Apokyn (apomorphine hydrochloride) for Parkinson’s disease

What is Apokyn for Parkinson’s disease?

Apokyn (apomorphine hydrochloride injection) is an approved injectable therapy used to treat off episodes — periods when symptoms return between doses of levodopa — in people with advanced Parkinson’s disease.

Parkinson’s occurs when the nerve cells that produce dopamine, a chemical messenger, gradually die, causing a variety of motor and nonmotor symptoms.

A mainstay among Parkinson’s treatments is levodopa, a precursor to dopamine. The brain converts levodopa into dopamine, boosting levels of the messenger molecule and easing Parkson’s symptoms. However, as the disease progresses, the medication often becomes less effective, resulting in off episodes between doses.

Apokyn aims to treat these off episodes by using a different mechanism to boost dopamine signaling. Its active ingredient is a dopamine agonist, a type of molecule that mimics the effects of dopamine in the brain by binding to the same receptors. This can help ease symptoms as a dose of levodopa wears off and dopamine availability declines.

The medication, given via under-the-skin (subcutaneous) injections, is marketed in the U.S. by Supernus Pharmaceuticals. It is also available in generic form. In Europe and Canada, Apokyn is sold by Britannia Pharmaceuticals under brand names such as APO-go and Apokinon.

Therapy snapshot

Brand name	Apokyn
Chemical name	Apomorphine hydrochloride
Usage	Used as an add-on therapy to reduce off periods in advanced Parkinson’s
Administration	Subcutaneous injection

Who can take Apokyn?

In the U.S., Apokyn is approved to treat intermittent off episodes in people with advanced Parkinson’s. It holds similar approvals in several other regions.

Apokyn’s prescribing information lists two contraindications, or reasons not to use, the therapy:

• if concurrently using 5HT3 antagonists, a class of medications often prescribed to treat nausea or vomiting
• if allergic to Apokyn or its ingredients, which include sodium metabisulfite

Apokyn is typically not recommended for people with major psychotic disorders because of the risk of psychosis exacerbation.

How is Apokyn administered?

Apokyn is administered as a subcutaneous injection via its provided injection pens. The first dose should be given under medical supervision, but after proper training on how to inject Apokyn, patients and caregivers may use the therapy at home.

Injections should be given as needed for off episodes, up to five times daily, with at least two hours between doses.

The Apokyn injection dosage can be set on the pen. The recommended starting dose is usually 0.1-0.2 mL (1-2 mg), which can be adjusted as needed, under medical supervision, to a maximum of 0.6 mL/6 mg. Dose adjustments may be needed for people with kidney problems.

Per the Apokyn pen instructions, the injection site should be rotated between the stomach, upper arms, and upper legs. If one injection doesn’t resolve an off episode, patients should not attempt to use a second dose during the same episode. Apokyn should never be given as an infusion into a vein, as this can cause serious side effects.

Apokyn can cause nausea, so pretreatment with the antinausea medication trimethobenzamide, starting three days before the first dose, is recommended.

Apokyn in clinical trials

The U.S. approval of Apokyn was supported by positive data from three placebo-controlled clinical trials involving people with advanced Parkinson’s disease who were on levodopa-based treatment. In all of them, the main goal was to evaluate changes in scores on the Unified Parkinson’s Disease Rating Scale (UPDRS) Part III, which evaluates motor symptom severity.

• The first study involved 29 participants who were experiencing at least two hours of off time a day and had never received Apokyn. Treatment with Apokyn during a medically supervised off-episode led to a significant, 23.8-point improvement in UPDRS motor scores compared with the placebo. With continued treatment over the next month, Apokyn controlled significantly more off episodes than the placebo (95% vs. 23%).
• A second study enrolled 17 participants who had been using Apokyn for at least three months. Each had two off episodes treated, in random order, with Apokyn or the placebo. UPDRS motor score improvements were significantly larger, by a mean of 17 points, on days that they used Apokyn compared with the days that they used the placebo.
• The third study involved 62 participants who had been using Apokyn for at least three months. They received either their normal dose of Apokyn, a slightly higher dose, or a placebo to treat an off episode. UPDRS motor scores significantly improved by a mean of 16.8 points with Apokyn compared with the placebo. There was no added benefit of the higher dose.

Apokyn side effects

The most common side effects of Apokyn include:

• yawning
• drowsiness and sleepiness
• dyskinesia, or sudden involuntary movements
• dizziness or orthostatic hypotension, marked by a sudden drop in blood pressure when standing up
• runny nose
• nausea and/or vomiting
• hallucinations (seeing or hearing things that aren’t there) and confusion
• swelling of extremities

Dyskinesia is a common side effect of levodopa therapy. Apokyn can cause dyskinesia or exacerbate levodopa-related dyskinesia.

Patients should also be monitored for less common but potentially serious complications. If any occur, dose adjustments or discontinuation may be considered. These include:

• excessive drowsiness or falling asleep during everyday activities
• severe orthostatic hypotension and fainting
• falls
• new or worsening hallucinations and psychotic-like behavior
• problems with impulse control or impulsive behaviors
• hemolytic anemia, a condition in which red blood cells are destroyed at a high rate
• cardiovascular complications and heart rhythm abnormalities
• serious allergic reactions
• prolonged and painful erections

Earlier versions of dopamine agonists carried a risk of internal scarring. While Apokyn has a different chemical structure than these early medications, it is unknown whether it can also cause this type of complication.

Certain side effects, including confusion, hallucinations, and falls, are more likely in people older than 65. Alcohol may increase the risk of symptomatic blood pressure declines and should be avoided when using Apokyn.

Suddenly stopping treatment with Apokyn can trigger potentially serious withdrawal symptoms, including high fever and confusion. Treatment discontinuation should always be done under medical supervision.

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