Oftentimes there are numerous agents within a class of medication. Ropinirole (Requip) and pramipexole (Mirapex) is an example of this. When comparing ropinirole and pramipexole, there are clinical differences that might alter which one you choose.
Comparing Ropinirole and Pramipexole Pharmacokinetics
The most obvious difference when comparing ropinirole and pramipexole involves pharmacokinetic differences. The two biggest differences involve how the drug’s activity is stopped by the body.
Renal Elimination – Pramipexole
Pramipexole is primarily eliminated from the body by the kidney. Because of this fact, the accumulation of active drug is possible in patients who have poor renal function. Dose adjustments may be required in this setting. Clinical monitoring for adverse effects would be important in patients with worsening kidney function.
On the flipside, ropinirole is significantly deactivated by the CYP enzyme system. Because renal elimination does not play as big of a role in breakdown compared to pramipexole, ropinirole is less susceptible to concentration changes due to worsening kidney function.
Drug Interactions – CYP1A2
While it is an advantage in some ways to avoid renal elimination as the primary way the drug’s activity is stopped, it can be a disadvantage as well. Ropinirole is deactivated by CYP1A2. This means that alterations in the activity of CYP1A2 may alter the concentrations of ropinirole.
Ciprofloxacin is one of the more common agents that could inhibit CYP1A2. By inhibiting CYP1A2, the concentration of ropinirole could rise and cause toxicity. Pramipexole would avoid this potential interaction.
When comparing ropinirole and pramipexole, the pharmacokinetic parameters like renal function and liver metabolism may alter which agent you select and which dose you might use.
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