure and electrocardiogram.
Intraoperative Effects While the preoperative use of metyrosine in patients with pheochromocytoma is thought to decrease intraoperative problems with blood pressure control, metyrosine does not eliminate the danger of hypertensive crises or arrhythmias during manipulation of the tumor, and the alpha-adrenergic blocking drug, phentolamine, may be needed.
Like all medications, Metyrosine can cause side effects. However, not everyone who takes this medication will experience them. Many side effects are dose-dependent and may improve as your body adjusts to the medication. Others may require dose adjustment or medical attention.
Contact your healthcare provider promptly if you experience:
Seek immediate emergency medical care if you experience signs of: