Infrequently (0.1-1%) occurring adverse reactions are congestive heart failure, psychosis, urinary retention, dyspnea, fatigue, skin rash, vomiting, weakness, slurred speech, euphoria, confusion, thinking abnormality, amnesia, hyperkinesia, hypertension, decreased libido, and visual disturbance, including punctuate subepithelial or other cornal opacity, corneal edema, decreased visual acuity, sensitivity to light and optic nerve palsy.
Rare (less than 0.1%) occurring adverse reactions are instances of convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide and suicidal ideation. (See WARNINGS)
WARNINGS: A small number of suicidal attempts, some of which have been fatal, have been reported in patients treated with Symmetrel. The incidence of suicidal attempts is not known and the pathophysiologic mechanism is not understood. Suicidal attempts and suicidal ideation have been reported in patients with and without prior history of psychiatric illness. Symmetrel can exacerbate mental problems in patients with a history of psychiatric disorders or substance abuse. Patients who attempt suicide may exhibit abnormal mental states which include disorientation, confusion, depression, personality changes, agitation, aggressive behavior hallucinations, paranoia, other psychotic reacitons, and somnolence or insomnia. Because of the possibility of serious adverse effects, caution should be observed when prescribing Symmetrel to patients being treated with drugs having CNS effects, or for whom the potential risks outweigh the benefit of treatment. Because some patients have attempted suicide by overdosing with amantadine, prescriptions should be written for the smallest quantity consistent with good patient management.
Patients with a history of epilepsy or other "seizures" should be observed closely for possible increased seizure activity. Patients with a history of congestive heart failure or peripheral edema should be followed closely as there are patients who developed congestive heart failure while receiving Symmetrel.
Patients receiving Symmetrel who note central nervous system effects or blurring of vision should be cautioned against driving or working in situations where alertness and adequate motor coordination are important.