New Once-a-Week Shot Promises Life-Changing Relief for Parkinson’s Patients

A once-a-week shot from Australian scientists could spare people with Parkinson's the grind of taking pills several times a day.

The tiny, biodegradable gel sits under the skin and releases steady doses of two key medicines all week long, aiming for steadier symptom control, fewer side effects, and a much simpler routine. Early lab tests look safe and effective, and the team hopes to move into human trials soon.

Weekly Injectable Breakthrough for Parkinson's

A once-a-week injection could greatly ease life for the more than eight million people who live with Parkinson's disease by replacing the daily routine of swallowing multiple pills.

Researchers at the University of South Australia (UniSA) have designed a long-acting shot that supplies a steady, seven-day dose of levodopa and carbidopa, the two main medicines used to control Parkinson's symptoms.

Details of their work appear in the journal Drug Delivery and Translational Research.

Biodegradable Delivery System Cuts Pill Burden

The formulation, made from biodegradable materials, is injected just under the skin or into muscle. It then releases the medication gradually for an entire week.

Parkinson's disease is the world's second most common neurological condition, affecting more than 8.5 million people. Although no cure exists, tremors, stiffness, and slowed movement can be managed with oral drugs that often have to be taken several times a day.

This frequent dosing can be hard on patients, especially older adults or anyone who has trouble swallowing tablets. Irregular timing of doses causes uneven drug levels, extra side effects, and less dependable relief.

Researchers Highlight Life-Changing Potential

Lead researcher Professor Sanjay Garg, from UniSA's Centre for Pharmaceutical Innovation, says the newly developed injectable could significantly improve treatment outcomes and patient adherence.

"Our goal was to create a formulation that simplifies treatment, improves patient compliance, and maintains consistent therapeutic levels of medication. This weekly injection could be a game-changer for Parkinson's care," Prof Garg says.

"Levodopa is the gold-standard therapy for Parkinson's, but its short life span means it must be taken several times a day."

Steady Week-Long Release via Smart Polymer Gel

UniSA PhD student Deepa Nakmode says the in-situ implant is designed to release both levodopa and carbidopa steadily over one week, maintaining consistent plasma levels and reducing the risks associated with fluctuating drug concentrations.

"After years of focused research, it's incredibly rewarding to see our innovation in long-acting injectables for Parkinson's disease reach this stage. Our invention has now been filed for an Australian patent," Nakmode says.

The injectable gel combines an FDA-approved biodegradable polymer, PLGA, with Eudragit L-100, a pH-sensitive polymer, to achieve a controlled and sustained drug release.

Lab Results Show High Release and Safety

Extensive lab tests confirmed the system's effectiveness and safety:

• More than 90% of the levodopa dose and more than 81% of the carbidopa dose were released over seven days.
• The implant degraded by over 80% within a week and showed no significant toxicity in cell viability tests.
• The formulation can be easily administered through a fine 22-gauge needle, minimizing discomfort and eliminating the need for surgical implant.

Broader Impact and Path Toward Clinical Trials

"The implications of this research are profound," Prof Garg says. "By reducing the frequency of dosing from multiple times a day to a weekly injection is a major step forward in Parkinson's therapy. We're not just improving how the drug is delivered; we're improving patients' lives."

Prof Garg says the technology could also be adapted for other chronic conditions such as cancer, diabetes, neurodegenerative disorders, pain management, and chronic infections that require long-term drug delivery.

The system can be tuned to release drugs over a period ranging from a few days to several weeks depending on therapeutic needs.

UniSA scientists hope to start clinical trials in the near future and are exploring commercialization opportunities.

Reference: "Development of an in-situ forming implant system for levodopa and carbidopa for the treatment of parkinson's disease" by Deepa D. Nakmode, Sadikalmahdi Abdella, Yunmei Song and Sanjay Garg, 7 June 2025, Drug Delivery and Translational Research.
DOI: 10.1007/s13346-025-01892-y