Apomorphine

How It Works

Apomorphine is the most potent dopamine agonist available for Parkinson's disease, stimulating both D1 and D2 receptor families. Despite its name, it is not related to morphine or opioids. It is uniquely used as a rapid-acting rescue medication for acute off-episodes — sudden, unpredictable periods when PD medications stop working and motor symptoms return. Apokyn is administered by subcutaneous injection; Kynmobi as a sublingual film; and Onapgo (FDA approved February 2025) as the first subcutaneous continuous infusion for ongoing motor fluctuation management.

Typical Dosing

Apokyn: test dose 2mg subcutaneous injection under medical supervision; usual dose 2-6mg per injection, max 5 doses/day. Kynmobi: start 10mg sublingual film; titrate to effective dose up to 30mg. Onapgo: continuous subcutaneous infusion via pump, dose individualized. Pre-treat with trimethobenzamide for 3 days before starting to prevent severe nausea.

Dosing is individualized by the prescribing physician. The information above is for general reference only.

Common Side Effects

• Severe nausea (requires antiemetic pretreatment for injection/film)
• Injection site reactions or nodules
• Yawning
• Drowsiness
• Dizziness
• Oral mucosal irritation (Kynmobi)

Serious Side Effects

Seek medical attention immediately if you experience any of the following:

• Severe hypotension
• QT prolongation
• Impulse control disorders
• Priapism (rare)
• Falls from sudden onset of effect
• Somnolence

Contraindications

• Concurrent 5-HT3 antagonists (ondansetron, granisetron) — risk of profound hypotension and loss of consciousness
• IV administration (risk of crystal formation and embolism)

Food Interactions

Not related to morphine despite the name. Injection form can be used regardless of food. Sublingual film should not be taken with food or water for 30 minutes before and after.

How Apomorphine Compares to Alternatives

Apomorphine is in a class of its own as the only rescue therapy for acute PD off-episodes. No other medication provides comparably rapid relief. Compared to oral PD medications: onset is 10-20 minutes (injection) vs. 30-60 minutes for most oral drugs. The continuous infusion (Onapgo) competes with the subcutaneous levodopa infusion (Vyalev/Produodopa) — both require wearing a pump, but apomorphine works through direct dopamine receptor stimulation while levodopa requires enzymatic conversion. Compared to Duopa (intestinal levodopa gel): apomorphine infusion does not require surgical PEG-J tube placement. The major trade-off is the side effect burden, particularly nausea, injection site reactions, and the need for antiemetic pretreatment.

When Is Apomorphine Used by Disease Stage?

Not used in early PD. Apomorphine is specifically indicated for patients with advanced PD (Stages 3-5) who experience significant off-episodes despite optimized oral therapy. Mid-stage PD (Stage 2.5-3): May be introduced for intermittent rescue use (Apokyn injection or Kynmobi film) when wearing-off episodes are unpredictable or socially disruptive. Advanced PD (Stages 4-5): All three formulations may be considered. Onapgo continuous infusion is appropriate for patients with frequent or prolonged off-episodes who want an alternative to Duopa or DBS.

Additional Notes

The only FDA-approved rescue therapy for acute off-episodes. Provides the fastest relief of any PD medication (10-20 minutes for injection, 15-30 minutes for sublingual film). Onapgo (approved February 2025) is the first continuous subcutaneous apomorphine infusion available in the US, providing sustained delivery for patients with frequent or prolonged off-episodes. Kynmobi sublingual film (approved 2020) provides a needle-free option. Patient/caregiver must be trained on injection technique for Apokyn.