What is the equivalent dose of long-acting ropinirole (dopamine agonist) for a patient taking 1mg of short-acting ropinirole (dopamine agonist)?

Equivalent Dosing of Long-Acting Ropinirole

For a patient taking 1mg of short-acting ropinirole, the equivalent dose of long-acting ropinirole is 1mg. The conversion from short-acting to long-acting ropinirole is a 1:1 ratio 1.

Conversion Process

When switching from immediate-release (short-acting) ropinirole to prolonged-release (long-acting) ropinirole:

• Use a 1:1 dose conversion ratio
• The switch can be done overnight
• Patients can take their last dose of immediate-release ropinirole in the evening and start the prolonged-release formulation the next morning

The pharmacokinetic studies of ropinirole prolonged-release formulation demonstrate that it provides continuous delivery of ropinirole over 24 hours with a smooth plasma concentration-time profile 1. When comparing the two formulations:

• AUC (area under the curve) over 24 hours is similar
• Minimum concentration (Cmin) values are similar
• Maximum concentration (Cmax) is slightly lower (approximately 12%) for the prolonged-release formulation

Benefits of Long-Acting Formulation

The prolonged-release formulation offers several advantages:

• Once-daily dosing improves medication adherence
• More stable plasma levels throughout the day
• Potentially fewer fluctuations in symptom control
• Faster titration with good tolerability 2

Important Considerations

1. The switch to prolonged-release ropinirole is generally well-tolerated

2. Most common adverse effects during conversion include:

   • Worsening of Parkinson's disease symptoms
   • Dizziness
   • Somnolence
   • Nausea

3. Most adverse effects resolve after dose adjustments 3

Special Situations

For patients on higher doses of pramipexole (another dopamine agonist) converting to ropinirole prolonged-release, a 1:4 conversion ratio has been found to result in the fewest discontinuations and dose adjustments 3. However, this does not apply to the specific question about converting from short-acting to long-acting ropinirole.

Monitoring After Conversion

After switching to long-acting ropinirole:

• Monitor for symptom control
• Watch for adverse effects
• Adjust dose if needed to maintain efficacy or reduce side effects
• Be aware that the full therapeutic effect may take several days to stabilize

Remember that the 1:1 conversion ratio is based on pharmacokinetic studies showing equivalent daily exposure between the immediate-release and prolonged-release formulations 1.