Clinical features:
(1) onset or worsening of Parkinson-like symptoms after starting a medication
(1a) tremor
(1b) rigidity
(1c) slowness of movement (bradykinesia)
(2) symmetric symptoms (Parkinson's disease is classically asymmetrical)
(3) remission of Parkinson-like symptoms after stopping the drug (but this may take several months to even years)
(4) improvement with antimuscarinic agent or amantadine therapy
The most common drugs involved are the neuroleptics, especially typical agents:
(1) haloperidol
(2) phenothiazines
(3) thioxanthenes
Key mechanisms are depletion of dopamine stores and/or blocking of dopamine receptors.
Other drugs involved:
(1) selective serotonin-reuptake inhibitors (SSRI)
(2) amoxapine
(3) droperidol
(4) metoclopramide
(5) prochlorperazine
(6) promethazine
(7) valproic acid
(8) alpha-methyldopa
(9) amiodarone
(10) calcium channel blockers
(11) reserpine
(12) cinnarizine
(13) flunarizine
(14) disulfiram
(15) pimozide
(16) tetrabenazine
Risk factors:
(1) AIDS
(2) higher dose of offending drug
(3) female gender
(4) use of central dopamine-receptor blocking agents
(5) susceptibility to extrapyramidal signs
