Are there intravenous (IV) or intramuscular (IM) options for Parkinson's disease medications?

IV and IM Options for Parkinson's Disease Medications

The only FDA-approved parenteral option for Parkinson's disease is subcutaneous apomorphine, available as intermittent injections or continuous infusion; there are no IV or IM formulations of standard Parkinson's medications. 1

Available Parenteral Formulation

Apomorphine (Subcutaneous Only)

• Apomorphine is administered subcutaneously, NOT intramuscularly or intravenously 1
• Available as ONAPGO for continuous subcutaneous infusion using a pump system 1
• Also available as intermittent subcutaneous injections for acute "off" episodes 2
• Requires premedication with trimethobenzamide 300 mg three times daily starting 3 days before initiation due to high incidence of nausea and vomiting 1
• Contraindicated with 5-HT3 antagonists (ondansetron, granisetron, dolasetron, palonosetron) due to reports of profound hypotension and loss of consciousness 1

ONAPGO Dosing Specifications

• Initial continuous dosage: 1 mg/hr subcutaneously 1
• Titrate in 0.5-1 mg/hr increments as needed 1
• Maximum continuous dosage: 6 mg/hr over waking hours (typically 16 hours) 1
• Extra doses of 0.5-2 mg may be administered up to 3 times daily with at least 3 hours between doses 1
• Maximum total daily dose: 98 mg per day 1

Why No IV or IM Options Exist

Levodopa Formulations

• Standard levodopa/carbidopa is only available orally 3, 4
• Extended-release oral formulations and levodopa/carbidopa intestinal gel (duodenal infusion) are available for continuous delivery 4, 5
• Duodenal infusion via percutaneous gastrojejunostomy tube provides continuous levodopa delivery but is still enteral, not parenteral 5

Other Dopaminergic Agents

• Dopamine agonists (pramipexole, ropinirole, rotigotine) are available only as oral or transdermal formulations 2, 4
• MAO-B inhibitors (rasagiline, selegiline) are oral only 2, 4
• COMT inhibitors (entacapone, tolcapone) are oral only 2, 4
• Amantadine is oral only 2, 4

Clinical Implications

When Oral Administration Is Not Possible

• Consider nasogastric or gastrostomy tube administration of crushed immediate-release levodopa/carbidopa 5
• Liquid levodopa formulations can facilitate absorption via feeding tubes 5
• For advanced disease with severe motor fluctuations, levodopa/carbidopa intestinal gel via PEG-J tube provides continuous enteral delivery 4, 5

Emergency Situations

• No parenteral rescue medication exists for acute severe "off" episodes except subcutaneous apomorphine 1, 2
• Patients must be trained on apomorphine use before emergencies occur 1
• In hospitalized patients unable to take oral medications, temporary worsening of parkinsonian symptoms is expected until oral route is restored 3

Important Caveat About Haloperidol

• IV haloperidol carries an FDA non-black box warning due to deaths associated with high doses and IV administration 6
• Intramuscular dosing of antipsychotics is the preferred parenteral route when needed 6
• However, haloperidol and other antipsychotics worsen Parkinson's disease symptoms through dopamine blockade and should be avoided in PD patients 6
• Drug-induced parkinsonism from antipsychotics is a recognized complication 6

Bottom Line for Clinical Practice

If a patient with Parkinson's disease cannot take oral medications, there are no IV or IM alternatives to standard dopaminergic therapies. 3, 4 The only parenteral option is subcutaneous apomorphine, which requires advance planning, patient/caregiver training, and antiemetic premedication. 1 For hospitalized patients, work with pharmacy to establish enteral access (NG tube, G-tube, or PEG-J) as soon as possible to resume oral/enteral levodopa therapy. 5