Apomorphine
Apomorphine
Apomorphine is a potent, centrally acting dopamine agonist derived from morphine by acid-catalyzed rearrangement. Despite its name and chemical origin, it has little to no opioid analgesic activity.
Therapeutic uses
- Parkinson’s disease: Used as a rapidly acting rescue treatment for sudden “off” episodes, particularly when oral medication is not working. It may be administered by subcutaneous injection or continuous infusion, depending on the formulation and clinical setting.
- Erectile dysfunction: In some countries and historical formulations, it has been used as a centrally acting treatment, although it is less commonly used today.
Mechanism of action
Apomorphine stimulates dopamine receptors in the central nervous system, especially D2-like receptors. In Parkinson’s disease, this helps compensate for reduced dopaminergic signaling in the basal ganglia and can improve motor symptoms.
Important adverse effects
- Nausea and vomiting
- Dizziness and orthostatic hypotension
- Somnolence or sudden sleep episodes
- Confusion, hallucinations, or other psychiatric effects
- Dyskinesias and impulse-control symptoms
- Injection-site reactions with subcutaneous use
Because severe nausea is common, an antiemetic may be prescribed before treatment. Dopamine-blocking antiemetics are generally avoided because they can worsen Parkinsonian symptoms.
Botanical and pharmacognostic context
Apomorphine is a semisynthetic aporphine alkaloid related to compounds found in several medicinal plants. Its pharmacological activity illustrates how structural modification of a natural alkaloid can produce a clinically useful dopaminergic medicine.
Apomorphine should be used only under medical supervision, with attention to contraindications, drug interactions, blood pressure, mental status, and the risk of excessive sleepiness.